Trip Report (in segments).

[scott nutter1]

First of all, this is our first trip with all systems at 100%!!
It has been 4 years of sweat, research, phone calls, and money. But she is worth it!!

1st leg, Houston to New Orleans.

The Paterson 455 with the MSD EFI is purring like a kitten. Zero issues, but with all the drag from the AC's, roof pod, and towing a Tracker my MPG is
right at 7 MPG. But I'm good with that because she likes doing the speed limit plus about 5 MPH on top of that at times. The 80mm brakes are working
fine, especially with being as heavy as we are. But I do see Dave Lenzi's mid wheel disc brake setup in the future.

The biggest improvement I've noticed on this leg is the drivability after putting on new ride height sensors that actually work! It really is driving
with a couple of fingers with crosswinds and passing semi's to boot. It's a whole new experience! I actually think a person could drive this while
drinking a martini and smoking a cigar (maybe more on that on the 2nd leg update!). But I also see the Keith V Microlevel system in the future.

It was amazing how much les fatigued I was after the 400 mile drive to New Orleans. Another first for me... I know I will have some issues in the
years, or months ahead, but I'm a believer in "if you treat the coach right, she will treat you right".

I would like to thank everyone who has helped out to get her to 100%, and the forum members with their informative posts.
This truly is our funnest trip to date!!
Next leg, New Orleans to Gulf shores state campgrounds!!

Scott Nutter.

--
Scott Nutter
1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21 final drive, Quad bags, tankless water heater, everything Lenzi. Alex Ferrera
installed MSD Atomic EFI
Houston, Texas

 

[powwerjon]

Scott,

If your running across I-10 running 70 to 75 MPH and running heavy then your doing extremely good on fuel milage. I typically run at 64-65 MPH on the interstates as I get the best milage which with our coach is 7+MPG. Does your cruise control work? That takes a lot of fatigue out of driving too.

J.R. Wright
GMC Great Laker MHC
GMCGL Tech Editor
GMC Eastern States Charter Member
GMCMI
78 GMC Buskirk 29.5’ Stretch
75 GMC Avion (Under Reconstruction)
Michigan

>
> First of all, this is our first trip with all systems at 100%!!
> It has been 4 years of sweat, research, phone calls, and money. But she is worth it!!
>
> 1st leg, Houston to New Orleans.
>
> The Paterson 455 with the MSD EFI is purring like a kitten. Zero issues, but with all the drag from the AC's, roof pod, and towing a Tracker my MPG is
> right at 7 MPG. But I'm good with that because she likes doing the speed limit plus about 5 MPH on top of that at times. The 80mm brakes are working
> fine, especially with being as heavy as we are. But I do see Dave Lenzi's mid wheel disc brake setup in the future.
>
> The biggest improvement I've noticed on this leg is the drivability after putting on new ride height sensors that actually work! It really is driving
> with a couple of fingers with crosswinds and passing semi's to boot. It's a whole new experience! I actually think a person could drive this while
> drinking a martini and smoking a cigar (maybe more on that on the 2nd leg update!). But I also see the Keith V Microlevel system in the future.
>
> It was amazing how much les fatigued I was after the 400 mile drive to New Orleans. Another first for me... I know I will have some issues in the
> years, or months ahead, but I'm a believer in "if you treat the coach right, she will treat you right".
>
> I would like to thank everyone who has helped out to get her to 100%, and the forum members with their informative posts.
> This truly is our funnest trip to date!!
> Next leg, New Orleans to Gulf shores state campgrounds!!
>
> Scott Nutter.
>
> --
> Scott Nutter
> 1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21 final drive, Quad bags, tankless water heater, everything Lenzi. Alex Ferrera
> installed MSD Atomic EFI
> Houston, Texas
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

 

[scott nutter1]

Hi John,
I've never liked cruise control, so I disconnected It. Just mental I guess.
But to be fair on the gas mileage, I will have a more accurate tally at the 1,000 mile mark on this trip. I'm guessing it's going to drop to 6 to 6.5
MPG. On this next leg we will be running with the dash AC on.
Scott.
--
Scott Nutter
1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21 final drive, Quad bags, tankless water heater, everything Lenzi. Alex Ferrera
installed MSD Atomic EFI
Houston, Texas

 

[Ken H.]

Scott,

It's always great to hear of a routine GMC trip. I've had many over the
past 21 years, including the 400+ miles to TN last Thursday and the return
yesterday. I don't attempt to compute gas mileage, but since I made that
trip in a rare configuration (without toad), I probably got close to the
fabled 10 mpg, cruising at the speed limits.

What I wanted to suggest to you is that you reconsider your plan on
mid-wheel brakes. With all due respect to Dave Lenzi, the physical fact is
that improving mid-wheel braking can only worsen the very worst feature of
the GMC's suspension system. Unless you include some variant of a
"reaction arm" system, improved center braking WILL worsen the tendency to
slide and flat-spot the rear-most tires. I've tried almost every variation
of mid- and rear-wheel brakes and every one of them, until I installed the
rear Manny Brakes, had that result. To the extent that I was running
4-wheel brakes before the Manny Brakes. Now, I have good, useable, 6-wheel
brakes with no "pole vaulting". I do wish the rear calipers were larger,
but I probably wouldn't really have better braking.

JMHO,

Ken H.

 

[scott nutter1]

Thanks Ken,
Something to think about.
BTW, your wiper system is a vast improvement. Especially the intermittent cycle.
Scott.
--
Scott Nutter
1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21 final drive, Quad bags, tankless water heater, everything Lenzi. Alex Ferrera
installed MSD Atomic EFI
Houston, Texas

 

[emerystora]

Ken
With Lenzi’s system on my mid axle and no brakes on the third axle I have fantastic braking even when pulling a toad and driving in the mountains. Since everyone has said that the rear axle gives very little braking I thought I’d try using no brakes there.

And, of course, I cannot slide or flat spot the rear tires or “pole vault” as I have no brakes on the rear axle.

The brake system was originally designed for a 30 to 40,000 pound two axle truck with duals on the rear axle. At first I was concerned that I might slide the center tires since they were not duals but that has not occurred in over 15,000 miles.

I used the system to replace the TSM 4 rear disk brake system. I thought I had good braking with that but the Lenzi single rear caliper on each side with the 13” disks gives me much, much better braking.

I also save the $1600 to $1800 cost of the reaction arm system as I don’t need one with my setup.

I’ll have my GMC at the Mansfield, Ohio GMCMI convention in October if anyone wants to drive it.

Emery Stora
77 Kingsley
Frederick, CO

>
> Scott,
>
> It's always great to hear of a routine GMC trip. I've had many over the
> past 21 years, including the 400+ miles to TN last Thursday and the return
> yesterday. I don't attempt to compute gas mileage, but since I made that
> trip in a rare configuration (without toad), I probably got close to the
> fabled 10 mpg, cruising at the speed limits.
>
> What I wanted to suggest to you is that you reconsider your plan on
> mid-wheel brakes. With all due respect to Dave Lenzi, the physical fact is
> that improving mid-wheel braking can only worsen the very worst feature of
> the GMC's suspension system. Unless you include some variant of a
> "reaction arm" system, improved center braking WILL worsen the tendency to
> slide and flat-spot the rear-most tires. I've tried almost every variation
> of mid- and rear-wheel brakes and every one of them, until I installed the
> rear Manny Brakes, had that result. To the extent that I was running
> 4-wheel brakes before the Manny Brakes. Now, I have good, useable, 6-wheel
> brakes with no "pole vaulting". I do wish the rear calipers were larger,
> but I probably wouldn't really have better braking.
>
> JMHO,
>
> Ken H.
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

 

[sgltrac]

I’ve had two gmc coaches. Both 77s. One with six disc and one stock
configuration. The stock braked coach had better pedal feel and braking
power/ response. It is likely that the pedal and response on the all disc
system was due to the integration (or lack thereof ) of the modified system
but that does not really change the arguememt. The stock brake system in
proper condition is plenty adequate. I am always towing something and
frequent the cascade mountain range.

My 2c

Sully
Bellevue. Wa

On Mon, May 6, 2019 at 6:10 PM Emery Stora via Gmclist <

> Ken
> With Lenzi’s system on my mid axle and no brakes on the third axle I have
> fantastic braking even when pulling a toad and driving in the mountains.
> Since everyone has said that the rear axle gives very little braking I
> thought I’d try using no brakes there.
>
> And, of course, I cannot slide or flat spot the rear tires or “pole vault”
> as I have no brakes on the rear axle.
>
> The brake system was originally designed for a 30 to 40,000 pound two axle
> truck with duals on the rear axle. At first I was concerned that I might
> slide the center tires since they were not duals but that has not occurred
> in over 15,000 miles.
>
> I used the system to replace the TSM 4 rear disk brake system. I thought I
> had good braking with that but the Lenzi single rear caliper on each side
> with the 13” disks gives me much, much better braking.
>
> I also save the $1600 to $1800 cost of the reaction arm system as I don’t
> need one with my setup.
>
> I’ll have my GMC at the Mansfield, Ohio GMCMI convention in October if
> anyone wants to drive it.
>
> Emery Stora
> 77 Kingsley
> Frederick, CO
>
> > On May 6, 2019, at 5:31 PM, Ken Henderson via Gmclist <

> >
> > Scott,
> >
> > It's always great to hear of a routine GMC trip. I've had many over the
> > past 21 years, including the 400+ miles to TN last Thursday and the
> return
> > yesterday. I don't attempt to compute gas mileage, but since I made that
> > trip in a rare configuration (without toad), I probably got close to the
> > fabled 10 mpg, cruising at the speed limits.
> >
> > What I wanted to suggest to you is that you reconsider your plan on
> > mid-wheel brakes. With all due respect to Dave Lenzi, the physical fact
> is
> > that improving mid-wheel braking can only worsen the very worst feature
> of
> > the GMC's suspension system. Unless you include some variant of a
> > "reaction arm" system, improved center braking WILL worsen the tendency
> to
> > slide and flat-spot the rear-most tires. I've tried almost every
> variation
> > of mid- and rear-wheel brakes and every one of them, until I installed
> the
> > rear Manny Brakes, had that result. To the extent that I was running
> > 4-wheel brakes before the Manny Brakes. Now, I have good, useable,
> 6-wheel
> > brakes with no "pole vaulting". I do wish the rear calipers were larger,
> > but I probably wouldn't really have better braking.
> >
> > JMHO,
> >
> > Ken H.
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

 

[scott nutter1]

I really do appreciate everyone's opinion on the rear brakes.
I'm still giddy because of the ease of driving with a working ride height sensor!
My 1st GMC was a fairly light 77 Palm Beach that I had for about 18 years and never left California with (except for the last ride to Texas).. That
one would stop with no problem, but I was never towing.
My 78 Royale is a heavy beast... and always towing.... the stock brakes are totally inadequate.. 80 mm's upfront are a improvement, but not the
solution..
Pedal feel is very important to me, and I hate the fade of brake shoes.. and I also think the most rear boogie brakes are completely useless. The only
reason I say that is that mine completely lock up when ever there is moisture on the pavement (and that is with minimal pressure on the brake pedal).
Why even use them? Maybe they give me 5% braking at most?
Scott.
--
Scott Nutter
1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21 final drive, Quad bags, tankless water heater, everything Lenzi. Alex Ferrera
installed MSD Atomic EFI
Houston, Texas

 

[Carl Stouffer]

I kind of hate to contribute to this discussion, since everyone has their opinion on what the best brake system is, kind of like oil and air bags, but
I really like my Applied GMC six wheel disc brakes and the Chuck Aulgur reaction arm system:

http://www.gmcmhphotos.com/photos/g5831-disc-brakes-2fchuck-aulgur-reaction-arm-install.html

With the possible exception of the P-30 master cylinder not being a perfect fit for the system, it has been great and has saved my bacon more than
once since I installed it. Before that, I had adequate brakes, but would skid the rear wheels under a panic stop condition. With the reaction arm
system, the coach hunkers down and stops like a sports car.

I also do my share of mountain driving (out here in the West, if you're not going up, you're going down) and I don't need to worry, as much, about
brake fade or overheated drum brakes. As an added bonus, the 'torque boxes' attached to the sway bars act the same as the true track system to keep
the back wheels in line.

Next to the recent engine/transmission replacement, it was the most expensive thing I have done to the coach, but totally worth it. The thing that
sold me on it was the substantial reduction in stopping distance as explained in the following Slide from Chuck:

http://www.gmcmhphotos.com/photos/cad-photos/p34215-swaybar-reaction-arm-combo-10.html
--
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles,
Solar battery charging. GMCSJ and GMCMI member

 

[jim kanomata1]

Were not comparing brake system properly.
TSM disc brakes are what we refer to as Baby caliper system and is no
better than the drum.Al Banscombe can validate what I'm saying as he is an
Engineer that can still crank out numbers and equations.
The Auguer reaction system utilizes the larger calipers and out stop the
drums and the TSM.
I dare anyone to slam on the brake at 60mph and see what happens. One will
go into a skid that will scare you.
Chuck Augler, Rick Flanagan, Nick G, and I spent few days doing tests on
our long parking lot and on two weekends on a closed road, so we know what
can happen.
Frank Condos, a Mechanical Engineer also addressed the design of the
massive intermediate braking as not very desirable.
Bottom line is that if it brakes well at lower speeds does not mean it will
behave at higher speeds, or panic stop.
Please do NOT compare the Chuck Auglur Reaction arm to the Manny unit as
our unit have the larger calipers. Manny system uses the TSM, which is way
smaller.
JUST BE CAREFUL when doing panic stops at higher speeds.

On Mon, May 6, 2019 at 8:33 PM Carl Stouffer via Gmclist <

> I kind of hate to contribute to this discussion, since everyone has their
> opinion on what the best brake system is, kind of like oil and air bags, but
> I really like my Applied GMC six wheel disc brakes and the Chuck Aulgur
> reaction arm system:
>
>
> http://www.gmcmhphotos.com/photos/g5831-disc-brakes-2fchuck-aulgur-reaction-arm-install.html
>
> With the possible exception of the P-30 master cylinder not being a
> perfect fit for the system, it has been great and has saved my bacon more
> than
> once since I installed it. Before that, I had adequate brakes, but would
> skid the rear wheels under a panic stop condition. With the reaction arm
> system, the coach hunkers down and stops like a sports car.
>
> I also do my share of mountain driving (out here in the West, if you're
> not going up, you're going down) and I don't need to worry, as much, about
> brake fade or overheated drum brakes. As an added bonus, the 'torque
> boxes' attached to the sway bars act the same as the true track system to
> keep
> the back wheels in line.
>
> Next to the recent engine/transmission replacement, it was the most
> expensive thing I have done to the coach, but totally worth it. The thing
> that
> sold me on it was the substantial reduction in stopping distance as
> explained in the following Slide from Chuck:
>
>
> http://www.gmcmhphotos.com/photos/cad-photos/p34215-swaybar-reaction-arm-combo-10.html
> --
> Carl Stouffer
> '75 ex Palm Beach
> Tucson, AZ.
> Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive,
> Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American
> Eagles,
> Solar battery charging. GMCSJ and GMCMI member
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--
Jim Kanomata
Applied/GMC, Newark,CA
jimk
http://www.appliedgmc.com
1-800-752-7502

 

[jerry work]

That was our experience, too, Todd. We had the Manny six wheel disk with o=
ne ton front end under the 78 Royale and bone stock suspension and brakes u=
nder the 77/94 Clasco. Both worked equally as well under all the condition=
s we encountered except the six wheel disk set up had no functioning parkin=
g brake. Both had aluminum 16=E2=80=9D wheels (Alcoa on the Royale and Wel=
d on the Clasco) and both had the same tires. Both were at proper ride hei=
ght all the time and aligned the same. Both were one hand on the wheel dri=
vers and we put around 10K miles a year on each. Knowing what I know now I=
would keep the stock brakes, have them rebuilt by a really good brake spec=
ialist and have one of our quality vendors add grease fittings to the front=
wheel bearings with re-machined hubs and knuckles. The jury is still out =
for me as far as the rear suspension is concerned. Both of ours retained t=
he stock one air bag per side set up with a wireless air pressure controlle=
r. I probably would now add the quad bag set up just for the limp out of d=
anger facility in the event one wheel or bearing went south. Jerry J=
erry Work The Dovetail Joint Fine furniture designed and hand crafted i=
n the 1907 former Masonic Temple building in historic Kerby, OR glwor=
k http://jerrywork.com =
Message: 3 Date: Mon, 6 May 2019 18:32:14 -0700=
From: Todd Sullivan To: gmclist =
Subject: Re: [GMCnet] Trip Report (in segments). Message-ID: =09 Content=
-Type: text/plain; charset "UTF-8" I?ve had two gmc coaches. Both 77=
s. One with six disc and one stock configuration. The stock braked coach=
had better pedal feel and braking power/ response. It is likely that the=
pedal and response on the all disc system was due to the integration (or=
lack thereof ) of the modified system but that does not really change th=
e arguememt. The stock brake system in proper condition is plenty adequat=
e. I am always towing something and frequent the cascade mountain range.=
My 2c Sully Bellevue. Wa =

 

[emerystora]

Well, Jim — I am not comparing TSM brakes to the Auguer system or to the Manny system. I am comparing Dave Lenzi’s system to previous systems I have used. I have never used the reaction arm system so I cannot address that. It doesn’t sound like you have ever tested the Lenzi system so you also really cannot compare it to what you have tried. I respect your expertise in a lot of areas but until you road test that specific system you cannot really opine on it.

When I put on the Lenzi brake kit and left the brakes off the rear axle, I tested the system to determine if I wanted to put the rear brakes back onto the rearmost axle, which I could easily do. One of my tests was to do panic stops, not at 60 mph but first at 35 mph, then at 50 mph and then at 65 mph. I DID NOT ”go into a skid that scared me” but rather had a very controlled stop. It did shove my torso forward but I had expected it to do so. I had been concerned with the amount of tread contact with the road on my rear braking tires but that did not prove to be a problem.

I am extremely happy with my setup and don’t expect to make any changes.

I also have an Engineering degree, from the University of Michigan which included Chemical Engineering as well as courses in Mechanical, Electrical and Nuclear Engineering so I can also “crank out numbers and equations” but I feel that can assist in the design of a product but the final product has to be tested to see if it works. I did adequate tests to satisfy me and Lenzi did several months of road tests before making it available to others.

I guess you and I will just have to disagree on the suitability of Lenzi’s system but I am a believer. It was designed to stop a 30,000 + pound truck with one rear axle and it does a super job stopping a 12,000 pound motor home.

Emery Stora
77 Kingsley
Frederick, CO

>
> Were not comparing brake system properly.
> TSM disc brakes are what we refer to as Baby caliper system and is no
> better than the drum.Al Banscombe can validate what I'm saying as he is an
> Engineer that can still crank out numbers and equations.
> The Auguer reaction system utilizes the larger calipers and out stop the
> drums and the TSM.
> I dare anyone to slam on the brake at 60mph and see what happens. One will
> go into a skid that will scare you.
> Chuck Augler, Rick Flanagan, Nick G, and I spent few days doing tests on
> our long parking lot and on two weekends on a closed road, so we know what
> can happen.
> Frank Condos, a Mechanical Engineer also addressed the design of the
> massive intermediate braking as not very desirable.
> Bottom line is that if it brakes well at lower speeds does not mean it will
> behave at higher speeds, or panic stop.
> Please do NOT compare the Chuck Auglur Reaction arm to the Manny unit as
> our unit have the larger calipers. Manny system uses the TSM, which is way
> smaller.
> JUST BE CAREFUL when doing panic stops at higher speeds.
>
>

 

[Ken H.]

It's beyond my understanding how anyone can expect 4 tires to apply more
retarding force to the road than can 6 tires. And that is exactly what the
result is when anyone uses ANY brakes, whether OEM or any other, including
ANY discs, with the original rear suspension system. It's simply
impossible for the rear-most wheels to apply full force to the pavement
when being lifted by the "pole-vaulting" center arms. Only reaction arms
allow the torque about the center wheels to be transferred to the chassis,
and thence to the front wheels, rather than to the center suspension arm
and thence to raising the rear of the coach -- to the extent of unloading
the rear wheels.

Personally I wouldn't for a moment consider again owning a GMC without
reaction arm rear brakes, whether Aulgur, Justico, Manny, Pryor, or some
other. There's simply way to achieve maximum braking force without
eliminating that leading suspension arm's adverse load transfer.

Ken H.

On Mon, May 6, 2019 at 9:10 PM Emery Stora via Gmclist <

> Ken
> With Lenzi’s system on my mid axle and no brakes on the third axle I have
> fantastic braking even when pulling a toad and driving in the mountains.
> Since everyone has said that the rear axle gives very little braking I
> thought I’d try using no brakes there.
>
> And, of course, I cannot slide or flat spot the rear tires or “pole vault”
> as I have no brakes on the rear axle.
>
> The brake system was originally designed for a 30 to 40,000 pound two axle
> truck with duals on the rear axle. At first I was concerned that I might
> slide the center tires since they were not duals but that has not occurred
> in over 15,000 miles.
>
> I used the system to replace the TSM 4 rear disk brake system. I thought I
> had good braking with that but the Lenzi single rear caliper on each side
> with the 13” disks gives me much, much better braking.
>
> I also save the $1600 to $1800 cost of the reaction arm system as I don’t
> need one with my setup.
>
> I’ll have my GMC at the Mansfield, Ohio GMCMI convention in October if
> anyone wants to drive it.
>
> Emery Stora
> 77 Kingsley
> Frederick, CO
>
> > On May 6, 2019, at 5:31 PM, Ken Henderson via Gmclist <

> >
> > Scott,
> >
> > It's always great to hear of a routine GMC trip. I've had many over the
> > past 21 years, including the 400+ miles to TN last Thursday and the
> return
> > yesterday. I don't attempt to compute gas mileage, but since I made that
> > trip in a rare configuration (without toad), I probably got close to the
> > fabled 10 mpg, cruising at the speed limits.
> >
> > What I wanted to suggest to you is that you reconsider your plan on
> > mid-wheel brakes. With all due respect to Dave Lenzi, the physical fact
> is
> > that improving mid-wheel braking can only worsen the very worst feature
> of
> > the GMC's suspension system. Unless you include some variant of a
> > "reaction arm" system, improved center braking WILL worsen the tendency
> to
> > slide and flat-spot the rear-most tires. I've tried almost every
> variation
> > of mid- and rear-wheel brakes and every one of them, until I installed
> the
> > rear Manny Brakes, had that result. To the extent that I was running
> > 4-wheel brakes before the Manny Brakes. Now, I have good, useable,
> 6-wheel
> > brakes with no "pole vaulting". I do wish the rear calipers were larger,
> > but I probably wouldn't really have better braking.
> >
> > JMHO,
> >
> > Ken H.
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

 

[Rdenney]

I suspect the issues of higher pedal effort with the rear disk brakes has
more to do with a large master cylinder than with the brakes at the wheels.
People use the P30 master cylinder to get the larger reservoir, to prevent
any likelihood of running out of fluid as the pads wear. But it also has a
bigger piston.

Bigger brakes don’t reduce pedal effort even when they improve stopping
power. It’s important not to confuse those two attributes, it seems to me.
Adding a couple of inches to the front brakes increases stopping power, and
rear disks add modulation capability. But drums have a servo effect that
reduces pedal effort, and the P30 has a bigger piston and that increases
pedal effort. So, we get better brakes, but with a higher pedal effort.

Seems to me what we need is the stock piston size with a larger reservoir.

I will continue to use the stock master cylinder. It means I have to check
my brake fluid routinely, but then I do that anyway.

I haven’t installed my kit yet (June, probably), but it certainly came with
two parking-brake-equipped calipers, and Karen wrote a whole section on how
to modify the cables to work with them.

http://www.machinesoflovinggrace.net/gmc/brakes/

Rick “who will eventually install a sensitized booster for routine stop
feel” Denney

On Tue, May 7, 2019 at 1:34 PM Gerald Work via Gmclist <

> That was our experience, too, Todd. We had the Manny six wheel disk with
> one ton front end under the 78 Royale and bone stock suspension and brakes
> under the 77/94 Clasco. Both worked equally as well under all the
> conditions we encountered except the six wheel disk set up had no
> functioning parking brake. Both had aluminum 16” wheels (Alcoa on the
> Royale and Weld on the Clasco) and both had the same tires. Both were at
> proper ride height all the time and aligned the same. Both were one hand
> on the wheel drivers and we put around 10K miles a year on each. Knowing
> what I know now I would keep the stock brakes, have them rebuilt by a
> really good brake specialist and have one of our quality vendors add grease
> fittings to the front wheel bearings with re-machined hubs and knuckles.
> The jury is still out for me as far as the rear suspension is concerned.
> Both of ours retained the stock one air bag per side set up with a wireless
> air pressure controller. I probably would now add the quad bag set up just
> for the limp out of danger facility in the event one wheel or bearing went
> south.
>
> Jerry
> Jerry Work
> The Dovetail Joint
> Fine furniture designed and hand crafted in the 1907 former Masonic Temple
> building in historic Kerby, OR
>
> glwork
> http://jerrywork.com
>
> ==================
>
> Message: 3
> Date: Mon, 6 May 2019 18:32:14 -0700
> From: Todd Sullivan
> To: gmclist
> Subject: Re: [GMCnet] Trip Report (in segments).
> Message-ID:
> m9wpozGHZZsByD2A>
> Content-Type: text/plain; charset="UTF-8"
>
> I?ve had two gmc coaches. Both 77s. One with six disc and one stock
> configuration. The stock braked coach had better pedal feel and braking
> power/ response. It is likely that the pedal and response on the all disc
> system was due to the integration (or lack thereof ) of the modified system
> but that does not really change the arguememt. The stock brake system in
> proper condition is plenty adequate. I am always towing something and
> frequent the cascade mountain range.
>
> My 2c
>
> Sully
> Bellevue. Wa
>
> ==================
>
>
>
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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>
--
'73 X-Glacier 230 "Jaws"
Northern Virginia
Offlist email: rick at rickdenney dot com

 

[Rdenney]

Maybe it’s just me, but I cower in fear when words like this are uttered
out loud.

When I bought the GMC, mechanic friends said, “Cool! Buy a good set of
tools.” And, “it’s like your house—something always needs repair.” It’s
true with any RV, no matter what its age.

But we are quiet about these things. The RV gods are capricious and don’t
like to be taunted.

(It’s great to have all systems working as they should, isn’t it?)

Rick “who has had many perfect trips in the last 16 years of GMC ownership,
but never with a perfect coach” Denney

On Mon, May 6, 2019 at 7:29 PM Scott Nutter via Gmclist <

> First of all, this is our first trip with all systems at 100%!!
>

> --
'73 X-Glacier 230 "Jaws"
Northern Virginia
Offlist email: rick at rickdenney dot com

 

[jim kanomata1]

I know we all have discussion, and take this as discussion.
I'm not here to put anyone down, but to point out what I feel I know.
Emory knows I respect him as a person and an Engineer, so as you read our
discussion, do not think for a second we are arguing.
One needs to hear me having discussions with lot of other people on other
issues and they all are my friends.

On Tue, May 7, 2019 at 1:16 PM Richard Denney via Gmclist <

> Maybe it’s just me, but I cower in fear when words like this are uttered
> out loud.
>
> When I bought the GMC, mechanic friends said, “Cool! Buy a good set of
> tools.” And, “it’s like your house—something always needs repair.” It’s
> true with any RV, no matter what its age.
>
> But we are quiet about these things. The RV gods are capricious and don’t
> like to be taunted.
>
> (It’s great to have all systems working as they should, isn’t it?)
>
> Rick “who has had many perfect trips in the last 16 years of GMC ownership,
> but never with a perfect coach” Denney
>
> On Mon, May 6, 2019 at 7:29 PM Scott Nutter via Gmclist <

>
> > First of all, this is our first trip with all systems at 100%!!
> >
>
> > --
> '73 X-Glacier 230 "Jaws"
> Northern Virginia
> Offlist email: rick at rickdenney dot com
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--
Jim Kanomata
Applied/GMC, Newark,CA
jimk
http://www.appliedgmc.com
1-800-752-7502

 

[78 Barbi]

ITEMS TO CONSIDER WHEN UPGRADING TO LARGE MID WHEEL DISCS ON GMC-MH

1/ Frank Condos made the following statement back in Dec. 2000 regarding possible problems one could encounter when using the mid wheel Harrison disc
system.
" The configuration with the large 12.5" discs clearly shifts much of the braking to the rear. Under dry pavement conditions this high percentage of
rear braking may not be a problem. However with wet or icy conditions an emergency stop can cause rear lock up and loss of control with excessive rear
braking (the reason ABS is standard on most pickup trucks)."

2/ One must remember that it's not your rotors, your brake pads or your calipers that ultimately stops your coach , It's your tire patch in contact
with the road surface that stops your coach. For those folk that are relying on 4 discs instead of 6, you are potentially sacrificing 1/3 of your
total braking capacity .

3/ With the design of our forward bogie arm we have not only the standard " pitch forward component " to contend with but also the " pitch forward
component " caused by the " pole vaulting " effect of said forward bogie. Even with 4 OEM rear drums at approx. 950 pounds braking force per wheel ,
it is possible to skid the rear most wheels due to bogie lift. This phenomena has been documentated many times by coach owners, myself included. The
" Reaction Arm " systems eliminated this problem completely and afforded owners maximum braking on all 6 wheels.

4/ With a " pitch forward" component of slightly greater than 50% , one winds up with 6000 pounds plus on the two front wheels , this is where the "
One Ton" front kits shine because they have the capability to address such loads. With that said; this leaves approx . 6000 pounds or slightly less
shared by the 4 rear wheels, But with between 0 and 175 pounds down force on each rearmost wheel , the weight load on the mid wheel set is still
approx. 6000 pounds shared by essentially 2 wheels at maximum braking with an OEM master cylinder at 1,000 PSI.

5/ Depending upon tire composition, temperature , road surface composition and whether the road surface is wet or dry , the friction component between
tire patch and road surface can vary from 0.85 G all the way down to 0.25 G. With the Harrison mid wheel disc system , the braking capability per
wheel at maximum braking of 1,000 PSI on an OEM master cylinder is 2,700 pounds braking force per wheel, assuming the worst case of a full 3,000 pound
load on the mid wheel , 2,700 pounds braking force / 3,000 pounds down force on the wheel , equates to 0.9 G braking force on said wheel. Therefore
even with maximum traction on dry a dry road surface , the Harrison system has the capability of locking the mid wheels in a panic stop situation .
Obviously at a higher master cylinder pressure or a larger rotor or caliper , the risk of lock up would be higher. Therefore the Harrison system
cannot even come close to competing with a reaction arm system when addressing a panic stop on a GMC motorhome , for every day general use the
Harrison system is fine BUT all brake systems are engineered for that ultimate " panic stop " situation . As the old saying goes " Pays your money and
takes your chances" .

Albert Branscombe, 78 Barbi , the 23 foot Birchaven

 

[RJW]

> ITEMS TO CONSIDER WHEN UPGRADING TO LARGE MID WHEEL DISCS ON GMC-MH

What a great discussion on brakes. Too bad I almost missed it because the topic is "Trip Report".
--
Richard
76 Palm Beach
SE Michigan
www.PalmBeachGMC.com


Coop Roller Cam 455, Howell TBI + EBL, 3.42 FD, Quadra Bag, Macerator, Lenzi stuff, Manny Tranny etc.

 

[scott nutter1]

***UPDATE LEG #2****
Not much to add, short leg of 200 miles.
Everything operating perfectly.
New Orleans to Gulf Shores Al. Staying at the state campground. BEAUTIFUL, full hookups, I highly recommend it.
The official drink is the Bushwhacker. I also highly recommend it!!
500 miles burnt 70 gallons, if my math is correct, that's 7mpg.
I learned a lot about rear brakes the last few days!!
Scott.
--
Scott Nutter
1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21 final drive, Quad bags, tankless water heater, everything Lenzi. Alex Ferrera
installed MSD Atomic EFI
Houston, Texas

 

[sandra price]

We have stayed there, too, Scott. It IS a beautiful park. Enjoy!

Sandra and Bob

On Wed, May 8, 2019, 12:13 PM Scott Nutter via Gmclist <

> ***UPDATE LEG #2****
> Not much to add, short leg of 200 miles.
> Everything operating perfectly.
> New Orleans to Gulf Shores Al. Staying at the state campground. BEAUTIFUL,
> full hookups, I highly recommend it.
> The official drink is the Bushwhacker. I also highly recommend it!!
> 500 miles burnt 70 gallons, if my math is correct, that's 7mpg.
> I learned a lot about rear brakes the last few days!!
> Scott.
> --
> Scott Nutter
> 1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21 final
> drive, Quad bags, tankless water heater, everything Lenzi. Alex Ferrera
> installed MSD Atomic EFI
> Houston, Texas
>
> _______________________________________________
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>