improve handling

Ken Shaffer

Ken Shaffer

Member
Sep 6, 2017
99
2
8
I have noticed considerable push and pull of my coach when semi's and box trucks roll by me. I have read posts or articles in the past that indicate
this may be problems with rear suspension. When truck gets about half way down my side, coach pushes away. After passing by, coach pulls towards
truck. I realize some of this is normal, but I think mine is excessive. My coach is a 73 and I believe I still have the original (smaller) bogie
pins. I see that GM had a recall on this years ago. I assume I can't roll this 46 year old coach in for this recall at my local dealer.

I have replaced knuckles/bearing (Lenzi), KB shocks (front), all tie rod ends and ball joints are good.
I greased bogies and replaced bearings and brakes on the rear. I did not replace the rear shocks yet.

Does anyone have a suggestion on upgrading my rear suspension or helping this cause?
--
Ken Shaffer
Marion Iowa
73 Canyon Lands, 455, Manny Tranny, Custom interior
 
> I have noticed considerable push and pull of my coach when semi's and box trucks roll by me.

same on my 26' - a trip to Ken Frey and a full alignment by him on my
coach fixed it.

--
Best regards

Peer Oliver Schmidt
PGP KeyID: 0x4196BF22
'76a 26' Eleganza II - Virginia, US
'73 23' Sequoia - Schleswig-Holstein, Germany
 
I should also add that I replaced the intermediate shaft with Alex Ferrera's and steering gear is centered.
the coach runs very straight on a good road and no wind. Add wind and some truck traffic and it starts to become work.

--
Ken Shaffer
Marion Iowa
73 Canyon Lands, 455, Manny Tranny, Custom interior
 
No, GM did not have a recall on this. However they did put out a service bulletin on changing the spindles to the larger size. 75-TM4 and 75A-TM4.

A service bulletin is NOT a recall.

They have a recall in 1974 for the rear wheel bearings but I you haven’t had failures with the rear bearings they must haver been replaced.

Emery Stora
77 Kingsley
Frederick, CO

>
> I have noticed considerable push and pull of my coach when semi's and box trucks roll by me. I have read posts or articles in the past that indicate
> this may be problems with rear suspension. When truck gets about half way down my side, coach pushes away. After passing by, coach pulls towards
> truck. I realize some of this is normal, but I think mine is excessive. My coach is a 73 and I believe I still have the original (smaller) bogie
> pins. I see that GM had a recall on this years ago. I assume I can't roll this 46 year old coach in for this recall at my local dealer.
>
> I have replaced knuckles/bearing (Lenzi), KB shocks (front), all tie rod ends and ball joints are good.
> I greased bogies and replaced bearings and brakes on the rear. I did not replace the rear shocks yet.
>
> Does anyone have a suggestion on upgrading my rear suspension or helping this cause?
> --
> Ken Shaffer
> Marion Iowa
> 73 Canyon Lands, 455, Manny Tranny, Custom interior
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
Ken,

What you're experiencing is normal to an extent, but if it is excessive, I guess it is NOT normal. It might b due to play in the bogie pins. With
the wheels jacked up and the pressure off the air bags, there should be little, if any, lateral movement in the arms. If they move in and out, it
might be time to do a bogie pin job on the rear suspension.

I have the Chuck Aulgur Reaction arm system on my rear brakes, and the sway bars that are part of that kit are attached to the torque boxes,
effectively preventing, or at least limiting lateral movement of the control arms. The 'True Track' or 'Sure Track' system will do the same thing and
would probably help.
--
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
 
Ken,

If you haven't done so, find a large parking lot and make a long sharp
turn, preferably to the left and stop while still in the turn. Get out and
look at your rear wheels. You'll be shocked to see their attitudes -- they
will no longer be in line but will be following the curve -- drastically.
The flexibility of the rear suspension arms you'll see in that experiment
also occurs as you go down the road: turbulence from passing vehicles,
road ruts, and any other disturbance will cause them to flex and affect
your steering. To me, one of the most dramatic incidents is when a rear
wheel inadvertently drops off the shoulder of the pavement -- getting those
rear wheels back on the road can be a real challenge, because they'll tend
to follow the dropoff rather than the rest of the coach.

Loose suspension pins will aggravate the flexibility problem, but True
Tracks (large roller bearings attached to the ends of the suspension arms,
running in vertical tracks on the side of the frame) will essentially
eliminate that lateral movement of the wheels, forcing them to only move in
coordination with the coach. In my experience, those are only need on the
center wheels, since the rear (trailing) wheels "follow the crowd" anyway.
The ultimate correction is a reaction arm system with included track
control. The Aulgur system provides some of that control as a side effect
of its trailing arm design. Manny's system (and IIRC, Pryor's) include
True Track style explicit vertical control.

Those mods won't eliminate ALL lateral motions -- even ride height, weight
distribution, roof loads, and tire pressures influence them -- but they'll
sure help a LOT.

Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI & EBL,
Manny Brakes & 1-Ton, Troy-Bilt APU, etc., etc., etc.
www.gmcwipersetc.com

On Wed, Jul 17, 2019 at 12:33 PM Ken Shaffer via Gmclist <

> I have noticed considerable push and pull of my coach when semi's and box
> trucks roll by me. I have read posts or articles in the past that indicate
> this may be problems with rear suspension. When truck gets about half way
> down my side, coach pushes away. After passing by, coach pulls towards
> truck. I realize some of this is normal, but I think mine is excessive.
> My coach is a 73 and I believe I still have the original (smaller) bogie
> pins. I see that GM had a recall on this years ago. I assume I can't
> roll this 46 year old coach in for this recall at my local dealer.
>
> I have replaced knuckles/bearing (Lenzi), KB shocks (front), all tie rod
> ends and ball joints are good.
> I greased bogies and replaced bearings and brakes on the rear. I did not
> replace the rear shocks yet.
>
> Does anyone have a suggestion on upgrading my rear suspension or helping
> this cause?
> --
> Ken Shaffer
> Marion Iowa
> 73 Canyon Lands, 455, Manny Tranny, Custom interior
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
We had the truck wake problem on our 78 until we added the Quad air bag tot eh rear suspension.

Previous to doing that the entire suspension and steering was rebuilt
We had no rut wander and on a road in good condition you could steer
with two fingers, however when trucks or busses passed us it would move us around a lot.

Once we installed the Quad air bag rear suspension that almost completely went away.
You still felt some push and pull but very little.

--
Tom Lins
St Augustine, FL
77 GM Rear Twin, Dry Bath, 455, FI-Tech EFI
Manuals on DVD
http://www.bdub.net/tomlins/
 
http://www.appliedgmc.com/level.itml/icOid/478

On Wed, Jul 17, 2019 at 12:23 PM Tom Lins via Gmclist <

> We had the truck wake problem on our 78 until we added the Quad air bag
> tot eh rear suspension.
>
> Previous to doing that the entire suspension and steering was rebuilt
> We had no rut wander and on a road in good condition you could steer
> with two fingers, however when trucks or busses passed us it would move us
> around a lot.
>
> Once we installed the Quad air bag rear suspension that almost completely
> went away.
> You still felt some push and pull but very little.
>
>
> --
> Tom Lins
> St Augustine, FL
> 77 GM Rear Twin, Dry Bath, 455, FI-Tech EFI
> Manuals on DVD
> http://www.bdub.net/tomlins/
>
> _______________________________________________
> 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
 
Ken,
I'm thinking rear tire pressure or tires may have something to do with it.
I've heard some people say running lower pressure on the middle set than the
rear helps their coach track straight.

Also, ride height, if you try lowering the rear it might be more stable.

Just some ideas, which may or may not affect your situation.

--
Bill Wevers GMC49ers, GMC Western States
1975 Glenbrook - Manny Powerdrive, OneTon
455 F Block, G heads
San Jose
 
Bill is very correct, since 1980, every seminar addressing the stability of
the coach mentioned how important to keep the rear height at what the
factory specified.
It is not only one thing, but few things that contribute to the handling
issue.

On Wed, Jul 17, 2019 at 12:42 PM Bill Wevers via Gmclist <

> Ken,
> I'm thinking rear tire pressure or tires may have something to do with it.
> I've heard some people say running lower pressure on the middle set than
> the
> rear helps their coach track straight.
>
> Also, ride height, if you try lowering the rear it might be more stable.
>
> Just some ideas, which may or may not affect your situation.
>
> --
> Bill Wevers GMC49ers, GMC Western States
> 1975 Glenbrook - Manny Powerdrive, OneTon
> 455 F Block, G heads
> San Jose
>
> _______________________________________________
> 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
 
Lowering the rear the proper amount compared to the front increases the caster which improves the characteristic for the coach to travel in a straight line with less weaving from crosswinds.

Conversely, raising the rear makes handling/steering "quicker" and with less effort in city traffic.

D C "Mac" Macdonald​
Amateur Radio K2GKK​
Since 30 November '53​
USAF and FAA, Retired​
Member GMCMI & Classics​
Oklahoma City, OK​
"The Money Pit"​
TZE166V101966

________________________________
From: Gmclist on behalf of Jim Kanomata via Gmclist
Sent: Wednesday, July 17, 2019 16:27
To: gmclist
Cc: Jim Kanomata
Subject: Re: [GMCnet] improve handling

Bill is very correct, since 1980, every seminar addressing the stability of
the coach mentioned how important to keep the rear height at what the
factory specified.
It is not only one thing, but few things that contribute to the handling
issue.

On Wed, Jul 17, 2019 at 12:42 PM Bill Wevers via Gmclist <

> Ken,
> I'm thinking rear tire pressure or tires may have something to do with it.
> I've heard some people say running lower pressure on the middle set than
> the
> rear helps their coach track straight.
>
> Also, ride height, if you try lowering the rear it might be more stable.
>
> Just some ideas, which may or may not affect your situation.
>
> --
> Bill Wevers GMC49ers, GMC Western States
> 1975 Glenbrook - Manny Powerdrive, OneTon
> 455 F Block, G heads
> San Jose
>
> _______________________________________________
> 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
 
The sure track appears as a nice addition! I, too, have excessive with road
crowns. I wonder if they would help. For the price, they couldnt hurt!

On Wed, Jul 17, 2019, 5:35 PM D C _Mac_ Macdonald via Gmclist <

> Lowering the rear the proper amount compared to the front increases the
> caster which improves the characteristic for the coach to travel in a
> straight line with less weaving from crosswinds.
>
> Conversely, raising the rear makes handling/steering "quicker" and with
> less effort in city traffic.
>
> D C "Mac" Macdonald​
> Amateur Radio K2GKK​
> Since 30 November '53​
> USAF and FAA, Retired​
> Member GMCMI & Classics​
> Oklahoma City, OK​
> "The Money Pit"​
> TZE166V101966
>
> ________________________________
> From: Gmclist on behalf of Jim Kanomata
> via Gmclist
> Sent: Wednesday, July 17, 2019 16:27
> To: gmclist
> Cc: Jim Kanomata
> Subject: Re: [GMCnet] improve handling
>
> Bill is very correct, since 1980, every seminar addressing the stability of
> the coach mentioned how important to keep the rear height at what the
> factory specified.
> It is not only one thing, but few things that contribute to the handling
> issue.
>
> On Wed, Jul 17, 2019 at 12:42 PM Bill Wevers via Gmclist <

>
> > Ken,
> > I'm thinking rear tire pressure or tires may have something to do with
> it.
> > I've heard some people say running lower pressure on the middle set than
> > the
> > rear helps their coach track straight.
> >
> > Also, ride height, if you try lowering the rear it might be more stable.
> >
> > Just some ideas, which may or may not affect your situation.
> >
> > --
> > Bill Wevers GMC49ers, GMC Western States
> > 1975 Glenbrook - Manny Powerdrive, OneTon
> > 455 F Block, G heads
> > San Jose
> >
> > _______________________________________________
> > 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
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
The Michelin LTX I had were great tires but had open block segments for wet and M&S. I now have Cooper HT3 and the center sections ard similar to the
LTX but the outer ribs are continuous not segmented. The seem to be more stabile with truck push as I feel there is less tread squirm. I run 65 fronts
and about 63 rears and as much caster as I could get stock bushings about 4 deg.
--
John Lebetski
Woodstock, IL
77 Eleganza II
 
I also have Cooper HT3 tires. If bogie pins are loose, can the bogies with smaller 73 pins be machined to accept the larger newer style pins that
would allow the bogie pin greasers. Or would my options be replace with original style pins and try to keep greased OR try to find a newer complete
rear suspension and rebuild that?
I have not been able to get my coach back into my shop to examine the rear suspension to see if anything is loose. After a two week vacation to west
coast, work is getting in the way of my hobbies!

--
Ken Shaffer
Marion Iowa
73 Canyon Lands, 455, Manny Tranny, Alum radiator, Alcoa wheels, Lenzi hubs/bearings, Howell EFI/EBL, Rostra Cruise, Custom interior
 
My beloved PO installed additional swaybars on the bogies, and I put on a set of True Track bogie devices, and I think my coach handles about as well
as any RV out there. Really, the limitation on cornering speed is when the overhead cabinets start to spontaneously empty.

The True Track devices made a BIG difference in the way my coach handles truck ruts or dropping a rear wheel of the edge of the road. Before, it was
"interesting", now both are pretty much non-events.
--
Mark Hickey
Mesa, AZ
1978 Royale Center Kitchen
 
Since we sell everything, we get lot of feedback.
Like anything, each coach differs.in the way theexisting parts are worn.
The Late Bobby Moore of KY I learned to respect as his understandings or
mechanicals ran paralell to mine and basic engineering .
He hounded me to start making the 2" front spacers.
He ran his over 120,000 miles w//o greasing the bearing. I asked him what
he was doing differently and he told me some new and things I already knew.
First is the Knuckles must be tight, to where one need to press it on the
bearings.Also the clearance on the bearing. Majority of people have no clue
as to how strong that bearing set is.
Setting the load out 2" will cause a positive and negative load at top and
bottom of each. A very basic Static 101 freshman Engineering course.
Yes, it will add little more load, but not enough to overload it,
Reason why people that install the 2" are having problems is the loose
knuckles and tie rods.
If the tires are toed in or out a little much the tires are skidding and
when one applies power, no traction and they blame the spacer, not the
origional defects.

On Thu, Jul 18, 2019 at 9:55 AM Mark via Gmclist
wrote:

> My beloved PO installed additional swaybars on the bogies, and I put on a
> set of True Track bogie devices, and I think my coach handles about as well
> as any RV out there. Really, the limitation on cornering speed is when
> the overhead cabinets start to spontaneously empty.
>
> The True Track devices made a BIG difference in the way my coach handles
> truck ruts or dropping a rear wheel of the edge of the road. Before, it was
> "interesting", now both are pretty much non-events.
> --
> Mark Hickey
> Mesa, AZ
> 1978 Royale Center Kitchen
>
> _______________________________________________
> 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
 
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