GMC :Picking up 2 New (to me) Transmodes

M

marcus mcgee

New member
Sep 29, 1997
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Well I must be crazy, but I have just purchased and registered two
Transmodes. They are in Weston Ct and we will be driving them back
to Rochester on Sunday.

One has some questionable brakes. When I went to look at them the pedal
was very soft and went almost to the floor. I have a spare Master
Cylinder, spare front calipers, hoses and some brake line. I also have
two spare rear wheel cylinders and shoes. If it is a bad rear cylinder
I thought I may just seal the two rear and use the front discs and two
center drums for the trip back. Any thoughts on what else it could be
and what I should look for?

We will be taking Route 81 to 17 and 84 into Weston and we thought about
taking the NY State Thruway back with the two coaches in case of break
downs. Again any thoughts taking the thruway back instead of Route 17?

Any thoughts on what we should do besides change the oil, check the the
trans fluid, and top off the coolant. We will bring spare hoses, and
belts. One is a 455 the other is a 403 - Are the belts different? I
already have spare belts for a 455.

Any suggestions would be appreciated.

Marcus McGee
 
Marcus,

The belts on the 455 are 2 inches longer than the 403. The block
deck height on the 455 is 1 inch taller which accounts for the longer
belts.

Hold on to that spare master cylinder you have if it's GMC original
equipment. The GMC master cylinder P/N 18008633 has a greater fluid
capacity for the rear brakes than a regular truck unit. It has a
displacement stamp above the front port. This two letter code must
match the code on one you pulled off your coach. If you cap off the
brake system on the rear set of wheels, you will be upsetting the brake
bias towards the rear making them lock up prematurely. I wouldn't do it
from a safety standpoint. Fix the brake system properly before driving
the coach. Having a 14000 pound vehicle swap ends on you in the event
of a panic stop isn't conducive to the safety of other drivers.

Make sure you purge all the old fluid out of the brake hydraulic
system. I use Declean which is available for that purpose from the
dealer. The type of fluid is very important. An excellent high temp
DOT 3 type brake fluid for motorhome use if available from Ford dealers
under part number C6AZ-19542-AB.

This information comes from the December 1996 issue of the GMC
Motorhome News.

- -Scott Woodworth
 
>
> Marcus,
>
> The belts on the 455 are 2 inches longer than the 403. The block
> deck height on the 455 is 1 inch taller which accounts for the longer
> belts.
>
> Hold on to that spare master cylinder you have if it's GMC original
> equipment. The GMC master cylinder P/N 18008633 has a greater fluid
> capacity for the rear brakes than a regular truck unit. It has a
> displacement stamp above the front port. This two letter code must
> match the code on one you pulled off your coach. If you cap off the
> brake system on the rear set of wheels, you will be upsetting the brake
> bias towards the rear making them lock up prematurely. I wouldn't do it
> from a safety standpoint. Fix the brake system properly before driving
> the coach. Having a 14000 pound vehicle swap ends on you in the event
> of a panic stop isn't conducive to the safety of other drivers.
>
> Make sure you purge all the old fluid out of the brake hydraulic
> system. I use Declean which is available for that purpose from the
> dealer. The type of fluid is very important. An excellent high temp
> DOT 3 type brake fluid for motorhome use if available from Ford dealers
> under part number C6AZ-19542-AB.
>
> This information comes from the December 1996 issue of the GMC
> Motorhome News.
>
> -Scott Woodworth

I agree with you, but these are out in the middle of nowhere and we need
to get them back where we can properly do the work. The closest garage
is about 30 miles from the coaches. I do plan to put the coach in as
best
shape as I can with the limited resources at this location. We will not
drive
it if I do not feel confident in the brakes. The brakes were fine up
until the
last use and I hope it is just a rusted line or broken hose.

I will make a note to check the oil line hoses as I also have spares of
those here
in my shop and will bring them.

Thanks
Marcus

PS:

Both Patrick and you are right. Use the heavy gauge wire (yours)and put
a fuse in
line (his). For the $1.98 it can't hurt and its only one for you. But
GM would
cut .10 if it thought it could get away with it.
 
Sounds like air or moisture in the brake system from sitting around.
However I would Check the vacuum to the power brake unit first. Also there
is a good test procedure on page 5-37 of the maintenance manual to test the
power brake unit. If that checks out OK than I would suspect the master
cylinder next and than a leaky wheel cylinder. All easy to fix.

>Well I must be crazy, but I have just purchased and registered two
>Transmodes. They are in Weston Ct and we will be driving them back
>to Rochester on Sunday.
>
>One has some questionable brakes. When I went to look at them the pedal
>was very soft and went almost to the floor. I have a spare Master
>Cylinder, spare front calipers, hoses and some brake line. I also have
>two spare rear wheel cylinders and shoes. If it is a bad rear cylinder
>I thought I may just seal the two rear and use the front discs and two
>center drums for the trip back. Any thoughts on what else it could be
>and what I should look for?
>
>We will be taking Route 81 to 17 and 84 into Weston and we thought about
>taking the NY State Thruway back with the two coaches in case of break
>downs. Again any thoughts taking the thruway back instead of Route 17?
>
>Any thoughts on what we should do besides change the oil, check the the
>trans fluid, and top off the coolant. We will bring spare hoses, and
>belts. One is a 455 the other is a 403 - Are the belts different? I
>already have spare belts for a 455.
>
>Any suggestions would be appreciated.
>
>Marcus McGee
>
>
>
 
> I will make a note to check the oil line hoses as I also have spares
> of those here in my shop and will bring them.

You may run into another problem with the steel oil lines under the
manifold being corroded. In a pinch you can remove the oil cooler
adapter(I think it takes a 1 1/4" deep well socket - but you can turn it
with channel-locks if you're careful) and replace the oil filter without
it(BTDT). Lightly loaded in cool weather it shouldn't be a problem -
just take it easy.

For the brakes - take some compression unions with you. You can use
these with the tubing to make temporary repairs. When my line rusted
through - I could have removed about ten feet of hose in front of the
rear wheels and probably been fine. I just felt better replacing
everything.

If they've been sitting a while, I'd put a quart of Marvel Mystery Oil
in each to help free the rings up. Some people question its worth, but
I've seen marvelous things done with it. My own GMC sat for three
years. I changed the oil and used a quart of MMO and after running for
10 minutes, it sounded like it had just been parked the day before.

Drive carefully!
Patrick
- --
Patrick Flowers
Mailto:patri63

The GMC Motorhome Page
http://www.gmcmotorhome.com
 
>

>
> > I will make a note to check the oil line hoses as I also have spares
> > of those here in my shop and will bring them.
>
> You may run into another problem with the steel oil lines under the
> manifold being corroded. In a pinch you can remove the oil cooler
> adapter(I think it takes a 1 1/4" deep well socket - but you can turn it
> with channel-locks if you're careful) and replace the oil filter without
> it(BTDT). Lightly loaded in cool weather it shouldn't be a problem -
> just take it easy.
>
> For the brakes - take some compression unions with you. You can use
> these with the tubing to make temporary repairs.

Patrick

Thanks for the tip on compression fittings. I assume I can get them at
Hdwr Store or do I have to go to auto supply? Do you know what size
the tubing would be, if not I can measure off my current coach.

I will add the Marvel and may just remove the oil lines before travel
to be on the safe side. If we cruise at 55-60 there are no really bad
grades on the NYS TWY. Also, since the interiors on these are fairly
sparse we do not have the ussual weight. My current Coach is only
9,100 lbs.

Marcus
 
>
> Patrick
>
> Thanks for the tip on compression fittings. I assume I can get them
> at Hdwr Store or do I have to go to auto supply? Do you know what
> size the tubing would be, if not I can measure off my current coach.

Any well stocked hardare or auto supply. I believe the brake line is
1/8in - take a short section with you to be sure. If you use
compression fittings, get them good and tight and stand on the brakes
hard(with the engine running) a couple times before driving to be sure
they'll hold.

> I will add the Marvel and may just remove the oil lines before travel
> to be on the safe side. If we cruise at 55-60 there are no really
> bad grades on the NYS TWY. Also, since the interiors on these are
> fairly sparse we do not have the ussual weight. My current Coach is
> only 9,100 lbs.

Another thing I learned just yesterday from Paul Bartz - the 403 oil
lines are longer than the 455 lines, so your replacements are probably
too short anyway. With the light loading, you should be fine without
the cooler.

Patrick
- --
Patrick Flowers
Mailto:patri63

The GMC Motorhome Page
http://www.gmcmotorhome.com
 
>
> Marcus, you will probably get mixed advice on this question-all of it
(SNIP)

Dave;

I already sent the TZE #s to you early this week.

Marcus
 
I have to really disagree with you guys in the method to replace a bad piece
of brake line. You CANNOT use a simple compression fitting to patch the
line. It has to be DOUBLE flare on the brake line Nothing else is safe to
use. the methods that you are describing are dangerous and almost certainly
will result in a complete failure of the brakelines. you need a spcial
flaring tool to put the double flare on the line so a compression fitting
can be added.

>In a message dated 98-03-27 10:14:54 EST, you write:
>
> Any well stocked hardare or auto supply. I believe the brake line is
> 1/8in - take a short section with you to be sure. If you use
> compression fittings, get them good and tight and stand on the brakes
> hard(with the engine running) a couple times before driving to be sure
> they'll hold. >>
>
>There are two brake line sizes 3/16 to disc and 1/4 to drums.
>
>Take Care
>Arch
>
>
>
 
>
> I have to really disagree with you guys in the method to replace a bad piece
> of brake line. You CANNOT use a simple compression fitting to patch the
> line. It has to be DOUBLE flare on the brake line Nothing else is safe to
> use. the methods that you are describing are dangerous and almost certainly
> will result in a complete failure of the brakelines.

Note - I said TEMPORARY repair. Marcus is just trying to get these
girls home.

Patrick
- --
Patrick Flowers
Mailto:patri63

The GMC Motorhome Page
http://www.gmcmotorhome.com
 
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