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Poor brake performance.

I have 89GV with drum brakes in the front. This RV is fairly new to me. I have many miles in diesel pushers and have owned a previous FT This RV has poor stopping performance in my opinion It also chatters in the front brakes when I back up sometimes. I have good air pressure, slack adj are set good. The air chambers have correct amount of movement. Is there anything I am missing or is this just the way this GV operates.

Re: Poor brake performance.

Reply #1 –
A GV would be no different than other coaches and trucks. Chattering is not normal, you could have oil on the drums from a leaking seal, check your backing plate for residue. If it is not the brakes causing it is possible front end parts could be causing it.
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: Poor brake performance.

Reply #2 –
Quote from: MichaelKranz –
I have 89GV with drum brakes in the front. This RV is fairly new to me. I have many miles in diesel pushers and have owned a previous FT This RV has poor stopping performance in my opinion It also chatters in the front brakes when I back up sometimes. I have good air pressure, slack adj are set good. The air chambers have correct amount of movement. Is there anything I am missing or is this just the way this GV operates.

I just went through this with our toad.  When I went through the brakes I re-used the old shoes because they looked new.  All the hydraulics are new yet I had a soft pedal.  When backing up I would hear and feel a grumble or a clunk.  Until the day I stepped on the brakes and thing got really noisy before the brake pedal headed for the floor.

One of my 40 year old linings separated from the brake shoe, and upon disassembly the other lining came off the shoe.  On one other shoe the lining didn't need much to be removed from the shoe itself.

On our '92 U225 I performed an impromptu brake test in Atlanta on a down hill off ramp that was shorter than I expected.
We needed to clean up the flat surfaces anyway.
1992 Foretravel Grand Villa
U225 SBID Build No. 4134
1986 Rockwood Driftwood
1968 S.I.A.T.A. Spring
1962 Studebaker Lark
1986 Honda VF700C
1983 Honda VF750C
Charlie, the Dog was broken out of jail 24 Oct 2023
N1RPN
AA1OH (H)e who must be obeyed.

Re: Poor brake performance.

Reply #3 –
Oshkosh/Foretravel installed a Lq4 valve in the dash.  Because of the drum brakes squealing in reverse.  Big shoe. Little shoe syndrome.  Part of the natural beauty of the vehicle.

Unless you wanted to bypass that brass colored valve in the dash so that the front shoes also work at moderate braking pressures.  More chatter in reverse.

Beavers on Gillig chassis had no such valve.  Loud chattering in reverse.

Several truck fleet owners bypassed the valve with much better braking being the result.

If you get on the brakes hard the fronts work.
"Riding and rejoicing"
Bob
1997 U320 40' Mid entry, build 5132,  wtbi ce27, 4th owner
2007 Solara convertible
2 prodeco tech outlaw ss electric bikes

1095 watts solar
08 Ls 460 and a sc430
2000 Ford F-250 superduty 4x4

Re: Poor brake performance.

Reply #4 –
Our coach is an '89 GV/Oshkosh Truck chassis, but disc brakes all around.
Strange yours is different
Nitehawk,  Demolition Lady, & our NEW master, Zippy the speeding BB cat.
1989 Grand Villa 36' ORED
Oshkosh chassis, 8.2 DD V8
2006 Saturn Vue AWD

Re: Poor brake performance.

Reply #5 –
The Oshkosh V917 has s cam drum brakes.  26,000 GVW.  Yours is 22,500.

V917 has air brakes,  yours are juice brakes(hydraulic)
"Riding and rejoicing"
Bob
1997 U320 40' Mid entry, build 5132,  wtbi ce27, 4th owner
2007 Solara convertible
2 prodeco tech outlaw ss electric bikes

1095 watts solar
08 Ls 460 and a sc430
2000 Ford F-250 superduty 4x4

Re: Poor brake performance.

Reply #6 –
 I have the same bus .87.88. 89 ish . Oshkosh 917. Drums .
 If you want a  hit list ;  Check the front hubs. If oil is missing, it oils up the shoes a little. De-grease and de glaze the shoes and drums. 
 
The rears are wedge activated . These need the adjusters to work and also degreased and de glazed .  The book says that you can adjust them from the back with the drums on . I could not . I adjusted them as tight  as I could  and  still get the drums back on .
 Fill the outer hubs with oil when replacing  the drums/hubs.

 I could not find any under dash  restrictor for the brakes. The only  large fitting is the horn pressure tap . If your bus has some sort of restrictor , it is near the pedal, IMHO. 

 Last; The D2 governor might be original . The newer D2 run at higher pressures. My new one runs at 130/105 ish. This made the
biggest improvement in the brakes.    I changed my air dryer at the same time .
  Now my brakes are adequate.  Not great , predictable .

Re: Poor brake performance.

Reply #7 –
Mike if you ride the brakes from speed several times quickly then jump out and check the wheels are all four hot? Or just the rears?  If they are all hot with long light braking someone removed the valve.  Brass part under dash with copper lines going to it

Here is the link.
https://www.anythingtruck.com/product/061-289144X.html

"Riding and rejoicing"
Bob
1997 U320 40' Mid entry, build 5132,  wtbi ce27, 4th owner
2007 Solara convertible
2 prodeco tech outlaw ss electric bikes

1095 watts solar
08 Ls 460 and a sc430
2000 Ford F-250 superduty 4x4

Re: Poor brake performance.

Reply #8 –
If you are greasing the brake zirks it could be over greasing. The lube grease will fall onto the brake shoes. It happened on my '87. I was not aware of it until I had the brakes worked on and the shop showed me.
1994 U280, Build 4490
Deming, NM.

Re: Poor brake performance.

Reply #9 –
Thanks for the link Bob.
 The brake and throttle air lines are bundled from the front to rear with no diversions.
The under dash air lines are for both gauges, with a T for the horns  . No brake lines as far as I can tell under the dash .
  I looked again this morning at the dash and pedals.  If there is a regulator it must be post pedal and at a t for the front lines. 
 I firmly believe that I have the brakes as good as designed. They work OK and clearly stop the fronts moving around at slow speeds trying to land on the parking boards.

Re: Poor brake performance.

Reply #10 –
It's there in the middle of the dash if you lift the lid.  The wheel check for heat was interesting as it had me call Oshkosh to find out why. 

I had my before mentioned truck fleet owner mod his brakes on the wheels by increasing the "can" size and he changed the "pill" in the brake pedal.  All four working with bigger cans and a different pill made a noticeable difference. 
"Riding and rejoicing"
Bob
1997 U320 40' Mid entry, build 5132,  wtbi ce27, 4th owner
2007 Solara convertible
2 prodeco tech outlaw ss electric bikes

1095 watts solar
08 Ls 460 and a sc430
2000 Ford F-250 superduty 4x4

Re: Poor brake performance.

Reply #11 –
Thanks for the info guys. I am going to pull the front drum to inspect the parts
 

Re: Poor brake performance.

Reply #12 –
One thing could be if you are a person who drives smoothly and brakes gently the shoes could be glazed.  Try a few really hard stops from about 30 mph.  Make sure that everything is secure first!  You might get lucky and it will fix it.

Keith

Keith, Joyce & Smokey the Australian Cattle Dog
1995 U320 SE Extreme 40' WTBI Build # 4780, with a Honda CR-V hopefully still following behind.
Motorcade # 17030
FMCA # F422159