2nd Gen Non-Engine/Transmission No brakes in reverse

[JAmos]

My dad has a 95 and he loses his brakes when backing up. What causes this? He doesn't have any trouble stopping when going forwards.



Jordan

 

[SSolderitch]

was anything done recently?

Maybe shoes installed backwards? Most cars run the bigger shoe to the front, etc. I seen a stuck caliper piston after pushing it in for new pads. Does the e brake cable work? rusted cables? Do you have fluid in master cylinder? rusted line will empty it.

 

[JAmos]

He's had the truck for prob the last 5 years and hasn't had anything done to the rear brakes. Near as I know its full of fluid as the brakes work good going forwards. I'll call him and have him do a good visual inspection to try to help diagnose.



Jordan

 

[GAmes]

Just a shot in the dark, but has he looked for any vacuum leaks? I know that the vacuum assist system on the 96 and earlier can be bled down, so that is one place to look.

 

[MCummings]

I've heard of this before, and in the end it was a lack of vacuum. You still have brakes, just no assist.



I don't remember the exact fix, but I do remember it was vacuum related, maybe a vacuum leak, or a check valve leaking.



Merrick

 

[Gene Arnold]

Sorry, I can't help solve the problem but it reminds me of a recurring bad dream I've had in various forms for many years. In the dream I'm coasting downhill backwards and the harder I push on the brakes, the faster I go. The dream is probably a sign of some great psychological disorder that needs to be identified-- or maybe it is because of what I ate the night before??



Gene

 

[moparmikeJ]

I understand that drum brakes are much more effective going forward rather than backward.

That being said, is it possible the fronts aren't working?

 

[JAmos]

I've put a couple sets of pads on the front of it so I think they definately are working. He has one or two stops in reverse before he says it will barely stop-like hooking up a trailer,or backing it up. I'll have him look for vacuum leaks.



Jordan

 

[surfbeetle]

You will need to check the lines going from the vaccuum pump up to the master cylinder brake booster. Also it is possible that your vacuum pump is not working properly. There is a rebuild kit for that from Gould Electric. Do a search in the forum for the kit if you need it.

Good luck.

 

[JAmos]

So if the vacuum pump is weak then it wouldn't make vacuum fast enough so basically providing one or two stops or braking attempts. But going forwards the rpms are up enough to make sufficient vacuum.



Jordan

 

[BSMcCauley]

Curious that the problem is only in reverse. Many replies suspecting a vacuum problem, but wouldn't that also cut the brakes out going forward as well? I second the earlier mention of stuck/frozen pistons in the rear brake slave cylinders. There are a front and rear facing piston in each of them with the front piston extending for forward-motion stops and the rear piston extending for rearward-motion stops. If the rear facing pistons are stuck or frozen, you will get minimal braking effort from the rear brakes. However, this does not explain the front disk brakes, which should work the same either way, although weight transfer issues would tend to just slide the front tires on a hard stop in reverse. I'd break the rear brakes down on both sides and satisfy myself that all was OK there as a starting point.



Problem I've had on my truck in the past is letting the rear brake shoes go too long and get down to metal-on-metal. The resulting metal chips flying around take out the axle grease seal. The brakes don't work at all on the rear when they are slicked down good with gear lube!:-laf