HELP... rear brake issues

[Haggar]

DDN,

 

Take a peek.  Lets see what anti-lock you have.  the computer would light the light only if it "thinks" it has a problem.  If it is getting false/bad information, but within the realms of its limits it will think it is OK.   Does your "ABS" light light up properly during key on test?

 

From what I am seeing the RWAL also has a CAB (controller anti-lock brake)...  The picture in my FSM shows a pump too, but that could be wrong.....  

 

Here is a trick, unhook your CAD, drive the truck in 4 wheel drive.  (the TC will turn the front drive shaft, but with the cad disconnected you won't get the hopping and such.  I would avoid parallel parking though..:))  The computers will tell the ABS system to not work.  It will cost a bit of fuel for a day, but this would take the ABS system out of the sequence.

 

The FSM says for rear brake grab or pull (if affects both rears) master cylinder or proportioning valve. 

 

If you have the RWAL only, it looks like it could be an accumulator only system..  If something in the valve or the accumulator has locked up, you get no relief of over pressure to the rear brakes, meaning they work too much.  (no proportioning.)

 

I am sure the 4wABS is similar, but uses a pump to pulse the systems. 

 

We may have to do a brake pressure test at the wheel cylinders.....

 

Hag 

[Buzzinhalfdozen]

If you want to disable the abs just pull the fuse or relay. The brake/abs lights will be on but the speedo will still work. 

From what I can tell all the rear wheel abs does is cut line pressure to the rear brakes if it detects a slip. Trying to stop on ice the front tires will lock up while the rear tires are free wheeling. Now pull the abs fuse and all 4 tires lock up. 

With that said obviously the abs module can control rear braking pressure. I suppose if the module is having problems it could be pulsating rear brake pressure giving you the shuddering.  

Edited May 5, 2016 by Buzzinhalfdozen

[dodgedieselnewbie]

Okay.. like I said.. I'm having drums turned again.. new Napa premium shoes and a flush. If I still have the problem after this I will unhook the ABS. 

I believe it's a 4 wire plug that I did have unplugged but it did nit effect my Speedo.. just had brake light and ABS light come on. If that doesnt work I'm putting in new master cylinder... then new proportion valve. Ugh

Edited May 5, 2016 by dodgedieselnewbie

[Haggar]

DDN,

 

One thing I thought of over coffee, make sure you put the primary (smaller braking surface) shoe forward.  This makes a HUGE difference.  (the self actuating nature of the bendix brakes depend on this to NOT over apply)

 

I would go combination valve before MC.  See the FSM page I have attached.  It tries to control early pressure balance (see metering function).

 

Brake pressure testing is not that expensive (though I want the killer OTC kit at 500 bones...)  It looks like Jegs/summit have kits at the 50 buck mark.  Just check your bleeder screw size to make sure the adapter is in the kit. 

 

Good Luck!

2001 FSM Ram 5-9.pdf

[dodgedieselnewbie]

Yes.. smaller shoes are and have been forward. Thanks a million for every reply. Will report back later... fingers crossed :-)

 

Edit

BTW.. I am still having an issue with my front right brake putting out twice the brake dust over the left.. and does have a slight pull to the right but not all the time. It's nit enough to pull me off the road but does turn the wheel a little.  Is there any correlation between the two issues?

Edited May 5, 2016 by dodgedieselnewbie

[dodgedieselnewbie]

Well.. system was bled and was clean as a whistle. Drums were cut and very little was taken off. New Napa Ultra Premium shoes installed... cha-ching

and............................................... ...........

I don't want to get too excited yet... but... after an hour and twenty minute drive all over Carroll County (man oh man.. lots of cops out there!)... nothing. So far.. so good. Fingers crossed! So.. my thought right now.. is bad/crap shoes. Time will tell...

[Haggar]

I hope that was all it was!!!!

 

Hopefully the rear brake problem is behind you. (pun intended lol)

 

Focus on that front.  The Right Front seems to be very susceptible to the collapsed hose thing, and therefore not relieving the pressure on the caliper.  I have had this failure and 2 Weekends ago one of my venture crew members went through that too... and due to not listening, he ended up with having to install a new rotor, caliper, wheel bearing assembly and drive shaft. (messed up the threads on threads on the drive axle.... those axles are not cheap btw...)

[dodgedieselnewbie]

I hope so too... and beginning to believe so after driving all over kingdom come today.. with not a hint of a problem. I only felt the front pull once today.. I replaced the front hoses a couple of weeks ago. I think it's in one of the calipers. Maybe the driver's side is the one that's not right. If it gets worse.. I'll replace both. 

 

Thanks again!!!