Loss of Breaks when backing...

[Ben Rumson]

I have a '95 with rear wheel ABS.



I constantly lose my breaks while backing when I hit the breaks a few times. Parallell parking is the worst - stop, reverse into the stall, forward a little, then reverse again, then forward a little more, then reverse into final position. Also when backing a trailer into a long narrow drive way if I have to reposition the alignment a few times.



When the breaks go, I can push the pedal all the way to the floor and have to push very hard just to get it to grab any stopping power. It feels like there's no pressure in the pedal. This is especially dangerous with a heavy trialer behind because even when the pedal is completely to the floor I have to gradually roll to a sliding stop.



I know you're not supposed to pump ABS breaks. But gimme a break, just backing into a drive way - sometimes never taking my foot off of the break pedal applying more then sometimes less pressure while letting the idle do the fueling?????



This is rediculous!



Is this normal and I have to live with it? OR is there someting I can do? In my opinion, something is wrong/broke/malfunctioning. I've never been in another vehicle that's done this.



What's up with this?

 

[barryg41]

H*ll NO, dont live with this.



I looked in the good book to see if there is a problem/fix situation for your truck and I dont see anything in it.



I dont have much to advise on your problem, but maybe you have or are getting air in your braking system. Maybe it works ok till you use them a lot.



I would check for air or heavens help us a leak. :--)



Wish I could say more to help.

 

[illflem]

The problem is that pre '97s have vacuum assisted brakes. If you are idling while using the brakes you will use up the vacuum after just a few stops. Vacuum is slow to rebuild at idle. Dodge's fix was to change over to hydro assist brakes that run off the power steering pump. Your fix is to give time in-between braking for the vacuum to rebuild. I've often thought that a guy could add a vacuum reservoir tank to help prevent this if he runs into the problem often. One gallon would be plenty. I've seen add on vacuum tanks offered for after market cruise controls on under vacuumed cars, under $15. Problem you might run into with a tank is if you do run out of vacuum it will take even longer to rebuild.

 

[moparguy]

Illflem is exactly right.

The only time I've really had a problem with this is when I had the idle set low, like 600 RPM or so, I really like it at that number, but the vacuum pump works better around 800 RPM.



It's start better as well at the higher number.

 

[Bob Horrell]

Dodge has a fix for this problem and you shouldn't have to pay for it. I complained about this "safety" issue when I had the problem and received a kit for the fix which I installed myself (I don't like anyone else working on my truck). The kit is P/N 04856425 and is listed for 94 to 96 trucks with automatic transmissions. I have a 5 speed and still had the problem. Can't imagine why it is only listed for automatics.

This kit fixed the problem. It consists of two vacuum canisters you add to the system to store more vacuum. They install behind the headlights in the dead space there and come with all the necessary hardware, hoses, and fittings to connect them to the vacuum hose that runs between the vacuum pump and the brake vacuum drum on the firewall.

Hope this helps. Let me know if you have any questions.

Bob

 

[Ben Rumson]

Yes, this certainly is a "safety" issue. I'm going to call the Dealership first thing Monday morning. I'm so glad there's a fix for this.



I've come close to wiping-out other vehicles (I can just see my ball and hitch knocking a hugh hole through some car's front grill and radiator), my garage door, and virtually anything that happens to be behind me at the time it goes out. It's a very stomach wrenching feeling to gradually roll to a stop and know that there's not much I can do about it. I've learned to hold my foot on the emergency break in case I had to stomp on it.



Intuitively, what you're telling me makes complete sense. I can certainly see how loss of vacuum ("pressure" as I described it) would make the pedal feel the way it does when it goes out - only happens while idling or slowly backing and rebuilds pressure (vacuum) once I get on the gas a little more.



Once it happens, I shift into Neutral and rev the engine for about 15-20 seconds before I try backing again and repeat as necessary - pain in the butt. This is not an occasional or intermittent problem. It happens almost every time I do any kind of extended backing at idle speeds.



My idle is set at 700 rmp.



Thanks for the help and solution suggestions - especially for the Part Number! If the dealership won't cover it, I'll research auxillary tanks and figure a way to accomplish the same thing.



Thanks again.

 

[Joe G.]

Ben,



If you keep your rear brakes adjusted it will still stop ok, just need a lot more brake pressure.





Bob,



Thanks for the info. This situation has always been a nuisance. Mine always stops but I have to stand up on the pedal to do it some times.

 

[amsoilman]

Ben,

My 94' was doing the same thing as yours. I corrected the problem by installing a tank under the drivers side of the cab, between the frame and the edge of the cab. I used a tank that had been used for A/C gas... ..... got it from a bus shop, then used a "T" in the vacuum line off the pump and ran the hose back to the tank. I can now apply the brakes 20 times without loosing brake pedal!

BTW, I'm just down the road from you!



Wayne

amsoilman

 

[Roger rodbolt]

Quote:

... . because even when the pedal is completely to the floor I have to gradually roll to a sliding

stop.



Ben,



I've experienced the loss of vacumn boost on my '94 and a '95 that I sold at 250,000 miles as others have mentioned. What I don't remember is the pedal going to the floor and the "sliding stop". Loss of vacumn should give a "hard" petal. I agree with what the other member have said in regard to the vacumn fix but you may have a master cylinder that is bypassing internally. I've not experienced this with our CTD's but it was very common on the Dodge gassers during the '70s and '80s. When the master cylinder bleeds off under light-constant pedal pressure it causes one braking axle to do all the work and usual the rear brake will lock and slide. HTH's.

 

[Ben Rumson]

Originally posted by Roger rodbolt

Quote:

Loss of vacumn should give a "hard" pedal. I agree with what the other member have said in regard to the vacumn fix but you may have a master cylinder that is bypassing internally.

Response: The pedal is "hard" and I have to stand on it to push it ALL the way to the floor before I get even the slightest benefit of any breaking response what so ever. When the pedal is completely and fully depressed his when some how, somewhere there happens to be enough grab to eventually take. Maybe there's almost no breaks at all and I'm simply coasting to a stop. On a few occasions, my rear end would cut a doughnut hole in the seat if it hadn't been in the air with me literally standing on the break pedal.



I've had cars that have had faulty master cylinder seals before and this feels different. Your point about possibly being a seal in the master cylinder is certaily noteworthy and worth consideration.



The manner in which the breaks go hard, and if allowed to "re-charge" for a bit, would lead me to believe it's due to insufficient vacuum reserve. I'll try an additional tank and if this doesn't work I'll look into the cylinder seals.



When I have time to work something up, I'll post a reply to let everyone know what worked.



Thanks for the help.