Jeep brakes!

[Euan McDonald]

Yes I do have a Jeep with dodgy brakes, I adjusted all shoes & bleed the system but still the pedal just about hits the floor on the first pump but is good on the second pump. I suspect the master is by passing inside, is there a common fix or later model conversion/upgrade?
Next year I will atend to the steering. (Keith)

[alleramilitaria]

i have 3 jeeps..... all 3 have to have the brakes pumped twice to stop them. yes its common.

[Geoff Winnington-Ball (RIP)]

I put some time on a '52 Canadian M38, and 30,000 miles on a '53 M38A1... their brakes were fine. Time to revisit/upgrade your basic brake components?

[Richard Farrant]

Originally posted by Euan McDonald
Yes I do have a Jeep with dodgy brakes, I adjusted all shoes & bleed the system but still the pedal just about hits the floor on the first pump but is good on the second pump. I suspect the master is by passing inside, is there a common fix or later model conversion/upgrade?

Euan,

Me again! I had a customer with jeep brake problems, it had been in an accident and a garage had repaired it including fitting a new master cylinder. They bled it numerous times apparantly, with pressure bleeder and still it had long pedal travel. The owner asked me to look at it, first check was shoe adjustment, but I quickly came to the master cylinder, stripped it and found a faulty rubber valve in the end. Some of the pattern ones on the market now have valves of different design to original Wagner Lockheed. Although they do the same job, their quality is suspect.

Since then I went out to a GMC with similar troubles, valve was culprit there as well.

Richard

[rob love]

If your Jeeps brakes really were "dodgy", they would squeel something fierce. They used to say of the old M37s:" If they didn't squeak, they worn't working".

If I insult your mechanical skills, please forgive me, but here goes:
-First, are the shoes adjusted fully. A major adjustment requires that the bottom adjusters be turned outwards ( Front one clockwise, back one counterclockwise, like a sprinkler). Back them off a smidgeon, and then adjust the uppers the same way and just back off so theres a bit of drag. The manual calls for feeler guages for this operation, which is even better.
(I saw a guy change 2 airpacs and 3 master cylinders on a M35Cdn cause he hadn't done a major adjustment.)
- Is the master cylinder adjusted so there is just a bit of freeplay before the pedal starts to move the piston? Too much freeplay and you won't get full use of the pedal...no freeplay and you will get buildup of pressure and the brakes won't release.
-If the shoes are new, have they been arced to the drums? If drums have been turned, the shoes may not have the correct curve to mate up to the drums.
-If the above is correct, have you bled from the furthest wheel from the m-cyl first to the nearest wheel last?
-Lastly, take it somewhere and have them bled with a bleeder ball. If they were bled by pumping the pedal, this is not nearly as effective as a bleederball.

If all the above were done properely, then perhaps it is the M-cyl as suggested above. All we ever had in the CF were Wagner, and 2 pumps of the pedal certailnly would not have been acceptable.

The old 9" brakes on the early Jeeps weren't that bad, and once the shoes mated up to the drums, could provide reasonable stopping power. The best brake systems are the 11" oversize brakes as were issued on the 1971 M38A1Cdn3s. They were self adjusting, and could stop on a dime.

[Mike K]

Euan

This topic was discussed on the G 503 forum recently

http://www.g503.com/forums/viewtopic.php?t=83714

The Master Cyl kit I purchased for the Chev. C8 was made in India , I was a bit dubious about it , but it has worked OK for years .

Some of the Indian stuff is crap quality though . The repro Land Rover stuff made there doesn't last very long in service .

Mike - in the land of fires . The Mt. Terrible fire is only 40 k away .... Help

[Lynn Eades]

Basically if you have a spongy pedal then the problem is air in the system.
If you have a solid pedal,(no air in system) then its an adjustment(travel) issue.
There should be a "residual line pressure valve in the master cylinder( first thing in, before the big spring)This valve is there to hold some pressure in the system to stop the pistons in the wheel cylinders from "relaxing" back, so as to keep your pedal "up" Yours may be missing yours.
Most times the problems are adjustment as per Robs input.
It may not be relevent here, but one area that many people make mistakes in, is in the fitting of the shoes, and or linings. The front shoe in each hub(all hubs) should have a long (full length lining. (this "leading" shoe is "self energising"and tends to "wrap on" during braking.) the rear shoe or "trailing" shoe, is fitted with a short lining. The reason for this is that the wear rate on the front lining is greater, and the larger area, evens out the wear over the life of the linings. Dodge acieved this with stepped wheel cylinders. This principle applies to all brake assemblies that have a single wheel cylinder, acting on two shoes, with fixed anchors. (Wagner- Lockhead, Jeep Dodge etc)
A braking "bias" is required in a system like a Jeep has, and this is accomplished by way of larger bore wheel cylinders being fitted to the front axle.
One last thing that sometimes is overlooked. Make sure the vent holes in the master cylinder cap are clear, and will allow the system to "breath" This is an "open' system which exposes and absorbs water into the brake fluid(hydroscopic?) These systems require more regular maintainence that modern "sealed systems" (the ones with diaphragms in the caps) All WW2 era vehicles run "open" systems on top of which,most are single circuit systems. In other words there is no emergency system.
If you have money to spend on your old M.V. dont take short cuts in this area.

[Lynn Eades]

We think of you guys with your fires, and it comes to mind just by looking outside. Our sky is very hazy ( well it was before the rain)