Drum Brake Damage - Post mortem?

[fenns7]

OK, altho' I try to do much of the work on my XJ myself -with help from the experts on this site - there are some jobs where I neither have the facilities (I have to work on-street) nor the ability which I hand over to a local mechanic. To date he has done a great job at reasonable price and doesn't get upset when I print off XJ specific instructions/guides to help.


A couple of years ago he replaced the original drum brakes (by then 20 years old) but on collection there was a distinct rubbing noise which I took to be a lack of adjustment on the brake shoes. I did a couple of very low speed hard stops to try and force an adjustment and I recall a bang and the rubbing noise continued so returned the XJ for him to sort it out. He took the drum off and filed something - maybe the shoe edge - but I wasn't paying close attention.


Anyhow, the noise had stopped and the XJ has been ok for two years until a few weeks ago when a 'dragging' noise started again and I decided I would attempt the job myself - confidence restored by the great tutiorials and photos on this site.


Here's what greeted me when I opened up the brake shoes:





That's the trailing edge shoe on the right side. That's some force applied to bend that Here's the end of the brake cylinder that the 'toe' on the shoe would have pressed on:





The left side was a mirror image:





and this shows the extent of the bend in the brake shoe arm which also bent the metal retaining tab - both circled:





So, how did this happen? Everything seemed to have been fitted exactly as instructed - even the green spring that holds the arm to the star wheel had been correctly orientated (an otherwise v. common error) - so he'd taken care. I'd really like to have opinions on what went wrong here so I can advise him - I'm sure he'll credit me the cost/labour against future jobs.


The inside of the drum itself was scored up where the top of the brake shoe was distorted so I've replaced the entire drum brake unit myself which was a big learning curve but very satisfying and I now own another set of new tools !


What was impressive was the handbrake (e-brake in the US) worked well and still held the truck on steep inclines and other than the recent noise gave no impression anything was wrong!

[RCP Phx]

Can't tell a lot because of the crappy pics, but it look like something froze up do to lack of lubrication/rust. Would be a great time for a disc brake conversion!

[fenns7]

If you click on any of the crappy pics Phoenix, you should see a much larger non-crappy pic



Now I've mastered them I like the old skool drum brakes - properly set up they work very well.

[maxbraketorque]

Totally OT, but how many XJs are on the road in London?

[RCP Phx]

Originally Posted by fenns7

If you click on any of the crappy pics Phoenix, you should see a much larger non-crappy pic



Now I've mastered them I like the old skool drum brakes - properly set up they work very well.

If you "mastered" them, you wouldn't be having this problem!

[RCP Phx]

BTW, the brake only self-adjust when going in reverse.

[XJI6191]

Originally Posted by RCP Phx

Can't tell a lot because of the crappy pics, but it look like something froze up do to lack of lubrication/rust. Would be a great time for a disc brake conversion!

A disc. conversion's not really an option in the UK because the parts aren't readily available.

[XJI6191]

Originally Posted by maxbraketorque

Totally OT, but how many XJs are on the road in London?

I'd say 1/2-dozen was optimistic

[RCP Phx]

Originally Posted by XJI6191

A disc. conversion's not really an option in the UK because the parts aren't readily available.

You can buy the stuff NEW on EBAY, you surely have access to that!

[four_shot]

I hope that the wheel cylinder was replaced. That much catastrophic damage is a safety hazard.

What are the chances that you could send a pic of the finished product? I'm concerned with the location of the adjuster cable. It should be on the trailing shoe (on the right in the photo) not the leading. Unless I'm mistaken in your description.

If you do post please specify left or right side. Cheers!

[XJI6191]

Originally Posted by RCP Phx

You can buy the stuff NEW on EBAY, you surely have access to that!

Must admit I'd never thought of that, as assumed it would be disproportionately, if not prohibitively, expensive - & anyway, my mind doesn't work like that.

Anyway, out of curiosity I've just had a look &, while there's not much choice, among all the pads, the odd caliper & occasional rotor I found a ZJ "large repair kit" comprising rotors, calipers, pads, shoes & even a complete fitting kit, from a reputable source - for a very reasonable £210 (say, a shade under $250). Have to say I'm very tempted, 'cos if I wait 'til I need to do another brake job, I'll probably have missed the boat.

Thanks for the thought.

[Rob Mayercik]

Yep, if you wait until you "need" to, odds are you won't have time to do the conversion and will have to just redo the drums again. Of course, if you have storage to lay in the conversion parts "for a rainy day", can tolerate them being on a shelf for a while until needed, and don't lose track of them, that's an option too.

If you're converting, you'd also need the backing plates from the donor vehicle and a new, longer set of wheel studs (believe front wheel studs would work) as well, so there's enough thread for the lug nuts to grab onto post-conversion. Not sure if the kit you priced included those items, wasn't clear from your post.

ZJ D35 disc systems are very common donors, but quite a few KJ ("Liberty" in North America, "Cherokee" elsewhere) models came with disc-equipped 8.25 rear axles. One minor advantage of using KJ parts is that the backing plates fit "out of the box" - the ZJ D35 backing plates require a little grinding to open the center holes to fit the 8.25's larger tubes (probably not applicable if your XJ has a D35 rear)

Question to RCP or anyone else who can offer insight - I keep reading here and there that many who have converted to rear discs have been unsatisfied with the holding power of the parking brake afterwards. Any thoughts on why this might be (the smaller "drum" inside the rotor and consequently less leverage on the shoes, problems adapting the actuating cables to the XJ, or something else?

[RCP Phx]

Originally Posted by Rob Mayercik

Question to RCP or anyone else who can offer insight - I keep reading here and there that many who have converted to rear discs have been unsatisfied with the holding power of the parking brake afterwards. Any thoughts on why this might be (the smaller "drum" inside the rotor and consequently less leverage on the shoes, problems adapting the actuating cables to the XJ, or something else?

I have also found the parking brakes to be lacking, I just used a set of premium shoes and don't use them until completely stopped. No issues with my direct fit cables!

[Rob Mayercik]

Sounds like you have a system that works for you, but the reduced holding power is one thing holding me back from doing the conversion myself.

The only time I've pulled the handle when moving was on a trail run where the two front caliber lines popped simultaneously, but my preference is to use the parking brake whenever I can to avoid putting the weight of the truck on the tranmission's park pawl (leaving aside whether it's good for the pawl, it does make it hard to get back out of park on hills if the brake doesn't hold well).

[XJI6191]

Originally Posted by Rob Mayercik

Yep, if you wait until you "need" to, odds are you won't have time to do the conversion and will have to just redo the drums again. . .

Now that is a very good point

Originally Posted by Rob Mayercik

. . Of course, if you have storage to lay in the conversion parts "for a rainy day", can tolerate them being on a shelf for a while until needed, and don't lose track of them, that's an option too.

Well the kit can't take up that much room - but must be too big for even me to misplace.

Time to bite the bullet & pull the trigger

Originally Posted by Rob Mayercik

. . . If you're converting, you'd also need the backing plates from the donor vehicle and a new, longer set of wheel studs (believe front wheel studs would work) as well, so there's enough thread for the lug nuts to grab onto post-conversion. Not sure if the kit you priced included those items, wasn't clear from your post. . .

Backing plates were the 1st thing I thought of when I was pondering what else I'd need. Might be able to pick up a pair of KJ ones from a Jeep dismantler, failing which there's a place in Germany that does them for a good price (everywhere else they're silly expensive, apparently. I knew about the studs and have some spare longer ones. I'll also need KJ parking brake cables, but they shouldn't be a problem.

Originally Posted by Rob Mayercik

. . . ZJ D35 disc systems are very common donors, but quite a few KJ ("Liberty" in North America, "Cherokee" elsewhere) models came with disc-equipped 8.25 rear axles. One minor advantage of using KJ parts is that the backing plates fit "out of the box" - the ZJ D35 backing plates require a little grinding to open the center holes to fit the 8.25's larger tubes (probably not applicable if your XJ has a D35 rear). . .

All export XJ's have D35's, because they had to have ABS, which is why I was looking at ZJ parts.

Originally Posted by Rob Mayercik

. . . Question to RCP or anyone else who can offer insight - I keep reading here and there that many who have converted to rear discs have been unsatisfied with the holding power of the parking brake afterwards. Any thoughts on why this might be (the smaller "drum" inside the rotor and consequently less leverage on the shoes, problems adapting the actuating cables to the XJ, or something else?. . .

My local mobile mechanic (who looked after my latest XJ for its PO) had a ZJ & he always said the parking brake was poor & defeated his efforts to get it any better than the minimum for an inspection pass. KJ's have a terrible reputation in that respect, the adjustment procedure is strange & they don't really respond to normal adjustment, although the set-up is no different from an XJ (or a '63 VW for that matter!). So a hybrid ZJ/KJ system should be fun - but the XJ has more pressing needs, so by the time this happens I'll probably have had to sort out the KJ's adjustment.