78 CJ5 rear drum size

[Agent915]

Hey guys, its been a while since I've had time to visit. Last time I was on I was chasing a rattle in my NP 435. I finally caved and took it to a shop. Turns out the noise was combination of a few things. One was the exhaust contacting the skid plate. Not certain, but LG may have suggested this early on. The main culprit, according to the shop is the rear brakes. They said that once it was on the lift, with someone underneath listening and someone else going through the gears, it was obvious. The right side is worse than the drivers side. They said that the shoes were "sticking out of the drums." I don't know if the wrong shoes were installed at some point or if the wrong drums were. I called the previous owner who purchased the Jeep new. He said it was "numbers matching" except for the Transmission . So its the factory axle. I am going to replace both the drums and shoes, but I don't know which ones, the 10" or 11". How can I determine the correct size? Any suggestions or ideas are welcomed!

Thanks,
Danny

 

[Torxhead]

I would first suggest measuring what the distance is across the inside diameter of the drum. It really sounds like you have 11" shoes on a 10" drum.

 

[Agent915]

Thanks Torx, is that even possible? I am at a total loss when it comes to drum brakes. How can I know which is the correct size drum for my Jeep? The part stores show both the 10 and 11 inch, but do not say which is correct for my application. I thought they could tell by model, year, engine size, whatever. But their system doesn't ask for any of those details.

 

[Hedgehog]

Simple .... measure the drums you have .... the backing plate will be close to the drum diameter. Measure the drums and get that size brake kit guts. I suppose you could have 11" drums with 10" brake guts.

 

[Agent915]

Simple .... measure the drums you have .... the backing plate will be close to the drum diameter. Measure the drums and get that size brake kit guts. I suppose you could have 11" drums with 10" brake guts.

Hedge, my concern is that I don't know which components are wrong. Are the drums correct and the wrong shoes have been installed, or the other way around? Once I have that answer I can buy all new shoes and drums. Will measuring the backing plate tell me the size I need?

 

[Peanut Butter]

Maybe we can get POSI or IO to way in on this. I too always wondered what years had the 11' and what years had the 10". You are right about the auto part stores. Go to Rockauto.com and you will find both listed.

 

[Hedgehog]

The backing plate will tell you what you want to know. Measure it and see. Or if the drum does a nice job of sealing most dirt and small rocks from getting inside the brakes, you haven the right size drums. ...... drums got smaller shortly after '75. Does your CJ have disk brakes up front? I've heard that the drums got smaller with front disk brakes. Both size brake drums with the proper backing plate will work. Finding the backing plate would be the real problem.

That doesn't mean someone hasn't gone with the bigger brakes. Since the PO said it was generally stock that probably didn't happen. A few minute with dirty hands will answer all your questions or pay someone else to get their hands dirty.

Yeah ... Rock Auto .... if you know what you are looking for why not go to a local supplier and get them from him/her. A local family would appreciate the pay check, the local grouchier would be glad to sell food to his family and the family wouldn't mind being able to eat dinner. Also the local government wouldn't mind the taxes to keep the roads indecent condition.

... Sorry PB, buying local is important to me. I know to many people who are loosing their business by folks getting local advice then buying off the internet. I buy local if I possibly can. Even if it costs a few dollars more.

 

[HackFabrication]

OEM 78 CJ would have the 11" rear drums. Jeep changed from the 11X2" to 10x1.75' after 1978 model year. Jeep Axle: AMC 20

If it was a late production 78, it is possible that AMC ran out of the rear ends with the 11" drums and put one for the next year's production in it. AMC was known for doing this sort of thing....

If it does have the 10x1.75 brakes, perhaps someone put an 11" drum on that side, without checking??? This would explain the shoes being exposed.

 

[Agent915]

The backing plate will tell you what you want to know. Measure it and see. Or if the drum does a nice job of sealing most dirt and small rocks from getting inside the brakes, you haven the right size drums. ...... drums got smaller shortly after '75. Does your CJ have disk brakes up front? I've heard that the drums got smaller with front disk brakes. Both size brake drums with the proper backing plate will work. Finding the backing plate would be the real problem.

That doesn't mean someone hasn't gone with the bigger brakes. Since the PO said it was generally stock that probably didn't happen. A few minute with dirty hands will answer all your questions or pay someone else to get their hands dirty.

Yeah ... Rock Auto .... if you know what you are looking for why not go to a local supplier and get them from him/her. A local family would appreciate the pay check, the local grouchier would be glad to sell food to his family and the family wouldn't mind being able to eat dinner. Also the local government wouldn't mind the taxes to keep the roads indecent condition.

... Sorry PB, buying local is important to me. I know to many people who are loosing their business by folks getting local advice then buying off the internet. I buy local if I possibly can. Even if it costs a few dollars more.

Thanks Hedge! Yes, I have front discs. I will pull the rear wheels this weekend and measure the backing plate.

And, for what its worth, I am 100% in agreement with you on "shopping local!" I work for a municipality and although we do shop for some things in larger towns or online, we always spend at home whenever we can. I generally will even buy just enough gas to get back home, then top off when I get there even though the price is a bit more! The "little guy" is getting crushed.....SAD. Thanks again for all your help and advise.

Danny

 

[Hedgehog]

Thank you for understanding my point of view on buying local. It is an internet world, I get that and you can't always get what is needed locally and locally does include a trip to a larger city. Sometimes internet sales are required, but not always.

 

[Peanut Butter]

Yeah ... Rock Auto .... if you know what you are looking for why not go to a local supplier and get them from him/her. A local family would appreciate the pay check, the local grouchier would be glad to sell food to his family and the family wouldn't mind being able to eat dinner. Also the local government wouldn't mind the taxes to keep the roads indecent condition.

... Sorry PB, buying local is important to me. I know to many people who are loosing their business by folks getting local advice then buying off the internet. I buy local if I possibly can. Even if it costs a few dollars more.

I think I only ever bought one thing from Rock Auto, and that was for my son-in-laws YJ. But they are a really good place to lookup parts and see for yourself what is available. Also, when you buy from AutoZone, NAPA, etc. you're buying from a franchise, not a local owner. When was the last time you ever saw the owner behind the counter at one of these. I understand buying local, buying USA, but I buy what I think is the best for me. Just as I would expect the CEO of a company to hire the best qualified person, not just somebody that was local to the area, only as an example.

 

[Agent915]

I think I only ever bought one thing from Rock Auto, and that was for my son-in-laws YJ. But they are a really good place to lookup parts and see for yourself what is available. Also, when you buy from AutoZone, NAPA, etc. you're buying from a franchise, not a local owner. When was the last time you ever saw the owner behind the counter at one of these. I understand buying local, buying USA, but I buy what I think is the best for me. Just as I would expect the CEO of a company to hire the best qualified person, not just somebody that was local to the area, only as an example.

PB, not judging at all brother! I do the same as far as researching parts and hey, if not for the internet I wouldn't be able to harvest all you guys abundant Jeep knowledge! I live in a SMALL town, approximately 5000 residents so shopping local takes on a whole new meaning when you know the business owners. Two of my favorite parts suppliers are O'Reilly's and CarQuest. I know both are franchises but the CarQuest is owned locally by a guy I went to school with and I have never been in there when he wasn't behind the counter. The O'Reilly's is a chain, but I am on a first name basis with the manager and most of his people. It's just small town life at its best. Everyone knows everyone. Like I said, I wasn't judging at all. Hope you weren't offended.

Danny

 

[Hedgehog]

I agree with what Agent 915 wrote. Like him I'm not judging anybody, especially not PB. One thing I have to say is, yes I know the parts stores are corporate stores. But the guy behind the counter is local and it's him that I support, along with the franchise owner, and the owner of the store, and the truck driver that delivers the goods to the store, and the local taxes the city/town/village get and keep local. It's all part of a chain of local people making a living on my purchase.

I have looked parts up on Rock Auto, but while comparing prices I don't find them to be that good and generally can find parts for the same money here in town.

 

[mstar]

Getting back to the original subject, have you found out anything ??
This is about the strangest thread I have read on here in a while.A couple things set off "red flags" for me .numbers matching ,brake shoes hanging out past drum. Just say'in . Why didn't they remove the wheel and drum and diagnose the problem. Does not seem possible to have that condition.No camera ? Hope you figure it out. mike

 

[Agent915]

I agree. I took the CJ to a Transmission shop. That's all they do, transmissions, no sideline stuff. He did take a few pictures to show me what they had found. I haven't had time to get it on stands so I can see first hand what he's talking about. Hopefully, that will happen this weekend. As far as the numbers matching statement I made, I was simply stating that I had talked to the previous owner, who bought the CJ new, to confirm that the axles had not been swapped. The only conversions made to the Jeep was from a 3 speed to a 4 speed, everything else is as it came from the factory.

 

[mstar]

Danny, thankyou for your public service and stay safe.
What you describe almost sounds like the axle shaft retainer has come off and the wheel,drum and axle are coming out of housing.This is possible and dangerous.I hope you are not driving this vehicle until it is repaired. I have seen this with a broken axle or a C-clip gone. Probably more than just mismatched parts unless someone was grossly incompetent. Either way it is not good and it didn't just happen with out some help. Good luck and hope you get it all fixed up for spring. mike

 

[Agent915]

Danny, thankyou for your public service and stay safe.
What you describe almost sounds like the axle shaft retainer has come off and the wheel,drum and axle are coming out of housing.This is possible and dangerous.I hope you are not driving this vehicle until it is repaired. I have seen this with a broken axle or a C-clip gone. Probably more than just mismatched parts unless someone was grossly incompetent. Either way it is not good and it didn't just happen with out some help. Good luck and hope you get it all fixed up for spring. mike

Thanks! You know, I had wondered if the axle may be "walking" a little when he guy at the shop described what he'd found. Are these axle shafts held in place with C-Clips like on a GM? If so, it may be a good idea to replace them too while its on stands. How big of a job would that be? It has the AMC20 rear end.

Danny

 

[HackFabrication]

Thanks! You know, I had wondered if the axle may be "walking" a little when he guy at the shop described what he'd found. Are these axle shafts held in place with C-Clips like on a GM?

It's been a long, long time since I pulled the axles out of my AMC20 , but I seem to recall the only thing that holds them in, are the flanges on the end of the axle tube. Some one with a recent experience, or better memory than I, will have the right answer.

 

[Agent915]

It's been a long, long time since I pulled the axles out of my AMC20 , but I seem to recall the only thing that holds them in, are the flanges on the end of the axle tube. Some one with a recent experience, or better memory than I, will have the right answer.

Hack, When I jack it up and pull/push on the rear tire, how much play, or movement should there be? I would assume it should be almost equal side to side, right?

Danny

 

[HackFabrication]

When I jack it up and pull/push on the rear tire, how much play, or movement should there be?

There should be very, very little, if any. If you've got noticeable in/out movement, you've got a problem somewhere.