Hey guys,
Over the past few months I have noticed a strange noise coming from my 74 REPU, but only under deceleration. I have replaced the fluid in both the axle, and trans, but the noise is still there.
Last year I had a leaky pinion seal, and bought a new one. I didn't trust myself doing such a job, so I farmed it out to a local repair shop(not an axle specialist, but a good trusted shop). I am now wondering if somehow they messed up the diff by not torquing something quite right on the pinion.Or perhaps not installing a new crush sleeve, or setting the pre-load up correctly. I left the factory shop manual with them to do the repair as I am sure they don't do a lot of 74 Mazda truck repairs.
Should I stop driving the truck? I really don't drive it much anyway, but should I totally stop before doing anything really major to the diff? Can I get this rebuilt by a axle specialist, and if so can they or I source parts for it? Could it be that the pre-load wasn't reset when they replaced the pinion seal. Is there a crush sleeve that wasn't replaced? I know I did furnish one to them, but I would assume they would get one if it were needed. Do you guys that know about diffs think getting parts for a 40 year old rare Japanese truck will prove difficult or impossible, or do you think bearings, and such are not something that will be hard to find? Any help on this is greatly appreciated as I really love this truck, and don't want to lose use of it for a long time which is what will happen if the diff explodes, and I have to use the spare on my project truck.
Thanks,
Chris
Sounds like a backlash adjustment.
Depends on what the strange noise sounds like.
If it whines then it is probably as Woody said.
I'm trying to upload a video I took the other day where you can hear the noise, but photobucket doesn't like it.
Chris, I haz a guy, want an LSD while its out?
Aren't these the same diff as the rx7s?
Not the same as an RX-7, much larger from what I have been told. There was a group buy on a kit to use an FD RX-7 Torsen a few years ago on the REPU board, but it seems the guy who was making them fell off the face of the earth.I am not sure I need anything that extreme anyway, I just want this thing to be back to normal. The Series 4/5 clutch type Turbo II will not work however. Only the FD, and from what I have learned the RX-8 diff.
Okay, so does anyone know a good shop in the Eastern MA area that could repair this diff for me? Also it seems as though the crush sleeve is NLA, so what do I or a shop do about that? Stretch the old one back out, and hope for the best? Source one from another similar axle like possibly the Courier perhaps? I have no idea how the differential works by the way aside from some sort of voodoo magic that makes the twisty force from the drive shaft turn a corner, and spin the axles.
You can also use pinion shims on the top of your existing crush collar to acheive a new crush, or have a buddy with a lathe machine you up a spacer and then shim it. Lots of people use spacers / shims to convert from crush collars in the 4x4 world.
Chris, start by popping the cover on that thing if you can if it even has a cover. I don't even know what they look like. Spray down the gears with some brake cleaner and let it dry. Put some colored grease like lithium on the gears and roll them around until the grease squishes out. You should be able to see where the gears are meshing. Compare the pattern to what you find on the internet. You will know right away if the pattern is off and you need to shim something. If it's a frontloader style rear end, just ignore me, I'll go away. My guess is the preload on the pinion isn't right and the crush sleeve or pinion bearings are compromised. Just ran into something similar in Al's TR8. I told him he needed carrier bearings. He took it to a very expensive shop that just replaced the outer axle(wheel) bearings. Guess what. The noise is still there. Whatever you do, don't do what Charlie just did. His had the same symptoms as yours, and his kid decided to crawl under there and tighten the pinion nut. 6/10 of a mile down the street.... BOOM!
No cover on this one Todd. I think it is the pinion bearing as well. Just need to find a place to repair it for me. Do you know of any place local that could do it for me?
Chris
Well I finally got a chance to remove the differential from my REPU today. Okay I am amazed it hadn't exploded a while ago. I found 4 large pieces of the pinion gear in the housing!! Not good!! I suppose I will be using the spare from my now parts truck. If I could figure out how to post pictures from my phone I would include one. Of course my home Internet is down so it is either the phone or nothing.
Chris
What are the chances that the ring gear is still okay? I don't see anything abnormal with it, but I really don't know gears at all. I know the pinion is bad. Could this be due to the shop not using the proper torque on the pinion flange nut?
Chris
airwerks wrote:
You can also use pinion shims on the top of your existing crush collar to acheive a new crush, or have a buddy with a lathe machine you up a spacer and then shim it. Lots of people use spacers / shims to convert from crush collars in the 4x4 world.
Shims were how they they did it before crush spacers. The Spitfires started with shims and later converted to the crush type all in the same differential.
So when I got home from work today I decided to install the unknown used differential from my now parts REPU. All went well, and 3 hours later my wife was helping me bleed the brakes in the rear, and I was off to play hockey. It is so nice having no noise from the rear axle anymore! Now to find a spare ring and pinion, or whole differential chuck to have as another hot spare in case this one starts making noise which I hope it doesn't. The only thing that was a problem in the whole re assembly was the fact that I forgot to tighten the rear lug nuts, when I took it fro a drive, and it felt really strange. I quickly pulled over, and had it rectified with a four way wrench, but I hurt my shoulder doing so. It sucks getting old!
