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My Camaro has a Ford 9” Rear end installed by the POwith 4.11 gears. The car makes around 400hp currently so nothing crazy, but I do get on it not uncommonly.
Up up until the other day the pinion angle has been off, but I finally got it set. Despite that being correct, I’ve been dealing with the common f body rear vibration and it’s seemingly pretty bad. It’s not the angle or tires. I took a video of the drive shaft while it was on stands and it looked good. Not sure what the problem is there.
But yesterday after a decent pull, I started getting a BAD rear end whine. And I don’t mean a whine you could just ignore, I mean 747 taking off kind of whine. It’s directly related to RPM, worst under acceleration but also makes some noise while decelerating. I figure it’s a gear mesh issue? I’m also thinking it could be that the pinion bearing just let go and now things aren’t aligned properly?
Unfortunately the 9” does not have a cover and requires the DS and other crap to be removed to inspect. And thoughts before I start tearing things apart?
EDIT: I did pull the plug and fluid came out slowly, so it’s not empty.
Can you run it on jack stands and see if the noise is coming from around the pinion area with a stethoscope or a screw driver up to your ear? Adjusting pinion Should have nothing do with this noise you are hearing. Gear whine is usually very loud under load and on decleration. Bearing noise with change a little bit with a load in and off it too but they are two different kind of noises
Can you run it on jack stands and see if the noise is coming from around the pinion area with a stethoscope or a screw driver up to your ear? Adjusting pinion Should have nothing do with this noise you are hearing. Gear whine is usually very loud under load and on decleration. Bearing noise with change a little bit with a load in and off it too but they are two different kind of noises
I ran it on jack stands today actually after I made the post. I can’t nail down EXACTLY where the noise is coming from as it’s so loud. It’s obviously in the rear end and at this point I’m confident it’s the gears.
I’ve begun pulling things apart, but I’m having trouble getting the torque arm off. I’m not optimistic about what I’ll find.
Is rebuilding the rear something I could do myself? I’ve read a lot about bearing pre-load, shims, mesh etc. not sure if I should just drop the axe and take it to someone? I figure it’ll be at least a bit cheaper if I don’t have to give them the whole car.
My rear got super loud due to damaged gears due to old gear lube and overheating. I pulled it and I could not see anything significant, because I don't know what I'm looking for. I took it to a shop and he was able to show me why it was bad and I had them put a new gear in and check everything else out. I have done everything on my car, rebuilt the trans, replaced a bent rod etc etc, and I chose to take my rear to an expert.
The torque arm bracket isn't too bad to get off if you drop the rear axle quite a bit and get a large breaker bar with a 4' bar on it, they are tight... if that is the trouble you are having. The clam shell at the front sucks too.
I don’t know what your mechanical skills. If you have good mechanical skills and with the info on the internet and a lot of patience you could do it. You also need the right tools to check pinion load, back lash, a bearing puller and a pressure to install the new bearings.
Unless you have broken gears it’s hard for me to believe the gears all of a sudden the gears started making noise especially since your fluid was full. It’s probably a pinion bearing that went bad.
I don’t know what your mechanical skills. If you have good mechanical skills and with the info on the internet and a lot of patience you could do it. You also need the right tools to check pinion load, back lash, a bearing puller and a pressure to install the new bearings.
Unless you have broken gears it’s hard for me to believe the gears all of a sudden the gears started making noise especially since your fluid was full. It’s probably a pinion bearing that went bad.
Mine went from normal loud to really loud during an AutoX and I could hear it in the video. No bad bearings, just damage to the gear. The shop I brought it to said he has seen this in many 9". He said there is a lot of contact between the gears (thus their strength) but it also has a lot of friction and heat. This can damage the surface of the gear increasing clearnace and causing a lot of noise.
Yes it is doable. Without the proper skills and tools it wasn't worth it to me. New gears and labor was under $400.
So we decided to drop the whole thing out of the car and take it apart. To my untrained eye, the gears look great. The oil is super shiny though which makes me thing the bearings are shot. I’m just going to take the assembly to a shop and have them take a look at it. I don’t feel like I should do it myself seeing as I don’t even have a press.
Umm... to me it looks good. Mine had burn spots on the contact pattern. Again I would take it to someone knowledgeable. My fear was not knowing what the issue was and "fixing" it and not fixing it. You check the wheel bearings yet?
Okay so we pulled it apart today. We had absolutely no bearing pre-load, the pinion depth was bad, pinion bearings were shot and the pinion itself was pretty sharp from having a really bad contact patch on the drive side (I didn’t get a good picture).
We we thought about polishing it, but I’ve decided I’m just going to replace the R&P, bearings and start over. Looks like whoever built it before really didn’t do a great job.
Fortunately for me I have a good friends who runs a shop and does these all the time. He and I are going to rebuild it once the parts come in.
Wheek bearings look look great but I had 1 bad seal that was leaking a bit. Regardless I’ll be replacing both bearings and seals.
01-26-2019, 10:15 AM
9” Rear End Whine 
