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Loud noise from the rear end..


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I was out quite a bit in the TR6 over the last couple of days and starting yesterday I noticed an odd noise that I initially mistook for road noise. Today on a short stretch of highway that noise got louder. It sounded like an exhaust clamp may have come loose. 20 minutes later back on some slower roads the noise got louder, now sounding like there was no exhaust system at all.

 

The noise was louder under load, less noise while going downhill.

 

I got home and was fully expecting to see an exhaust problem but there was nothing wrong. I jacked up the rear end, removed the rear wheels and ran the engine. No issues. I put it into 1st gear and I can clearly hear something mechanical coming from the rear end at about the same speed as the prop shaft rotation. It gets louder as I increase speed.

 

Prop shaft UJ's are hard to get at from underneath but they look ok. The two drive shafts are CV's and all front and rear wheel hubs/bearings feel ok.

 

As this point I'm thinking that I have some catastrophic failure in the differential but I'm surprised that there was not more warning if that is the case. Before I start pulling the thing apart I wonder if anyone has any other suggestions or tests that I can do ?. Given the noise I dont think I can do any more harm than is already done and I have a long driveway to play in.

 

Stan

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Whew... It's the CAR...

 

 

Your title had me concerned, Stan.

 

I've had differentials wear out -- more typically an increasingly loud whine. Loud like no exhaust silencer I don't know. Wheel bearings will make a growly noise, which at least would seem to be in the frequency range you're hearing. I'm thinking the differential cover or wheel bearings have gotta come off for inspection.

 

It'll be interesting to hear what other folks on here with much deeper experience think about it.

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Whew... It's the CAR...

 

 

 

Very funny. My wife does accuse me of tuba practice in the morning.

 

Here is the car on axle stands, wheels off, running in 1st gear at idle speed.

 

https://vimeo.com/224133981

 

If I stop the rear hubs from rotating the noise does not change so I think it is coming from the prop shaft or diff. At driving speeds especially under load the noise is LOUD, just as if the exhaust had fallen off.

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Yeah, a wheel bearing would need a load to really growl, probably a side load.

 

U-joints can do some funny things. Did the car shake?

Edited by Don H.
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Yeah, a wheel bearing would need a load to really growl, probably a side load.

 

U-joints can do some funny things. Did the car shake?

 

No vibration, performance normal. Just a loud noise under load like the exhaust had fallen off and some odd mechanical noises.

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Stan,

 

Sounds like a broken tooth in the diff.

 

Is it possible a bolt has come loose on the prop and is hitting the diff mounting or something else?

 

Cheers

 

Graeme

Edited by graeme
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I had one of the securing bolts come loose on the crownwheel and started to "flick" the housing, that's what it sounded like.

 

Mick Richards

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+1.

rhythmic knocking noise.

 

If it is there when you stop a drive shaft then that limits it to prop shaft and diff.

 

Inspect around all moving areas for shiny wear mark - you may get lucky.

Remove prop and check out he UJ's.

If all OK remove diff back plate and see inside.

 

Roger

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Thanks for the suggestions. I like Mick's idea of a loose crownwheel bolt. I was trying to think of what kind of gear failure would make that kind of racket but still allow the car to move.

 

Unfortunately accessing the UJ's on the prop shaft is a bit of a project on the TR6 as the prop shaft is boxed in with the exhaust system but the exhaust has to come off anyway if the diff has to come out.

 

Stan

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Stan,

 

Just drop the rear plate and check the torque in situ of the bolts (if you can get access, I can on a live axle car), you may have to drop the oil ! :lol::lol:

 

Mick Richards

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Stan,

 

Just drop the rear plate and check the torque in situ of the bolts (if you can get access, I can on a live axle car), you may have to drop the oil ! :lol::lol:

 

Mick Richards

 

I will drain it to start with and see what we have in the oil. I added a drain plug the last time I had the diff out. The rear cover is also the rear diff mount on the TR6 but I think I can get that off without pulling the whole unit out.

 

It sure would be nice if this was a loose bolt.

 

Stan

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I still have not identified the source of this noise but I drained the oil from the diff today through the small drain at the bottom of the case. There is likely more debris still in the case but this is what came out with the drained gear oil. Ruler is on the mm scale.

 

20170705_174012_zpsldixlh2h.jpg

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Gulp ! Doesn't look good.

 

Mick Richards

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Rob nailed it. In fact two broken pinion pieces lying in the bottom of the case. Here's one of them.

 

20170706_152058_zpsej9yrfm4.jpg

 

Had the diff on the bench in under two hours including removing the mid and rear exhaust system.

 

Glad I found the culprit, now to decide what to do. Options are repair it, swap it for another used one or replace it with an R200 diff for an all Goodparts rear end.

 

I'm impressed that I was able to limp home around 10 miles with the gears in this condition.

 

Stan

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Diff rebuild end of sorry Stan.

 

No doubt about that now Neil. I understand that the crownwheel and pinion need to be replaced as a set so this is not going to be a cheap repair, probably around $600 in parts plus another $600 in labor to fix it.

 

Stan

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Stan

But do they know what correct parts to use and how to set it up right?

 

There are a few specialists, one just a few hours south of me, that have the expertise. I just found a used matching crownwheel and pinion set in the basement that look ok so I may get away with not having to buy those parts. I have taken a TR6 diff apart before but never assembled one. That whole backlash thing looks intimidating to me.

 

Stan

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If you rebuild the diff, I presume you'll use new bearings, so I don't have to remind you not to apply new-part preload torque to old bearings.

 

The R200 setup is very good. I had one on my car, and would do so again.

 

Ivor

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If you rebuild the diff, I presume you'll use new bearings, so I don't have to remind you not to apply new-part preload torque to old bearings.

 

The R200 setup is very good. I had one on my car, and would do so again.

 

Ivor

 

After looking at all the options I decided to go with the Nissan R200 LSD, 3.69 ratio, from a low mileage Infiniti Q45. . It should be delivered today.

 

Stan

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After looking at all the options I decided to go with the Nissan R200 LSD, 3.69 ratio, from a low mileage Infiniti Q45. . It should be delivered today.

 

Stan

Good choice.

Peter W

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  • 3 weeks later...

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