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Rear End Noise


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Hi All,

 

I am looking for some assistance with rear end noise. While I appreciate it is a common issue in older models, its now happening on the TR6 too.

 

When driving yesterday there was a noise from the back end of the car which grew louder fairly quickly. It gets worse as I move up through the gears. I have been under the car today and cannot find any loose bolts or see anything obvious which may be catching as the prop shaft/axle turns.

 

There is a little bit of play on the nearside rear wheel if I rock it from top to bottom but I wouldn't say its a huge amount. The offside is solid. I have recently serviced the car and greased the UJs as I have done every other year.

 

I would describe the sound as a "knock knock knock" as if something rotating is hitting a static object as it rotates. It disappears when I remove my foot from the throttle, which may suggest the diff but I really only have to rest my foot on the throttle (rather than actually accelerate) for it to return. I put the car on axle stands and engaged 4th to see if I could locate the source - but can't be sure - though it didn't sound as bad in this set up. However, that may just be because the car is amplifying the sound into the cabin.

 

Reading through other posts on the forum I can only assume its the diff or the rear hubs - but I am not sure how to narrow it down beyond that. We're off on a 1700 mile trip in a few weeks, so I really need to get this fixed.

 

As ever, any and all suggestions gratefully received.

 

Thanks.

 

Steve

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Thanks Rob - older posts have suggested that could be the culprit too. It seems that the replacement cost is the same whether its the hubs or the diff but I don't want to replace one and discover it was the other. Removal doesn't seem to difficult but I am not sure I would be able to open the diff to look for broken teeth.

 

I will check the hub nuts too though.

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Hi Steve.

 

Last year I lost a few teeth, well a couple of big chunks from the crown wheel and the pinion coming back from France. Under any sort of load/acceleration it was fairly quite but as soon as I lifted at all the noise was pretty graunchy.

Hope this helps in some small way.

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Hi Steve,

you should be able to check the rear hubs simply by jacking the wheel up -

rotating by hand - feel for smoothness, lack of any rough noise/feel and no clonks.

 

Loosness when rocking by hand 12-o-clock/6-o-clock should not produce any knocking noises unless extremely bad - but it shows the hub is on the way out.

(do not get it refurb'd etc these are getting very old - buy new).

 

As time is running out for you if you remove the diff you should be able to remove the back cover quite easily and see inside for any damage.

 

Roger

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Hi Steve.

 

Last year I lost a few teeth, well a couple of big chunks from the crown wheel and the pinion coming back from France. Under any sort of load/acceleration it was fairly quite but as soon as I lifted at all the noise was pretty graunchy.

Hope this helps in some small way.

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Yes Steve, that’s what made me think it may be useful info. Before the diff let go, it was getting increasingly whiny. I would check your hubs etc and check the UJs as when they are on their way out they start to click.

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Hi All,

 

I am looking for some assistance with rear end noise. While I appreciate it is a common issue in older models, its now happening on the TR6 too.

 

When driving yesterday there was a noise from the back end of the car which grew louder fairly quickly. It gets worse as I move up through the gears. I have been under the car today and cannot find any loose bolts or see anything obvious which may be catching as the prop shaft/axle turns.

 

There is a little bit of play on the nearside rear wheel if I rock it from top to bottom but I wouldn't say its a huge amount. The offside is solid. I have recently serviced the car and greased the UJs as I have done every other year.

 

I would describe the sound as a "knock knock knock" as if something rotating is hitting a static object as it rotates. It disappears when I remove my foot from the throttle, which may suggest the diff but I really only have to rest my foot on the throttle (rather than actually accelerate) for it to return. I put the car on axle stands and engaged 4th to see if I could locate the source - but can't be sure - though it didn't sound as bad in this set up. However, that may just be because the car is amplifying the sound into the cabin.

 

Reading through other posts on the forum I can only assume its the diff or the rear hubs - but I am not sure how to narrow it down beyond that. We're off on a 1700 mile trip in a few weeks, so I really need to get this fixed.

 

As ever, any and all suggestions gratefully received.

 

Thanks.

 

Steve

Hi Steve. The other point you mention, if I read your post correctly? Is play in your nearside hub, that to me is very serious as some TR garages suggest that it is often the prelude to the stub axle searing off and you loose that wheel! Also play in the rear hub is an MOT advisory.

 

Bruce.

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I also get a "clicking" sound from the rear, which keeps pace with wheel revolutions. Could be the diff, I suppose, but the U-joints were all new when this started, and the rear hubs are Good Parts replacements, so they're unlikely to be the issue. I never thought to pull the drums, but that's clearly something to be done.

Edited by Litespud
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My ujs on the drive shafts clicked just like litespuds until I made an extra special effort to ensure all the grease I pumped into them actually made it to the intended place ie inside the uj rather than outside of it.

 

Cheers

 

Dave

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I dont have a drain plug unfortunately so will have to remove and dismantle to find out if the diff is damaged.

 

As for the UJs, I have greased them every year and it looks like the grease is going in. In any event, I would describe the noise Im hearing as more than a click, but you never know.

 

Im wondering if it would be possible to remove the hubs and run the car to see if the noise is still there (ie the diff rather than axle related) or would that be a silly thing to do?

 

Steve

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I dont have a drain plug unfortunately so will have to remove and dismantle to find out if the diff is damaged. Steve

Here's my healthy differential internals- after cleaning out of lot of gook.

 

To remove the rear diff cover- while it is still in place- undo the (8) 1/2 inch head bolts, have a drain pan ready to catch 2.5 Imperial Pints (3 Quarts US).

 

Turn a rear wheel while watching the gears turn- it will be obvious if any are chipped, a hunk of metal will fall out.

 

This will not be a wasted effort- chances are the gear oil needs to be replenished with fresh oil.

I used double gaskets & high temp sealer when refitting the cover. BTW, the cover fits on two ways- only one is correct. Re-torque 26-28 lb ft.

 

While in and about, make sure the air vent pin on top right side is free to move. You can just see it in the silver cover pic.

 

Cheers

Walt

post-13442-0-67051900-1519824158_thumb.jpg

post-13442-0-41667800-1519824181_thumb.jpg

Edited by Sapphire72
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Here's my healthy differential internals- after cleaning out of lot of gook.

 

To remove the rear diff cover- while it is still in place- undo the (8) 1/2 inch head bolts, have a drain pan ready to catch 2.5 Imperial Pints (3 Quarts US).

 

Turn a rear wheel while watching the gears turn- it will be obvious if any are chipped, a hunk of metal will fall out.

 

This will not be a wasted effort- chances are the gear oil needs to be replenished with fresh oil.

I used double gaskets & high temp sealer when refitting the cover. BTW, the cover fits on two ways- only one is correct. Re-torque 26-28 lb ft.

 

While in and about, make sure the air vent pin on top right side is free to move. You can just see it in the silver cover pic.

 

Cheers

Walt

 

Sapphire72 - I would love to have a look at the cogs in situ, but although I think I could probably get to all 8 bolts, I'm not sure how I'd actually get the cover off without removing the exhaust and removing all the mounting bolts. Am I missing something??

 

This link may contain information helpful to the diagnosis...or just add to the confusion.

http://www.onallcylinders.com/2012/03/30/quick-guide-to-diagnosing-differential-driveline-noises/

Poolboy - thanks for this. I think it may have helped.

 

I have finally managed to brave the sub zero temperatures of the garage, lift the car, remove the wheels and have another look. I took the brake drums off to make sure they were not interfering and when turning the wheels I can hear a distinct clunk clunk clunk. Not totally sure yet whether that's the hubs or the diff but as it sounds pretty much the same from both sides I am going to assume its the diff. I've attached a couple of videos in which the noise can be heard.

 

(Edited as previous links didn't work - hope these do!)

 

https://photos.app.goo.gl/v5TKOyhUm8SqhSZe2

 

https://photos.app.goo.gl/Hyv2YbX435kYQP7V2

 

 

I guess the next thing to do is remove the hubs and see if the noise is still there..... :unsure:

Edited by Percy TR6
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Hi Steve,

you do not need to 'remove' the hubs. Simply disconnect at the diff end and then collapse them on their splines.

 

Roger

 

:rolleyes: Why didn't I think of that.....thanks Roger. As soon as my I can properly feel my fingers again I'll get back into the garage. :)

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Hi Steve,

the other day I popped down the garden to feed the birds after just a few minutes I couldn't feel my fingers and after a few more I had to give in and go in doors - completely frozen fingers - ow.

 

Good luck with the diff.

 

Roger

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Sapphire72 - I would love to have a look at the cogs in situ, but although I think I could probably get to all 8 bolts, I'm not sure how I'd actually get the cover off without removing the exhaust and removing all the mounting bolts. Am I missing something??

 

 

Yes, you would probably have to remove the rear portion of the exhaust system in order to get the rear diff cover off and to gaze inward toward the gears.

 

Roger's idea about disconnecting the hubs at the axle shafts & diff flanges is a good one. That way you can turn the prop shaft to determine if the noise is diff related-

or is it hub related?

or is it universal joint related?

or a loose Armstrong lever shock mount?

or a cracked right-front diff mount?

Edited by Sapphire72
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