Jump to content

Dodgy clonk at the back end


Recommended Posts

Hi Rich,

without cleaning my prop splines the movement was obvious. It would still be thou's but noticeable.

Also I could feel a positive stop as the play finished.

 

Tomorrow I'll remove the O/S driveshaft and see what is going on there - with/without greased splines.

 

Roger

Link to post
Share on other sites

Roger,

We must have been following each other.. I have also just come back from a 1000 mile trip to Cornwall in the TR..

Stayed in Portloe, so also went past signs to Grampound road (in fact now I think about it, I drove through!). Stuart, hadn't picked up that you were there! Then moved to Fowey for a week.

Wierdly, I also have a clonk and am going to spend today having a look at the back end of the car. Also have a rear end vibration at part throttle at 70mph. Not too bad, just a bit annoying.. Chassis is new as are the mounting rubbers for the TAs and Diff.

Cheers

Tim

Link to post
Share on other sites

Hi Folks,

I removed and stripped down the OS driveshaft this morning. This is an area where the smallish clonk appears to coming from.

 

After many years and miles of use it looks perfect.

Even with all the grease removed there is significant friction between the steel/Rilsan coated splines.

I also held the shaft in the vice and tried to rotate the shaft using some big mole wrenches and levers - no movement.

 

As the clonk isn't that alarming I think I will live with it.

 

Roger

Link to post
Share on other sites

Hi Roger, one of our members had a similar clonk which could be replicated by rocking the car back and forth with the rear wheels in a certain position, it turned out to be one of the UJs !

Link to post
Share on other sites

Hi Roger, probably obvious but rocking with car in gear.

Link to post
Share on other sites

Hi Roger,

Couple of years ago I had the same clonking. After replacing the most of the rear transmission and suspension with no improvement I then put the car over a friends pit and with someone rocking the car back and forth with my ear close to the diff it was obvious it was backlash in the diff. I had the diff rebuilt. Now the clonking has returned. There is something like 5/10mm radial ( bit difficult to measure ) play of the prop shaft flange. Why? Maybe the bearings were not fully seated and have now bedded in? A fellow club member has just rebuilt his TR5 diff successfully so with his help I will rebuild it myself this winter. This does not help you but I think a lot of parts are often needlessly replaced before the diff is confirmed as being the culprit.

Alan.

Link to post
Share on other sites

Hi Alan,

my propshaft was defo in need of replacement.

The driveshafts look and feel good. They are in fact 4 years old and not the 9 I thought yesterday.

 

The input flange on the diff has apprx 4-5mm of rotation.

The output flanges on the diff have way more that this.

 

The diff was looked at in May by, up till now, a very good garage.

When they opened it up they considered it did not need rebuilding but simply a 'tightening of the bearings'.

Maybe this has moved other gaps/tolerances.

 

Roger

 

Never to fear it isn;t bad so I'll drive it until it gets worse and then have a full rebuild.

 

Roger

Link to post
Share on other sites

While the prop shaft is off try re-torquing the flange nut on the diff pinion input. That wil confirm preload on the pinion bearings. If it is a big nyloc nut be cautious as that may indicate that the pinion uses a collapsible spacer,rather than the solid type which will be found with split pinned nut.

Peter W

Link to post
Share on other sites
  • 1 month later...

Hi Folks,

  back to the diff.  I have been driving the car rather carefully and have managed to avoid serious clunking - but it is still there if I forget.

So I have arranged to have the diff looked at again. As I will be near the Propshaft people in Kidderminster I will also pop them in to see if they need any work.

Today I removed the diff.  It actually feels very good - but what should a very good diff feel like.

Nice and smooth, no notchiness, bearings feel good. No oil leaks. The amount of play is not as great as I thought it was when insitu.  Definite head scratcher.

The drive shafts also feel very good. The splines have agood resistance to sliding. The UJ's are new (May 2018) and also feel very good.

 

Over to the experts out there.

Roger

Link to post
Share on other sites

Roger 

Ive had 3 diffs reconditioned by two different specialists , both of whom came well recommended.

2 diffs from one of the specialists felt very notchy when turning output shafts after reconditioning, but I was assured this was how they were meant to be .The second specialist confirmed this was correct despite the diff he had reconditioned being nowhere near as notchy.

I have to say I was a bit nervous about this, but when a fellow member was in trouble and needed a new diff, he had one of the two "notchy" ones but he found it to be spot on, quiet , smooth  and no clonks at all - he was very happy and I trust he still is.

From my experience then, notchy appears to be fine - hopefully one of our forum diff specialists can expand on this and explain why this is the case, if indeed it is!

Waiting nervously!

cheers

Rich 

Link to post
Share on other sites

If the diff has been recently rebuilt it should be quite stiff to turn by hand although it shouldn't really be notchy. The sun gears will feel notchy if they are properly shimmed.

Have you got wire wheels, are they moving on the splines?

Rgds Ian

Link to post
Share on other sites

Hi Rich/Ian,

                     there is no notchiness. The input/output flanges rotate quite smoothly.

There appears to be just a little slackness but nothing to get anxious about (I think).

Ali wheels.

 

I have been trying to visualise all the parts of the drive chain when the clonk happens.

Reverse to forward & forward into reverse can do it.

Taking foot off peddle, putting foot on peddle.

If at the same time as taking foot off peddle I press the clutch the  no clonk.

The only area that I have not renewed recently are the diff rubber support bushes. Maybe all the removal/fitting has upset them

 

We shall see what the experts think.

Roger

Link to post
Share on other sites

Hi Ian,

      not  stupid question at all. Thankfully they are /were tight. I wish they hadn't been.

 

The GB is at the menders - we shall see what traspires.

The drive shafts went back to Proptech in Kidderminster and have been deemed spot on.

I shall get new Superpro rubbers for the diff and have a good lok to see if anything is knocking on/around the car.

 

Roger

Link to post
Share on other sites

Hi Bob,

         well spotted. I've been driving up and down the country this morning and my brain is still in kidderminster.

It is the Diff.  If I had to put money on it I would say the Diff is good - but the clonk started after it was removed/fitted.

I will be fitting new SuperPro mounts when it goes back.

 

Roger

Link to post
Share on other sites

Hi Folks,

                the diff is back in. The SuperPro diff mounts are fitted. everything is buttoned down.

On the test drive the clonk of last week has reduced a good amount but there is something still there.:angry:

 

I'll take it for a long run when the weather dries out a little and see what is going on.

 

Hmmmm

 

Roger

Link to post
Share on other sites

I suppose I shouldn't tempt Providence Roger but I can honestly say that on the RBRR my car remained clonk free. No longer do I have to feather the clutch on taking up drive and even snapping the throttle shut, undesirable anyway since it can unsettle the vehicle, fails to evince a noise. From what I hear and read this is quite rare for an IRS car and it is certainly the first time for mine in many, many years. I cannot put it down to any one change but can only think that recent new prop shaft UJs, new replacement CV drive shafts and  new Super Pro diff mounting bushes have combined to produce my state of euphoria. I have the one piece rear diff cover and axle mounting from a TR6. I must confess I only changed the front lower cup mountings, leaving the upper rubber cones in place. I will change these when the diff has to come out - maybe I will go to a 3.45 for higher gearing, I am not bothered about losing out on acceleration from rest as I do not compete in traffic light Grands Prix.

Tim

DSC00550.JPG

DSC00551.JPG

Link to post
Share on other sites

Hi Roger,

I found on my TR4A that a couple of the large washers bottomed out on the studs before compressing the Superpro bushes allowing the diff to rock slightly. It was not easy to see that they were not compressing the bushes and I spent some time chasing clonks as you are.

I remedied this by purchasing extra washers and drilling a clearance hole allowing them to go over the step on stud, then fitting the standard washer.

Cheers

Graeme

Edited by graeme
Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...

Important Information

Please familiarise yourself with our Terms and Conditions. By using this site, you agree to the following: Terms of Use.