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TR4 Gearbox clutch issue


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This is a weird one. So had gearbox rebuild completed (Sheffield boys) and at same time had clutch plate and cover rebuilt and upgraded and all new components fitted. After an initial good start within 60 miles gearbox failed and could not engage gear on the move and sounded horrific, overdrive also rebuilt alongside gearbox also failed to disengage at any point despite trying to run cones in over 20 of the 60 odd miles so had to keep tapping plate with hammer to release in the end the gearbox sounded so bad had to abandon tests fortunately I am aware not to reverse the car with OD engaged.

Roll forward 3 months able to return to the the problem another gearbox arrived (from Sheffield) took other new one out again and found it to be full of metal shards in the oil and oil black ..not good.

So new replacement gearbox in (stag unit this time) and out for test. Failure of gears to engage again third not staying in!

So you can put in 1st on drive move forward and then reverse etc no issues it will do that all day. Good pedal travel all fluids checked rod clearances all checked. Out on the road at very low speeds gears will engage but as speed increase no gear selection possible without massive grind as if clutch engaged, however put in clutch pedal and engine revs increase showing clutch disengaged but no gear selection possible above say 10mph. Back on drive same test in 1st and reverse all good. I cant believe a second gearbox can fail in 2 miles so now suspect the rebuilt clutch or plate but what could cause that and seems to be speed related? Also when you change gear on the road at speed it feels like you are trying to change gear without using the clutch and you feel the cogs disengage rather than the clutch.

I am now suspecting the clutch but cannot think what would cause this. Clutch plate to 'flywheel side' was noted when fitted and all other seemed fine, Uprated release bearing used and hardened tapered pin and additional roll pin in clutch cross shaft no play in bearing carrier or cross shaft as all new.

Any ideas appreciated as this one has got me stumped.

Ok post script... Overdrive now active this was electrical issue now resolved. 

However same issue with gears but now tested further  on the road no clutch disengagement despite full pedal/ever travel. Tested by putting OD in then pushing clutch pedal mild change in revs still but pulling and engaged in drive. Final test funny internal noise no gear selection possible and full drive engagement locked in drive clutch pedal action no change limped home in locked gear and knocked into neutral to enter drive/garage.

So jacked up car all good on fluid and lever travel? put car in gear rotated rear wheel with clutch pedal in still in drive! Changed gear became out of drive but then by continually pushing pedal and rotating wheel drive became on off intermittent which directly relates to the gear change issues.

Conclusion thus far is failed clutch plate springs or plate release but does not appear to be gearbox apart from third gear will not stay in when it is driving without physically holding it in place if use overdrive it knocks it out. So probably another poor gearbox and now clutch cover fail.

 

 

 

 

 

 

 

Edited by ogriboy
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"Uprated release bearing used and hardened tapered pin and additional roll pin in clutch cross shaft...."

Both sheared?   That would be unlucky.  

Was the cross-shaft etc swapped between the 1st and 2nd gearboxes?  If it was, surely a sheared pin would be found - if not swapped that would need two similar failures.  Only common factors would be hydraulics or the clutch cover/plate.

Edited by RobH
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No shaft and  shaft/pin all moving correctly (you can do that from under the car and would need to break hardened pin and roll pin. Both shafts inspected and both good no broken pins new shaft with both boxes. I have bled out the system a good 25mm of rod travel is noted. 

The clutch slip appears to be intermittent so binds up then releases but definitely binds up when clutch pedal fully depressed.

I suspect a failed clutch cover or plate jamming on the shaft.

Edited by ogriboy
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Ok so stripped out the box last night 3 hrs of pain but the problem was revealed when removal of clutch cover was carried out. This is a plate with 50 miles on it supposedly upgraded for performance.IMG_0765.thumb.jpg.da394ce15a07cf6bfdbf28b9c8eec50d.jpg

I think thats the end of this thread no more to say lost for words!

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Could have had the input shaft hanging on the plate when assembled back to the engine?, has to be very square to line it up,  also doesn't look like the usual plate, spring centre showing on both sides usually.

John

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No issues with shaft hanging I know how to do and always use guide rods in and out. My view is the lining let go, the chunk found was 25mm square this then rotated into the freed clutch plate and jammed it against flywheel like doing a massive clutch drop this then sheared the plate. This is why the drive wheel locked when clutch pedal depressed but could be rotated back to clear and then would jam again as rotated forward after a few turns. Fortunately no steel made contact with flywheel or clutch plate but it was coming in a few more miles.

 

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Linings will only come off or be damaged, if the driven plate is allowed to overspeed.

This will happen if you drive up a slop, dip the clutch and let the car run backwards faster than it was driven up.

If the clutch is clamped together its very unlikely that the linings will come loose. The engine will only rev to lets say 6000 rpm, if you were to drive up a slop, and dip the clutch (leaving the car in gear) and run back say 50 meters quite fast the speed of the driven plate driven by the diff could well exceed the 6000 engine rpm limit of the plate. The linings will come off.

This used to happen very regularly of Tractors with hedge cutters, drive in a slow gear up a slop, dipping the clutch to do another run up the hedge, and roll back faster than what was driven up and the linings would fly off big time, seen it happen many times, customers expense, no warranty!

John

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  • 2 weeks later...

Looking at it it doesn't look so much as if the lining has come off - more than the plate has disintegrated and some of the lining detached.

There were some poor quality driven plates around a few years ago.

I assume it was installed with the correct orientation?

Did they find anything wrong with your original rebuild of the gearbox when you sent it back to Sheffield?

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Andy..The gearbox went back for full rebuild and upgrade as a start of this whole saga I rebuilt it originally inc overdrive in 1986 and it lasted 42k hard Miles. The laycock clutch and cover were rebuilt by another specialist and installed exactly correct prior to return of gearbox, flywheel removed and refaced. The first rebuilt box failed and has now been out and was full of swarf after 5o odd miles and O.D would not disengage from day one and 3rd dropped out on overrun from day one. A second stag box was sent as emergency gesture but I could not fit until recently.  But it was obvious something was still wrong from outset  so pulled this box within 4 miles and then also the new rebuilt clutch to find what I did.  This box was then fitted along with another rebuilt clutch cover and B&B plate (the laycock could not be saved)

All back in position now and undergoing road tests, so far so good. Still easing out of 3rd on overrun but I now suspect the recent G lever shroud being too stiff as without this on it remains in place.

Inspecting the first rebuilt box which failed shows binding and lock up on rotation when in gear and a casing full of swarf and grinding from bearing or layshaft and this was a supposed uprated unit inc OD. Don't suppose it went above 60mph and 3k rpm. 

So being super cautious checked out as much of this Stag box as possible without stripping and found undone loose bolts to the slider rod selector cover plate. If these drop out they can seize the gear rods!!

Moral...Should have done it myself (if you want a job doing!) but time and age steered me into a situation I have always tried to avoid. If suppliers thought less about the bank balance and more about the quality they put out things might improve.

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On 8/29/2019 at 7:58 AM, ogriboy said:

Ok so stripped out the box last night 3 hrs of pain but the problem was revealed when removal of clutch cover was carried out. This is a plate with 50 miles on it supposedly upgraded for performance.IMG_0765.thumb.jpg.da394ce15a07cf6bfdbf28b9c8eec50d.jpg

I think thats the end of this thread no more to say lost for words!

Whooa !! That's serious! Looks like a friction pad came adrift.

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 Now looking further into the failed gearbox for clues as to why 3rd gear drop out within first miles could be possible as I am now also experiencing this with the second rebuilt gearbox already. I think the pic demonstrates some of the issue. These are the retaining plungers in the selector rods. The one on the left is correct the one on the right has had the pinnacle ground off from use the was the one securing the selector rod in place. No bearing in mid you can buy these from supplier stock how is this acceptable in a costly full  and uprated gearbox rebuild?

The investigation continues!! 

IMG_4452.thumb.JPG.a20de46771bd384200cf7236c8034122.JPG

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  • 4 weeks later...

Update and conclusion to the saga. It turns out the flat topped plunger is for reverse (if the rod cut out is profiled to receive it) this one was on 3/4th selector rod. And no the rod was not cut to receive it in any event.

Rebuilt the control part of the revised box with new springs and balls the new springs being some 5mm longer than those retained checked the pulling force on the selector rods to spec also increased slightly over standard given the issues. All back in place managed to replace the anti rattle spring and plunger in gear over base (tricky item to fit) good feel to movement. Now completed some 300 miles without issue. To the gearbox rebuilders credit they took the time to come and meet me to collect the first box and go through the findings based on my evidence and photos. Apologies received and box taken away for full examination and review. As I pointed out if they are genuinely committed to quality they should take the feedback and use it as clearly something is wrong in quality control or the skills available. As for the clutch, the cover and plate was returned to supplier for examination and was returned with new Borg and Beck plate (the laycock not reusable now) with cover again rebuilt this time the plate measuring exactly 8.5" instead of 8.5/8". No explanation for failure other than some grease found in cover!! No charge but got the feeling I was a bit of an irritation to them but then I only spent £700.00 ( and G knows how much over 30 plus years) on the parts I needed. Return Postage cost was turned into a purchase credit so as I had noted the reverse light switch was not working saw this as the offset but was sent one at half the price (non original) saving supplier £10.00. Shows the foremost priority in my view. As it happens it was a rod height issue and two finer washers cured it so original back on.

I would however like to say on a positive note that the large TR supplier based in Lincoln dealing with all other matters was excellent in all aspects of supply, quality and consideration. Amazing! I trust now I do not need to engage in the supplier world for some time and must continue to do more myself to preserve and protect the vehicle. Maybe its time we saw some kind of google type star rating for suppliers so feedback forms part of the profile as with most businesses including my own so purchasers can make a more informed choice but probably 20 years too late now judging by recent articles in TR action.

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