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Clutch release bearing


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Which is best clutch release bearing, just got my box out to look at some leaks and found this amount of wear on the Koyo bearing I fitted not so long ago, I was surprised what a big diameter the bearing has had on the clutch fingers.  The bearing still runs freely, but is a heavy bearing.

John

TR5 Clutch1.jpg

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That's a lot of wear John over a short time?

Makes me wonder the release bearing has been completely disengaging? Either that or the fingers are of poor quality.

Andy 

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Hi John,

ideally you need to the bearing to spin very very freely.

It is the relative movement between bearing and the fingers that produces the wear.

So either keep the bearing turning (constant contact) or have a free spinning bearing.

However when you buy a bearing they are rarely free spinning.

I have a RHP bearing and it is working well. It wasn't that free when installed but I would suggest that it is now.

I often feel that the Koyo is just too hefty for this position.

 

Roger

 

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Hi Roger

I think you may be right about the clearance when the clutch is released. I thought I had it per the Williams book.

There seem to be many options for mounting the slave cylinder, what should the correct position be?  It has a long slave rod.

Bracket engine side or gearbox side?

Slave on front or rear of the bracket?

Is the picture in Buckeye's correct?

I think also the spring in the slave cylinder could have something to do with it as well as its keeping the bearing against the fingers all the time, should I fit a less strong spring in there?

John

Edited by John L
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Hi John,

the slave goes where ever it fits correctly. Sounds obvious, but if it is on the wrong place it will not be able to be set up correctly.

The Moss webcat shows the bracket on the rear face of the GB flange, with the slave on the engine side of the bracket - https://www.moss-europe.co.uk/shop-by-model/triumph/tr5-6/clutch-transmission-drivetrain/clutch-systems/clutch-system-tr5-6.html

The slave cylinder is self adjusting and will always allow the fork to keep in the forward direction. This may allow fractional touching of the CRB on the diaphragm.

On my 4A I fitted the TR4 return spring.  It removes the self adjusting  but allows you to set the gap on the rod.

If the CRB is not free to rotate then it will possibly wear the fingers or squeak as it touches.

Roger

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John

My opinion for what it's worth

It looks to me like the wear could be being caused by the clutch being "depressed" by incorrect setting of the push rod length. A spring if fitted should normally pull the clutch off and provide a clearance between diaphragm fingers and release bearing. 

Irrespective of a spring being fitted the slave cylinder piston should be fully pushed forward when setting the push rod length. 

The shape of the wear marks however suggest to me that the fingers are being pressed well forward when this wear is taking place like either the release bearing is partially seized when underload or clutch travel is being restricted by something fouling.  Maybe the release bearing is the problem but are there any witness marks on the nose of the gearbox front cover? Is the driven plate in the correct way round? Is the clutch a proven assembly of parts?

All the best in your endeavours to get to the root cause

Rog

 

 

 

 

 

 

 

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Hi,

for me it looks like this release bearing does not run absolutely free.

Some of you guys want to do the very best and give the bearing extra grease - but you have to fit the release bearing on the gear box as it comes out of it's selling box.

Extra grease brakes the bearing and allows not to eccelerate it immediately, what is needed when you use it with clearance.

Additional due to the worn fingers you bearing looks like being too big and to static, what need extra energy to eccelerate.

On my TR4A clutch (with clearance) I washed out all the grease the previous owner put there, oiled it with "white oil" (also known as “gun oil” / “sewing machine oil” and checked it on my late with 2.000 revs. I was able to brake it at once with one finger (finger is still on my hand :))!

That works well since years without any attention. I will have a look on it next winter.

Ciao, Marco

Edited by Z320
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I've been using the TRF Magic Clutch kit comprising Koyo bearing, Sachs PP and LUK disc since the last century. I'm guessing I've done over 100K miles with them ( 2 cars ) and haven't had any issues whatsoever - best setup I know of and that includes the Laycock which is also very good, just more abrupt engaging.

They key in my experience is that I twigged misalignment to be the chief gremlin in circulation with these and got mine aligned properly every time beginning with my first TRF kit.

I'm with Stagpowered above; it's probably a misalignment issue causing the TOB to scrub on the PP fingers in an orbital pattern. Not what it was designed to do!

Tom

 

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Thanks for the various replies, I think the main problem has been that I've had the slave cylinder mounted on the wrong side of the gearbox and also the slave cylinder on the bracket, and so the push rod has bottomed out in the slave cylinder, and so contacting the fingers, hadn't noticed any slip at all. It was ok when first fitted 3 years ago, but perhaps the clutch plate has bedded now and I hadn't noticed it was tight

The bearing hasn't been noisy, its only that investigating oil leaks on the gearbox again, that I have discovered it. Now having got the box out I was getting a bit of a rattle at idle, I now find I have some teeth missing off the front lower layshaft gear,  Oh dear. It never stops does it.  I cannot see any reason for this failure, layshaft bearings and shaft were changed 3 years ago, layshaft is still unmarked. 

The dowel bolts are in the correct places and I don't see any other alignment issues.  Cross shaft has had new bearing last time. 

The sleeve that runs on the gearbox snout is a gold coloured one and is able to run free, its not pegged so is rotating as well.  The Koyo bearing is still I think a bit stiff to turn, and perhaps its just that that is causing the issue, like Marco says perhaps I should wash it now and oil it?

Just need to track down some good quality parts again.

John

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HI John,

there are three types of bearing carrier material.

There is steel - which I find good on my 4A

Phosphour bronze (dark gold colour)as used on the side screen cars. These work well and many TR6 owners believe this is the one to use.

Brass (bright gold colour) as used on many saloons. These do not work with the standard TR fork. The pins dig in, The saloon cars use slipper pads to spread the load.

 

If you go for the Gold colour again ensure it is Phosphoyr bronze as this is harder than the Brass.

 

Roger

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On 6/13/2019 at 8:29 PM, RogerH said:

Hi John,

ideally you need to the bearing to spin very very freely.

It is the relative movement between bearing and the fingers that produces the wear.

So either keep the bearing turning (constant contact) or have a free spinning bearing.

However when you buy a bearing they are rarely free spinning.

I have a RHP bearing and it is working well. It wasn't that free when installed but I would suggest that it is now.

I often feel that the Koyo is just too hefty for this position.

 

Roger

 

Hi Roger!

I would have to agree with Roger. But the design of the RHP bearing to me is suspect as it is a low cost item intended for industrial applications? I am not certain that it s/b used in automotive applications! Yes I know it works to a degree but the major design fault to me is that it is not sealed and as soon as it is fitted and used the grease inside it starts to fly out and in a very short time there is no grease inside. During my years of ownership of my TR I have had a least 6 of them as they have suffered from the scream, some failed as soon as the clutch was operated, caused by no or very little grease inside or the grease has gone hard.  I note now that my local bearing distributor has these RHP bearings all in sealed bags. There are other designs out there which are sealed and can take heavier loadings. I think it is time to find something else that works? The TR Spares development fund s/b on to this?

Bruce,

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My RHP release bearing, running with the rest of grease an added gun oil 8 (?) years ago, works lovely.

Due to the construction of the housing the centrifugal forces can not throw the oil out.

Perhaps you realized I'm working on a "Sachs" hydraulic release mechanism?

It is exactly the same construction, also not sealed, much smaller, so less static,

running not as free as my oiled one - but always in contact pressed by a strong spring with about 10-12 kg.

Edited by Z320
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7 hours ago, AarhusTr6 said:

I bought the bronze one from rimmers and it would not fit (really tight) . . they denied they were at fault and said maybe I had a GB from another car!!!

Rich

 

If there's any  doubt it's worth checking the GB serial number. In the 50 odd  years my  my CP was made it has been fitted with  a 2000 box complete with TR6 selectors and a TR6 type A overdrive.

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