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JohnD

Why is this 'dint' there? And why so much wear?

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I've just taken the engine and gearbox out of SofS - new engine going in.

I inspected the release bearing on the gearbox housing, and it looks like this:

775716319_IMG_20191215_1731161.thumb.jpg.b328cbb7df9edabb52ea7a00a1502d6c.jpg

There is a 'dint' on the back of the housing - it's there on every such part I've seen, so I presume it's supposed to be there.     It's obvious from the witness marks that the release lever yoke has been bearing on the dint and has worn the side of the land that it runs in.      The opposite side has a similar wear mark:

1104962931_IMG_20191215_1731251.thumb.jpg.abec76acb1f4d7cd06c847d75a4eb8c6.jpg

The dint clearly stops the housing spinning when the clutch is depressed.

But why the excess wear?    I have another, which looks like this:

1057408042_IMG_20191215_1731501.thumb.jpg.944c64edfd5bca3273bfde490af25146.jpg

271004754_IMG_20191215_1731591.thumb.jpg.6855338f8fc3979b0bcb98c1129c7481.jpg

Similar wear, but much less.

So, why is the dint necessary? Is it so that the release bearing itself takes all the load?     

And why is there so much wear on the one I've just taken out?     Could it be from me 'riding' the clutch?   

My only other observation is that one of the pins on the clutch release lever is loose.     If that has been 'chattering' would that wear the release bearing housing as seen?

Thanks!

John

Edited by JohnD

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There was a thread on this on the TSSC forum recently.  Apparently the dint in the end is a factory installed feature to stop the bearing carrier spinning.  Consequently it also determines where the fork pins sit and where they wear the upper face of the groove.

I must confess that I've never seen one of these "dinted" ones in the flesh.  All the ones I've seen have had a roll-pin installed across the groove instead to do the same job and causing the same concentration of wear.  You can drill new holes and move the roll pin to make the fork pins bear on a fresh area and the same would work on your dinted one.

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In my fairly limited experience, I've also only seen the ones with the pin, but it causes the same kind of wear.  As Nick says, you can easily relocate the pin.  You could also add a new dint to the dinted ones to get a fresh wear surface.

Ed

SDC10648a.JPG

SDC10698a.JPG

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Thank you, guys!   Of course!  Just install a pin far enough around for the lever pins to bear on a new surface.

I imagine that this is neither a precison task or a high stress installation, as shown by the frankly weedy pin seen in Ed's part.  Something I could do, on my pillar drill, possibly using a small bolt if I could thread the hole.

That would mean that the part could be repinned at least three or four times!

John

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Hi John,

I have had similar issues on my 4A clutch RB. these are my thoughts.

Steel RB carrier has a pin as you do not want the steel RB carrier spinning as it may well seize up on the GB nose extension. Thus it has a roll pin installed.

The early TR's (TR2 -4) had a Phozy Bronze RB carrier with a standard fork with round engagement pins. These work well and owners swear they are better than the steel version (this of courses is not true !!!). These early cars also had the spring clutch cover.

The later TR's (4A -6) used a steel RBC. This may or may not have had a roll pin (but should have had) These do work well if installed properly.

Problems.

The saloon cars used a Brass RBC. This is much softer (and cheaper) than the Phozy Bronze. So rather than use a standard fork with round pins these use slipper pads that spread the load.

Sadly the suppliers are now supplying the saloon RCB for use on all TR's (as well as steel if that is what you want). The Brass allows the standard fork round pins to dig in.

This has a couple of problems  - 1 - the depression gets deeper and deeper.  2 - you loose clutch pedal travel  aaarrrgggghhhhh.

Having a rotation restrion from new on the Phozy Bronze is madness as it will eventually dig in.

The attached pic shows a brass RCB with about 20,000miles on it. Note its golden yellow colour (Brass)  It needs to be dark (old gold) in colour.

Roger

 

 

P1030171a.jpg

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Thank you, Roger!

I have no memory of the origin of the RB carriers I have.       I've searched for ways to tell brass from Bronze, as perhaps my worn one is brass, but all the suggested non-destructive ways are as subjective.  Both mine look older and golder than the one you showed, but colour is one of the subjective methods.      Others are file it, bronze is harder.

A clock site suggested file/wire wool an area clean and put vinegar on it (or I presume any weak acid?)    Brass will "fizz" as the zinc is attacked, and the surface will go pink - it becomes pure copper.   Any comments, or does this need a strong acid?

Also found this interesting colour chart of the Copper Alloys: http://www.metalreference.com/Forms_Copper_Alloy.html   Which shows such variation that I'm none the wiser!

John

 

Edited by JohnD

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When I was at work I could have used a 'conductivity' tester.  Brass is in the high 20% compared to annealed copper (IACS) - typically 28%

Bronze is usually much lower perhaps down to 7 -10% IACS.

 

Under a decent microscope brass has a nice smooth surface. Bronze is grainy.

Brass is ever so slightly magnetic (honest).  Brass insn't at all.

But colour is the easiest method along with the file.

X-ray spectroscopy would show the zinc in Brass and  Tin in Bronze.  Not every body has one of them.

Roger

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You guys have inspired me to take action and answer my own question!

First the result of action:

302319875_IMG_20191216_1819011.thumb.jpg.f1c4d4f915aed7e8ee425cf5ded2cb4e.jpg

Roll pin inserted to place the lever pins in an unworn part of the groove.

 

Then, drilling for the pin yielded curls of swarf, which other reading tells me mean my release bearing housing is BRASS.    Bronze would give flakes.

The roll pin has an OD of 3mm unfitted;  I drilled a 2.5mm hole.    Is that cosher, O proper engineers?

John

PS  Nick, are those Witor slippers intended to fit over the pins in the release lever.   So fittable to the existing leever, without fettling?  J.

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Don’t know John.......... Never seen any in the flesh. Probably intended for T2000 rather than Vitesse/GT6.

How big are your pins relative to the width of the groove?

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This is from memory, but i think my pin was less than 3 mm, but in this case, size doesnt matter that much, within reason.  If the pin went in, the hole size is fine.

If you drilled all the way through the larger flange, but only part way through the smaller one, and the pin length is appropriate, it will be captive with the bearing in place.

Ed

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I believe the slippers are T200 and/or TR.

Pics attached. I think to groove is wider than on a GT6, but there might be enough meat available on the GT6 one to re-engineer it if you were so inclined.

My original GT6 carrier was the bronze flavour, with roll pin recently added to move bearing point away from original 'dint'.

Ian

071.jpg

072.jpg

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Thanks, Roger and thanks Ian, esp to know that someone else had done the same as me,without disaster!

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What puzzles me is why stop a bronze/brass carrier from rotating. 

 

Roger

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Explanation on other site - to stop squeal.

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Hi John,

yes, I read that but am not convinced.

When you consider how stiff the release bearing is to turn I would suggest it is the bearing on fingers that is the problem.

However, my set up does not squeal, squeak or screech - it is a steel Carrier with no pin.  Am I tempting fate.

 

Roger

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Stiff?   The release bearing???    Mine spins to a finger flick!

John

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Hi John,

my RHP bearings have always been stiff to rotate.

It may be that they should be permanently engaged so as to keep spinning and run free'r .

The the diaphragm clutch on the 4A/5/6 is self adjusting so will always be touching or close to the fingers.

 

Roger

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