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MG MGB Technical - Clutch release carbon bearing condition

Hi,

I would like to have your expert opinion on the condition of the carbon clutch release bearing shown on the picture below(part of a Sachs/Borg&Beck new kit).
The outer chamfered part is dented in several places (especially one at the bottom of the picture) and I do not feel comfortable using it - but I am really no expert.

Thank you very much for your input !

Gerard

PS sorry about the poor picture quality from my cell phone camera



GBP

I wouldn't have thought it was a problem, unless there
are any obvious cracks.
Dave O'Neill 2

I'm sure it would work, but I would worry that they have dropped it in stores. I would return it.
Stan Best

There seem to be quite a few chips out of the base of the carbon. I would worry that these would be stress raisers and result in cracking in use. Return it, It is of poor quality
Iain MacKintosh

It will be fine to use that.
G Britnell

I vote to replace it. It's been damaged, that is a fact. It is just not worth the trouble of finding out, at a later date, that it should have been replaced when you had the chance. RAY
rjm RAY

All anyone can tell you is that the shape of your throwout bearing is not the same as the original factory part. Whether the chips which seem to be missing are caused by dropping of the bearing, the bearing being poorly packed inside the shipping kit, poor quality of materials used in the carbon portion of the bearing, or some other reason, no one is going to be able to tell from a photograph. All anyone can say is that the part is obviously damaged.

Considering the amount of work involved in replacing a throwout bearing, I would not install an obviously damaged part into my car.

Les
Les Bengtson

Here here Ray. There are cracks in the thing that could well spread and cause the carbon block to disintegrate. This is one of the most inaccessible parts of the car and the last thing you want to have to do is to have to pull the engine out again and say I wish I had.....
Iain MacKintosh

Thank you all for your prompt feedback, I will follow majority rule and get a replacement !
Gerard

PS : Les, this bearing came with a Borg&Beck kit (with Borg&Beck Made in England stamped on the clutch cover (with the pin-type design, similar to the original design AFAIK). Kit was sold in a SACHS box under part number JT9694.
GBP

Gerard. I purchased, several years ago, three Borg and Beck clutch kits. Previously, the throwout bearing was delivered in a separate cardboard box. With these kits, the throwout bearing was in the same box as the clutch and pressure plates. Two of the three throwout bearings showed the same sort of damage your photo illustrates, indicating to me that the throwout bearing needed to be better protected in shipping. When I contacted the supplier of the kits, he examined those in stock and wrote back that three out of four showed a damaged throwout bearing and that he would, in the future, inspect each of the kits before shipment to ensure a good bearing was sent.

This was several years ago and, from your experience, either no change was made in the packing of the throwout bearing or there are still some of the old kits being sold. Mine were in a white box and were labeled Borg and Beck.

Hope you have a new bearing and it is installed by now. Good choice to post the photo and ask about it.

Les
Les Bengtson

Les, thank you for your comment. Same packing issue : the bearing was wrapped in a corrosion-preventing paper but left unattached in the box. Not sure I will eventually manage to get a replacement from the parts store.
Just in case, did anyone try the Borg&Beck bearings currently offered by TRF (The Roadster Factory) ?
TIA
Gerard
GBP

Gerard. All of the various suppliers used to sell the throwout bearings as a separate part. They, also, sold complete clutch kits which consisted of the pressure plate, clutch plate (driven plate), and a throwout bearing. Any company should be able to provide you with a throwout bearing in a cardboard box.

As to The Roadster Factory, they were, for many years, a Triumph oriented company, thus many of us have not dealt with them. None of the Triumph owners I know, who have dealt with them, have had any negative comments about the quality of their parts. But, remember, many of these parts for our old cars are coming from the same single source of manufacture. Thus, a Borg and Beck bearing should be the same part regardless of which retail store you purchase it from.

Les
Les Bengtson

Pin-type design? Does this mean the roller bearing has a roll pin through the side of the casting to retain the carbon ring? If so do not use it, they shatter in short-order.

PaulH Solihull

Nope, here is what I meant (see picture)
Gerard

GBP

Gerard -
That is NOT a correct clutch cover. It does not have the flat table or bearing surface for the release bearing to contact.

TRF supply MGB parts as well as TR parts, and they are obsessed with "best quality available". If it is not good they will tell you, and when possible they have parts reproduced to better than original quality. That said, I expect all B&B carbon bearings are coming from the same place, just be sure you don't get one of the now "we hope", out of production roll pin ones.

FRM
FR Millmore

Not a picture of the actual cover but one from the net that shows well the crown "pin type" design.
Re: TRF, I have only had good experiences with them (on TR parts).
Gerard
GBP

Hello Gérard,

My next move for my B will be to swap for a roller bearing, which will be a trouble free solution.

Have a look at:

http://www.mgexperience.net/article/diy-roller-throwout-bearing.html


Salutations,


Jean G.
Jean Guy Catford

"swap for a roller bearing, which will be a trouble free solution"

Ha! In a moment of madness I fitted one, and shortly after it started wittering just as it started to take up the weight of the clutch. Then I started reading about pull-off springs which prevents rapid wear of the bearing by pulling it clear of the clutch cover. Needless to say my supplier had not heard of the problem or the so-called solution. Fortunately it didn't get any worse, and many thousands of miles later it seems to have stopped ... which could be a sign of impending failure. The madness bit is that unless I leave it in at the next clutch change (would you?) it is a complete waste of money, and I wouldn't fit one again. Correctly manufactured and installed carbon bearings should last the life of the friction plate. Having said that the V8 has one as standard, and that doesn't have a pull-off spring. They are required to be replaced with the rest of the clutch. I'm attaching a picture of a new and an old where the friction plate had worn down to the rivets. Correctly aligned the boss on the clutch cover should fit inside the bearing casting as the carbon wears down, this old bearing is potentially only about 1/3rd worn.

PaulH Solihull

Paul, Doug Jackson, at mgamgb.com, makes the adjustable slave cylinder mounting kit that I posted here some time ago. I installed one of his kits, in '93, after hearing about premature failure of the roller bearings. I had used one, that came with the heavy duty Borg and Beck clutch kit, that I had installed a few months earlier. It allows you to set the throwout bearing so that it is not in constant contact with the pressure plate, consequently increasing the life of the throwout bearing, be it a roller bearing or one made of carbon. I've only had to adjust the unit twice in almost 18 years of use. The roller bearing has never given me any problems. RAY
rjm RAY

This thread was discussed between 20/05/2011 and 28/05/2011

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