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MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG TD TF 1500 - Release bearing question

Anyone know of a source for a quality release bearing for a TD or TF gearbox? I've heard negative things about the usual supplier's RBs.

Tim
Timothy Burchfield

I have not heard or experienced anything negative about the carbon TOB's; the ones you need to stay away from are the ball-bearing ones.

Tom Lange
MGT Repair
t lange

I've never had a problem with the Moss units. I have them in all my British cars. Currently about 50K on my daily driver MGB's clutch and all is well.
Steve Simmons

I think I read about some after market ones that had a roll pin of sorts that held the carbon ring into the iron housing and some reported (I think on other forums, possibly Sprite/Midge that they had come apart after some usage. Can anyone confirm?
John Quilter (TD8986)

I don't know about those issues, but I can report that I have a midget 1500 bearing from Moss in my TC (custom clutch assembly) and it has had no issues in the past 20,000 miles or so.
Steve Simmons

John Quiller
The carbon thrust bearings with the roll pin were a cause for concern with Midget & Sprite owners.
Nos appear to be better than the latest products.
Some carbon release bearings can be converted to roller bearings.


Alan Anstead

My TD has about 3000 miles on the rebuilt transmission and throwout bearing. I went with the roller bearing system (prior to reading the issues about it).

So with the rebuild of the TD, I pulled the transmission and put a new clutch and throwout in it. Used the carbon one this time.

I did check out the roller throwout that came out. I see no wear on it and it seems to work fine. But again, that is with only about 3000 miles on it.
Bruce Cunha

Bruce
Why not continue with your roller bearing. Modern cars use them and modern bearings last for many thousands of miles.
Like the arguments about silicon brake fluid there will always be detractors on any subject.
But what is the actual experience and ability of those detractors?
You could fit the carbon and it fail within a few hundred miles?
Alan
Alan Anstead

Its been discussed on here previously and if I remember correctly, the roller bearing is not suitable because the way it moves is not perfectly linear, unlike on a modern car.
Dave H
Dave Hill

Alan,

Here is my response from the archives as to why you should NOT use roller bearings for the clutch bearing.

"There are two reasons to retain the carbon thrust bearing:

1/ It is designed to wear, this is to compensate for the wear on the clutch linings. without this, the clearance would need adjusting more often. on modern cars there is some sort of automatic wear take up system on the pedal.

2/ As the bearing on the TD moves in and out it traces an arc, this means that it is only centered in one position, this could cause failure on roller bearings, however the carbon can handle this misalignment. Again on modern cars the roller bearing is constrained to move in a straight line by a tube around the primary shaft."

1952 TD

John
J Scragg

Not had any problems on my Sprites with my homemade rollers over many miles. They have proven popular amongst friends on their cars also.
Each to their own!
Alan
Alan Anstead

The following may be telling grandma how to suck eggs for everyone here but just in case and as a reminder and instruction to new readers -

How to Not Destroy Your Clutch the Easy Way -
https://www.youtube.com/watch?v=d173K60GSU8

Nigel Atkins

Bearing type throwout bearings need a guide to keep them in perfect alignment, as everyone knows, T series cars are lacking this, even though it works with the carbon bearing, it's a very sloppy setup. Here's a proper mount for a bearing, either using forks or hydraulics. PJ



PJ Jennings

Oops my response above comes over a bit brusque.

John Spragg. I would not / could not dispute what you say. A centrifugal release bearing is the optimum presentation which a fork system does not achieve.

However on Sprite and Midgets with fork and hydraulic the roller release bearings do appear to work. Time and high mileage alone will tell.
One bearing that I use, depending upon the application, does, due to its design, allow for a certain self centring (see pic).

The complaints that I have received have been about the carbon thrusts with the roll pin (which are good castings for fitting a roller into) or more modern carbon thrusts. NOS would seem to be the way to go if using carbon thrusts.



Alan Anstead

Here's John Twist's explanation on why roller bearing release bearings are a bad idea on an MG.

https://www.youtube.com/watch?v=4KIdkOWVcGg

Tim
Timothy Burchfield

I think the roller bearing style release bearings work fine with the finger type pressure plates such as those that are used with the B&G lightweight flywheel.

Jim
J Barry

I'm going with John Twist's theory. I also run an Austin America (1300) and those have a factory roller bearing. With the same driving techniques as my MG, I'm on my third roller bearing in 108,000 miles. Luckily these bearings can be changed with the engine in situ.
John Quilter (TD8986)

I actually have a carbon throwout bearing that was on a spare transmission I picked up. It could be original. I was looking at it and noted that it looked new. The face was perfectly smooth and there were no chips in the edge.

So I grabbed my caliper and checked it. The old bearing was significantly shorter. So unless the originals had less depth for the carbon. This one is used.

My theme for this rebuild is to try and make it as close as I can to what it would have come from the dealer as.

Not necessarily a concourse show car, but trying to use as much of the products that would have been used from the factory.
Bruce Cunha

This thread was discussed between 08/03/2019 and 10/03/2019

MG TD TF 1500 index

This thread is from the archive. The Live MG TD TF 1500 BBS is active now.