MGB & GT Forum

There have been a couple of threads recently about the roller throwout bearing or release bearing that British Parts Northwest is supplying. Mine arrived today so I thought I'd post a couple of shots for posterity and for the curious (and for the entertainment of the pathologically critical.)

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1970 MGB Black Label OD, APT VP12, Fidanza Flywheel, Flowspeed Head, Hilton AUD405 HS4 SU's, Schlemmerized Distributor, Pertronix Ignition, Saturn Alternator, 15" Dayton Wire Wheels, Falken ZE 912's, Falcon Big Bore
1972 MGB GT Blue Label OD, APT VP14, Fidanza Flywheel, Flowspeed Head, HIF SU's, Schlemmerized Distributor, Points Ignition, Saturn Alternator, 15" GC360 Wheels, Falken ZE-950s, Peco Exhaust, Frontline Costello front valance

Thanks, Looks nice.

What is the housing made of ? Looks like plastic ?

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10/73 BGT - The Aconite Bandit

Say No To Rubber Baby Buggie Bumpers

Greg.

Thanks for posting this. I got a complaint on this style of bearing from a customer. he chucked it into his lathe and found that there was runout in the body of the bearing. Not sure if this is a common thing, also not sure if it is really a problem. Just a concern.

I've been looking into roller bearings for some time and did run across a different one that I'm going to test fit. The problem is that you can never tell how good they are until after they have been in cars for a while.

Here is the image the customer sent to me:

Here is an image of the throw out bearing I'm looking at carrying. The body is cast iron and there is a delrin thrust face to allow for the non-centric location caused by the throw out arm. The big problem with roller throw out bearings is that they want to be centered on the clutch cover. The MGB throw out arm doesn't allow this due to the changine angles as the clutch wears. There must always be some sliding of the throwout bearing face to the disc. The traditional roller throw out bearings don't take this into account, so you will always have some metal to metal wear. This new design with delrin facing may be the answer.

Back in the 80's I worked in 2 different MG garages and neither would use the roller bearing throwout bearings due to
repeated come-backs. Back then they were made by QH and weren't as high-tech looking as the ones shown which appear to
have taken some cues from those used on Triumphs.
We found that the carbon throwout bearings had a long enough service life to last as long as the clutch disc.

Rich

Rich.

The roller bearings are coming back to life again, due to the problems caused by inferior quality carbon bearings coming onto the market over the last few years. Those problems are hopefully now over (fingers crossed) as the incorrectly manufactured bearings have been shut down and hopefully will never reappear.

A while back I did try to gather data on first hand experience with the roller bearings of the day, but nothing was conclusive. According to the receipts that came with my 1970 MGB there is a roller bearing in it, installed some time in the early 90s.

FWIW, I have installed two SD1/TR8 replacement clutch kits sourced from Rimmer. Mine has been in two years the other in a MGB V8 conversion about 8 years. The TO brgs have housings of some sort of composite/plastic that evidently isn't a problem. If you have seen my drag race video, you know I don't baby my cars. So the "plastic" doesn't upset me so much. I also believe the SD1 design is called a self centering? Perhaps that is what Kelvin is refering to as a problem in an MGB? Once again I will state that my MGB has a roller style that was there when I bought it in 92 and hasn't been a problem. I also will admit that I have absolutely no idea who made it.

In any case, I really don't have a big issue with the carbon brg. If you could buy one that fit without filing or grinding I'd be ok with it. MG installed them from the factory and they seem to hold up under normal circumstances. Just need to get one that matches the original. The last one I got didn't match any of the dimensions of the original. Perhaps an improvement on the design??? I'm sort of sceptical of that since it wouldn't fit in the fork without modification.

Edit: Kelvin, I was typeing as you posted. I'm glad to hear that the carbon brg quality issues are being adressed. Sounds like you and I may have the same TO brgs in our cars. I have one out of a parts car, made in UK. You are welcome to use it if you would like it for a possible development project.



Edited 1 time(s). Last edit at 2010-01-28 07:49 PM by underdog.

Interesting post Kelvin thanks!
I went downstairs to try to replicate that photo or do some measurement to compare, but I can't see how I could capture the end and ensure the hole is centered in a chuck when the outer shape of the end is not round. (It has that squared off protrusion.)
The best I did was to put the contact face down on a reference surface and rotate the body around. The position of the hole seemed to be consistant. I imagine though that after it's put into production the heat must cause some movement that wouldn't be seen in an iron body. (or maybe not, I don't know much about high tech plastics)

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__________________________
1970 MGB Black Label OD, APT VP12, Fidanza Flywheel, Flowspeed Head, Hilton AUD405 HS4 SU's, Schlemmerized Distributor, Pertronix Ignition, Saturn Alternator, 15" Dayton Wire Wheels, Falken ZE 912's, Falcon Big Bore
1972 MGB GT Blue Label OD, APT VP14, Fidanza Flywheel, Flowspeed Head, HIF SU's, Schlemmerized Distributor, Points Ignition, Saturn Alternator, 15" GC360 Wheels, Falken ZE-950s, Peco Exhaust, Frontline Costello front valance

For interest sake hHere's a pic of what I'm guessing is a old style roller throwout bearing on my 1970. Inner circle (with the white paper) spins freely against the outer circle.

Looks quite new but I was getting a shudder when I pressed and let out the clutch about half way through the motion. Members suggested it was likely a throwout bearing about to go. Now I wonder if it is the nature of this older type of bearing.

I can't seem to attach the file. Here's a link to an older post instead.

http://www.mgexperience.net/phorum/read.php?1,1004278,1005168#msg-1005168



Edited 1 time(s). Last edit at 2010-01-28 07:59 PM by sdyck.

Greg.

The question was raised by a person who had been given this bearing by a shop as a replacement for a carbon one that had failed. He wanted to know my opinion of it, because he was concerned.

I had no experience with this design and told him that. Based on his own examination, he decided to use a carbon bearing. Personally, if it was my car, I'd give it a try.

I can't use that kind of determination to recommend products for Moss to carry, so at this time I'm going to try the roller bearing sample in one of my personal cars and see how it goes.

Just to add that the one I have sitting here has the number 415600 and GT Britain stamped on it. Also, the face that contacts the pressure plate is convex or domed..not flat. Perhaps that was done to help with the problem of the fork arangement on the MGB?

Jim.

I think you are correct, the domed surface would help.

I think Steve is describing the symptom you would get if the roller bearing was off center too much. Still, I'd be in favor if a good design was around. I'm interested to know how the BPNW design works out.

What needs done is: Design a new throw out arm to go along with a new bearing so it rides dead center. Why not invest in a bullet proof system and perfect it, it's good business and I'm sure if would be a good seller. I'm surprised the Almighty MOSS has not thought about that, instead of all the glam bull**** they have instead.

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10/73 BGT - The Aconite Bandit

Say No To Rubber Baby Buggie Bumpers



Edited 1 time(s). Last edit at 2010-01-28 10:46 PM by Elfis Presley.

It seems that the roller is distributed by AP Driveline. A regular release bearing goes for $19.95 from Moss (190-300). The roller is $27 from BPNW. If anyone wants to try one, I can get it for $21 plus shipping. For the extra $1.05, it might be worth a try.

But if you want to do it right, get an annular throw out bearing that fits over the input shaft and presses straight out - always parallel to the clutch. Didn't Hap do a whole bunch of those by using a Saab part?

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Basil C. Adams
1956 MGA Coupe (Show Car)
1957 MGA Roadster (Driver)
1958 MGA Coupe (Racecar)
1959 MGA Coupe (unrestored)
1960 MGA Coupe (unrestored)
1960 MGA Roadster (Driver)
MKIII Elva Courier (E1056)
1967 427 Cobra
1972 Alfa Romeo Montreal
A coupla late MGBs
1960 Austin Healy BN7
More Cars than Brains