TR2/3/3A TR3 new clutch?

[TRclassic3]

Here's an opinion question. I'm about ready to swap out my tranny for a newly acquired A type OD. I'm wondering about clutch replacement. I know one school of thought would be to go ahead and replace it as long as I'm in there anyway, while another would be "if it ain't broke don't fix it". I have not been having any difficulty or signs of wear with the clutch. So my question is, about how many miles should a clutch last before becoming questionable?

 

[Don Elliott]

I ran my 1958 TR3A from new and had to change the clutch lining once in 1992 or so with about 100,000 miles on it. The new one has been driven another 88,000 miles with no issues.

My pressure plate is still the original one except I have changed the springs twice and the three fingers once. Before changing the three fingers that the throw-out bearing pushes against, the radius on the tips of the three fingers became flat and I re-radiused them a few times. I had to MIG weld new metal there because they were so thin.

Since 2004, the last time I had it all apart, I have had no problems.

If you are changing the pressure plate at any time for any reason in a TR3, I prefer the one with the three fingers - not the one with the 20 or so star fingers which come in towards the center. I once drove a TR4 with a clutch like this and I find that the clutch with the 3 fingers is much smoother, just as fast, and it doesn't "WHAM" with a surprise as you slowly release the clutch pedal like the ones in the TR4s and later. I heard that these are made for a SAAB and are very "sudden" because they were designed to work with an engine with 200 HP. So if you race your car and have it boosted, maybe you would need the later "stiffer'" pressure plate.

If you decide to replace the clutch, remove the flywheel and replace the pilot bushing in the rear of the crankshaft. You should do this because of the new transmission so the input shaft will stay centalised and the front-end in this pilot bushing. They only cost a few dollars. Soak it in and jar of oil for a week or so beforehand.

 

[TR3driver]

My experience with the stock clutch was similar to Don's. Best I can recall, I put about 150,000 miles on it without changing anything. Unfortunately I swapped gearboxes several times during that period, and accidentally put the wrong TOB back in, which failed a year or so later.

The "many fingers" (aka diaphragm) clutch is for a TR4A through TR6. While some vendors have sold the wrong pressure plate as Don describes; the correct pressure plate works quite well. I have one in my TR3 and my only complaint is a tendency to chatter first thing in the morning. As soon as it warms up a bit, it works just fine. And likely if I would fix the oil leak at the rear main seal, the chatter would resolve itself too :wink:

But there are other changes required to use the later clutch, including either redrilling the flywheel or using a TR4A flywheel; and shortening the gearbox front cover. Not recommended unless you have a specific reason for doing so.

 

[TRclassic3]

Don and Randall

Thanks for the advice. As I beleive the current clutch to only have about 20K miles on it I will let well enough alone. I had the transmission out about 4 years ago and upgraded the fork (including extra bolt through the shaft) and bearing (Koyo as I recall)and bronze sleeve. Even though it's a TR6 A type, I'm replacing the 4A (at least I think it's 4A and not a 4)currently in the car, so some of the conversion issues have been done. I measered the bell flange and compared to the one that is in the car and they are the same.

Thanks again for the info.

 

[TR3driver]

Even though it's a TR6 A type, I'm replacing the 4A (at least I think it's 4A and not a 4)currently in the car, so some of the conversion issues have been done. I measered the bell flange and compared to the one that is in the car and they are the same.

One thing to watch for, the later TR6 gearboxes had thicker flanges. I had to install longer studs into the cylinder block, and shorten the clutch pushrod. Pretty sure I used longer bolts all-round as well.

 

[Don Elliott]

Here's that later gearbox with the thicker flange. You can identify it easily from the protruding cast bosses where the longer studs and bolts are required to secure the bell housing to the rear of the engine block.

 

[TR4nut]

Inspect the throw out bearing carefully - the lifespan of the one I last used was less than 20k miles.