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TR4/4A TR4 & 4A Clutch pressure plates?

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karls59tr

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It seems the Quinton Hazel pressure plate that I bought on Ebay many years ago for my TR3 is actually a TR4 plate. I compared it to the plate I took off the 4A today and there are some differences between the two. The 4A center hole is 4&3/4" wide and the center hole on the 4 plate is 5" wide. Other than that there dosn't appear to be a whole lot of difference between the two pressure plates and they are both the diaphragm type. Is there any reason I can't use this 4 pressure plate on my 4A?
 
I used a Quinton Hazel clutch set when I restored my TR4A back in 1984/1985 and didn't have all the great resources we have today. :smile:

Although it worked OK, it was one of the ones with the extremely high release force. If I had known that I would not have purchased/used it. Of course it's hard to tell what they are supplying today. Any identifying numbers or marks on the pressure plate itself? Also, do you have the QH part number?

Scott
 
racingenglishcars said:
Didn't the 4A come with the diaphragm type? I believe it had three dowels as opposed to the coil spring / 3-finger pressure plate with two dowels.
Click to expand...

Yes, that's right. IIRC the bolt circle is slightly different as well.
 
Scott In white paint on the side of the pressure plate is the #1181. On the Quinton Hazel box it's stamped 10015 Nov 81. On each of the 3 sides of the QH plate there is a 1/2"x3"steel flex strap(Not up on clutch plate terminology?)There are three abutments that come off the circular plate casting.The 3 flex straps each attach to an abutment. On the original TR4A plate that I took off the straps are mounted under the abutments but on the QH plate these straps are mounted "above" the abutment! I'm pretty sure the QH plate is for a 4A as it is identical to the one I took off the 4A except for the mounting points described above. (Iwill try to post pics) Maybe the difference in the mountings would account for the heavy pedal on the QH plate you had??? How bad was the release force on yours? I may use this QH plate as it is in perfect condition. Karl
 
Karl,

So sounds like that part is circa roughly the same era as the one I used. I found an old QH catalog showing the Q10015 part number listed for the TR6 so I would have expected that to also be applicable to the TR4A. The catalog shows a QH1008 pressure plate for the TR4A for some reason.

What was interesting was the list of other cars that this pressure plate was used for as well.

1969-71 Bedford 14/35 cwt. CF 97000 Van, 1599, 1975cc petrol
1969-74 Bedford 14/35 cwt. CF 97000 Van, 4/108 engine

1973-74 Triumph Dolomite Sprint
1965-74 Triumph 2.5PI Mk. I, II
1969-74 Triumph TR6

1972-74 Vauxhall Viva HC 1800
1972-74 Vauxhall Ferenza 1800
1973-74 Vauxhall Magnum 1800
1973-74 Vauxhall Magnum 2300
1972-74 Vauxhall Victor FE 1800
1972-74 Vauxhall Victor FE, 2300
1972-74 Vauxhall, VX4/90 FE
1968-72 Vauxhall Victor FD 3300, SL (Estate)
1968-69 Vauxhalll Ventora FD I, II, to ch. OV252009
1962-70 Vauxhall Veloz, Cresta PB, PC, Viscount to ch. IV324999
1972-74 Volvo 140 Series (B20 eng.)

Regarding how hard it was to operate, I do recall that it took quite an effort to keep it engaged at extended stops. I would take a look at the Buckeye Triumphs article on TR6 clutches (TR250/TR6 Reliable Clutch) to see other documented information on different brands having different release force.

Scott
 
Karl,

Interesting, I just checked the TR4A SPC and they did have a different part number for the pressure plate and disc than the TR6. The throw-out bearing part number was the same.

TR4A
Pressure plate 212132
Clutch disc 212526
Throw-out bearing 142465

TR6
Pressure plate 214321 (Borg&Beck) 215422 (Laycock)
Clutch disc 148146 (Borg&Beck) 148402 (Laycock)
Throw-out bearing 142465

As far as I know everyone lists the same part now for TR4A and TR6, but I do wonder why Triumph had different part numbers.

Scott
 
HerronScott said:
As far as I know everyone lists the same part now for TR4A and TR6, but I do wonder why Triumph had different part numbers.
Click to expand...
I don't know, but it seems very likely to me that they put heavier springs in for the bigger motor (remember it went from ~100 bhp to 150, a 50% increase), and then decided that the stiffer clutch would be OK as replacement behind the 4A motor. There was a lot of pressure to reduce overall parts count, as it's always cheaper to make 100,000 of a single part than 90,000 of one part and 10,000 of another similar part.

Somewhere, I've got a fairly thick book that is nothing but a list of the factory-approved supercessions. Can't lay my hands on it at the moment, but ISTR the TR6 clutch being listed as replacement for the 4A clutch.

Also FWIW, my TR250 parts catalogue has a different number than the TR6, only for the Laycock pressure plate (214388). The other parts match the TR6 numbers above.
 
Ok, I was mistaken. I found the supercession list and it shows:

old new
212132 GCC140
214321 GCC139
214388 215422
215422 GCC139

So the factory never listed the TR6 clutch as a replacement for the TR4A clutch. I'm guessing that means it was the aftermarket that decided they were equivalent. Just like that SAAB racing clutch!
 
It seems to me that when I had a TR6 trans rebuilt for my TR3 years ago I just bolted it up to the 3 flywheel and clutch and the only mod I had to make was to drill new holes in the rear trans mounting bracket about 3/4" back. So it would seem that the 6 trans will mate with a 3 clutch! What's the upshot guys? Should I try this TR6 pressure plate on my 4A and save a few bucks? :smile:
 
TR3driver said:
I don't know, but it seems very likely to me that they put heavier springs in for the bigger motor (remember it went from ~100 bhp to 150, a 50% increase), and then decided that the stiffer clutch would be OK as replacement behind the 4A motor. There was a lot of pressure to reduce overall parts count, as it's always cheaper to make 100,000 of a single part than 90,000 of one part and 10,000 of another similar part.
Click to expand...

I had that same thought as well but didn't really want to throw it out there without any more knowledge on the subject.

Scott
 
karls59tr said:
What's the upshot guys? Should I try this TR6 pressure plate on my 4A and save a few bucks? :smile:
Click to expand...

Karl,

Really your decision here and whether you want to take the risk of being unhappy with the results if it does have the high release pressure and you can't live with that.

If you either don't expect that the high release pressure will be a problem or don't mind pulling the transmission to change it then you can certainly give it a try. Other than the high release pressure I had no issues with it and put 75,000 miles on it in 5+ years, but so far you only have a sample of 1. :smile:

Scott
 
Years ago I had a PP rebuilt by the local B&B rebuilder. He asked if I wanted the rover V-8 spring (diaphram) installed and I did. It does have a much stiffer feel and has performed flawlessly since the early 1980's. I replaced the disc once just because I had it apart. Before doing this I had more than a few PP failures, none since. You'll get used to it and have no issues.
 
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