1098 clutch pressure plate

[ColinChandler]

Hello everyone,

I was just wondering how much horsepower a 1098 clutch pressure plate can transmit before things become marginal?

Obviously its more than man enough with a standard 1098cc engine and I have one in my 1275 Minor combined with a Ford driven plate and a Sierra gearbox. Again it gives no problems so I just wondered if anyone has any experience using this pressure plate with higher tuned 1275's. Basically will it be nearing its limit now or will it still have a little bit more oomph in reserve?

Many thanks, Colin.

[bmcecosse]

It's only a problem if you do 'racing' starts and gear changes. How much power do you think you have ??

[ColinChandler]

Hi BMC,
The engine I'm going to use will have around 100 bhp.
Thanks, Colin.

[bmcecosse]

Should still be ok if you treat it with respect.

[ColinChandler]

Thanks BMC,
I'm not into wild starts so the car's just for average driving.
Cheers, Colin.

[bmcecosse]

With 100 bhp it's going to be some average !

[philthehill]

I would suggest that a 1098cc clutch cover would not be capable of transmitting 100 bhp and even with gentle use it would not last long
Having been down this route and found the clutch failing at about 80bhp I had to upgrade the cover and centre plate.
I used a 7.5" AP cover and centre plate fitted to a modified Midget flywheel. The parts were obtained from MOSS Performance.

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Note the comment regarding power in excess of 90bhp on the MOSS parts listing which I will endorse from practical experience!
At least with the 7.5" clutch you will have a good selection of covers and centre plates to choose from. Just make sure that you have the right number of splines to the centre plate.
Currently using a 7.5" RS2000 AP competition cover and centre plate transmitting in excess of 130bhp at the flywheel.
If you lighten the flywheel make sure that you do not take too much off as the flywheel can disintegrate if the pressure plate loading is excessive. To cope with the additional flywheel loading I have a special steel flywheel fitted.

[bmcecosse]

But I imagine you are doing 'racing' starts and changes Phil! If the power is dropped/clutch released/gear changed/clutch engaged - and then power reapplied I don't sees an issue. I did once rip the centre out of a 948 clutch plate....but it had seen 'some action' ....

[philthehill]

With the current engine/clutch yes - but the comp Minor and my Series 2 were on the road years ago with smaller 998cc engines developing less than 80bhp and the standard 1098cc clutches then fitted were struggling.
For peace of mind I personally would upgrade the clutch assy.
The problem with developing extra power above standard is that you improve/upgrade the clutch and you move the weakness further down the transmission. For example:- upgraded the engine the clutch fails, upgraded the clutch and the gearbox fails, upgraded the gearbox and the half-shafts fail, upgraded the half-shafts and the diff fails and so ad infinite - you upgrade the engine and you start all over again upgrading the transmission.
Been there done the transmission blues and got the tea shirt as well as the video.

[ColinChandler]

Hello BMC and Phil and thanks both for your advice.
Yes, you put things very well Phil. With the clutch now "almost" sorted ie I need a more substantial one, I can move along the line. The Sierra gearbox will be ok and the halfshafts are already uprated which then just leaves the diff to ponder. Stopping is fine too with discs at the front and Wolseley drums at the rear. Hopefully things are progressing in a balanced way.
Thanks again, best wishes, Colin.