Clutch advice please

[Davidb]

Hi all, So I am in the process of building up an engine for my Elan using a BDD crank and 84mm block for fast road use. I have hit a snag in that the clutch that came with my car-which was raced in period-is a 7.5 inch with solid disc-no springs. I have been advised that this will not stand up very long, especially as I intend fitting a 3.54 cwp. I have yet to get a flywheel to fit the crankshaft and was thinking of just using an ordinary six bolt. I am on a budget with this... What do the experts suggest?

[Davidb]

OK, I will respond to my own question: What is the size of the standard clutch in an Elan?

[nmauduit]

standard lotus twin cam clutch is 8.5" as offered from various vendors

[Davidb]

Thanks for the response !

I did a little more research and found that, according to this forum anyway, the four speed cars had an 8" clutch disc and the five speed an 8.5" clutch disc.

This puzzles me since on my car the clutch is 7.5" and the flywheel, which shows no sign of having been re-drilled, is the original four bolt, cast iron item.

So, were earlier cars fitted with 7.5" clutches?

[nmauduit]

I believe racers tend to use lower diameter clutches (if need be multi plates) for reduced inertia momentum... I'm not the best person to talk about that as I don't have extensive experience of clutches and certainly would not give advice in that matter - just wanted to point you to a direction of research to keep your ball (elan) rolling... if you have a specific requirement as far as torque is required (I see you have an exotic crank, high capacity engine...) you may have to be careful with your choice. I have fitted a "heavy duty" 5 speed clutch (Helix from QED) and I'm happy so far (only 10 - 12 hours though, and not a super torque engine either)

[Davidb]

Thanks again!
So no problems with the bigger clutch hitting the bellhousing?

[Davidb]

Well, I think I just found my answer: I found a worn out 8.5" racing clutch assembly in the boxes of parts that came with the car-unfortunately no flywheel though. It seems the flywheel was changed at some point to use a smaller clutch-these were fitted to Cortina Mk2s and Caterham Sevens among others...
The trials and trepidation of having a car with "History".

[nigelrbfurness]

Sounds about right. Cortina Mk1 GTs had a 7.5in clutch and they will work in an Elan if the right release bearing is used, though not recommended for long life...