Please visit the Club's website https://www.dloc.org.uk/ to join. Visit https://www.dloc.org.uk/adhoc to DONATE towards the cost of the forum.
Please don't post someone's email address to avoid it being harvested by spambots and it's against GDPR regulations.
Always look at "ACTIVE TOPICS" to see all posts in date & time order as they are sometimes moved; or look at "Your Posts".
Please add Reg. nrs. when posting a photo or anything about a car as this will help searches. Don't add punctuation next to nr. as this negates search.
CHANGED YOUR EMAIL ADDRESS since registering?, click your username and check your address in User Control Panel, Profile, Account Settings.
If you want help to register, use "contact us" at page bottom for help.

SP 250 clutch

Post Reply
Warsash 2
Posts: 332
Joined: Sun Feb 28, 2016 1:53 pm
Location: Southampton

SP 250 clutch

Post by Warsash 2 »

Hi
I seem to remember a discussion on clutches for a SP250. I am having the engine rebuilt and the last clutch thrust bearing only lasted 3000 miles. Even dsome one resting their foot on the clutch could not burn it out that quickly. I thing it was suggested that there are/were some diaphragm clutches available for the SP. Does any one know who has them?
Thanks in advance
Regards

Colin

Vortex O'Plinth
Extra-Wise Man
Extra-Wise Man
Posts: 1065
Joined: Fri Feb 12, 2016 8:15 pm
Location: Gloucestershire

Re: SP 250 clutch

Post by Vortex O'Plinth »

There were actually a batch of diaphragm clutches produced specifically for the SP. Check with Barry Thorne, he may still have them, although I think I had the last one. They were interchangeable with the original clutch and used the original clutch plate and release bearing. A common retrofit nowadays is a Healey 3000 unit although I believe the flywheel needs to be drilled for the dowel pins and a release bearing with adequate stand-off needs to be sourced - I'm sure someone else will elucidate. There's a fair amount of post on the subject on this forum and the old one.
Nick

"Don't bother with the Air & Space Museum - there's nothing to see.......".

Fossil
Wise Man
Wise Man
Posts: 516
Joined: Sat Feb 13, 2016 5:08 pm
Location: Helensburgh, Argyll

Re: SP 250 clutch

Post by Fossil »

Colin

I fitted an A-H BJ8 diaphragm clutch to the SP250 between 2011 and 13 when the engine was rebuilt and the conversion to V8 saloon Jaguar 4 synchro mod box done. It is the same as the 9.5 inch Jaguar clutch. My main reasons for doing it were that it lightens the clutch release pressure substantially and that it copes with up to 200bhp (the original clutch can slip in top gear in some circumstances). I bought mine from Denis Welch the A-H specialist supplier; there is a website.

I regret that I cannot answer your question about the release bearing because of the conversion which used the Jaguar release mechanism. However I know that Wilf Stevens fitted one at around the same time as me because we exchanged ideas at the time. He retained the SP clutch plate because the splines are different on the SP input shaft, but I don't recall him mentioning any issue with the release bearing. He may have mentioned it in one of his technical guides, if he did one about the diaphragm clutch conversion. Yes the SP flywheel needs to be drilled for the second dowel.

Once done it transforms the clutch action, highly recommended!

B regards

Fossil

A.N.Other
Wide Man
Wide Man
Posts: 551
Joined: Tue Feb 16, 2016 12:45 pm
Location: Leeds

Re: SP 250 clutch

Post by A.N.Other »

The thrust bearing must have the correct fork lugs. If the lugs are too shallow then the bearing doesn’t sit central to the assembly when the clutch is used. That in turn causes rapid wear on the carbon face.
It is possible nowadays to get a plastic bearing to replace the carbon one. They last much longer, probably longer than the rest of the clutch assembly.
Colin,
I may be slow but I’m rough as well !

Ian Hastings
Posts: 163
Joined: Tue Mar 15, 2016 3:00 pm

Re: SP 250 clutch

Post by Ian Hastings »

Most large towns have a motor factor who specializes in clutches and brakes so take your old plate and cover with their release bearing into them and they should be able to fix you up with a matching diaphragm clutch. Some clutches fitted to various models of Transit and Sherpa vans, Land Rovers and SDI Rovers will be suitable. Originally I fitted the Austin Healey clutch from BT but the throw out on the pressure ring was 22 thou which wrecked the thrust bearing in less than 300 miles!
Drilling the flywheel to fit new dowels is not essential as these are only there to locate the cover plate whilst you fiddle to screw in the bolts. You can do that with only one dowel remaining.
It is important to check the function of the slave cylinder as the push rod length may need adjusting to ensure adequate travel of the internal piston to actually operate the clutch. Push the piston back in as far as required, you may even need a longer rod.
Whilst you are doing all this it is a good idea to replace the locating bolt that locates the operating fork on the cross shaft as these have a habit of fracturing and also fit a small spring from the slave cylinder mounting bracket to the operating lever to ensure there is not constant contact between the release bearing and the cover plate. It needs to be stronger than the slave cylinder internal spring; it's not essential but every little bit helps reduce the wear. Just about every other car has them so why not the SP?

Post Reply