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 conversion

JimL
Posts: 44
Joined: Sun Feb 28, 2016 8:05 am
Location: Aberdeenshire

SP 250 clutch conversion

Post by JimL »

I'm soon to pull the gearbox to fit a overdrive unit at the same time I intend to change the clutch to a diaphram type Can anyone give me a note of the parts required? I guess a Healy 3000 clutch is the way to go or I believe a Ford Transit clutch is another option. Part Nos would be a great help for the pressure plate, driven plate and release bearing and release bearing carrier, re-dowling the flywheel won't be an issue for me. Any tips most welcome. JImL

gc0700
Posts: 82
Joined: Wed Sep 21, 2016 8:29 pm
Location: Bury St Edmunds

Re: SP 250 clutch conversion

Post by gc0700 »

I did this job a month or two back. In my case I simply called Barry Thorn and explained what I wanted. They all turned up a few days later.
In my case I kept the original driven plate and release bearing carrier and just replace the pressure plate, driven plate and release bearing.
Barry also has a clutch alignment tool available, if you ask nicely😊
Tim

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

Re: SP 250 clutch conversion

Post by A.N.Other »

Do you know of JFO 263 an SP in Aberdeenshire. It's been done on that one and I think I left the details in the manual or parts book that went with the car. I have done this a few times using various combinations of boxes but don't have the details anymore, that could be where the mention of a Transit plate comes from.
Wilf, Dragon on the forum, is always a good source of info on these matters.
That said I am lucky in that I live near an excellent supplier of just clutches. The kind of place that you walk in, show the guys what you have and they go to the shelf and come back with the bits you require. If they could help over the phone, I don't know. They are called Calder Clutches based in west yorkshire. They did a diaphram pressure plate, clutch plate and and thrust bearing all for under £100.
The first time I did the job I got the bits from an AH specialist, BJN8 bits if I remember and it cost nearly £400.
You could try a clutch supplier where you are !
Colin,
I may be slow but I’m rough as well !

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

Re: SP 250 clutch conversion

Post by Fossil »

I obtained a BJ8 clutch cover and plate from Denis Welch the online AH and other parts source, perhaps the same one that Colin used? I understand that it is identical to the Jaguar 91/2 inch diaphragm clutch, at least that's what was on the invoice.

Cheers

Geoff

sebsdart
Posts: 43
Joined: Tue Feb 23, 2016 6:15 pm
Location: Orne,France

Re: SP 250 clutch conversion

Post by sebsdart »

I got a diaphram plate and release bearing from Simon at Manners,he said something about there being a stock of these available as they were originally for the manual 250 v8 saloon.
Seb

daimlersteve
Helpful Person
Helpful Person
Posts: 496
Joined: Wed Mar 09, 2016 11:20 am

Re: SP 250 clutch conversion

Post by daimlersteve »

I did this exercise recently. Regarding clamp and release pressures of what appear to be identical pressure plates.
The org. Healy cover has 1400 clamping lbs and 290 lb release 9 very light pedal) . The Jag version Six cyl version seems to have been standardised at 2100lb. so will have a higher pedal pressure. Then there is the Cosworth Sierra that looks the same but has 1750 lb and 305lb release just to throw into the mix. This is the one i have used in my latest iteration of an SP motor.
All these from "AP" or the later company names of the same supplier.
AP Racing are not in any way associated but have a very good web site for selection of clutches.
Steve

David S
Posts: 188
Joined: Sun Feb 21, 2016 9:23 am
Location: Forest of Dean

Re: SP 250 clutch conversion

Post by David S »

Interesting all this..... Mine has a Land Rover clutch cover now, it is diagphram type. It says both HE5798 and URB100760 on the AP Borg & Beck boxes label.
However, I would have thought the easiest way of lightening the pedal is to put a bigger master cylinder on.

Clutch is nice and light.

on a separate note..... Daimler Steve, please can you advise of the correct clearance between the [Toyota 5 speed, 12mm] spindle on the front of the gearbox and the [bronze] bush in the 1" crankshaft. I have to make a new bush and not sure of sizes.

David

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 conversion

Post by Vortex O'Plinth »

David S wrote: Wed Sep 20, 2017 9:17 pm ...However, I would have thought the easiest way of lightening the pedal is to put a bigger master cylinder on.....
If a larger diameter master cylinder is fitted this will result in a lower hydraulic pressure in the hydraulic system for a given applied pedal force, so a larger master cylinder will increase pedal force, not reduce it.

Conversely, if a larger slave cylinder is fitted, the pressure generated in the system by the pedal force will be applied over a larger area, generating more force to release the clutch and so requiring a lower pedal pressure.

If changing cylinder sizes, the effect on pedal travel should be taken into account. A larger master cylinder will transfer more fluid for a given pedal travel, so pedal travel to release the clutch will be reduced. However, a larger slave cylinder will require more fluid to travel the same distance, so pedal travel will be increased.
Nick

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

daimlersteve
Helpful Person
Helpful Person
Posts: 496
Joined: Wed Mar 09, 2016 11:20 am

Re: SP 250 clutch conversion

Post by daimlersteve »

Hiya David. the 12mm spigot is too small for a bush ( org. was a bearing.) Colin at 5 speed conversions here in nz presses a bearing inner onto the shaft to give it a much larger bearing surface applicable for a bush. Dont recall the size but if you contact him he should tell you what he uses.
steve

JimL
Posts: 44
Joined: Sun Feb 28, 2016 8:05 am
Location: Aberdeenshire

Re: SP 250 clutch conversion

Post by JimL »

Thanks Fellows for lots of very good information.
I somehow like the idea of going with the Cosworth Sierra pressure plate. Steve I guess there is no re-drilling or other mods to carry out if using this one?
I assume the release bearing and bearing carrier to use is the Healy 3000 one?
I guess the 1400lb clamping force of the Healy pressure plate would be more than enough for a standard tune SP250 or was there a reason for upping it to the Cosworth 1750lb clamping force. I guess this increased release pressure will load-up the crankshaft thrust bearings a bit when disengaging the clutch though, but probably not enough to cause any concern.
No doubt the Land Rover cover plate would be the most cost effective. Thanks for posting the part No. HE5798 and URB100760 on the AP Borg & Beck, most useful.
Was wondering if the Manners 250 v8 saloon has a much higher clamping force than the Healy or Cosworth pressure plates. Seb did you notice much difference/increase with the force required to operate the clutch?

Post Reply