The V8 Owners Forum -

Tom
Did you see the post regarding the flywheel sizes?
cheers
P

Hi Paul, Yep saw the post and just given them a ring- heavy duty one anywhere between £180-£280..! I think I might be making my own up to get it going first then getting a heavy duty one made up if it appears to be a weak link!

Hi TC,

Just in case you missed them. I posted some photo's on the previous page.

Ged

Ah! Thanks Ged I had gone straight to the 2nd page. They are some funny old joints on the ends!!! Not sure if I'l be using SD1 prop

Those joints look like a serious weak spot, surely they must be replaced by UJ's on a heavy duty prop? Dont suppose anyone has a pic of an MGB prop now?

...take 2!!!

My TR7/SD1 prop has a Jaguar sliding front end to it. The rear bolts to the diff as normal.

topcatproduction wrote:Ah! Thanks Ged I had gone straight to the 2nd page. They are some funny old joints on the ends!!! Not sure if I'l be using SD1 prop

Those joints look like a serious weak spot, surely they must be replaced by UJ's on a heavy duty prop? Dont suppose anyone has a pic of an MGB prop now?

...take 2!!!

Hi TC,

I've given those props a lot of abuse over the last 20 odd years & I haven't broken one yet. I have twisted a few rear axles though.

I'm just aware that the blower might be upping the proper low down torque to, well, quite a bit! I looked at a couple of Jag XJ6 ones on ebay and they didn't appear to have sliders?? What other jag models will have a flange to fit LT77? 2T torquey cars would appear to be a stronger option...

I may be wrong TC but I think the lt77 might break before the prop shaft.

you have a point

Tom
be guided by the drive shafts, the diff gives you a ratio drop of about 3 to 3.5 :1 depends on ratio, take the diamiter of the drive shaft at it's narrowest point and devide by the square root of the diff ratio, if the propshaft is bigger in diamiter than this at it's narrowest point then the drive shaft will fail first. as an example, if the drive shaft is 1.5" diamiter and the diff ratio is 3.44 then anything over 0.81" should be fine. or just find out the diamiter of the output shaft of the lt77 and provided that is bigger than that your box will fail first.
Mike

TC the smallest diameter on the SD1 propshaft is 1". Just in case you want to do some calculations.

Tom,

Are you needing LT77 to sierra cosworth if so the Hoyle IRS for the MGB uses a cosworth diff which is mostly mated to a LT77. as does the Hawk Cobra that can use the same IRS.

Obviously length will come into the equation but if you can find out who makes the propshaft they would probably do one to your required length.

For links just Google Hawk Cars and Hoyle, John Hoyle is quite helpful.

Kevin.

Cheers guys, I'm using cossy drive shafts too which are pretty beefy (compared to the mx5 ones!!!) I'd say about 26mm diameter at a guess. I just wanted to make sure the prop wouldnt fail- LT77's are £40-50 each, making a prop up will cost more! I was shown a prop from a Supra that was twisted like a bit of pasta! Noticed XJS props are very cheap and made to handle 300 horses with a lot of weight- so should be way more than adequate for me! They also have a slider built in- so just have to stick a cossy diff flange which I may have found on the back- or make an adapter.

What do you think to this http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 0354015706

It might even be exactly the right length! There are a couple of xjs ones on ebay at half the price, but I'm not going to buy them if the sellers cant be arsed to answer simple questions.

Just got another quote, company called Firow said they could modify the diff end of an XJS prop for £65 (plus vat, postage, and my postage too them so about £85 +vat) or just fabricate me a new one for £145 + Vat. Price seems pretty good, for the sake of an extra £60 which I would have to buy a prop for, about £40 and risk the UJ in the good end being knackered and needing a refurb it makes sense to just get one built.

Any thoughts before I go ahead? Oh- can someone also confirm the flange diameters and bolt PCD's of LT77 and sierra lsd flanges? Measuring them under the car might not be perfectly accurate...