Club Triumph

Morning all,

I've got myself a donor herald which has a MK3 spitfire engine with a 1500 single rail gearbox and J type overdrive already fitted. The herald is a wreck so I want to remove the engine and gearbox to put them in my MK3 spitfire. Obviously the propshaft will not be the right size in the herald at the moment.

I've found online the various lengths of propshaft for different Mks of spitfire but I haven't found any dimensions so you can mix and match. Can anyone confirm what size propshaft I'd need? I assume the difference of length is down to the single rail box being a bit bigger than the 3 rail so using a 1500 overdrive propshaft should work but I don't know if anything else factors into this.

Cheers for your help!

This site has some useful info:

https://www.canleyclassics.com/?archive=propshaft-problems

Hi Tight wad,

I've seen the stuff on canleys website but I was looking for clarification that the difference in size of the propshaft is down to the size of the gearbox+overdrive and not some other factor that was changed between the mk1-4 and the 1500.

Cheers

Well according to that info the early Spitfires with 3 rail OD boxes had a propshaft 1" longer than the later ones fitted with the single rail unit. The Herald data also confirms a 1" length difference between these two types of gearboxes hence there isnt be any other factor involved... 

Oh excellent thank you, I hadn't actually clocked the herald figures so hadn't put two and two together! Hopefully that'll be the answer then.

Many thanks.

Quoted from aknight123456-

Morning all,

 

I've got myself a donor herald which has a MK3 spitfire engine with a 1500 single rail gearbox and J type overdrive already fitted. The herald is a wreck so I want to remove the engine and gearbox to put them in my MK3 spitfire. Obviously the propshaft will not be the right size in the herald at the moment.

 

I've found online the various lengths of propshaft for different Mks of spitfire but I haven't found any dimensions so you can mix and match. Can anyone confirm what size propshaft I'd need? I assume the difference of length is down to the single rail box being a bit bigger than the 3 rail so using a 1500 overdrive propshaft should work but I don't know if anything else factors into this.

 

Cheers for your help!

You need spitfire 1500 od  length prop, but (assuming you have the mk3 diff, squarish front flange, 1/2" spanner bolts) you need the mk3 type rear flange on the prop.

In all honesty, I would buy new for a propshaft. An out of balance prop makes life miserable, and swapping UJs let alone a flange can put it out (real experience) and a 45 year old prop with a CV joint will probably be beyond its best. 

Get it in the car, measure, then call Dave Mac....

Thanks for the info Clive! Yeah I'm definitely getting a new propshaft, hadn't thought about the flange though! Just curious...who's Dave Mac? 😅

Dave Mac propshafts who manufacture and overhaul propshafts in Coventry.

As a guide James Paddock does new 1500 OD props for 110 +vat and then of course, as Clive says, youd have to change over the rear flange. However an alternative to this would be to swop to a higher ratio 3.89 diff from another Triumph model as these have the same case but with a 1500 flange. This would only worth doing if you want to reduce your engine revs for cruising and its probably best to get advice from others as to the suitability...