Mating 2500TC engine to TR4a gearbox

[sentwistle1419]

After 25 years of owning a 2500TC Vitesse convertible I am now switching to a TR4a.  I love the 6 cyclinder engine so much that I am swappig it into the TR.

I am sure there are people in the club who have done this swap and so can I ask for some advice please.

The work will be done by a local mechanic who used to work at the local Triumph dealership then at SAH here in Leighton Buzzard.

The 2.5l to be used is from a 2500 TC (estate) so it comes with twin SUs.  The engine has been extensively rebuilt inc. rebore and new valves.

We have hit a snag as the clutches seem totally different as per this photo.  The TR parts are on the right.

ANY suggestions welcomed!  If we can find a centre plate with the right spline and not too much hub, we can drill the adapter plate to suit most of  the bell housing holes and drill the bell housing for the top three block studs.

Thanks Steve

[NonMember]

What gearbox did you have in the Vitesse? The clutch plate on the left looks like a fine-spline Dolomite 1850 one, which would be a common fit on a Vitesse with an "uprated" gearbox using Dolomite internals (it's not quite that simple but pretty close) which was a common mod at one time. My Vitesse is like that, as is my GT6.

I would expect a 2500 saloon clutch to be much more like the TR one in your right hand photo.

[sentwistle1419]

22 minutes ago, NonMember said:

What gearbox did you have in the Vitesse? The clutch plate on the left looks like a fine-spline Dolomite 1850 one, which would be a common fit on a Vitesse with an "uprated" gearbox using Dolomite internals (it's not quite that simple but pretty close) which was a common mod at one time. My Vitesse is like that, as is my GT6.

I would expect a 2500 saloon clutch to be much more like the TR one in your right hand photo.

Thanks Rob, I will try to check that.

Steve

[johny]

Have I got this correct, your basically making a TR5? Your want a 2.5TC engine to mate to a TR4 gearbox so what has the fine spline clutch got to do with the set up?

As said your Vitesse probably had a Vitesse flywheel fitted to suit an uprated 'small chassis' gearbox and clutch. Now you would probably be best off with a 2.5 flywheel as it is designed to work the 'large chassis' gearboxes and clutch like the TR's....

[thescrapman]

TR4 gearbox will have a big input shaft, much larger than a saloon. Saloon uses same clutch as standard Vitesse , so 10 spline.

TR box clutch will be very heavy as well in use.

Sell the TR box and fit a saloon box. Needs to be an A type overdrive one.

And you get a lighter clutch as an added bonus.

[johny]

If you do swop gearboxes the only thing you might have to be wary of is the first (and possible other gears) ratio as I believe its varies for different models. This makes sense for example with the saloon as its heavier than a TR although of course there might be difference in axle ratios as well. Ive found this site helpful:

Gear Ratio Speed Calculator for Standard Triumph Drivelines - RichyRichRacing