Help with GT6 engine mountings

[BiTurbo228]

Does anyone know any dimensions for the GT6 engine with regards to the chassis? I know that they're mounted on at an angle fore-aft, with the rear of the engine lower than the front, but does anyone know by how much? Or, say, the height of the rear from a given piece of bodywork.

I need to weld on new brackets onto my Spitfire chassis to mount the TR6/2500-type gearbox, but I'm not sure what sort of height it needs to be mounted at.

[Nick Jones]

I suggest you worry more about the position of the propshaft flange as the gap between the chassis and the bottom of the handbrake recess in the prop tunnel is not very large.  I reckon you want to aim for a comfortable miss between the bottom of the prop/top of chassis and no more.  You can always pack things up a little but going down is harder.  The prop rubbing on the floor makes a nasty noise........ (guess how I know that  :X)

Nick

[BiTurbo228]

Nick_Jones wrote:

The prop rubbing on the floor makes a nasty noise........ (guess how I know that  :X)

Nick

Ooh dear. That doesn't sound pleasant.

I haven't got a prop at the moment. I'll need to get one made up to go between my TR gearbox and GT6 diff. I suppose I could use the old propshaft as a dummy, and go from there.

Actually, I wonder whether the bigger gearbox will fit within the cutout in the body, or whether I'll need to do some modification there.

[Nick Jones]

The floor may need a bit of a trim.  You also need to consider the speedo drive (there should be a right-angle thingy).  Not sure about the TR/saloon box, but I know that the speedo drive wanted to share space with chassis when I used one of the longer 1850 derived J-type gearboxes in my Vitesse.

Nick

[Richard B]

You want the two flange faces, diff and gearbox to be as parallel and in line as possible.

The more out of position they are, the more driveline vibration & shorter UJ life you will have.

[BiTurbo228]

Nick_Jones wrote:

The floor may need a bit of a trim.  You also need to consider the speedo drive (there should be a right-angle thingy).  Not sure about the TR/saloon box, but I know that the speedo drive wanted to share space with chassis when I used one of the longer 1850 derived J-type gearboxes in my Vitesse.

Nick

I hadn't considered that. Shall have to keep and eye on that when I mount it. How did you get around that?

Richard_B wrote:

You want the two flange faces, diff and gearbox to be as parallel and in line as possible.

The more out of position they are, the more driveline vibration & shorter UJ life you will have.

Gotcha. Shall see if I can get a bit of a dummy driveline hooked up so I can do some testing. I reckon it'd probably be a good idea to build some adjustability into it as well. Laterally with a slot as opposed to a simple hole, and height with shims or something.

[esxefi]

you wont have that much adjustability as the centre dash brace will limit you.

I had a vibration with my prop for some time with a big box fitted and tried various ways of aligning flanges(one way using a pen laser mounted in a machined boss which bolted onto the flange at either end).

in the end it was the prop which was out of balance,and it being a bespoke built one to boot.
but rebalanced and refitted and all ok.

the flanges shouldn't really be out of line enough to cause any major issues but as Richard says the more parallel the better.re clearances.you can get one built using a smaller diameter tube giving more scope for adjustment.

the angle drive;-it's tight.you may have to relieve the chassis rail inner flange to make it fit,and the route for the cable is not very suitable.
i ended up going for a digital speedo using pickups on the front hub.

[BiTurbo228]

esxefi wrote:

you wont have that much adjustability as the centre dash brace will limit you.

I had a vibration with my prop for some time with a big box fitted and tried various ways of aligning flanges(one way using a pen laser mounted in a machined boss which bolted onto the flange at either end).

in the end it was the prop which was out of balance,and it being a bespoke built one to boot.
but rebalanced and refitted and all ok.

the flanges shouldn't really be out of line enough to cause any major issues but as Richard says the more parallel the better.re clearances.you can get one built using a smaller diameter tube giving more scope for adjustment.

the angle drive;-it's tight.you may have to relieve the chassis rail inner flange to make it fit,and the route for the cable is not very suitable.
i ended up going for a digital speedo using pickups on the front hub.

How much did your custom prop cost, and who did you get to make it? I'll be looking for one of them in the not-too-distant future, and I've been recommended Bailey-Morris but I haven't done all that much research.

Also, is your digital speedo just a little readout or its own separate dial? I've been considering getting one as I'll have a bit of a mish-mash of parts, but I'd prefer something that used the original dial-face at least.