Noobish question about transverse LMP and GT gearboxes

[chernaudi]

I've wondered for a while about how transverse gearboxes work on MR and FR GT and LMP cars. I know that XTrac. Ricardo and Hewland make primarily transverse gearboxes for LMPs and GTE/GTLM and GT3/GTD cars.

My big question is how does the internal layout of a transverse LMP or GT gearbox. Namely, how the input shaft drives the transmission and diff clusters? Could someone help me visualize how this layout works in these applications?

[jimclark]

https://www.google.com/search?q=tran...t=firefox-b-ab

[Richard C]

Originally Posted by chernaudi

I've wondered for a while about how transverse gearboxes work on MR and FR GT and LMP cars. I know that XTrac. Ricardo and Hewland make primarily transverse gearboxes for LMPs and GTE/GTLM and GT3/GTD cars.

My big question is how does the internal layout of a transverse LMP or GT gearbox. Namely, how the input shaft drives the transmission and diff clusters? Could someone help me visualize how this layout works in these applications?

It depends upon if you have a transverse or longitudinal driveshaft. So for example, with a longitudinal driveshaft, then a longitudinal gearbox makes sense. A simple example is a FWD road car (tons of diagrams available online for this). The engine crank shaft, gear cluster, differential and drive axles all operate on parallel axis.

But I expect you are more interested in the combination of a longitudinal crank with a transverse gearbox. So with a longitudinal crank, regardless of transmission style, at some point power flow has to be rotated 90 degrees to arrive at the drive shafts. For a classic longitudinal gearbox this happens with an output shaft that has a pinion gear and a ring gear on the differential (tons of diagrams online for this as well).

It seems that for most transverse gearboxes that have a longitudinal input this happens shortly after power enters the gearbox (I think before the gear cluster). Then at that point everything is longitudinal including the differential. Very similar to a classic transverse as in a FWD car.

As suggested in the post above, you can Google around to see some power flow diagrams. I did a quick search myself and while you can see photos of the exterior, I didn't find a quick example that shows the power flow very well. You might also find something on one of the manufactures website such as Xtrac...

https://www.xtrac.com/sectors/motorsport/sportscar/

Richard