The V8 Owners Forum -

I'm currently running a suffix C LT77 behind a 4.6 RV8 in my Robin Hood kit car. I rebuilt the box myself with new bearings, synchros and oil pump and it's been fine for around 4K miles.

The only real issue it that it's rather low geared in 5th (0.83:1) because I'm running A 3.64 7.5" Cosworth Scorpio diff so 70mph is 3000rpm and whilst it's quite happy doing these revs, it doesn't need to be. The is a 3.3 diff available for the 7.5" diff but given that the box is probably the weakest link, changing that makes more sense at this stage.

I've built a few LT77's and I'd looked at building one with a taller 5th gear when I managed to get hold of an 72A suffix L R380 which is clearly a much better box. I've given it a quick check over and everything seems to be in good order but I'm going to swap out the 0.73 5th gear for 0.73 set which should drop the revs a bit in top.

While the box is out I'n thinking about changing the clutch. I'm using an new SD1 Borg and Beck clutch at the moment but I'm thinking of some engine upgrades in the future so a better clutch might be a good idea. The car is only used on the road and the missus also drives it so I don't want anything too fierce. Is the AP CP2394-60 Cover and the CP2346-4 Driven plate a good choice or are there better options? Any suggestions welcome.

I'm assuming you're aware the 5th speed housing is larger and moves the gearstick pickup and mountings further back?

Yes, I've cut and shut a remote linkage 25mm and it works fine.

Can you fit taller rear tyres? This would also help with the gearing.

Tom.

I would go the diff route imo.. I run a 7” 3.14 Sierra diff with a R380 in my seven, which is fine. They are a little tricky to get hold of, though you can get a new gear set and the diff rebuilt if it’s not an original 3.14. Road and race did mine, shoved a qualified ATB in at the same time. A bit pricey but worth doing launches off the line PDQ , donuts easy as well.

Rear tyre diameter is on the limit with 205/50 15's so not really on option.

Diff ratio change would be a last resort, the choices for 7.5" diff are far more limited and I'm not prepared to go down to 7" and have to swap driveshafts as well.