ok guys im in a bit of a dilemma about this so im asking for some advice. ive got the t4 2L conversion in chaos( the bug im rebuilding) and i would like it to rev a little lower at 110km/h. at the moment it revs at 3500 at 110km.
im going to do the the 1302 box but am undecided if i will put the 3.88 r&p in or a taller 4th. the deciding factor will be how much it will affect the torque of the engine when cruising. so if any opinions and past experience on this will help me choose. note i cannot afford to buy a lbug box as i have poured most of my money in to the car and dont have much, plus i have a spare box from the car i used for the body.

anyone?

I had a 2 ltr type 4 engine in a notch and used an "L" bug box with a .82 Kombi top gear, dropped the revs to around 2700 rpm at 100 K's.

how did it go with the hills dave? did it have enough torque?

anyone else?

Barls
Whichever way you go, the taller you make your top gear the LESS grunt it will have.
You need to work out which option give what final ratio.

If you fit the taller (faster) diff then ALL the ratios in the box will be taller.
If you just fit the taller 4th gear, the the bottom 3 gears will be as is now but the car will have longer legs in top gear. However, the jump between 3rd and 4th will be greater and may shit you off on highway running where it may bog in in 4th but have to rev its tits off in 3rd.

IMHO, I would alter the diff ratio nad keep your gear ratio spread between the gears as is. The taller low gears will not bother you as much as a big jump in between the higher gears.

L8tr
E

thanks mate still havent decided which way to go as it seems a big jump to the 3.88 from 4.1 but the would be a huge gap from 3rd to 4th the other. might have to weigh this one up a bit more

Hi Barls

The 4th gear in a 3.88 box and 4.125 box work out about the same. So to get the lesser dropoff in power when going from 3rd to 4th a 3.88 with would be better, as both boxes use the same 1st, 2nd & 3rd.

Steve

so the 3.88 diff in the 4.125 box would be the better option rather than the taller 4th

Hi

If your not racing for pink slips the gaps arnt a big deal, what Dave Becker suggested is the maybe a good way to go. But you already have 2 x 4.215 boxes so maybe get a taller 4th put in one of them. Trying to advise someone on ratios is like buying underwear for someone you havent seen, you dont know what suits thier needs.

Steve

thanks steve as you said it wont be racing well not offically maybe just at the trafic lights