The V8 Owners Forum -

hi all, this might be for the auto geatbox users, who manual shift them, when you go down the strip what gear are you in when you cross the line, im still in 2nd and just about doing 6000rpm. Ive got another c;w;p to put in,but just wondered what wondered what gear other peeps was in, rich

Im in 4the @ 5600 goning over the line with a 5 speed manual.
Waht were the terminal speeds you were running??

I had my first go a couple of weeks ago not many runs, 3 good ones, i found on the first it changed into 4th just befor the finishing line, zf 4 hp22, so on the next decent pass i held it in 3rd and did a 15.66 at 88 mph,not flying by any means but it was an improvement, back end is a jag with 4.09 gears and 28'' tall tyres, plenty of room for improvent and loads of stuff to leave behind in the tent !

You must have long legs on the box or diff Rich??

I'm running a Chevy TH350 in my MGB and I need 3rd gear. I have a 3.07:1 Diff and I'm using 24" diameter rear tyres. But I'm still a bit short in the legs for my car. I cross the line at around 11.5 to 12.00 seconds in 3rd gear at approx 5800 rpm.
My engine makes best torque at 4000 rpm. So I need bigger rear tyres I think.

According to Mr. Haynes, the later SD1 Autos had a 2.85:1 back axle. Taking the gear ratios for the BW65, you end up with the following:
Axle = 2.85:1
1st=2.39:1
2nd=1.45:1
3rd=1:1
Wheel = 195/70 = 628mm dia = 1.97m circumference

6000rpm in
1st = 880rpm wheel = 65mph
2nd = 1452rpm wheel = 107mph
3rd = 2105rpm wheel = 155mph

Which fits with my recollection of being able to exceed 60 in 1st!

Chris.

oops forgot to add it was just pulling about 4500 rpm

tyres are 225x60x15 ,the box is a tf727 3 speed , terminal speed was 99mph, for a carbed rover rear gearing was 3.09 which mine is, ive got a new 3.44 to go in soon, rich