The JB3 & JC5 ratio differences?

[cliolord]

I have wondered about this for awhile....It seems that my old valver engine with the JB3 gearbox had a totally different ratio in 4th gear to the JC5? 4th gear seems shorter in my JC5 box than the JB3 box did and seems to work alot better aswell. It will give around 107mph on the willy limiter on JC5 box 6,500rpm. I can't actually be sure if 3rd gear was also a shorter gear in the JB3 aswell? I can remember the revs dropped much more through a 3rd to 4th gearbox on my valver setup though. Has anyone notcied this? Sorry about the dragged out information lol

[Riley]

i was told that the 5th gear is longer in the jc5, but who ever it was who told me wasnt certain. My valver does about 110mph off limiter in 4th so sounds about the same to me

[richy]

my valver running jb3 box will do 112 in 4th at 7200rpm(ish)

[MAXIBOY]

well according to haynes

jc5 jb3

1st 3.7 3.1

2nd 2.1 1.8

3rd 1.3 1.3

4th 1.0 1.0

5th 0.8 0.8

041 3.3-1

045 3.4-1

046 3.9-1

048 4.2-1

005 3.6-1

010 3.6-1

015 4.2-1

the last are final drive ratios depending on box and code.

[webermaniac]

JC5 4-th gear is 1.029
JB3 4-th gear is 0.968
JC5 and JB3 3-rd gear is 1.321

[northy]

4th is around 105mph in my standard ecu'ed williams car.

sounds about right to me.

[Martin]

my old 19 box gave 120mph in 4th....willy box only 110ish

[2 live]

19s are geared diffrently again tho mate

[nyk]

I thought the 19 used the JB3 same as the valver ??

[MAXIBOY]

same box different ratio,s