Page 1 of 1
1098 gearbox to 948 engine
Posted: Sun Mar 12, 2017 3:35 pm
by jagnut66
Hi,
I just wanted to confirm that when I'm fitting my 1098 gearbox to my 948 engine I will need to use the 1098 speedo in conjunction with it, as it will be calibrated to the gearbox, whereas the 948 speedo won't be??..................
Many thanks,
Mike.
Re: 1098 gearbox to 948 engine
Posted: Sun Mar 12, 2017 4:41 pm
by philthehill
Do not forget that the 1098cc rear axle ratio is different at 4.22 whereas the 948cc rear axle ratio is 4.55 and that will have an impact on the accuracy of the speedo.
Re: 1098 gearbox to 948 engine
Posted: Sun Mar 12, 2017 11:08 pm
by jagnut66
Thanks Phil,
I want to fit the 4.22 diff as well, as soon as I find a Morris 1000 axle casing at a fair price.
Best wishes,
Mike.
Re: 1098 gearbox to 948 engine
Posted: Mon Mar 13, 2017 5:25 pm
by philthehill
Re: 1098 gearbox to 948 engine
Posted: Tue Mar 14, 2017 8:35 pm
by jagnut66
Thanks Phil,
Unfortunately this is collection only and it's down in Essex, if it were close to hand I'd jump on it.
Mind you I don't blame them, the postal price would be horrendous and probably just put people off.
I am tempted though, this is a fair price as you get the lot for it.
I just don't have the means to collect it at present. Thinking cap on.
Many thanks,
Mike.
Re: 1098 gearbox to 948 engine
Posted: Wed Mar 15, 2017 11:23 am
by IslipMinor
Mike,
Replying to your original post. The speedo is calibrated to the rear axle ratio, not the gearbox (apart from the 803 engined SII that had a different skew gear ratio in the gear box). The speedo drive ratio in all the 948/1098/1275 gearboxes is the same at 2.6:1.
You may even find that retaining the 948 speedo head with a 4.22 axle gives quite an accurate true speed reading - the originals can be quite optimistic! Worth trying with a GPS and see what it shows?
Re: 1098 gearbox to 948 engine
Posted: Wed Mar 15, 2017 11:51 pm
by jagnut66
Thanks for the clarification. By retaining the original diff for now then it sounds like I'm safe to carry on using the original speedo, as the 1098 box won't affect its accuracy, such as it is...................................
I like the thought that my speedo is optimistic!! 
Best wishes,
Mike.