Board logo

R1 diff ratio ?
Kosmo - 28/9/06 at 07:26 PM

I have some more questions..... what diff ratio would be best with an R1 engine and what size wheels ?

Thanks,
Kosmo

[Edited on 28/9/06 by Kosmo]

scoey m - 28/9/06 at 07:33 PM

diff ratio people recommend different i have gone for 3.38 sierra 7" but some people say 3.14/3.62

smart51 - 28/9/06 at 08:07 PM

195/50/15 and 205/60/13 are much the same size and are popular.

A 98 R1 with 195/50/15 and a 3.62 diss will give 52 MPH in 1st and 73 in 2nd with 120 in 6th. A 3.38 will give a bit more in each gear but will slightly less acceleration. A 3.14 will reach about 60 in 1st but that bit less acceleration.

Its all down to what you want. More acceleration = higher numbered diff. More top speed / lower cruising RPM = lower numbered diff. The lower the number the rarer and more expensive. I have a 3.62.

dilley - 28/9/06 at 09:05 PM

If your looking for a 3.38 I might know someone who can help you out

Hellfire - 28/9/06 at 09:32 PM

quote:
Originally posted by Kosmo
I have some more questions..... what diff ratio would be best with an R1 engine and what size wheels ?

Thanks,
Kosmo

[Edited on 28/9/06 by Kosmo]


That really depends on what you are building and with what running gear. Most of the answers above assume you'll be using Sierra running gear. If that is the case, the next decision you need to make is whether you want an LSD or not and how much you want to spend.

Personally, if it's Sierra running gear, I'd go for a 3.38 non LSD diff with rear drum brakes to enable 13" wheels to be fitted.

Regards
Phil

[edit] Oops. Just noticed you're building (or hoping to build) a striker, therefore Sierra gear I presume. [edit]

[Edited on 28-9-06 by Hellfire]

progers - 29/9/06 at 07:10 AM

As an all round compromise 3.38 is the best ratio to go for, although 3.62 might be tempting because of the cheaply availble LSD option - it just means you will rev higher while crusing and top out at 120 ish (depending on tyre size) - This could be ain issue on trackdays if you plan to do them. You'll not notice the difference in acceleration between the two. Don't go near a 3.14 its too tall for an R1.

As for 13" wheels, with a striker there is no problem getting a disk brake set-up - something like compomotive CRXs will fit fine over standards sierra calipers fine.

Cheers

Paul

Kosmo - 1/10/06 at 08:32 PM

I have a chance of a 7.5" 3.64 cosworth diff, is anyone using this with an R1 ?

Is the 7.5" diff much heavier than 7" ?