Hi guys what is the best diff/rear brake setup for an R1 indy ??

As you're building an MK Indy, I assume you are limited to Sierra (without having to do alterations) In which case it depends whether you want limited slip or not. If you do, then there ain't a great deal of choice XR4x4 or XR4i with ratio of 3.62 to 1. If you don't want limited slip, you have more choice and if you don't mind making small alterations to MK's chassis, the sky is the limit.

It all depends on what you want really. Top end speed or quick acceleration. If you search, you may be able to find a spreadsheet detailing various alternatives. Or someone could post a link to it................

Whatever you want

3.38 is good, the lower the better for a bec. Bear in mind if you want to play about you could always put the lsd from a 3.62 or 3.92 into a 3.38.

Ned.

Dont want to do any alterations.
Is it better to have an LSD or not what are you using hellfire?
Is it better to have drums or discs ?

Diff wise you are better off with 3.38 for general use 3.62 for performance. LSD is always an advantage but more pronounced on the track. Drums are lighter and easier to set up. Discs if you want the looks but are heavier.

HTH Gordon

Well I'm running a 3.92:1 diff and it goes like stink up to 110 which is quite fast enough for the road in my book, brake wise discs will require twin master cylinders with bias bar or pressure limiter to get the correct brake split front to rear at SVA........much simpler to just go drum....still stops on a ha'penny!

Ben

LSD is heavier...
LSD gives better traction on roads in't wet apparently.
LSD means you can do perfect donuts... allegedly!

'sup to you - we're running LSD

Heard a few negatives from track guys about 'em but...