R31 Help

[tmiller45m]

I need help with a R31 chassis I picked up last year- not sure if this forum is still used or not. Please advise.

[Marc Miller]

I need help with a R31 chassis I picked up last year- not sure if this forum is still used or not. Please advise.

Sure thing - this forum is used regularly - what questions do you have?

[highwayman9011]

Marc,
I dont know how to post new thread and i need some info if possible. My son runs an r31 in a jr rotax setup. He is 5 10 and appx 175 lbs. We normally race at OVRP and we just raced at NJMP in Milleville NJ. What is a good base set up for this kart. It has all freeline parts I have been floating around a 53.5 to 54 inch rear width, 1 large 1 small front spacer 3mm toe out. front bar in The rear axle is aN A axle 362 mod. 1 how do i read axle info .I know this is a soft axle from what i am told It had an around 450 modulus axle we just bent ,thats why the 362 is in it. He complains it gets tight towards end of race and i have done alot to try and take out rear grip etc. where should camber castor be? I took out front bar at millville and pushed out front wheels to limit he said turned great but twitchy/sensitive. I understand why it is twitchy but i know that setup isnt the answer.
Also We have an 03 cr32 w 40mm axle . I have the banana brake set up I am going to put on it. We need it for a backup and question is. Should I put in a 50mm axle or can I or would you know a base set up for a similar feel . I know 40 to 50 mm axle feel different but unless I can get parts reasonable dont know if expense is worth it.

Anthony

[Chris Lobaugh]

Can you tell me a bit more about the kart specifically which R31 it is? Can you adjust the rear ride height? Is the 2nd rail on the left side welded in? What seat are you using?

The baseline set up for an R31X to is 1040x50x2-F axle, middle bearing in (to begin with but you need to test with it out or loose), 100mm hubs set at 23.5 cm from the casette to the outside of the tire (which puts you around 54.5"), 75mm front hubs set at 2 thick and 1 thin spacers wide on 17mm spindles, .5 degree caster in, camber 0 to -2mm, toe at 2 (3 is fine), front bar in.

Are you sure that it is a Freeline axle? They only made the "A" in a limited run and then changed to the "B" material shortly after. Either way it is too soft for the weather that we are going to be racing in for the next few months. If I was using a 40 I would definitely have an "M" in it for the remainder of the season and probably test something even harder than that if rubber starts to build on the track.

let me know on the seat and I can help with some seat dimensions also

[highwayman9011]

Hi, Its a 2008 r31 left rail out, adjustable rear ride height,unsure of seat brand but it best of my recolection it had a small white sticker that i believe said birel and i can see part of what looks like f6 of whats left of sticker. We have 2 left side bars and 1 r/s bar on seat, the axel in it is a B my spare is an A and i think the axel we got it with was around a 460 modulus mabey an F ? Its bent and in my trailer at track kart is in my garage thou.Center bearing is out. His weight is appx 460 lbs with him in it give or take 3 lbs (Rotax Jr) 40 lbs over . He turns 16 in December. Freeline mag rims Hi tech freeline rear hubs pn 5800.00.42

[highwayman9011]

:) The r31 has the 50mm axel and the 2003 cr32 has the 40 and was a seperate question...sorry

Thanks

[Chris Lobaugh]

okay the baseline is more or less the same except 1040x50x2-F axle down (chassis up). If you can find another F axle you'll be better served than either the B or A...the A is probably a Righetti Rhidolfi and is about the same stiffness as the B. When you had the F in the kart did the rear of the kart hop at all?

Seat dimensions are as follows (that is an IMAF seat which is what the kart came with); 61.5 cm from the front rail to the front edge of the seat on the left side, 61.5 to 62 cm on the right side, 22.5 cm from the top of the axle to the top of the back of the seat, bottom of the seat flush with the bottom of the frame rails.

[highwayman9011]

Chris, Is it worth the expense to update to 25mm front spindles?

[highwayman9011]

Also The kart had little if any hopping wit the F axle

[Marc Miller]

Chris, Is it worth the expense to update to 25mm front spindles?

Highway -

The 25mm spindles will make initial turn in quicker. Depending on track conditions, it is something you may want to consider, but certainly not necessary.

[highwayman9011]

Ok I will try these set ups on an off day and see how he likes it . I will keep you informed

Thank You , Anthony