Any special considerations for older Chassis setup?

Chassis Setup, Tires & Handling Forum
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2007 Birel R31 SV - Yamaha KT100

I need help with - General - looking to understand if older chassis designs require anything special from a tuning perspective vs. newer chassis? This particular R31 has a fixed 4th rail, is it worth removing or is the thing so flexed out at this point that’s not a good idea?

Chassis is in decent shape, bottom isn’t really flattened anywhere, I went over it completely and found no broken welds. I have no real back history on it other than the guy I got it from used it for hobby and not racing. I know it’s old and worn at this point but I’m trying to make the best out of what I’ve got before I decide if I’m committed enough to jump to a newer chassis.

Only thing I see “wrong” is it has a TON of front camber and is wearing the inside of the front tires as a result. Currently the car has 1 degree caster pills maxed out which I understand is contributing to the camber gain. Previous owner did not have corresponding pills for camber but those will be here any day to install and re-align. I’m still not sure i can get to 0 camber based on how much is currently in the chassis. don’t know if this is a result of age and flex or chassis design or what? It’s consistent side to side using Sniper lazers so I don’t think it’ an indication of the chassis being bent.

What I’ve tried so far - Everything. This is my first year of Karting. Just doing this on the club level for fun while I support my nephew who’s just starting. I’ve mis-understood concepts and gone the wrong way, then corrected those concepts and gone back the other way. Just really curious is there’s things to consider for older / stiffer chassis that might not apply to some of the newer softer chassis?

I have a decent driving background (held a couple NASA TT lap records for awhile) but I know I need to always work on the nut behind the wheel specifically when it comes to karting which is a new discipline. I’m within .75 seconds of the leaders at our local club, and at 35 lbs over the min weight I’m assuming alot of that is the need for me to get my behind on a cardio machine and fix the weight. Looking for any other insights that might be valuable. It’s nice to find an active karting forum that actually works to bounce ideas off of people.

-Andy

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Welcome Andy and thanks for the kind words. Can you drop a couple of photos of the chassis? Typically the pinch bolt (if fitted) is removed. I remember the model of chassis, but I don’t have a vision of it in my mind.

Excessive camber wear on all four corners is not too unusual in karts due to the extreme caster angles run, and the dynamic camber change they cause.

Otherwise, I wouldn’t say there is anything specific to older chassis perse. The soft/stiff thing to me is very relative and I’m still not convinced that chassis actually go soft. Rail and spindle C bracket sag are real, but in terms of going “soft” I think it’s more perception over reality.

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I apologize for not having actual pictures of my kart handy to post but the one in this link appears to be the correct, later vintage of the R31 that I have.

http://www.corsart.org/2008_07_17_459.html

I believe (and correct me if I’m wrong) that the pinch bolt you refer to was on the earlier models and went away by the time the 2007 changes rolled around.

Kart has 25mm front spindles with hubs, 50mm F (medium) rear axle, etc.

It does not have adjustable camber / caster setup, that vintage used “pills” to offset those values. Despite having caster pills in it now (top) I don’t think I can get back to 0 degrees of camber with the kart on the stand. Is hat the spindle C bracket sag you refer to where it’s just gained camber over time even in the neutral position?

Thanks,