January 9, 2017 at 3:16 pm #76533
I have a 2010 Birel R31 (purchased new in 2013) racing in the World Formula class. I am about 2 sec per lap slower than I need to be to be competitive.
Went testing last week and tried all sorts of chassis setups: Long vs short torsion bar, different front track widths (1 to 4 spacers inside the wheel). Camber pill set at max camber, camber pill set at min camber etc. etc..
My lap times were within 3/10ths no matter what the setup (55 sec lap).There is no discernible difference between my laps when I look at Race Studio.I changed one thing at a time and did 5 laps to get a reasonable average. I drove at maybe 95%, making sure I hit my marks consistently rather than overdriving. Maintained consistent tire pressures.
So, is my chassis cracked or worn out? Am I like Alonso and can drive around any handling issue (:-))
Is there something huge I’m missing?January 9, 2017 at 7:41 pm #76538
Glenn L RiggsParticipant
I would try to make it as loose as possible an still drive it see if that helps if it does your probably binding and if a lower horsepower engine it will kill your lap times but still feel pretty wellJanuary 9, 2017 at 8:42 pm #76539
2 seconds off most likely the majority is driving. It’s truly hard toes up a setup to get over one second off if the driver is very good. Cracked frame or brake dragging a really the only possibilities.January 10, 2017 at 5:32 am #76543
See if you can get a front runner driver to take it out. I did that when I first started my son. Ended up my son was just as fast. We won our first race.January 10, 2017 at 2:32 pm #76586
Thanks for all the input. Just so you know, I’m a pretty experienced driver having run in multiple classes over the years (KT100, KPV, Rotax and now WF) and this is the first time I’ve ever encountered such an unresponsive chassis/frame. I do agree the driver or tires or engine could contribute to the absolute lap time. But I don’t think the driver is contributing to the lack of chassis response to tuning.January 10, 2017 at 3:36 pm #76589
Rob, not questioning your experience or lack of driving skills on other types of engine packages. But there is a difference with the 4 cycle thing, and it does take a while to get caught up with the fast guys, to the point it makes you question the chassis, driver, engine, carb, etc.
Did you just start 4 cycles?
Were you already fast with this kart/engine package at some point, and just recently started noticing you are slower now?
Please don’t be offended, but this will help narrow it down.
I’m still trying to figure it out myself, as this driving style is a bit more sensitive, and requires to minimize turning effort.
If you were already fast running with the front guys, and recently you’re losing speed, then yes, you may have an issue there, and you can ignore my questions. Hope this helps.January 10, 2017 at 3:53 pm #76590
Wasn’t concerned that you suggested driving.Just wanted folks to know that I’m not a complete newcomer.
To answer your question, no, started in WF a year or more ago. Had some time off with motor issues and other things but before I was reasonably competitive -certainly not this far off. And, yes, changing from Rotax to WF, did require a big change in set-up.But the kart did initially respond to changes.
Now doesn’t respond to the big changes I make. For example changing torsion bars has previously made a big change, now it makes no difference.
Got to think it’s the chassis.January 10, 2017 at 4:35 pm #76591
That makes sense.
Check all the welds under the seat, cross bars, front and rear cross member, also check the ties welded between the frame rails at the engine side.You’d be surprised, even a small hairline fracture will do that.
May also be a good idea to put it on the table after you inspect for cracks.January 12, 2017 at 12:39 pm #76720
This is Mark Traylor (Tommy’s dad) we have been running birel at PKRA and I am trying to support other birel owners as much as possible. Go ahead and PM me and I will give you my phone number. I have a granite surface plate we can use to check the kart, put it on scales etc. I can also do a leak down on the engine and head for you and see if that is part of the problem. Also I know you don’t run every race so how old are your tires?
MarkMarch 12, 2017 at 7:10 pm #79181
You didn’t mention how big you are and how big the track is. Might be aero?
FAA certified jet engine and aircraft technician,
Nicholson Speedway class champion 2001,
Yamaha KT100 Service Center,
41 years karting experience
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