View Full Version : Axel types

Eric Rosenberg
10-04-2004, 09:09 AM
We run the R31 with a 50mm "F" axle. Our driver is rather tall (6') and heavy (180 lbs) and we're battling an over stuck condition at most tracks. We're thinking a softer rear axle would be helpful... but can't determine which model Freeline axle to purchase.

We run without the rear bar, the side rail bolts are left loose or out and we've tested without the front bar as well. At most tracks we're running -1/2 to -1 full degree of negative caster to take some more grip out. Toe is at zero static. We run the front one spacer low (just past the mid-point) but with the extended porch we will tear throught the bottom of the nose if we run another spacer lower. Seat placement is to spec. We generally run 9-10 pounds front and rear (depending on track and temps).

Gary, what would you suggest? What is the next softer 50mm axle?

Thank you for the help.

Garry Lobaugh
10-04-2004, 11:09 AM
I have a few questions. First is the axel up or down? If you put the axel up it would give you less grip. You could try to lower the back of the seat.(I have gone as low as 8cm off the axel when axel in in the down postion. ) As far as the next softer axel, the D 2.0mm is next in line. That is avaible in 1040 1000

Eric Rosenberg
10-04-2004, 12:12 PM
Thanks for getting back to me Garry. The axle is down so the rear of the chassis is up. You're right, I could lower the chassis for less rear grip. The seat is a Tillet XL so it's about 19" from the seat bottom to the top. If we rotated the seat back, I'm afraid that we'd have to raise the front a considerable amount as the seat bottom is already hanging below the chassis rails.... but we could consider that as well.
Regarding your axle reco, on your axle chart I only see "K, M, F and B". Doesn't a softer axle loosen the back end? What can we do to correct an over stuck front?
Thank you again,


Mike Walpole
10-04-2004, 02:13 PM
Eric - my experiance with Tillet seats is they make the kart tight compared to the Birel seats. I don't know why, but it's a big difference. Since the Birel seat is not as deep (Not as much lateral support.) as the Tillet, you can add Tillet Ribtech seat wings to the seat for more support. I have done this and they add a lot of support to the seat without changing the handling qualities of the kart.

As far as rasing the axle and lowering the frame, that is a pretty big change and will loosen the rear of the kart about the same as going to a softer axle.


Eric Rosenberg
10-04-2004, 03:11 PM

Thank you for the follow up.
My son is a pretty big, broad back 6' foot kid. I know exactly what you mean about the factory seat, it's smaller and not nearly as deep, we tried the one that came with the chassis but within a couple of laps he was VERY uncomfortable and could not drive the kart. Not only isn't it deep enough but the seat has a pronounced "hour glass shape" to it and was very tight about the waist. For this reason we had to go with the Tillet.
I had heard that the chassis was sensitive to this sort of change so perhaps that's what were experiencing right now.
Would you have anyother suggestions on getting some of the grip out of the front? Without failure, our best times have been coming right at the middle lap of every race session.... like clock work and then we start getting tight and the times go up.
Thank you agian for you input.

Mike Walpole
10-05-2004, 08:01 AM
I'm 6', 220# so I can relate to the seat problem. The Birel XXL seat is the only Birel seat I can fit in, but it is too loose at the top. The Tillet Ribtech wings make the seat narrower and deeper at the top, which is what I need. The symptoms I had with the Tillet were similar to yours, which was start way loose, good in the middle and tight at the end. The Birel seat made the kart more consistant through the run with fast, consistant lap times from lap 2 or 3 until the end.

Why the difference? I don't know for sure, but the Tillet is taller and softer (more flexible) than the Birel seat. The seats are different and, obviously, it makes a difference.

As far as taking grip out of the front, take out caster using the caster/camber pills until you start to get a push on entry. Then, back up and fine tune with front width. Also, try to maintain the stock camber when you take out caster. The Birel karts I have worked with R932, CR32V, Q31 all like to have the camber close to stock and equal side to side. (BTW, the stock camber on all 3 karts is different, so you will have to check yours with 0 pills.)

Eric Rosenberg
10-07-2004, 12:10 PM

Thank you for the input. What is the cost of this softer axle?


Garry Lobaugh
10-08-2004, 05:02 PM
Axle price is $165.