Help am29

Cameron · 12-05-2005, 09:59 PM

I made a mistake..... freeded up the kart too much...... what is your base line for a 29 with bridgestone c's...we are running narrower than I though we would.......we are quick but HELP........

Chris Lobaugh · 12-06-2005, 07:16 AM

If by" freeing it up too much" you mean that you made the rear of the kart loose you can do a number of things. First, though, what did you do to free it up? I am guessing that you shortened the wheelbase and maybe moved the axle up? Lengthening the wheelbase would help and then dropping the axle back down would also give the rear of the kart more grip. Let me know if this helps or is even applicable to what is going on with your situation. I bet if you look at the changes you made and back track a bit you'll figure it out for yourself.

Cameron · 12-06-2005, 11:56 AM

Chris,

We had a cold track but it started to get grip after the heat race. We went out with long wb axel high in carriers F 2.5 short hubs 51 in wide freeline mags YHC Bridgestone 19f 20r psi +1/2 caster 0 camber 4mm toe out 3 spacers front rh high no bar... we were in a Jr super sportsman, after the heat race Cameron the kart as a bit tight (not quite a hop but binding then letting loose), and we slowed down at the end, our fast lap was on lap 4 of 10. I dropped to 17 18 psi and widened the rear to 51 in. we were slow until lap 9 of 12, in the heat we ran second and were as fast as the leader until we fell off at the end. In the main we were .5 to .7 sec off until lap 9 when we got to with in .2 of the fast time. I think we were too conservative with the rear width, but 51 in seems to narrow

The kart looked good on the track where I could observe, but we were just slow...Cameron said the kart felt solid, fine,???he said he was hitting his marks but we were just slow until late in the race.

Any Ideas

Taylor

Chris Lobaugh · 12-15-2005, 08:28 AM

Where are you racing. Are you using 4.5 tires on both front and rear? What are the seat location dimensions (from the front bar wher the driver heel would rest to the front edge of the seat, top of the axle to the top of the back of the seat, bottom of the seat in relation to the bottom of the frame rails)? What are your hot tire pressures? Are you running with additional seat struts? How big is the driver and how much weight do you have on the kart? Where is the weight mounted?
thanks,
chris

Cameron · 12-16-2005, 09:46 AM

Chris.

Good morning,

We are in southern California

Class is Jr Super Sportsman 4 hole yam. 4.5 / 6.0 yhc's driver is 5'1" and 90lb with gear, (class at 300) all of the weight is on the seat,5# each front edge under the legs 8# in the middle of front of seat 10# left hip area,6# motor side hip,2 10# and 1 8# on the back, we are 43% nose and 50% side ( we srarted closer to 42% but could not dial out a push) I can change the weight height on the back of the seat , I start with the 8#er on the bottom and the 10's high. Birel sm seat. left front 60cm rt 62.5 cm at bottom of frame rail, rear 25 cm off axel, Seat struts yes. Hot tire pressure was inaccurate,

We are running the ar 28 in HPV 2 and want to run a 28 in rotax Jr, Cameron in testing likes the 29 with the HPV better than the 28. It has been cool but the tracks are getting rubber, not like July at an IKF weekend but good grip, Do you feel the 28 will work better in a high grip situation? and or with the added HP of the HPV or Rotax ?

The ar 28 base line is seat at 57.5 cm 60 cm 25 off axel 5 mm below the frame rail f 3 axel 100mm hubs freeline mags 52 1/5 3rd bearring tight, +- 2.5 spacers fr high + 1/2 caster 0 camber 4 toe out......we start at 14 15 and drop as the track gets grip...we have been as high as 19/20 in the cold morning.

We tried spun Mags on the 29 and had sucess, we also are having better balance with the cg higher ( seat tiped forward and higher with the weight), and + caster

Thanks for your help...

Dave and Kyle are great, and we are getting a handel on both karts, I just want to see what you have come up with on your end and we can compare notes...

Chris Lobaugh · 12-26-2005, 11:30 AM

Okay,
In my opinion 51" is too narrow with 6.0" tires.
In high grip situations I have had better luck with the AR28. Not because of the tubing size so much as the difference in geometry of the frames between the AM aand the AR.
It sounds like you have a pretty good handle on things and you are right; Dave and Kyle are great.

12-05-2005, 09:59 PM	#1
Cameron Junior Member Join Date: Jan 2008 Posts: 15	Help am29 I made a mistake..... freeded up the kart too much...... what is your base line for a 29 with bridgestone c's...we are running narrower than I though we would.......we are quick but HELP........

12-06-2005, 07:16 AM	#2
Chris Lobaugh Birel Specialist / Engineer Join Date: Jan 2008 Posts: 237	Re: Help am29 If by" freeing it up too much" you mean that you made the rear of the kart loose you can do a number of things. First, though, what did you do to free it up? I am guessing that you shortened the wheelbase and maybe moved the axle up? Lengthening the wheelbase would help and then dropping the axle back down would also give the rear of the kart more grip. Let me know if this helps or is even applicable to what is going on with your situation. I bet if you look at the changes you made and back track a bit you'll figure it out for yourself.

12-06-2005, 11:56 AM	#3
Cameron Junior Member Join Date: Jan 2008 Posts: 15	Re: Help am29 Chris, We had a cold track but it started to get grip after the heat race. We went out with long wb axel high in carriers F 2.5 short hubs 51 in wide freeline mags YHC Bridgestone 19f 20r psi +1/2 caster 0 camber 4mm toe out 3 spacers front rh high no bar... we were in a Jr super sportsman, after the heat race Cameron the kart as a bit tight (not quite a hop but binding then letting loose), and we slowed down at the end, our fast lap was on lap 4 of 10. I dropped to 17 18 psi and widened the rear to 51 in. we were slow until lap 9 of 12, in the heat we ran second and were as fast as the leader until we fell off at the end. In the main we were .5 to .7 sec off until lap 9 when we got to with in .2 of the fast time. I think we were too conservative with the rear width, but 51 in seems to narrow The kart looked good on the track where I could observe, but we were just slow...Cameron said the kart felt solid, fine,???he said he was hitting his marks but we were just slow until late in the race. Any Ideas Taylor

12-15-2005, 08:28 AM	#4
Chris Lobaugh Birel Specialist / Engineer Join Date: Jan 2008 Posts: 237	Re: Help am29 Where are you racing. Are you using 4.5 tires on both front and rear? What are the seat location dimensions (from the front bar wher the driver heel would rest to the front edge of the seat, top of the axle to the top of the back of the seat, bottom of the seat in relation to the bottom of the frame rails)? What are your hot tire pressures? Are you running with additional seat struts? How big is the driver and how much weight do you have on the kart? Where is the weight mounted? thanks, chris

12-16-2005, 09:46 AM	#5
Cameron Junior Member Join Date: Jan 2008 Posts: 15	Re: Help am29 Chris. Good morning, We are in southern California Class is Jr Super Sportsman 4 hole yam. 4.5 / 6.0 yhc's driver is 5'1" and 90lb with gear, (class at 300) all of the weight is on the seat,5# each front edge under the legs 8# in the middle of front of seat 10# left hip area,6# motor side hip,2 10# and 1 8# on the back, we are 43% nose and 50% side ( we srarted closer to 42% but could not dial out a push) I can change the weight height on the back of the seat , I start with the 8#er on the bottom and the 10's high. Birel sm seat. left front 60cm rt 62.5 cm at bottom of frame rail, rear 25 cm off axel, Seat struts yes. Hot tire pressure was inaccurate, We are running the ar 28 in HPV 2 and want to run a 28 in rotax Jr, Cameron in testing likes the 29 with the HPV better than the 28. It has been cool but the tracks are getting rubber, not like July at an IKF weekend but good grip, Do you feel the 28 will work better in a high grip situation? and or with the added HP of the HPV or Rotax ? The ar 28 base line is seat at 57.5 cm 60 cm 25 off axel 5 mm below the frame rail f 3 axel 100mm hubs freeline mags 52 1/5 3rd bearring tight, +- 2.5 spacers fr high + 1/2 caster 0 camber 4 toe out......we start at 14 15 and drop as the track gets grip...we have been as high as 19/20 in the cold morning. We tried spun Mags on the 29 and had sucess, we also are having better balance with the cg higher ( seat tiped forward and higher with the weight), and + caster Thanks for your help... Dave and Kyle are great, and we are getting a handel on both karts, I just want to see what you have come up with on your end and we can compare notes...

12-26-2005, 11:30 AM	#6
Chris Lobaugh Birel Specialist / Engineer Join Date: Jan 2008 Posts: 237	Re: Help am29 Okay, In my opinion 51" is too narrow with 6.0" tires. In high grip situations I have had better luck with the AR28. Not because of the tubing size so much as the difference in geometry of the frames between the AM aand the AR. It sounds like you have a pretty good handle on things and you are right; Dave and Kyle are great.

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