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Author Topic:   chassis tilt/ rake
jbracing
Dirt Full Roller

Total posts: 44
posted June 02, 2005 07:22 AM  
I am new to sprints, and I'm helping a driver who is starting his first full season in one. I've been reading everything I can find on chassis setup, including, of course, the Steve Smith book. One of our tracks is fairly flat, and gets very slick.
I was thinking about taking some tilt out to get better side bite. 1) does this really work? (winged limited sprint) and 2)
does it matter when you add the turns to the left side to accomplish this? In other
words, if the car is already set up, and I add 1 turn to the left front and left rear,
will this affect anything other than the tilt? 3) same questions as applied to rake.
Thanks, JB

2nd2none
Dirt Forum Champ
Total posts: 755
posted June 02, 2005 08:55 AM  
I'm going to attempt to answer this, as it is my first year racing sprints and its been a pretty descent start...top ten in points and a heat race win so far....anyways, from what I've experienced on our super dry slick tracks, taking tilt out helps but the biggest thing I've noticed is when it is slick to crank LR weight into the car. You gotta be careful with this if the track takes rubber you'll be driving a bicycle goinrcn44h can probably answer this better.

goinrcn44h
Dirt Freak

Total posts: 205
posted June 02, 2005 09:10 PM  
Well,
I will first say I will tell you what I believe to be the truth as I have been taught, but with a disclaimer of sorts. Reason being, what 1 person feels and likes may be the exact opposite what another person likes or feels. There are so many factors and dynamics going on during corner entry it literally boggles the mind and not just mine or yours. Trust me here, even the top and I mean TOP guys wrestle with similar issues with the driver or themselves.
I posed a similar question to a very top all-star wrench/brother/head mechanic and his non explanation actually made sense as to what he was and wasnt saying. basically it was that off blocks , with the exception of a consistant 1/2 turn here or there, the desired result can be achieved without completely having to change your driving style. If ya drive a sprint car, you know that they in a way act different every time ya drive one. yet similar of course. I also have put it to use in recent weeks and find at some tracks , less is more, and predictable goes a long way in the grand scheme.
Back to the issue, your description is a bit incorrect by what I know and have been told and taught. adding left rear - left front is two different things and ultimately have very different effects on the chassis and where it effects it. left front weight will tend to increase RR sidebite as its adding LF-RR weight percentage. or its a RR heavy adjustment. adding LR weight will decrease sidebite but add forward bite off the corner. doing both may increase overall chassis roll and sidebite simply because its raised the roll center and increase the rate of weight transfer to the right side. That adjusment will tend to induce a push across the middle in my opinion and likely loosen the car a bit on entry and may help forward bite off.
What would 'I' do, based on what I like and believe. to add sidebite on entry and middle I would add 1/2 to 1 turn in the RR, but I also would reduce stagger, as well as easy up the RF and LF shocks in drastic sit. also slide the RR in will help sidebite at a bit more predictable rate. but again, this is for me and what I like. I will say I excell at slick and love the slick type drivers input racing I enjoy, given the fact you are able to move around somewhat of course. follow the leader tracks blow, and winning on one is hollow and unfullfilling in my opinion. but lets not go there either.... lol
hope this confuses you as much as it has me for years...
44H

jbracing
Dirt Full Roller

Total posts: 44
posted June 02, 2005 10:13 PM  
Thanks for the responses, 44H I was hoping you'd jump in. This is one of the very few
forums I've found with real tech info for
sprints. I've been through the archives, and
gotten a lot of useful information from your
posts and others. BTW, this is a Stealth chassis. The book talks a lot about tilt and it's effects, and from that I believe taking some out might help, but I'm unclear
on how to do it without messing up the basic setup. Thanks again, and more responses are welcome.
JB

goinrcn44h
Dirt Freak

Total posts: 205
posted June 05, 2005 11:00 PM  
My chassis is a stealth also. standard 86-40 . very consistant car.
44H

2nd2none
Dirt Forum Champ
Total posts: 755
posted June 07, 2005 08:47 AM  
I'm posting this so maybe what few sprint car drivers on the forum can start helpin each other out.

I'll post my complete setup I ran for my heat race and feature this past weekend.

The heat race had a little bit of moisture around the rim if you didnt run there it was dry slick every where else. I had 1000 LF, 1025 RF, 1025 LR, 1000 RR. 15" stagger, RR spaced out 17.5" LR out 14". 6psi in RR, 3psi in LR this is on hoosiers. Hard RR (mandated) medium LR. 5/4 shocks on both fronts, 4/7 LR, 5 RR. I had it blocked 3" front 4" rear with a turn in the RF & LR. On the scales this set me up with 60 lbs of RR. ASCS rules with the wing all the way back.

The car was descent. I started inside second row, was able to get to the top going into 1 sitting in 4th position. The car was a little loose coming off but was able to get passed 2 cars and finished 2nd.

For the feature the moisture was almost completely gone on the top of 1 & 2 and there was nothing in 3 & 4, although it did start to take a little bit of rubber. I put another turn in the RF & LR this set me at 40 lbs of RR weight, I moved the RR in to 16.5" and left every thing else the same.

I started outside second row for the A, the car was fast. I ran 2nd most of the race to the points leader and around lap 7-10 I swapped positions each lap with last years point champion until he finaly got me and thats where I finished, 3rd.

The car was real fast as slick as it was but still not hooked up as good as the 1st and 2nd place car. What do you guys see that I should of done different to help get me off the corners better?

Keep in mind this was the 4th race I've ever ran before.

Thanks, Jimmie.

jbracing
Dirt Full Roller

Total posts: 44
posted June 08, 2005 07:49 AM  
Jimmie,
I obviously don't have any answers for you,
as I'm new at this too. Just to satisfy my curiosity though, are you scaling your car in the pits, or do you know your corner weights and the effects of various changes by experimenting in the shop?
Thanks,
JB

[This message has been edited by jbracing (edited June 08, 2005).]

2nd2none
Dirt Forum Champ
Total posts: 755
posted June 08, 2005 08:17 PM  
I've played with it on the scales at the shop...changing bars, jacking weight, wheel spacing etc.

2nd2none
Dirt Forum Champ
Total posts: 755
posted June 09, 2005 08:07 AM  
I've loaded the video from the A feature to my website.
http://jimmiehobbsracing.com/june%205%202005%20A%20feature.WMV

Warning this is a 39mb file....

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