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Author Topic:   Alignment ?
Kromulous
Dirt Forum Champ
Total posts: 796
posted April 14, 2005 08:09 AM  
Most say to align the right side wheels, why?

I see LM's all the time with the RR tuck in about 4" versuses the RF. I was on Dirtworks site and seen some pics of cars that had the RR tucked in just like modern LM's.

Why? what does it do? makes a car looser in tighter off i presume, but i really dont know.

There is a local driver, ex LM driver that runs a Mod now, has a Rocket Mod, no idea if it was made by the same LM manufacurer or not but it says Rocket on it. Anyway, this car is wild looking, the rear end is considerbly narrower than the front end, and both the LR and RR are tucked in compared to the front, but the RR has more.

The car looks dialed, its hooked up. Lays over on the RR hard and it seems to do it at will. Drives straight off the corner as well.

Anyone ever play around with offsetting the RR in, compared to the front end, and have any thoughts on doing it?

Thanks, Krom.

wfoondirt
Dirt Forum Champ
Total posts: 505
posted April 14, 2005 08:31 AM  
Moving the rr in typically will tighten the car on a slick track because it decrease ls%. The narrower track width also causes more lateral weight transfer. It also increases the roll couple which is genarally accepted to tighten a car also.

The problem I have with doing this is that unless the car was specifically designed to be run with the narrow rear track you end up with significantly different roll angles front to rear. Basically the rear will try to make the front roll which is not very efficient. But with the cars alot of people run today that have the torsional rigidity of a wet noodle I don't think its as detrimental to performace as it would be on a more rigid car. I think the old addage of aligning the right side wheels is a holdover from the days of more rigid cars. Having the left side wheels slightly out of alignment doesn't affect the roll angle as much as the right sides.



dirtbuster
Dirt Forum Champ
Total posts: 2007
posted April 14, 2005 09:32 AM  
having the axle moved to the left will tend to tighten the car all around. Tightens in because of the extra vertical force on the RR and tightens off because the LR is now driving furthur to the left of the centerline of the car which will try to turn it to the right.

I havent heard many people say to align the rightside tires on dirt, most times I hear line the left sides and leave the RR tucked in. Maybe on asphalt you would want the right side tires lined up.

Kromulous
Dirt Forum Champ
Total posts: 796
posted April 14, 2005 10:14 AM  
Seen it in Circle Track and some other places.

Anyway, this year i got a new rear end housing 61" centered, with a 3" offset wheel on the LR and a 4" on the RR both of my rear tires are narrower than the front.

The Ford clip with 4" offsets across the front is 76" wide, so 77" when i put a 3" on the LF. Wheelbase is 108, so its wide and short, kinda like me LOL.

I was wondering if i should try to line up there rear in some fashion, i think i will run it this way and find out.

A&M Motorsports
Dirt Maniac

Total posts: 117
posted April 14, 2005 10:19 AM  
WF0, how much would you say to move the right rear in if a person was to do so. If I remember correclty UMP states that the tire edges must be visible outside of the body.

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Artie Perilloux
A & M Motorsports

dirtbuster
Dirt Forum Champ
Total posts: 2007
posted April 14, 2005 10:23 AM  
I think I do remember seeing that in Circle Track, but I cant remember the article.

In my experience moving the rear tires to the right or at least the RR will loosen the car. On a hooked up tacky track this will prob help.
On the dry slicked over stuff we run on here you need as much sidebite as you can get so we move the rear to the left or move RR offset in to put more of the weight of the car over the RR tire to stick it for sidebite, or tighten the car.

On our chevelle stubbed car the front track width is like 64" (center of wheels W/ 3" offset) and the rear is 60" at teh center of the wheels. The RR is set inside 2-3" from the RF. WE tried running the right sides more lined up last year and the car just wouldnt stick to a slick track.

wfoondirt
Dirt Forum Champ
Total posts: 505
posted April 14, 2005 10:47 AM  
quote:
Originally posted by A&M Motorsports:
WF0, how much would you say to move the right rear in if a person was to do so. If I remember correclty UMP states that the tire edges must be visible outside of the body.


Your more limited with a mod than a lm on the ammount due to the narrower tires. So you can only get ~2" without physically moving the whole rear end to the left or going to a narrower housing. If you move the whole housing you have to move all you suspension mounts to compensate.

As far as UMP rules go, I have never had the rr outside the body and have never told to change. I usually have the rr tucked in just enough so it can't rub the body.

Personally I do very little with wheel offsets anymore. I usually design the suspension around 4" offsets and pretty much stick with them. Now if I'm working on a someone elses car that I'm unfamiliar with and need a quick fix at the track I might throw some different offsets on to get through the night.

zeroracing
Dirt Forum Champ
Total posts: 1875
posted April 14, 2005 12:35 PM  
I put the left side tires in line with the car, then step the rr in about 2-4 inches of the rf, depends on car and what i am doing, andoffsets available.

CCGRT9s
Dirt Full Roller

Total posts: 31
posted April 14, 2005 01:16 PM  
Think about this, everyone used different backspacing to tune the car years ago because the rearend could not move due to mono leafs and normal leafs. With a modern 4 bar/ z link, the rearend moves to the left and accomplishes the same thing. Especially with a short panhard bar. Does this make sense to you guys?

A&M Motorsports
Dirt Maniac

Total posts: 117
posted April 14, 2005 01:25 PM  
WFO, I was mistaken, only the left rear tire must be visible. Thanks for all of the input.
Can you recommend where I can locate a lift arm and mounting brackets for the 9" housing.
Almost forgot to ask the length of the lift bar for a 108 wheelbase car.

Thanks

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Artie Perilloux
A & M Motorsports

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