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View Full Version : How to get the LF up???



bobracing32
09-21-2011, 11:22 AM
Currently running a sportmod 3 link 07 harris. I cannot get the left front tire to lift at all. lf 500 lr 450 lr 225 rr 175 53% rear 50.2 cross The left front of the car seems so heavy im not sure what to do to lighten it up. I would like to try the setup with the tire off the ground, but need some setup advice. Any ideas or advice will be greatly appreciated?

dirttrackrocker
09-21-2011, 11:50 AM
Just a few suggestions.. More rear % lots of LR bite. And get your RF to weigh more than your LF.

bobracing32
09-21-2011, 12:10 PM
Ive tried and where from 0 to 100 lbs heavier on lr. How much should i go? Also how much heavier should the right front be?

bentfender
09-22-2011, 10:21 AM
more LR bar angle less RR bar angle move all lead up as high as u can maybe have to move it to the right

dluna11w
09-22-2011, 10:51 AM
Put LR in top hole if it isn't already there, put RR at around 5 degrees or a little less. 80 to 100 lbs of bite.

Don't be concerned with the amount of weight on the lf versus the rf. Every car I've owned the LF is heavier to get the LS % where it needs to be. 53% is too low on the rear in my opinion. 4 bar cars can get away with less rear percent, but a 3 link needs at least 56% (again, in my opinion)

There is still a good chance it won't pull the LF. If your LR is hitting the underslung at full hike, it probably isn't going to happen. If your shock is limiting the travel before hitting the underslung, you need to put an extension on the shock to allow for more travel, IF your mounts are not adjustable. Most I've seen use a 1" extension on tacky and 2" on smooth and slick. It's all about the amount of travel on that LR. The rear steer REALLY comes in hard when you let the LR drop too much, so just becuase it looks neat, it most definitely isn't always the fastest way aroudn the track.

racin6mod
09-22-2011, 05:12 PM
why do you want the left front up off the track. with the crate motors(low hp) I would think having the car free up would be faster and easier to handle.

bobracing32
09-22-2011, 05:33 PM
ok its an over slung car. lf431 rf549 lr644 rr470 This is what i have now. The car is currently on the scales. Does this sound anywhere in the ballpark? Also what about the panhard bar angle any ideas?

dirttrackrocker
09-22-2011, 06:40 PM
You still need more rear %. You can't change rear % without actually adding weight. Rear needs to be 56% minimum, but try to get around 58%

humanetiggor
09-22-2011, 09:14 PM
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stock car driver
09-22-2011, 11:12 PM
You still need more rear %. You can't change rear % without actually adding weight. Rear needs to be 56% minimum, but try to get around 58%

Most guys I know racing IMCA sportmods have gone to 12 gallon cells and run very low rear weight.. with a 350hp crate motor you dont need any rear, you need to free the car up.

One of the big name A mod drivers in my area went to sportmod and was down to 48% rear last I knew to get the car to turn. He went down because they dropped the A mods in his area.

TeamGRT12x
09-23-2011, 03:45 AM
I'd go with
51.5 Left
57 Rear
100 Pounds of left rear bite

Your front wheel weights will be about even at these percentages.

Your panhard bar needs to be about 1" below pinion on the backside of the rear end with 5" of rake. It needs to be as far to the left in the car as you can get it as well.

Stiffen up your front springs, at least a 550 in the right front.

Left side trailing arm in the top hole, right rear 4th hole up.

You don't need to three wheel to be fast but keep the car rolling.

dluna11w
09-23-2011, 10:04 AM
One of the big name A mod drivers in my area went to sportmod and was down to 48% rear last I knew to get the car to turn. He went down because they dropped the A mods in his area.

Our sport mods run the spring in front on the LR and on top on the RR with a solid top link. That is amazing to me that he could do well with 48% rear. I can't imagine it would be on a very slick track. If I don't have over 56% rear it is tough to keep it hooked up for me. Maybe they are running less pullbar angle with this setup as well to keep from shocking the tires.

BOBRACING: If it is overslung, what is limiting your travel on the left rear? If it is the shock, get an extension on the shock to get more drop. Your car is pretty light with those numbers at 2094. The left side is 51.3, but my opinion is that you should bump up the rear percent. We also run stiffer front springs on 3 link cars that 4 bar because I think it is important to get that weight transfer back to the rear tires.

stock car driver
09-23-2011, 11:08 AM
Our sport mods run the spring in front on the LR and on top on the RR with a solid top link. That is amazing to me that he could do well with 48% rear. I can't imagine it would be on a very slick track. If I don't have over 56% rear it is tough to keep it hooked up for me. Maybe they are running less pullbar angle with this setup as well to keep from shocking the tires.

BOBRACING: If it is overslung, what is limiting your travel on the left rear? If it is the shock, get an extension on the shock to get more drop. Your car is pretty light with those numbers at 2094. The left side is 51.3, but my opinion is that you should bump up the rear percent. We also run stiffer front springs on 3 link cars that 4 bar because I think it is important to get that weight transfer back to the rear tires.

Totally slick track most of the time, sandy base in the dirt also... Sportmods here have both springs on top of the rear housing per the rules.

Hes not the only one running low rear with a crate, the crate has no power I cant imagine why you would need that much rear.

I run 51.5 max in my stock car with 500hp on the same 8 inch tires with oem rear suspension etc.

dluna11w
09-23-2011, 01:49 PM
Very interesting.

So, maybe it is steeper bar angles and softer front springs to make it act somewhat like a 4 bar car than what we do around here. But when you say limited crate motor and keeping the car loose, I don't picture a jacked up car that's crazy up on the bars. We run a crate against other spec 360's here. Sounds like I need to do some research over the winter on this.

ask0329
09-23-2011, 02:46 PM
I'm only posting this for ameusment if anything. This was my first year in IMCA so huge learning curve moving up from 4cyls.

When I got my car it had no LR shock. I asked the guy why and he said it was set up to lift/hang the Left Front tire. Its an underslung car and the rear tube was notched for the rear end to drop. 3-link suspension. I've never heard of such a thing as only running 3 shocks and neither had many of the drivers at my local track. Regardless I knew better and picked up a shock and ran the car as it was for 8 races. I dont own scales so I had no clue where the set up was. The car was tight and pushed real bad, but being new to IMCA I just accepted it and kept plugging away. So with 2 races left in the year one of the top guys offered to set my car up for me and I brought it over to his shop. We put it on the scales and he went over everything with me so i knew what the set up was compared to how it drove. The front ride heights where 1.5 inches high and the rear was .5 low. It had 190lbs of LR in the car. We got the ride heights set up, changed rear springs, adjusted a bar or two and the rear percentage down to 80lbs. The car was totaly different. Took me hot laps and a heat race to get adjusted. After that I was way more competitive and actually able to race with people. I know my car never hung the LF but I dont believe its all its cracked up to be.

dluna11w
09-23-2011, 04:09 PM
BOBRACING - I was going to mention something about adjusting wheel weights as well. Make certain that you are adjusting on all corners of the car and not just always the LR and RR, etc. I always get my ride heights as close as possible before putting the car on the scales. After that, the scales should really just be needed to set the LR bite in the car.

LM14
09-23-2011, 07:55 PM
Why do you want to pick up the LF? Your car was built with 4 wheels for a reason, use them.

More LR bar angle (up to 28*) and try to lose rear % and free up the car. Most people have their cars too tight.

SPark

millerracing
10-10-2011, 04:12 PM
but it " Looks " cool with the lf hangin :rolleyes:

millerracing
10-10-2011, 04:15 PM
lf431 rf549 lr644 rr470 is his scale numbers ? i normally dont see the Rf weighing more thank the Lf

boom 20
10-17-2011, 08:23 PM
ran a 1991 local built car in imca northern sport mod so no help so we played left rear bar 26degree up rr bar flat pull bar 30 some long and 20 degrees panhard 26 degrees mounted even w bottom of pinion 55 left 54.8 cross 55 rear 240lbs of bite would just hang lf coming off won points at one track 3rd at one and 4th at another

RACER88mod
10-30-2011, 07:20 PM
Put about 55 lbs on the right side of the car up on the right side rail just inside of the nerf bar of the frame i couldent get my lf down and when i took the 55 lbs off fixed the problem hope it helps

bobracing32
05-28-2012, 09:35 AM
Thanks for all the input. I havent tried this setup yet. Hopefully in another week or two i will.hope for more info or input thanks