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Thread: preload question.

  1. #1
    Member JUNIOR BUILDER
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    preload question.

    My nova,the pass- front tire comes up while the drivers side comes up very little so the car looks twisted.Do i need to take out some preload or add preload? My thinking is take out some preload.CORRECT?

    THANKS,BILL

  2. #2
    Junior Member JOURNEYMAN
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    How does the react off the line? Is it going to either side or straight.

  3. #3
    Member JUNIOR BUILDER
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    It goes straight off the line.. It's way out of wack in the front,meaning the pass-side is way up while the drivers side is a little up and the drivers rear tire looks like shit while the pass-side slick looks much better.The drivers slick looks like it was tearing the rubber off while the pass slick still has that smooth look.I put a new set of slicks on yesterday.

  4. #4
    Senior Member EXPERT BUILDER
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    usually the drivers side front pulls first..Something is out of whack for sure..

  5. #5
    The sum of the right front and right rear wheel loadings must...I repeat, MUST...remain equal at all times, both during the launch and while it is parked. Same with left side. If this weren't true, the car would start rolling over. So, assuming the car is symmetrical (left side sum equals right side sum), you definitely have unequal loading of the rear tires with the situation you describe. Yes, you need to back off on the preload.

    This is VERY unusual and I'm amazed you were able to accomplish this only with preloading. This usually requires tricks like asymmetric link arrangement and/or adjustment or front end spring rate differences or rebound limiters. Very surprising!

    Incidentally, this is no worse than the left front lifting first. It's just that it's very unusual that you were able to more than overcome the driveshaft torque with preloading.

  6. #6
    Member JUNIOR BUILDER
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    I took this car to a chassis shop here in ohio and they messed it up so bad i could only get about half track with it because it was darting all over the track.So what i did was replace everything in the front-end and had it lined up.The chassis shop scaled it out which they ended up putting a lot of preload in the car which made the drivers corner sit around one inch lower than the pass-side which i told them i did not like it nor want it like that!! What did they do? Heated the pass-side spring too lower the pass-side which made the car dart all over the track which i rebuilt the front-end and replaced the front springs and then took out all the preload untill the car sat level on all four corners which worked pretty good untill 1st time out this year which another racer told me about the pass front coming way up while the drivers wheel only came up about two inches or so..Finding a good chassis shop in ohio seems out of reach..Bill

  7. #7
    Senior Member MASTER BUILDER
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    Super Chevy Show

    BBB555 (Bill),
    I received my Popular Hot Rodding, yesterday. It is the September issue and you are in it. A little write-up and a picture of you under the hood. Congratulations!!

    Check your PM.

    Bill M

  8. #8
    Member JUNIOR BUILDER
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    I have been watching for it but could not find it..Thanks for the info.I was to be in the super chevy magazine as well but have not found it yet either.

  9. #9
    Senior Member DYNO OPERATOR
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    You did not tell us what you are using for suspension bars on the rear or if you have an anti-roll bar.

    To me it sounds like you have several things out of whack as you call it. The fact it is driving straight is really mind boggling to me. I can only surmise that bars are creating a preload and different spring presures are counter acting it.

    I have seen only two cars lift the right front and keep the left front down and on both cars I was the one doing experimenting with bar and spring pre-loads. Even those did lift the left front on first gear change but a little down track were lifting the right front. That was only during research and expermenting. They were not left to run like that. One car was a clutch car and I had a 120 # spring on the right and a 90# spring ont he right with far too much bar pre-load cranked in trying to solve a down track problem of it driving to the side under power. Turned out the whole problem was fornt suspension alignment and not originating from rear suspension at all. The other was a car that was driving to the right hard and I really cranked on the bars. It looked funny when it lifted the right front in 2nd. That one had a tire that was growing more on one side than it was the other side. Took forever to find that problem.

    I suggest to begin with working out your spring rates and getting the right to left in the rear even if possible but at least within 70 lbs of each other. That is with zero pre-load in the bars. Make a pss and video it or have a good obser watching. Be prepared of the car to go either side or straight and at the first hint of driving to one side back off and back to the pits. If it is driving to the right you will need to increase pre-load to the right rear if it is driving to the left decrease the right rear pre-load.

    If you have an anti-roll bar unhook it anytime you are making any rear adjustments and connect it back afterwards. I like them to have all bolts and pins not binding with all weights including driver in the car. For some reason Mustang factory style 4.links are different and the anti-roll bars need to be adjusted like David Wolfe says to do it.

    Ed

    Ed
    " Let all things that hath breath, praise the Lord. Praise Ye the Lord" Psalms 150 vs 6.

  10. #10
    Member JUNIOR BUILDER
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    ED,thanks for all the info..I'm going to go too the track SAT and play with this thing.It's a ladder bar car with a diagonal bar (I guess that's what it's called? I have 110 rear springs set dead even.This is not a high powered car,502 pump gas motor running 10.60's on motor and maybe 9.30's on the spray.It 60's 1.5 motor and 4.6 on the spray.The front shocks are 90/10's with small block springs in the 280 psi range.Car weighs in at 3,500 with me in it.BILL


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