dparker

What topspeed said will work in setup. In my experiences, when you go with alot more HP engine your car will have a tendency to go right. Due to striking the tires harder. Usually you need more preload. If thats the case then shorting the passenger side adjuster bar a bit will a add a little preload. I'm basing this on the fact that your car was going straight with the other engine.

TopspeedLowet

Actually Dparker, a high powered car will go left, not right. The turning condition he has is no doubt, due to the rear pointing that way or random preload, old tires, shocks with unequal adjustment etc. He said that they just made an adjustment in the squareness of the diff in his first entry prior to testing the new engine, that fact may have eluded your prognosis. When you make real power in a door car like 1200 or so you will find that negative preload is your friend. I have a car that I built and drive that needs no preload at all, in fact I use 1/2 flat negative to keep from going left. But I'm only running My crap in a door car at 7.62 ET at 187.22 MPH for what it is worth.

dparker

Sound like you running faster than we are. Fastest in our crew is 7.90s. But not one of us has been able to get away with less than 50lb more on the right rear and 70lb more on the left front. On scales mine is 65lb heavier right rear and 90lb heavier left front.

TopspeedLowet

[quote="dparker"]Sound like you running faster than we are. Fastest in our crew is 7.90s. But not one of us has been able to get away with less than 50lb more on the right rear and 70lb more on the left front. On scales mine is 65lb heavier right rear and 90lb heavier left front
[/quote

The right rear does not need to be heavier than the left ever. I have 494# on RR and 557# LR but the left front is heavier than the right by 54#

TopspeedLowet

To add detail to the scale report I just gave, that car has an anti roll bar and a 4 link. When the tires feel the 920# of torque the preload is a bit of a joke to the rod ends and causes binding in the suspension which will cause major traction loss at that moment of bind. This is why I am big on getting the correct instant center on a given combination to avoid using mechanical bind (Pre load) and excessive pinion angles to get off the line. The less pre load you use the better the car or dragster will behave on the big end and under deceleration. The bind condition is constant and you are crutching the suspension for the first 10' and have to deal with it all the way down the track. If you look at any Pro stock car scale report it will be the same or very similar to mine with the RR lighter than the left.

dparker

I really don't see what your saying. I've used Ed With edvancedengines concept over the years and In my experiences have not had any problems. Not to say I'm disagreeing with you. But this is what Ed has on his chassis post....

What happens when Torque hits Rear End from Driveline;
Know and understand that anytime torque is applied that your left rear tire will be trying to push down and your right rear tire will be trying to rise looking from the rear of car. All cars in any kind of racing or activity will exhibit this twisting motion if there is any form of friction coefficient existing between the tire rolling surface and the ground/track/road. The tendency will still be there to twist the rear with torque even with no tires or wheels. It is when you start to hook that it really shows up.

If your rear end was not attached with brackets, when the drive shaft rotates in the counter-clockwise movement (looking from rear of car), the entire rear end assembly would rotate counter-clockwise like a propeller if it were suspended in the air and had room to move. The drive shaft rotates in the direction that engine torque is applied to it. Even attached with bars and suspension it still wants to rotate.

Always keep in mind that As greater torque is applied the rotational force will be greater so as power increases the car will want to pull to the right, which we counteract by suspension preloading in adjustments. If doing any bar preloading do know that even only 1/2 turn is an extreme adjustment from neutral load position. We usually preload bars in increments of portions of a nut flat when we are close. 1/2 of a flat can make a car go straight that was trying to veer to the right. Too much bar preload will pull us to the left and quickly can get us into the wall.

TopspeedLowet

well Dparker,My pointing out that a high powered car WILL go lift pretained to a HIGH powered car, Like pro mod and pro stock and the like. This blog info does not address the set ups in high powered cars. I can not and do not disagree with the basic info in this snippit you cut and pasted off the net for general info. But in a car that is neutral on preload and goes left needs NEGATIVE preload and that is a common need in high powered cars reguardless of what this guy posted and now you posted. This info ASSUMES that the differental is square and all suspension mounts are square and correct which is why I went on with the explination of how to check that on his car prior to giving a bunch of random advice that likely does not apply. I don't like to hear (racers) mechanically say that if she goes right it need more pre load because they don't know any other way to correct or locate the likely true culpret, and will not likely fix the problem. You can pre load to your hearts content on your own stuff because you probably know your own car well, but I personally do not recomend to someone needing advice on there suspension, to preload prior to determining where the set up is in the first place weather it is square, plunb etc. This is why I try to explore the entire combination as apposed to plagerizing someone else's log book. I don't want to send a guy or gal in to the wall or wreck there car with vague canned advice that jumps over the 20 steps that are required to do the task accurately.
Good luck to you all and enjoy the read

dparker

Your exactly right, sometimes I think as it would pertain to my car. Kinda what I would do is mine were doing the same thing. Its always better to ask a few questions before giving advice. Your right, getting everything straight should be done first. But a 2x3 9sec. ladder bar car just reacts different to changes than a 7sec all round tube prostock chassis.
You ready to sponsor me one of those chassis? I promise to put it in the winners circle...

TopspeedLowet

I wish I had the Jack to throw your way buddy. I have only been building a few sets of headders so far this winter. No full fab cars to help my bottom line this season
Thanks for the reply though, I appreciate your commentary and friendly comments on this site. Sorry I can not float you a new chassis to play with.
I hope to have more work next year to help my program finance's as well.
I hope every one here is able to get through the season safely with there budgets they have, that is why I believe getting good advice is so important lately.
Thanks again Dparker for your thought provoking comments
Bruce

altune

Thanks for all the comments pertaining to this problem. I have a better idea as to what is happening on the car now. I just need to spend some time tweaking it. Spring preload, preload on the ladder, etc.
Damn power always causes problems. ( or the lack there of )
I'll keep you posted on progress.
Thanks
Al