Info Needed on TA Height
Info Needed on TA Height
(OP)
In my last post Greg and Norm got me to understand the IC on a GM torque arm suspension. I think I am up to speed in the IC,thanks Norm and Greg.
I am still failing to understand what the TA height(raising or lowering) does to the IC when you have parallel lines with the LCA's or they just wont intersect for a mile.
If you raise the TA from the stock imaginary line or lower it what does it do to the IC if ya also move the LCA's so it's line is parallel with the TA change and the perpendicular line off of the nose of the TA is not moved much.What do you use for a reference point the CG? Or the anti squat line?
What does all this do to weight transfer an a drag car? You might want to refer to my previous post also.
THANKS
Larry.
I am still failing to understand what the TA height(raising or lowering) does to the IC when you have parallel lines with the LCA's or they just wont intersect for a mile.
If you raise the TA from the stock imaginary line or lower it what does it do to the IC if ya also move the LCA's so it's line is parallel with the TA change and the perpendicular line off of the nose of the TA is not moved much.What do you use for a reference point the CG? Or the anti squat line?
What does all this do to weight transfer an a drag car? You might want to refer to my previous post also.
THANKS
Larry.





RE: Info Needed on TA Height
Jason S.
RE: Info Needed on TA Height
I moved the TA up 1-1/2" and the car stood on the bumper and came down on the wall. Nothing else was changed including the pinion angle. This leads me to believe that the height of the TA has a lot to do with bite. The LCA's were lets say running a parallel line to the TA and had been running there for some time.
I have another post with all the details if you will look, it may give you more info as to what happened without making another long post.
RE: Info Needed on TA Height
From my experience, I'd have to agree with Greg and Norm. Changing the TA front mounting height does nothing in terms of instant center or antisquat. Obviously you are concerned with damaging your car again, but this could simply be a case of a very sticky track that particular day. You really need to get more data points to be able to pin the problem on any one parameter. If you are on the edge of wheelstands anyways, the chassis could be very sensitive to small changes like weather, tire pressure, track surface condition. It might not be easy to pin down the problem considering testing could be damaging. I would install wheelie bars and then go to a testing session. Once you determine the problem you can take them back off and be class-legal again. Otherwise you are going to have to limit launch RPM and avoid the possibility of a reoccurrence.
Cheers,
Joest
RE: Info Needed on TA Height
Jason S.
RE: Info Needed on TA Height
The training wheels are already on.
This car has been very consistent over the past couple of years.We have run this track most every weekend so that's a given. The car was the same as it's been for the whole year with nothing changed but air pressure. We went up 2# so it would spin and not stand up,guess what.
There is something going on with the TA height in the car and I don't understand it. The car runs a 1.32 60' consistently and it will pull the wheels for about 15' and about 12" high and set them back down gently. I was looking to get in the 1.2's 60' but that will have to wait until next year (repairing)
I don't know if the reference point is the CG or the anti squat line.The TA was above the AS line so it should not have put it on the bumper. What I was after was the whole car to raise and plant harder so I could go up on the launch RPM's. The front end has limiters also and they let it travel about 2". Sooo if I cant get to understanding how to adjust it I will have to go back to the way it was.
This isn't the first TA late model Camaro I have seen do this but I didn't raise the TA as much as them and the effect shouldn't have been as much.
Any help is much appreciated.
RE: Info Needed on TA Height
I made longer links for the front,which has a heim end,and raised the front mounting point 1-1/2" from where the original mount was for the aftermarket TA. Then I readjusted the pinion angle back to 2*. The TA has never been parallel to the ground,it has almays been angled up at the front.
LR
RE: Info Needed on TA Height
RE: Info Needed on TA Height
I have all that down pat.What if the lines do not intersect? If ya draw a vertical line from the TA down to the line of the LCA's this is the IC,correct. OK but at what height is it? Is it the attaching point of the TA or is it some wear along the line?
Correct me if I'm wrong but as I see it you have to know the CG of the car. Then you point the TA AT the center of gravity with the projected line through the center of the TA from axle center to attaching point. Then you try to get the LCA angle to intersect the front TA mounting point.To me this would be ideal if the car will bite.If the car wants to stand up which way do you go? Do you bring the TA down,more angle on the LCA's,or both to get the IC further back in the car.
From that point if you raise the TA or take upward angle out of the LCA's far enough for the lines to never meet then where is the IC. The thing that has me confused is if the lines never meet going to infinity and do you want the TA line parallel with the ground below the anti squat line. This should make it wheel stand more if the LCA line is such that they never intersect.
RE: Info Needed on TA Height
Jason S.
RE: Info Needed on TA Height
Yes it is an aftermarket TA. The front mounts where the tunnel brace was mounted and on top of the cross tubing with 2 links that pivot. It is about the same angle as stock but don't mount to the tranny. The rear mounts in the same way as stock,except it is mounted to a 9" Ford rear instead of the 10 bolt stocker. It is adjustable for pinion angle also.
The rear has LCA relocation brackets that allow me to adjust the LCA angle. Now they are at a slight uphill andle from rear to front(2*-3*). I can get more but to get less I have to adjust the ride height of the car which is do able. It has adjustable coil overs in the front with 300lbs per inch springs,with travel limiters if needed,no anti roll bar and adjustable Koni shocks in the rear with coil springs of 175lbs per inch and height adjusters and the factory anti roll bar.
LR.
RE: Info Needed on TA Height
If what Jason is saying is true about the intermediate link, then raising the TA front mount up or down will change the angle of the intermediate link effectively lengthening or shortening the TA. I'd suspect that with an intermediate link, instead of drawing the line at the front of the TA vertical you will draw it through the pivot points of the intermediate link. If the link is short the articulation will be high and a slight changes in TA front height will significantly change the effective TA length. A shorter TA will, of course, increase bite by increasing the antisquat.
Joest
RE: Info Needed on TA Height
If you run a string from center of rear axle through the heim end center on the front of the TA, then run another for the LCA's the lines will never meet carrying it to infinity. Actually the angles are going away from each other. The LCA's are a slight uphill angle(2*) and the TA has a 8-10* angle up at the nose. It is about the same angle as the stock one just doesn't go as far forward. The links at the front mounting point for the TA are 90* to the ground or car.They are straight up and down.
RE: Info Needed on TA Height
See post above also-- this was an after thought.
When I drop the line straight down from the TA front mounting point and it intersects the LCA line that is the front to rear IC. At this point how high is it and what do you use as a reference to measure the height? Ground to ? CG height? If I angle the LCA's severely and get the TA string and the LCA string to cross behind the TA front location point,is that cross point the IC? If I take angle out of the LCA's to make the strings cross in front of the TA front mount (4" ahead) is that the IC Just further forward?
LR
RE: Info Needed on TA Height
RE: Info Needed on TA Height
Thanks Joest
The strings would be running forward from the rear axle.In the car the lines running forward are going away (farther apart) from each other on account of the angles. The string for the LCA's is a slight angle and the string for the TA is at way more of an angle upward. I am putting the strings like you would measure a 4 link.Am I doing it wrong? There is no argument from me I am just trying to learn how to figure the adjustments for a TA setup and get it straight in my mind.
I think the light JUST came on!!!!!!
See if this makes sence in a country boy manner.
The LCA's determine if it stands up or not.
The car is being PICKED streight UP by the TA at the front mounting point.
The angles of the LCA's determine if the rear of the chassis is pushed up to keep the front down (the front will rise but not stand up if there is sufficent angle upward on the LCA's)The whole car will raise instead of the rear trying to run under the front wheels(wheelstand).If the angle of the LCA's is right at parrellel with the ground then when the TA LIFTS the LCA's try to push the back of the chassis down and helps it wheelstand.Because of the TA not able to pick the front end off the ground without the LCA's helping it, this plants the tires harder.
Am I even close???
RE: Info Needed on TA Height
-Joest
RE: Info Needed on TA Height
Man it is simple when you can see it. I want to thank everybody that responded and helped with my questions.
Now maybe I can run with the training wheels pinned up.
Thanks again everybody.
LR
RE: Info Needed on TA Height
The diagram you posted is for a typical slider mount TA. The diagram is different for a TA with a short verticle front link. It turns into more of a 4 bar mechanism instead of a slider mechanism.
Jason S.
RE: Info Needed on TA Height
Yes, I agree. I wanted to start with the basics first.
RE: Info Needed on TA Height
In what respect are the lines different?
LR
RE: Info Needed on TA Height
-Joest
RE: Info Needed on TA Height
It has a poly bushing on the cross bar with 2 links that go up to the heim end. I keep the links straight up and down.
Is the only way to change the IC is by to moving the front LCA mounting point up or down?
The way it is set up now is the rear is the only point that can be moved on the LCA's.
From your diagram it appears the IC always is in the same place (depending on ride height). Even the % of anti squat can't be changed unless you move the front LCA mounting point. If you could run the line from the rear LCA mount through the front LCA mount and then to the centerline of the front wheel at CG height then where it intersected the line at the front of the TA mount would be the IC and where it intersected the vertical line at the front wheel would be the % of anti squat.Don't know if that is the way it works or not? Confused again...
LR
RE: Info Needed on TA Height
RE: Info Needed on TA Height
The training wheels are already on. No more crashes on top of the wall.
Again THANKS for everybody's help and THANK YOU Joest.
LR