To much wheel hop

[models916]

cut it out!

I cut one full loop on front and rear coils so they sit in the spring channel the same.

 

[jim_ss409]

I used PST Polyurethane bushings and boxed the control arms on my 62 Convertible. It doesn't hop and it's pretty quick off the line for a big car. (1.71 best 60' with 9" slicks) I'm not sure boxing the lower arms was necessary but I think boxing the upper arm is worthwhile. There's a lot of pull on the upper arm. The cross member it attach's to was ripped off of the frame on the right side of my 62 when I got it. I re-enforced that area while I had the body off.

Aubrey, I'll be interested to see how well your car hooks with this change. I think it's going to help a lot. Getting the 60' times down to where they should be is the last piece of the puzzle.

 

[TomO]

Does anyone know where the instant center is located on our cars? I do not have acess to 4 wheel scales to find out. I have read old posts and found that horizontally it was estimated to be around the bolt up location of the carrier bearing. I could not find any info on the verticle position.



Tom

 

[dq409]

aaaaah, but JIMMM!...
you neglect to mention that you have 5 foot ladder bars securing the rear end housingno1: :stooges

:

O,,, but Oz,,,,,, I took those off several years ago,,,, Old picture,,,,

Look closer,,,, besides,,, when I launch she is flat and steady,,,

 

[CDNpontiac409guy]

I should have been paying attention

Well, JIMMM!... that's amazing

BTW... GREAT PICTURE of launching bang

 

[bubbletop1961]

Hey tomo. Ill post this pic. Tomo and I have been talking a little about this. This is a drawing I did to scale,( although some measurments were just taken with a tape). I figured this would give me a good idea where to start. The blue lines are the extended line of the control arms in the factory mounts. The red line is drawn with the upper rear mount moved up 2 inches. Who thought such a simple change would effect it so much. I already have a bracket made and tacked togther. Just need to finish it. please any thoughts, chime in.

 

[bubbletop1961]

Here is a couple of pics of the bracket.

 

[jim_ss409]

Hey tomo. Ill post this pic. Tomo and I have been talking a little about this. This is a drawing I did to scale,( although some measurments were just taken with a tape). I figured this would give me a good idea where to start. The blue lines are the extended line of the control arms in the factory mounts. The red line is drawn with the upper rear mount moved up 2 inches. Who thought such a simple change would effect it so much. I already have a bracket made and tacked togther. Just need to finish it. please any thoughts, chime in.

I think moving the instant center down and in like that will work great. They say that getting the instant center in the right place is the key to a good launch. The back end of these X frame cars tends to squat on acceleration. It looks fast but it's actually slower. The best description I've seen of how this works goes like this... Imagine you're standing on a bathroom scale while holding up the back of a car by the rear bumper. If you suddenly lifted the back of the car a few inches you'd put extra weight on the scale. Of course the extra weight would only last for a second or so while you were lifting but that's all you need. If you apply the same effect to the rear tires that second of extra weight plants the rear tires increasing the traction. This gets the car moving quicker and the extra acceleration causes more weight to be transfered rearward. The result is a good launch. When the instant center is too far forward the rear springs absorb some of the down force right at the exact instant when you most need the traction. If the tires start to spin you don't accelerate quickly and so you also loose much of the weight transfer that comes as a result of acceleration.
They say that if you watch cars launching at the dragstrip you can see some trends... Many GM's with stock trailing arm suspensions squat a bit off the line and never get great traction. (instant center too far ahead) And many leaf spring cars tend to hit the tires really hard but only for a split second then spin. (instant center not far ahead enough) I read one article that suggested that the instant center should be roughly between about 32" to 48" ahead of the rear axle and about 6 to 8" from the ground for most cars. But they say that different cars have different requirements depending on tire type, gearing, wheelbase, automatic or stick, fast car or slow car. The whole thing's a little over my head but I did gather that as long as you're in the ballpark you can fine tune the suspension with shocks and spring rates. And of course if you've got a low powered car with huge slicks you'll never spin a tire anyway, but the quicker you get the more important the instant center becomes.

 

[models916]

some help here

check here for info

http://www.carcraft.com/techarticles/116_0402_rear_suspensions_increased_traction/index2.html

 

[64CAYNE]

Thank you all for all of the advise. I know there are many options but maybe how I use the car wasn't explained as well either.
#1 It's mostly a cruiser. Of course i hammer it on the open road here and here and that is where I'm getting the hop. remember now, at this point, i want to lay down rubber, not hook up and go. LOL
The look I want is the sleeper. I will be getting rid of the Cragars soon to put on some Rally type wheels. I do want the car slighly lower in the front as I think the front tires just seem to small for those wheel wells.

I will be putting this cr on the dyno in the next month or so just to see what it does, and then i will decide if it ever goes down the track. I do want to go take it to the track at least once. Again, just to see what it will do. They have the friday night drags here where anyone can run.

I guess from everything I've seen through all of these posts, my game plan for the car for my use should be as follows.

1. First and formost, stiffen up the rear end. Lose the airshocks and add airbags in the springs. I think this is very affordable and should help me a bunch.

2. I have a welder so boxing the lower arms would be a easy fix. Worst case if they are too far gone is getting aftermarket ones. Also replacing all the bushings.
Also taking a look at the upper arm and possibly replacing it.

Unless I'm way off, this should help my performance.

Let me know if it this sounds like a reasonable plan of attack for what I want out of this car.

And thanks again for all the input guys.

JJ

 

[Ronnie Russell]

JJ, sounds like a good plan of attack. I would think you will see much improvement. Let us know how it works out........

 

[bubbletop1961]

I would say your on a good path. The airbags and aftermarket upper control arms can be backups if the rest doesnt work The losing the air shocks, New bushings, And boxing lower arms sounds like a great place to start. Not to mention pretty reasonable on the pocket book, And all not hard to do and fun. Let us know how it works.

 

[tripowerguy]

I'd bet money that if you get rid of the air shocks and get a good set of QA's set them on firm your wheel hop will disappear. I'm not saying you will hook-up you may boil the hides bad but no wheel hop. Of course I don't know the condition of the bushings or if all the arms are secured but all things being good condition I'm sure the wheel hop will be gone. Roy

 

[tripower]

JJ, I think your on the right path. Also I think I would replace the bushings before I boxed the trailing arms, loose the airshocks and, I think you will be there. Good luck and keep us posted.

 

[bubbletop1961]

Not trying to steal the thread, But it wont let me repost the pics on page 2 in a new thread. Any have any coments in the instant center drawing I did along with the pics of the bracket I made. Wanting to get it finished up soon, Wondering how you guys went about doing the same and results of the upgrade?

And 64cayne how is your car coming along. Get the wheel hop fixed yet. Which step did ya pick first. be sure to let us know the results.

 

[jim_ss409]

Bubbletop, I don't know all that much about this stuff but your modification looks good to me. It'll be interesting to see how it works.

 

[Bam59]

hi, to repost pictures you need to go to usercp then down to attachments
and delet your pictures. then you can repost them. hope this helps mike

 

[64CAYNE]

No, I'm going to get the QA shocks and start there. Just haven't had the time lately to get anything done. I'll keep you all updated when I attack the issue again.