Rear Suspension Video

[Bobby Fazio]

I am looking for advice for the rear suspension on the SS/L Mustang. Here is a run from Atco this past weekend. Changed springs three times 110lb, 130lb, and in this video 150lb. The front end was not moving much due to coil over setup with not enough shock travel. The car tends to drive the right rear tire down and the left front tire up no matter where the shocks are set. The shocks in this run were set 12 clicks on the rebound and 7 clicks on the compression. When I try the stiff compression and soft rebound the rear tires bounce like a basketball and the sixty foot is very slow. These tires are M/T 29.5/10.5stiff sidewall. Lastly the ladder bars are in the bottom holes for maximum weight transfer. Thanks!

[Dyno]

The spring just supports the weight of the car, the shock controls the movement. The spring should compress about 25% of the spring height. I think the 130 & 150 spring are to much. The shock moves much less than you think. The shock will first go into a rebound/compression movement, about .25 - .40/.60 - .80 A rear shock sensor tells alot. With the stick, you need a different setup than an auto. Talk to Randy Mans at Fastshocks, he can help you out. 612-306-5387

[Robert Simpson]

Bobby, what a great video. I do not pretend to know anything. But, I would assume that with a stiff sidewall tire it would rebound (bounce very quickly). I would assume it would be the shock adjustment and the clutch setting on the hit vs the importance of the weight of the springs. By the way what camera did you use, it is very clear. I like the car. Thanks again.

Robert

[njk53]

It was hard to tell and correct me if I'm wrong, it looked like the spring was not compressing much if at all.

[Bobby Fazio]

Thanks Robert, it is a Go Pro 960 that I purchased back in 2011. My uncle and I made a mount for under the car. I just realized that the video looks kind of weird because YouTube has a smoothness enhancement on. That's why the camera is doing weird zooms and what not. I just turned it off and hopefully soon it will be back to original. Also, Thanks for your input Dyno.

[Jeff Lee]

" Lastly the ladder bars are in the bottom holes for maximum weight transfer. Thanks!"



I disagree with this statement. As I've never had a car like yours, a 4-speed with a little engine, all I can do is offer an opinion. I'm guessing you only have low 400HP and torque is as bad as it gets because it's a little 289 with low compression and all. That being said, I would think I would place the ladder bars further UP and then make my shock adjustments using the lighter 110# springs. I don't think a car like yours has enough "giddy up and go" to warrant having the IC way up front and attempting to carry the car. I'd hit the slicks harder with the ladder bar moved up. Then you might see some changes with shock adjustments. And of course, I'd have the shocks dyno'd to make sure all is well with the shocks. No matter how new or old they are.

[Bobby Fazio]

Originally Posted by Jeff Lee

" Lastly the ladder bars are in the bottom holes for maximum weight transfer. Thanks!"



I disagree with this statement. As I've never had a car like yours, a 4-speed with a little engine, all I can do is offer an opinion. I'm guessing you only have low 400HP and torque is as bad as it gets because it's a little 289 with low compression and all. That being said, I would think I would place the ladder bars further UP and then make my shock adjustments using the lighter 110# springs. I don't think a car like yours has enough "giddy up and go" to warrant having the IC way up front and attempting to carry the car. I'd hit the slicks harder with the ladder bar moved up. Then you might see some changes with shock adjustments. And of course, I'd have the shocks dyno'd to make sure all is well with the shocks. No matter how new or old they are.

Ahh ok good point Jeff, thanks. That makes sense. Why then would you choose the 110 springs as opposed to the other 2?

[ss3011]

It is very hard to tell what is going on at full speed. You can take the video and slow it down using Microsoft Live Movie Maker, its part of the Windows Essentials package. You can slow it down to 1/8 speed and do a better analysis of what is going on, Cool Video !!

[FED 387]

springs look as if they are "almost" totally stationary little to no compression or expansion at all on the initial launch leads me to believe they are too stiff--- look at the video if you can put it in "slow motion" things hapenning to fast on the normal speed hard to see whats really going on in 1-2 seconds--I would put ladder bars all the way up to top hole to preload the chassis just to see if it likes it--- if it does then tweak the shocks a bit a little at a time to see what happens if it likes that then go to changing the springs go from the softest or the firmest all the way to the extreme opposite--- I would only do maybe 100-150 foot long plus squirts to see your results--- dont waste time doing anything longer you just want to get the car to launch who cares what it does in the 1/8 or 1/4 work on that later--- just remember for every .01 in the 60 foot usually means .02 in the 1/4---you are not looking for subtle differences now you want radical changes then you can fine tune what ever it is you are trying to do by changing shocks, locating points or spring rates and even rear tire pressure to---- you are not gonna solve this in 2 minutes unless you get lucky and hit the right combo right away----my 2 cents ---FED387

[Jeff Lee]

Originally Posted by Bobby Fazio

Ahh ok good point Jeff, thanks. That makes sense. Why then would you choose the 110 springs as opposed to the other 2?

Primarily be because your car is so lite. Springs just hold the car up, if not enough, pre-load them which works better anyways. I bought 110# springs for my AMX as I thought I was going SS. And that would have been 3160#'s with driver and well over 600 HP with a stick.
You may want even lighter than 110# springs.