my suspension

I have been through just about every suspension mod in the book.

Version 1.1:

Front:

Rear:

Version 2.0:

Looking for more drop and stiffer suspension:

Front:

Rear:

Version 3.0:

"Soft spring/big bar":

Front:

Rear:

Version 3.1 (more rear drop):

above plus:

  • Western Chassis front hangers

  • UHMW nylon slider box spacers

 

 

Below is a photo of the Version 2.0 front suspension.

Version 3.0:

 

 

For the mean streets of L.A., the 1,100 lb springs and old-spec Hotchkis leafs have just become too much for me.  Maybe I'm getting old.  Plus, the old-spec Hotchkis leafs are now spec'ed for crew cabs and Harleys, which have more weight in the rear.  By removing the spare, class II hitch, and rear bumper, I have taken even more weight off of the rear, which makes the back a little too bouncy for rough streets.

 

One strategy for handling is a compliant suspension with maximum anti-sway bars -- race car engineers call this "big bar/soft spring."  The theory is that using stiff springs for roll control comes with a ride quality penalty.  But using uber-stiff anti-sways to control roll allows you to run softer springs for better ride quality on rough roads.  Anti-sways actually add spring rate in turns.  From what I know, Hellwigs are the biggest, baddest anti-sways in town.

 

I'm going to give the big bar/soft spring strategy a try.  Using spring rubbers in the front and helper airbags in the rear, I hope to be able to crank up spring rates at the track to compensate for the looser springs.  The downside is that these methods will raise the ride height slightly, exactly at the time that you want it the lowest.  A 4-link rear suspension with coilovers on all corners would be the ultimate, but that's just not an option for me right now.  I don't have the time to prototype and fab it up.

 

Shocks remain an issue.  I can't seem to get the QA1s dialed in, even after having custom heavy-duty valving done by D&D Race Tech.  Pitstain has done some interesting research on potential Bilstein "Sport" and Koni shock candidates.

 

For those lucky enough to live where the streets are smooth, or use the truck primarily for track events, my "Version 2.0" suspension handles fantastically.  The changes are all driven by the need to tame rough roads.

history:

I installed Hotchkis front and rear springs and anti-sway bars immediately after I bought my truck.

I installed QA1 shocks with Stan Martin's heim joint kit shortly thereafter -- the stock shocks didn't control the heavy Hotchkis springs well.

Next up was a Ruslow panhard bar and some Metco traction bars.

Here are some Version 1.1 rear photos (click on images for larger versions):

  

     

I ran this setup for about two years.  It performed well both on the street and the track.  I have had some quality control issues with the QA1's, though.  Four blown shocks in about 15,000 miles.

Looking for a slightly lower ride height and better handling, I installed a set of DJM upper and lower control arms and 1" shackles.  My target was 17" center of wheel cap-to-bottom edge of fender.  The 1" shackle/Hotchkis leaf combo was right on the money.

But lowering the rear this far causes all sorts of clearance issues.  I had to remove the bed support over the panhard and grind away several areas on the frame to provide clearance for the rear anti-sway.  And I am now forced to use tiny (less than 1" tall) button bump stops, so hard hits in the rear are eye-opening.

I added some Air Lift Slam Air helper airbags to restore load hauling capacity.   With the rear this low and any kind of load in the bed, the axle is pretty much sitting on the bump stops.  But with a few pounds of air in the bags, I can carry just about anything.

Some So-Cal rear shock extenders were a lifesaver.  The lowering had put the shocks near the end of their useful range.  The So-Cal extenders allow the shocks to sit lower and more upright, both good things.

 

Many people have reported that So-Cal makes a special version of the extenders for Lightnings where each side is somehow different.  Mine are identical.  I can't see why there should be any difference between the two sides.

The front was a bit more challenging.  My experiments are recorded here.  I finally found the right drop with Ruslow 1,100 lb springs and 1" solid spacers

The table below shows the actual drop on my application (measured from the center of the hub to the fender lip). 

 

stock

Hotchkis

DJM arms/Ruslow coils/1" front spacers/1" shackles

Drop

Front right

Front left

Rear right

Rear left

19"

19"

19.75"

20.25"

18"

17.75"

18"

18.5"

16.25

16.5

17.25"

17.25"

2.75"

2.5"

2.5"

3"

 

 

 

 

 

 

 

 

VERSION 3.2:

 

home

07/31/2009 Tim Skelton