shock absorbers

New shocks are required with the stiff-sprung Hotchkis or Roush systems.  Without new shocks, the truck will ride like the shocks are worn out--jiggling over small bumps and bucking over large ones.

Easily the most popular performance Lightning shock is HAL's 12-way adjustable QA1 shocks.  Just turn the dial pictured to the left and the shock goes from soft to rock solid in 12 steps. 

Unfortunately, I have had four out of five fail within 15,000 miles.  QA1 replaced the first one (a leaky rear) immediately, with free overnight shipping, but read me the warranty when the next one failed about 18 months after I bought it.  Stupid.

After about 15,000 miles, only one was working properly.  One of the rears had no rebound (adjustment knob did nothing), but plenty of compression.  The other rear had no compression (adjustment knob made it a little stiffer), but plenty of rebound.  One of the fronts was completely blown out, with no resistance in or out on any setting, it popped up like a gas-charged shock, and made a gurgling noise.

I sent them to D&D Race Technologies for rebuilding and testing on the shock dyno.  Here is what I posted:

Here is the diagnosis (I may not be 100% correct on all of the below, but it is the best of my understanding):

No sign of user error.

The failure mode is simple: There is a washer in the shim stack that is forced up on the compression stroke. One the rebound stroke, the washer is forced back down onto the carrier. Think of it as a trap door.

This washer is only .006" thick. Mine are "shattered." This allows the oil to flow unimpeded in either direction, i.e., the shocks are worthless. The solution is a bit more complex than just throwing on another washer. It will just break again. We can use a thicker .008" or 0.010" washer, which will resist breakage better. But this will stiffen up the shock on the compression stroke. No problem, I can just run the shocks on a lower click setting to compensate, right?

Nope. The rebound stroke would now be mismatched to the compression stroke.  Road shocks are designed with a strong rebound bias (way more rebound resistance than compression resistance). So I would go from a (just a guess) 30c/70r to a 50/50 shock. And the compression stroke at the same number of clicks would be brutally stiff.

So Denny is going to put in one of these thicker washers, but drill a small (about .003") [edit: must be 0.03"] hole in the piston with a mill. The oil can flow freely through this hole. This will reduce the resistance on compression to compensate for the stiffer washer. It will also generally make the shocks a little softer on little bumps, but the main circuit can handle the high-velocity stuff (sounds a little like IAS theory to me). Another benefit is that the shocks will work less hard on a road course. The drilled holes will allow at least some oil to move unimpeded back and forth across the piston, which will help keep the oil cooler. And further help keep the new washers from breaking again by lessening the load on them.

All this tech is actually going to come cheaper than I thought. Since my shocks have so few miles on them (#$^%ing QA1), Denny thinks that the seals and wear parts are okay to reuse. My money will all be going into the revalving and testing.

Finally, Denny explained that the QA1s that we use are super digressive, meaning that small changes on the lower end of the click scale have big effects, but changes on the upper end of the click scale are so small that they have very little effect. So I was wasting my time trying to sense the difference between 8 and 9; I should have spent more time experimenting down at the lower end of the scale.

QA1's are widely available, but the best bet is to buy them from Ruslow (Stan Martin).  Stan sells the right parts and can also offer installation advice.  Stan also sells custom upper shock mounts with heim joints as opposed to the stock threaded rod/rubber bushing setup.  The stock mounting setup can cause squeaks and binding.

The below photo shows the passenger side mount on SW Thomas' truck.  He used a single bolt through the middle and apparently recycled one of the stock washers.  Note in the photo above that I drilled the mounts for four 1/4" bolts to keep the mount from rotating.

The bed must be raised to install the upper shock mounts, but in the long run it saves time as they make shock removal and replacement easier.  Contact Ruslow through his forum at NLOC.

QA1 now makes double-adjustable shocks, but they are super expensive.

Another option are the stock Bilsteins, the Hotchkis Bilsteins, and "Sport" valved Bilsteins.  This tidbit from Pitstain:

According to Bilstein Tech support they are FIRMER than factory and specifically for the Lightning......nobody seems to buy these because of the hoopla surrounding the Hotchkis jobs, which in reality are NOT custom at all, but are in fact spec'ed for VAN duty.

However they are best suited to a drop spindle or a-arm setup as they are for stock height Lightnings....extenders would be required in the back for sure as well.

2WD Pickups F150 Front (BE5-2478-H1) $64.95

2WD Pickups F150 Rear (BE5-2479-H1) $64.95

Bilstein HEAVY DUTY shocks ("H0" suffix) are the standard OEM equipment on our trucks.

Bilstein SPORT shocks ("H1" suffix) are 30% stiffer than the heavy duty.

Bilstein describes the difference like this:

HEAVY DUTY (HD): For most vehicles including full-size sedans, SUVs and trucks. These shocks provide improved handling and stability without sacrificing ride comfort. They offer super damping ability that makes them ideal for heavy hauling for occasional off-road use, while maintaining an exceptional “street” ride.

SPORT (S): For the performance-minded driver, Bilstein “Sport” shocks deliver absolute mastery of the road surface. Designed to push a car’s suspension to it’s performance peak, these shocks are well suited for use with special springs, antisway bars or other suspension upgrades.

For the ultimate Lightning shocks, look to Penske's 8100 series, pictured to the left.  They are double adjustable, and can be made to order, but cost $600 each (4 times the cost of the QA1's).

After calling Bilstein, I found some new rear shocks from the Bilstein Motorsports catalog.  They are 7" stroke ASNs with digressive valving (part # B46-ATAD7).  I had Bilstein assemble and valve them like the stock shocks (they normally come in a kit for people who know what they are doing).  I've very impressed with the fit and finish.  They use 3-piece spherical bearings on the top and bottom and are supposed to be field-rebuildable (although the top of the shock says "do not remove).

The ASN series have threaded aluminum bodies that accept a reasonably priced coilover kit.  The SN series is identical, but with a non-threaded steel body.  Since I may one day run coilovers, I sprung for the extra coin for the ASNs.

I machined some spacers for the bottom mounts.  The shocks are about an inch from their full length, but I'm lowering the rear a bit more, so I'm not sure whether I will need the SoCal extenders any more.  I will check the travel with the o-ring indicators after a bit more driving.

Update:  I replaced the RUSlow mounts with stud-to-eye adapters from Air Ride.  But the hole in the chassis is much larger than the 1/2" bolt supplied by Air Ride.  So I used a thick washer, and bored the chassis hole out to the OD of the washer.  The mounts are secured from the rear by a fender washer.