Ballpark valving leaf-sprung solid-axle with Bilstein 7100

[tsm1mt]

I have a short-course racer that's live axle front and rear 4x4 with leaf springs and will probably remain that way for a while, thanks to rules and class restrictions.

Last time I weighed it, I was at 2400lbs nose, 1600lbs tail, on a 100" WB.

I've been running some Bilstein 14" travel 5100s up front. I believe the standard valving for these is 255/70, but I don't know for certain that's what my 5100s are running.

I'm at about 12" of vertical travel up front with the leaf springs.

Due to race damage, I'm changing things up a bit, and the 5100s are going to the rear to replace some lesser shocks.

I just bought a pair of 7100 14" Reservoirs for the front.

They're 255/70 valving, and I'm considering revalving before I put 'em on the rig.

I'm not certain of the spring rates, though 300lbs/inch comes to mind for a ballpark.

Front suspension seems to be working pretty well at the moment, but since the 5100s can't be revalved, I've never played with valving, and given the weight of the rig I could probably use a little more.

I definitely know it when a shock mounts comes apart. Rear shock failure leads to the rear bottoming out hard all of the time, while I don't recall *noticing* the front bottoming too hard after the front mount failed (bolt was in single shear), but I was already out of the throttle thanks to the rear failure.

For a leaf sprung rig, should I go heavier on the front shock valving with single 7100 reservoirs? 360/80? Bilstein recommends dual 7100s at 360/80 for a Bronco, but they're running front coils..

Just hoping to get a little closer on the first try.

By "short course".. races are usually under 30 minutes at a shot, though sometimes an hour. On Memorial Day I did two 20 minute heats, and the front shocks (5100s) were hotter than I wanted to hold onto for more than a moment with a pair of Mechanix gloves on, but I didn't notice a significant fade from the front (definitely noticed the lack of rear after the RR shaft failed).

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[Ramsey_ElWardani]

Sent a PM.

[tsm1mt]

Sent a PM.

The result of Ramsey's PM and a phone conversation was that I decided to try the 360/80 valving, the stiffest "stock" valving Bilstein offers, in the front.

I foolishly built my front mounts wrong, and broke a shaft the first race with the new shocks.. replaced it, and changed the entire front shock mounting arrangement to run the heim bolts front to back, making the shock pivot around the bolt as the solid front axle articulates, and using the heim misalignment to compensate for the front to rear movement of the axle is it goes from full droop to full bump.

Raced it for the first time after that last weekend. It *felt* better from the driver's seat. I managed to land several jumps without losing any teeth and it felt like it landed fairly flat, and didn't pound the bump stops before the suspension recovered, so the shocks were slowing the compression enough to help avoid the stops.

On bigger jumps, the rig still bounced after the landing - my assumption is it's just the lack of suspension travel and after bottoming out, there's still too much energy and the whole rig kicks up.

Unfortunately, I had a substitute video team in place, and they earned everything I didn't pay them. No video to help me decide how to adjust my tune.

All I have to go on is it FELT better, and that's a big improvement in itself.

All 4 shocks were sufficiently hot after just a dozen miles of racing, but I noticed no face between the start and finish (though video would've confirmed that)

One scenario for this winter's overhaul and upgrades is to move the 360/80 single 7100 reservoirs to the rear (singles), and run a pair of 255/75 7100 Res and a pair of 255/75 non-rez 5125s up front.

FWIW, all 4 corners are currently mounted more or less straight up and down. That translates into roughly 12" of travel on both ends, leaving a little fudge to help me refrain from ripping part the 14" travel shocks.

[BlueCoyote]

IMHO you need more shock.
Our straight axle Toyota runs Deavers and pulls 11-12" travel.
Started of with 2 2.0 Fox's. Was not happy with it. Then went to a single 2.5" King by pass shock. It would work for a while, then fade.
We then added a 2.5" King resevoir shock next to the 2.5 bypass and is works fine.
JMHO, but SAS leaf spring trucks need lots of shock.....

[tsm1mt]

IMHO you need more shock.
We then added a 2.5" King resevoir shock next to the 2.5 bypass and is works fine.
JMHO, but SAS leaf spring trucks need lots of shock.....

I agree, I want/need more shock. It's an evolutionary thing as damage and finances allow.

I'm trying to decide if coil-overs can be in my future before I buy too much stock in smooth-bodies.

I remember when I first put the rig together and complained about the $120 I spent on *all 4 shocks*.. worked fine for straight-line drags.. now $200 a corner doesn't seem so bad.

[1450-ranger]

Just by a SAW, all are threaded, then buy the coil kits and springs and you have a C/O.

[cosmo]

The same can be said for a Bilstein or a Fox shock.You can order your shocks with a threaded can.Later, add coilover hardware as needed.

[tsm1mt]

The same can be said for a Bilstein or a Fox shock.You can order your shocks with a threaded can.Later, add coilover hardware as needed.

And everyone probably already knows this, but the smooth-bodies are cheaper than the threaded bodies, so if you're never going to add the coil kit, buy the smooth-body (better yet, buy a smooth body used from someone else that decided to step up).

Thus the Class3 thread.. trying to decide if I could remain within the Class without retaining the leaf springs as primary suspension (but retaining the solid axle concept). Of course, while I run 14s up front now with the leaf packs, I'd move to 16s if I linked the front and limited it to the class-spec'd 15" of vertical travel.

[tsm1mt]

Update: I'm still polishing my turd - it shines a bit more after a rollover and fresh body n' paint.

I haven't weighed it lately, I suspect I lost some weight from the tail and added some to the nose, so the old 2400 nose/ 1600 tail is off.

I've progressed to where I'm running a single pair of Bilstein 5125s in the back, 255/75 valving. I'm running the stock leaf springs (but SOA, and they're on their last legs) with some heavy duty bump stops.

I don't notice the rear bottoming while racing, but don't have any recent video to really confirm.

Up front, I've gone to two 7100 RR shocks per corner. One pair is the set I had valved to 360/80, the other set is a stock valving of 255/75.

The 360s are hotter after a race, the 255s cool-ish. I haven't noticed any fade yet.

I've also added 3" Fox bumps to the front, with maybe 1" of up-travel before I get into the bumps (front springs are shot, too).

Bumps are hot after a race, with only a 1/4" band of dirt on the shaft.

It seems to land well, does not land harshly like before, and I launch it as hard as I can these days, intead of fearing for the results.

I don't know that I'm going to make any more adjustments or tuning to it - I'd bought some 2.5" SAWs to put the back, but instead of adding 'em to this truck, they're going on an entirely new chassis, so I'll be starting over on the shock valving efforts.

Next week, 9/16, I'll be taking it over the big fast jump that was causing me to rebound back off the ground before. It'll be interesting to see how the video turns out.