Softer rear spring

[supertruck]

At the track this week, one of the other drivers, after watching me practice my S10, took a look at my RR leaf (stock rate lowering springs) and told me to remove the RR lower short leaf to "free up the truck". He said it made a big difference in his, let it come off the corner much better. And he is one of the fastest out there. I was having to blip the throttle on exit to keep it under me, fighting a tight/loose condition. My question - the trucks are usually tight. Softening the RR adds crossweight. How does a softer RR help the exit if the truck is already a little tight? I'll find out this Saturday since I've made the change, but I'm just curious - you chassis experts on here can probably teach me something.

[38racing]

I was wondering how it worked out supertruck. I'm in the process of building a new truck for next year (s10) after I rolled mine this last year. My rr leaf spring was softer and worked great on rubbered up tracks, but horrible on tacky tracks (I race on dirt). I was also wondering where you got the lowering springs. I've found some online, but they're all exspensive.

Our rules state that the leaf springs have to use stock front mounts, but we can use adjustable hangers in the back as long as they're in the stock location. I would like to try lowering springs to drop the center of gravity so I don't get so much role and weight transfer. Thanks for the help.

[Headhunter]

Why not just put racing springs under it. The milti leaf are cheaper than lowering custom springs.

[empiretrucks]

If you are tight, it means your left rear is over biting the right rear. If you are loose, then your right rear is trying to over bite the left, but isn't grabbing because there is just too much side pressure on it which likely is because you have too much weight transferring to the right, taking too much bite off the left. So....

If you were tight on exit, then basically your weight isn't transferring enough to the right. By softening the right side, then more weight will transfer over, freeing the truck up.

Obviously there is more to getting the handling together than this, but this should explain why the rear springs have the effects that they do on handling.

[supertruck]

after removing the small leaf from the LR, as a fellow racer suggested. I went out for a practice and the truck was so tight on corner entry that I drifted up a full lane before I was at the apex and totally lost the corner. Changing my entry line did not fix the problem so I put the leaf back in and figure I'll try something else when next season starts. I also plan on going to Landrum leafs in the rear, just have to figure out what rates I need.

[84Dave]

SuperTruck........... I'm not a leaf-spring expert, but they likely work like our Pro-4 coil-overs. Remove that short, bottom leaf & the RR spring rate DECREASES. Then drive the setup into a corner, the chassis rolls more @ the rear, and additionally loads up the RF. The chassis pushes worse. And 'snaps' loose @ corner exit because you have the steering wheel turned to the left too far, trying to overcome the mid-turn push. If I had been advising, I would have recommended installing an additional short leaf @ the RR to INCREASE the spring rate, reduce the rear roll, unload the RF, & I believe the mid-turn performance would have been much better. All the above assumes the rear is staying decently 'straight' in the chassis during turns. Is the track dirt or pavement? -Dave-

[Racedad]

Softening the RR with no other changes will make the truck push worse.Those of you who have never driven a 4 cyl S10 with a typical setup on an asphalt racetrack cannot imagine how tight these are coming off turns 2 and 4.Scarey to drive,
real tight,"herecomesthewallholycrapwilliteverturncheck yourunderwear" tight.
Typical setup is remove a few leafs and add lowering blocks which results in a very low roll center which is defined by a line drawn through the leaf eyes.Front eye mounts under the framerail which is quite low.Not enough power to break the rear loose.Rear rolls over hard coming off the turn resulting in a bad push and a hot chewed up RF tire.
The following is take it for what it's worth or leave(leaf-hehe) it,I'm not going to spend time defending this,it works for me:
My favorite setup for asphalt or dry slick dirt is actually really soft old Caravan springs with some leafs removed,a bit stiffer on the RR but the truck actually rides on a big RR rubber snubber from mid turn to just off the turn. This dramatically raises the spring rate and the roll center when it's on the snubber.You need to get rid of the stock snubber from the framerail and it's mount because it won't let your travel go low enough then fab your own mount and use a modern snubber hopefully outside the frame rail.Your snubber needs to just barely keep your axle tube from hitting the bottom of the framerail.
Your snubber will define the roll center so go high,get above the tube,like think top of the backing plate.
The rear roll center is a big deal if you try to tune these entirely with springs you will need to go real stiff RR.

[empiretrucks]

I guess I should have added, that was for dirt....

[return to dirt]

tried to reply to this 3 times but 4m kept messing up. i used to have a nissan hardbody i raced. i modified both rear springs the same. i think they were 4 leaf stock. i would get rid of the 2 short leaves. then take the next leaf and move it foreward until the end is a few inches short of the front spring eye and redrill it. i then used an overload leaf from a d50/mitsu which is straight and about 1/2in thick. i moved it foreward until the end was under the spring eye and drilled it for the center bolt. the overload leaf acts like a liftbar/traction bar. i would use the front torsion bars to get the cross i would need for the track condition. i would also change air pressure or wheel spacing on the right rear depending on track conditions. i didn't use any lowering blocks. i did use a piece of heavy conveyor belt on the frame on the right rear for if the housing bottomed on the frame. this setup had very good foreward and side bite.

olin

[96MiniTruck]

In my experience at Langley, when you soften the RR spring, the truck will push like a freight train. Adding in a short leaf will really free up the back end, often too much.

John

[steveshawjr]

take the short leaf out of the lr and leave the rear clamp off its what we do with our camaro we have always found a softer lr is the way to go wit h leafs