Suspension And Drags?

[rice_me_up]

hi all.

i did a search with no success.

ive heard that for drag cars, soft suspension is better.

whats the science behind it? my assumption would be the stiffer the better...

thanks.

James.

[Sydneykid]

hi all.

i did a search with no success.

ive heard that for drag cars, soft suspension is better.

whats the science behind it? my assumption would be the stiffer the better...

thanks.

James.

By "softer" I assume you mean spring rates and shock damper rates. "Soft" does not mean that sloppy, worn bushes are OK.

At launch the idea of softer spring and shock rates in the rear is to lessen the hit of torque, such that wheelspin is lessened. At the same time a squatting rear end (in a RWD application) allows transfer of weight off the front to the rear. This also gives more traction, not just at launch but for some time thereafter.

cheers

[rice_me_up]

thanks sydneykid.

your knowledge is only exceeded by my attractiveness (jokes)

cheers. james.

[lukits01]

I have adjustable rear dampers, If I set it to maximum softness the car feel underdampen, like its riding on springs, bounces up and down on uneven roads, so I adjusted the damper setting stiffer and it rides fine now. But when I go down to the drag strip should I set it back to maximum softness again?

[Sydneykid]

I have adjustable rear dampers, If I set it to maximum softness the car feel underdampen, like its riding on springs, bounces up and down on uneven roads, so I adjusted the damper setting stiffer and it rides fine now. But when I go down to the drag strip should I set it back to maximum softness again?

By the sound of it the shock adjustment is for rebound (shock extension) only. This is OK for drags on the front, let’s the front wheels droop fast for nose lift.

But not so good for the rear, where you need less bump (shock compression) valving so the rear squats under acceleration. You actually need more rebound (shock extension) valving on the rear to hold the back down for better weight transfer. Plus, more rebound (shock extension) valving helps to reduce the axle tramp

This is why single adjustable coil overs are pretty much a waste of time on a drag car.

My suggestion would be to run the front shocks on full soft (for more droop) and wherever you feel most comfortable on the rear and enough to avoid any axle tramp.

cheers

Edited May 29, 2006 by Sydneykid

[lukits01]

By the sound of it the shock adjustment is for rebound (shock extension) only. This is OK for drags on the front, let’s the front wheels droop fast for nose lift.

But not so good for the rear, where you need less bump (shock compression) valving so the rear squats under acceleration. You actually need more rebound (shock extension) valving on the rear to hold the back down for better weight transfer. Plus, more rebound (shock extension) valving helps to reduce the axle tramp

This is why single adjustable coil overs are pretty much a waste of time on a drag car.

My suggestion would be to run the front shocks on full soft (for more droop) and wherever you feel most comfortable on the rear and enough to avoid any axle tramp.

cheers

Makes sense to me, thanks

The shocks in question is GAB adjustable damper, so they are not coilovers

I would have thought the adjustment would be for bound not rebound

To make matters worse, the stickers on the front shocks have peeled off so I cant tell what they are set at

But I'll try to go by your advice first SK, cheers

[Duncan]

all skylines runn coilover shocks, it just means the shock sits inside the spring

[R33S2]

where you need less bump (shock compression) valving so the rear squats under acceleration. You actually need more rebound (shock extension) valving on the rear to hold the back down for better weight transfer. Plus, more rebound (shock extension) valving helps to reduce the axle tramp

The shocks that do the right things in that quote are they shelf items (that would just replace the shock) like this for the R33 that you know of? Or are they specialist item?

[Sydneykid]

The shocks that do the right things in that quote are they shelf items (that would just replace the shock) like this for the R33 that you know of? Or are they specialist item?

Specialist item, they need to have separate bump and rebound adjustment. That's an expensive proposition, minimum $1,000 per corner. Consequently most guys have specially revalved shocks, we use Bilsteins, cost around $1600 for all 4.

cheers

[R DIRTY 3]

Lukits, to figure out exactly what your shocks are doing at what adjustment the only way to tell accurately is to put your shocks on a "shock dyno". I can help you with that. PM if interested.

Regards

R Dirty 3

[lukits01]

Specialist item, they need to have separate bump and rebound adjustment. That's an expensive proposition, minimum $1,000 per corner. Consequently most guys have specially revalved shocks, we use Bilsteins, cost around $1600 for all 4.

cheers

seperate bound and rebound shocks require remote reservoir am I correct? Besides the usual japanese names, what else is out there? Moton? Pensky Racing? Quantum and aragosta

Is drag suspension setup mainly focussed in shock absorber and spring combination?

[Sydneykid]

seperate bound and rebound shocks require remote reservoir am I correct? Besides the usual japanese names, what else is out there? Moton? Pensky Racing? Quantum and aragosta

Is drag suspension setup mainly focussed in shock absorber and spring combination?

Toe and particularly camber change are important as well

Add to your list Proflex, DMS, Ohlins, Sachs, Koni, Bilstein, Dynamic and few hundred others.

The Aragosta's I have seen are Ohlins.

cheers

Edited June 14, 2006 by Sydneykid

[lukits01]

Hey SK,

attached is a print out of my wheel allignment settings

What would you advise for increased traction down the 1/4 mile?

The car is an Auto and it allready has pineapples set for best overall handling rather than traction

[Sydneykid]

Hey SK,

attached is a print out of my wheel allignment settings

What would you advise for increased traction down the 1/4 mile?

The car is an Auto and it allready has pineapples set for best overall handling rather than traction

The rear toe is pretty much zero, so that’s OK. But the rear camber (as usual for a lowered Skyline) is terrible. It needs to be zero at the very least and if possible 0.25 degrees positive. It looks like they have used the standard adjusters to remove as much as they allow (1.35 to 1.1).

My suggestion would be to fit 2 rear camber kits ($123 X 2), that will give you more than enough adjustment.

I would also move the rear subframe alignment bushes to the maximum traction position.

cheers

[lukits01]

I asked for -1 Rear Camber as I thought this would give the best overall handling. Not sure if it would have been possible to dial out more.

By moving the rear subframe alignment bushes to the maximum traction position you mean setting the pineapples to induce more squat? How much of an affect would this have on the handling for everyday driving and suppose if I go to the occasional track day?

Would Rear subframe mounts like the ones from Noltec improve anything?

[Cubes]

Would Rear subframe mounts like the ones from Noltec improve anything?

If your current ones are buggered yes.

[lukits01]

If your current ones are buggered yes.

How can I tell?

[2rismo]

Everyone goes too soft in the rear on Skylines for the drags and it is DUMB!

Hands up who wants 1/4 of their rear tyres on the tarmac???

Didn't think so.

My rear suspension is hard as buggery

[Thunderbolt]

Everyone goes too soft in the rear on Skylines for the drags and it is DUMB!

Hands up who wants 1/4 of their rear tyres on the tarmac???

Didn't think so.

My rear suspension is hard as buggery

I agree. Probably best to have hard suspension at the rear, so it dosen't dip down too much and throw the camber out of whack. Soft suspension would be useful up front though, to get good weight transfer happening.

[neil_se]

Yes, but only so long as you've got good sticky tyres with enough sidewall flex to avoid wheelspin.