Wheel Spin Problems Need Advice

[FLOGGED]

Hey guys been up to the drags twice recently and i'm pretty disappointed
i have a n/a fg xr6 5 speed auto, now its usually running constant 14.1 - 14.3
with a average of 2.1 60ft.

I have changed my rear springs out for very low springs and changed my tires (from ATR Sport 2's to Nitto invo's) (245/35R19)

now when i ran a few days ago i was running high 14's to low 15's, i cant seem to launch i just keep wheel spinning, i have an open diff witch doesn't help but with my old tires / springs i could almost launch as hard as i wanted recently i have gone from 2.1 60' to 2.5 60' cant seem to get traction?

the tires i have changed to are apparently "high performance" tires at almost $300 each i would expect them to have at least some grip. (Nitto Invo's)

Weather i just take off fast or launch at even 2k rpm they will just spin (even on the street taking off quick they wont grip)

could this be a cause of bad tires or my rear springs? The springs have almost no movement in them (i always thought that springs can make a big difference on how a car puts power to the ground, hence drag racing suspension you can buy.) could no movement in the rear springs be causing me to spin?

I have tried the car at 40psi all the way to 30 psi, cant really go lower as i have to inflate / deflate at the servo as i don't have a pump and don't want to drive on the road with below 30 psi.

Cheers guys, any help is very appreciated

[99AUXR]

Flame suit on.

I ran nitto invos in a 295/30R18 and I cant tell a difference in traction and almost the the Achilles ATR sport I have on now with 245/40R19 don't have any less traction and possibly a touch more.

Im keen to throw on a set of 275/35R18 Pilot Super Sports and see how they go. But tbh I was rather un-impresses with the Invos. And I got terrible wear.

[Maka]

Try 22 - 25 psi in the rear tyres, the rear springs sound like they are too stiff for 1/4 mile duties. I would pm Giant, he's got plenty of experience & knows his stuff Imo. Good luck!

cheer's, Maka

[Seaton]

If you have them, put the stock rear springs in for the drags. It will help.

[FPV GTHO]

How low is low? MM not SSSSSSSSSSSL.

IMO the springs are undoubtedly what's done it. Especially if as you say there's almost no movement, as not only would they be lower but much stiffer. You need a soft rear spring to get the weight to transfer.

[FLOGGED]

Originally Posted by FPV GTHO

How low is low? MM not SSSSSSSSSSSL.

290mm from center of wheel to start of the wheel arch so the top of the tire is in the guard. ill just put my old lowered springs in, they seemed to work fine.

[FPV GTHO]

Originally Posted by FLOGGED

290mm from center of wheel to start of the wheel arch so the top of the tire is in the guard. ill just put my old lowered springs in, they seemed to work fine.

Stock is somewhere around 360-370mm for XR's so that's a sizeable chunk taken out of your rear suspension.

[Road Games]

Originally Posted by FPV GTHO

How low is low? MM not SSSSSSSSSSSL.

IMO the springs are undoubtedly what's done it. Especially if as you say there's almost no movement, as not only would they be lower but much stiffer. You need a soft rear spring to get the weight to transfer.

Not true ... I have proven a solid rear makes for the fastest 60' and et if the rubber grips

It's all about the tyres and practice...

[FPV GTHO]

Originally Posted by DAZZLR

Not true ... I have proven a solid rear makes for the fastest 60' and et if the rubber grips

It's all about the tyres and practice...

Well the tyres are just the final part of the suspension

[40gt]

I would say it's a tire choice issue.
I have Nitto Invo's - 20x 10 - running 295s and I have trouble starting at any rpm without them lighting up in any mode except super gentle on the throttle.

My next set of rear rubber will be the Toyo R888Rs.

[Road Games]

Don't stress ... track prep at Willowbank is real hit and miss....

My ETs are still sitting here...

Get some 15"s if chasing a number , otherwise stick with daily rubber and NO burnout !

30psi is low enough to run a 13 on 17" s for me...

Mid 14's with 19" s

15 flat with 20"s lol

[FLOGGED]

Originally Posted by DAZZLR

Don't stress ... track prep at Willowbank is real hit and miss....

My ETs are still sitting here...

Get some 15"s if chasing a number , otherwise stick with daily rubber and NO burnout !

30psi is low enough to run a 13 on 17" s for me...

Mid 14's with 19" s

15 flat with 20"s lol

im keen on your ET's was trying to message you 2 weeks ago but said your messages where turned off. what size are they?

[OZYWALKER]

Invos go pretty well with some heat in them, drop the pressure and do a burnout.

[Road Games]

Yep listen to these guys ....

[Giant]

My best guess is its the low springs preventing enough rear weight transfer / rear squat.

Did you fit matching shorter shocks? Shorter bump stops?

Good chance your riding on the bump stops which is unhooking your rear tyres.

We ran a 14.02 on 205 50 16 Nexen rears. Stock XT springs and shorter bump stops 22psi.

[Giant]

Invos do suck until worn in. But ATR Sports 2 are no better. So that just leaves the springs.

[BOSS351]

Cant say why youve gotten slower, but id only do a tiny burnout to get the water off the tyres, dont get too much heat into them as theyre road tyres and not designed to be red hot