FWD Suspension Setup for Drag Racing

[RichardB]

Guys,
I'm sure this has been covered a millions times before, and I apologise, but I'm interested in hearing from people who are pulling 1.4, 1.5 or 1.6 60' times in FWD DSM's

I was down the track last weekend and did a 10.45@142 but my 60' times are crap, on that run 1.87

I've got loads of power left on tap to play with but need to get my 60' times down

At the moment I run

MT 26.0/10.0-15
D2 coilovers all round with 21kg springs
front traction bars
front anti lift straps
I'm launching with 7200rpm and 0.5 bar boost off the line and sidestep the clutch
quaife diff
ppg 4 speed drag gearbox


Heres a slow motion video of my 1.87 launch
Slow-mo Launch #2 - YouTube

Here's a a couple of pics....

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[Pipnorcali]

What's your tire pressures

 

[shortydtp]

Things I notice.. tires are not wrinkling like they are suppose to.. whats your tire pressure??

Front suspension seem too stiff. what spring rates are upfront?

 

[RichardB]

What's your tire pressures

7 psi

Popped in another PB at the weekend [email protected], but still crap 60' times of 1.861 we did get it down to 1.71 over the weekend though.
FTO 10.369 @ 149.16 - YouTube

 

[shortydtp]

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I am bored in the interwebz

7 psi

Popped in another PB at the weekend [email protected], but still crap 60' times of 1.861 we did get it down to 1.71 over the weekend though.
FTO 10.369 @ 149.16 - YouTube

try bringing the tires down to 5-6 psi? do you have a way to cut some power down on 1st gear? boost by gear?

also whats gear do you do your burnouts?

 

[RichardB]

try bringing the tires down to 5-6 psi? do you have a way to cut some power down on 1st gear? boost by gear?

also whats gear do you do your burnouts?

We do burnouts in 2nd gear, we do run boost by gear and run wastegate pressure in 1's and 2nd which is 1.2 bar.

 

[rhamlinii]

We do burnouts in 2nd gear, we do run boost by gear and run wastegate pressure in 1's and 2nd which is 1.2 bar.

To much boost in 1st and maybe 2nd. 350 HP is all that need to cut 1.50 ft's if it fully hooked. Lower you gate pressure, and maybe run c02 to help ou reach maximum boost. I also think the front suppension is to stiff aswell. You may to try a different compound slick as ithink that the problem. Fucus on the 330' and everything else will work itself out.

 

[RichardB]

To much boost in 1st and maybe 2nd. 350 HP is all that need to cut 1.50 ft's if it fully hooked. Lower you gate pressure, and maybe run c02 to help ou reach maximum boost. I also think the front suppension is to stiff aswell. You may to try a different compound slick as ithink that the problem. Fucus on the 330' and everything else will work itself out.

Ive modified the suspension and it hooks up better, but I still have too much power, I need to get more power out..

10's FTO - YouTube

 

[turboglenn]

best 60 foot i've had has been a 1.8, but i was launching hlf assed since i'm not a drag racer, I had a quaife LSD also, but with tires too large on the rims

The best thing i found was to balance the front weights with coil overs or sway bar shimming (rear balance didn't matter to me since it wasn't doing much but being towed along)

But 600lb/in rear springs make sure the weight stayed up front (i had bought themfor fronts but played with things here and there) and i ran the 250 lb ones up front at the drags..

jacked the rear end up high as i could with coil overs and then used the placeiworked at's scales to balance weighton the front tires best i could (got them within 25lbs of each other) jacking the left rear up hard

take front sway bar offso the front end can settle and act independantly from one side to the next (gus mahon< has tons of info it's all what i picked up reading about his 12 second mini van... you can find his stuff archived on the dodge garage site.. the car was not fun to DD this way but it did make it take off fast, the LSD alone made even street tire launches go from roasting tires at 4200 2 stepping to needing 5k + 2 stepping to not bog

 

[kiggly]

Looks like 8" wheels, you should use 10" minimum. I am running 12" rims. Back in the day switching from 7" to 9" rims with 26x10 was instantly 0.2 off the 60'. Looks like some tire shake of the hit too. I was in the high 1.4's with wheelie bars then. I think on that tire size now I could be in the 1.3's with the bars, but it is a different animal than without.

Kevin

 

[RichardB]

Looks like 8" wheels, you should use 10" minimum. I am running 12" rims. Back in the day switching from 7" to 9" rims with 26x10 was instantly 0.2 off the 60'. Looks like some tire shake of the hit too. I was in the high 1.4's with wheelie bars then. I think on that tire size now I could be in the 1.3's with the bars, but it is a different animal than without.

Kevin

Thanks Kev, thats exactly the sort of input I need, your right I am running 7" on the front, I need to source some 9"

I've got way too much power coming out the trap, I need to get that down, I took ignition out at the weekend about 80bhp worth and dropped my 60' by almost 0.1

 

[snowborder714]

We do burnouts in 2nd gear

Is there a pro to this over doing it in first? First time with slicks at the strip not too long ago and I was doing mine in first.

 

[kiggly]

Go for some 10" wheels. You're doing pretty well for 7" wheels. If you get weld wheels I think it was a 5" backspacing on the 10" units. They are common mustang wheels.

Kevin

 

[Acobreli]

Go for some 10" wheels. You're doing pretty well for 7" wheels. If you get weld wheels I think it was a 5" backspacing on the 10" units. They are common mustang wheels.

Kevin

Hi, Kevin.
I&#180;m in the same boat. MT 26x10x15 and 15x8 wheels and bad 60' times.
I&#180;ll try to find some 15x10 wheels.
But what tire pressure do you recommend ?

Thanks.

Agnaldo Cesar
Eclipse 95 GS-T FWD (manual)
4g63 2.0t - E85 - Bullseye s362
BRAZIL

 

[turboglenn]

Hi, Kevin.
I&#180;m in the same boat. MT 26x10x15 and 15x8 wheels and bad 60' times.
I&#180;ll try to find some 15x10 wheels.
But what tire pressure do you recommend ?

Thanks.

Agnaldo Cesar
Eclipse 95 GS-T FWD (manual)
4g63 2.0t - E85 - Bullseye s362
BRAZIL

that's damn near the exact combo i was running last time out, and oen thing i can say is that M&H racemastersd seemed to hook better than the MT's, and my M&H were 24.5 x 8.5 x 15 and my MT's were 26 x 8.5x 15..i pulled the 1.8 on the M&H racemasters


But that was so long ago i was only on 19-20psi 57 trim, stock 7 bolt, open diff and still ran a 12.08 @ 119 (best time to date since we no longer have a 1/4 mile close enough to make it an easy night of racing, and god forbid i break hours away with no trailer (both 1320's left are about 3 hours away)

 

[RichardB]

were doing 1.7 60' at the moment on 7psi

 

[turboglenn]

Wow, I don't think i ever went below 10 or 11 out of fear of spinning the tire/tube and getting a flat, usually i ran 13psi

 

[kiggly]

I think somewhere in the 7psi range on the 26" tires, depending on weight. Adjust until the tires just start to wrinkle sitting still and start there. This will be a lower pressure than it did on the wider wheels. Play with it and find the sweet spot. My car hits the same 60' times from 5.75-6.25psi, which is a best of 1.241 and 4 others in the 1.24x's.

Kevin

 

[Acobreli]

Thank you RichardFB, Turboglenn and Kiggly.
This is a very usefull information.
I´ll try 7psi next time I go to the track.

RichardFB, I don´t want to hijack your tread but I think this discussion is a good opportunity to share information that can be very helpfull for both of us.

I have K-sport coillovers with adjustable shocks, 13 kg springs front and 15 kg springs rear.
I usually set up the rear shocks as hard as possible.
But I don´t know if the front would be better as soft as possible or in a mid range.
What do you think, guys ? And what do you think about the spring rates ?

Agnaldo Cesar
Eclipse 95 GS-T FWD (manual)
4g63 2.0t - E85 - Bullseye s362
BRAZIL

 

[RichardB]

Thank you RichardFB, Turboglenn and Kiggly.
This is a very usefull information.
I´ll try 7psi next time I go to the track.

RichardFB, I don´t want to hijack your tread but I think this discussion is a good opportunity to share information that can be very helpfull for both of us.

I have K-sport coillovers with adjustable shocks, 13 kg springs front and 15 kg springs rear.
I usually set up the rear shocks as hard as possible.
But I don´t know if the front would be better as soft as possible or in a mid range.
What do you think, guys ? And what do you think about the spring rates ?

Agnaldo Cesar
Eclipse 95 GS-T FWD (manual)
4g63 2.0t - E85 - Bullseye s362
BRAZIL

I've just switched to 600lbs up front and 1000lbs on the rear and that seems to have helped. I had stiffer all round and the car seem to bounce down the track.

 

[shortydtp]

we like to check and reset the tire pressure after the burnout.. we see about .75 to 1psi increase after the burnout.

 

[1qkfwd]

One other thing is make sure the alignment is where the camber hits close to zero when you launch. Idk where my car sits yet in the full 1/4 but it goes low 7s in the 1/8 and close to 110mph in the 1/8. Last time out the car would 1.6 with first gear burnouts and low 1.7 with 2nd gear burnouts. This is on m/t 26x8.5x15 on a 7" wide wheel. I did read on m/t site that you can get the tires to hot and they will glaze over. Oh an my tire pressure was at 8psi and the cars weight distribution is 60/40.

 

[RichardB]

Last time out the car would 1.6 with first gear burnouts and low 1.7 with 2nd gear burnouts. This is on m/t 26x8.5x15 on a 7" wide wheel. I did read on m/t site that you can get the tires to hot and they will glaze over

Now thats interesting I've not heard that one before, everyone I know does a 2nd gear burnout some even do 3rd.

 

[Dsmkauai]

Is there a pro to this over doing it in first? First time with slicks at the strip not too long ago and I was doing mine in first.

Doing your burnout in second gives you more wheel speed and helps get the tires going faster for a better burnout. Anyone else have a better explanation please chime in.

 

[RichardB]

Go for some 10" wheels. You're doing pretty well for 7" wheels. If you get weld wheels I think it was a 5" backspacing on the 10" units. They are common mustang wheels.

Kevin

I think Ive sourced some 9" and some 10" that I can borrow to do some testing with before I purchase

should be interesting to see how they compare.