Lowering your car, affect on your 1/4 time?

Doogstar · 11-12-2006, 10:45 PM

Just wondering how lowering your car affects your 1/4 mile time.
Is it better aerodynamically? or is launch affected?

xr8ute · 11-12-2006, 11:30 PM

Hmm...I'm subscribing to this thread. Very interested to hear people experiences with this.

I would be worried about reducing the amount of weight transfer to the rear of the car....unless you had a pretty tricky rear-end setup to both lower the car, and move the centre of gravity to a better position to assist rear grip off the line.

Firefox7 · 11-12-2006, 11:37 PM

Quote:

Originally Posted by xr8ute

Hmm...I'm subscribing to this thread. Very interested to hear people experiences with this.

It's actually a good question when you think of it. I'm also curious.

Cheers

RIPGMH · 11-12-2006, 11:40 PM

Lowering your car, at least for the rear usually has the added bonus of a stiffer ride which generally aides in traction.

brenx · 12-12-2006, 12:02 AM

Can't say my car being lowered was ever an issue for a street car on the strip. My XB is 2" lowered at the front and 3" at the rear. Fastest I've ever gone in my sig was in this config and totally stock shocks.

Supposedly raising the front, adding 90/10's and a traction bar (ie Oztraks in my case) is supposed to work better. I did the above apart from raise the front and I didn't go any faster than my PB. So? I don't know really. At this stage I'd say lowering has very litttle negative affect at all in my case. I've lifted the front left wheel before. Not much bit it did lift. The weight transfer couldn't have been that bad?

I'll be interested to hear from someone who had their car low and raced then raised it. I was told by the owner of frdpwr (also user name) that his car was slower when lowered. You'll find his thread in the windsor section.

**ebxr8240** · 12-12-2006, 12:35 AM

Low and firmer springs don't add to traction..my 60ft went up .2..

Doogstar · 12-12-2006, 12:35 AM

Interesting replies so far, I looked up FRDPWR's thread. Seems he raised lifted the car up a couple of inches but made some other changes, so no conclusive proof. Although he went from an average 11.3@124mph to 10.53@127mph, not too shabby.

Quote from FRDPWR: yeh i was wrapped i wasnt expecting a 10.5 to be honest, i cant wait for the photos to come out on full boost
we changed the coil, lifted the car up a few inches, used a bigger scoop and used a full slick. MickyThomson 28x10.5
this is how high the car was

**Polyal** · 12-12-2006, 09:09 AM

Im no expert, but this is how I would see it.

If your rear end is to stiff then it will obviously have no give, depending on how you launch it will effect your 60ft more than anything.

Its that initial force that is pretty important to harness, the better your rear end soaks up the drive then the better your launch. So to soft or to stiff and it wont be that efficient.

Where that perfect point is I am not sure, but I would say most standard suspension would be good.

If someone dumps there car, with hard shocks then that would slow them up at the start IMO.

I have nothing to base this on other than "common sense".

Sledgehammer · 12-12-2006, 09:17 AM

Quote:

Originally Posted by Polyal

Im no expert, but this is how I would see it.

If your rear end is to stiff then it will obviously have no give, depending on how you launch it will effect your 60ft more than anything.

Its that initial force that is pretty important to harness, the better your rear end soaks up the drive then the better your launch. So to soft or to stiff and it wont be that efficient.

Where that perfect point is I am not sure, but I would say most standard suspension would be good.

If someone dumps there car, with hard shocks then that would slow them up at the start IMO.

I have nothing to base this on other than "common sense".

Pretty much it.

To be effective in drag racing you need to promote weight transfer from front to rear. A soft rear is needed and a front setup that will allow lift and slow the return (this is why most cars use a 90/10 front shock).

A low suspension usually means a hard suspension as well and does not promote weight transfer, great on the circuit / street but not drags.

**Bluehoon** · 12-12-2006, 09:23 AM

For a BA at least, if the shocks and springs are too stiff, the tractive effort and twisting (compensation) absorbed by the CV's will casue them to snap...

It's a delicate balance....

Live axle is the go IMO, no issues at all, just go...

Craig · 12-12-2006, 10:28 AM

Quote:

Originally Posted by Sledgehammer

Pretty much it.

To be effective in drag racing you need to promote weight transfer from front to rear. A soft rear is needed and a front setup that will allow lift and slow the return (this is why most cars use a 90/10 front shock).

A low suspension usually means a hard suspension as well and does not promote weight transfer, great on the circuit / street but not drags.

I reckon Sledgehammer has it pretty much spot on......

I'm no expert either with suspension cars (having raced top fuel and funny car for years) but from the past years racing endeavours with both sedans and utes we have found that by lowering the vehicle it seems to suffer the most. When the vehicle is raised to say standard XR8 height the performance is better. These cars need suspension travel in the first 60ft....

ratter · 12-12-2006, 12:11 PM

Besides the normal softer ride with standard height cars that helps weight transfer another point is, the higher car will have a higher centre of gravity which will also help promote weight transfer.

ToddZC · 12-12-2006, 01:18 PM

Hopefully by the middle of January I can supply a definitive answer to this question, as I will be trialling a 1" raised front suspension on my Fairlane. Although it has done a best 60' time of 1.470, it usually 60's anywhere between 1.50 to 1.60, very inconsistent. The car currently has very little front suspension travel, when I jack the car off the ground the full suspension travel is only about 1.5". I have the Koni shocks set at the lowest rebound setting on the front, so in an attempt to give the car more front suspension travel, I'm putting in a 1" spacer above the front struts. I can then either leave the car raised 1" with the same small suspension travel, or wind the front springs down 1" to the original ride height and gain an extra 1" of suspension travel. At this stage, I'm leaning towards the second option. All this is in an attempt to get more weight transfer on the launch, and hopefully lower and more consistent 60' times.
Any advise is more than welcome.

Quadcams · 12-12-2006, 08:54 PM

My theroy is if you car is lowered you have less travel in the suspension and usually stiff springs as well therefor when you put the power to the ground there is no give and will be much easier to break traction much like the way drag slicks work with there soft side walls ie when I went from MT streets couldnt launch any more than 3800rpm but with slicks 4800rpm which equates to better 60's.

G&D F6 · 12-12-2006, 09:19 PM

Once i had a suspension package installed on my bf i improved 1 tenth on my 60ft. I had numerous runs with my standard setup and improved consistantly after the upgrade. My rear springs are still fairly soft though.

347_XR8 · 12-12-2006, 10:16 PM

I have had fair few issues with axle tramp with my car being as low as it is. There is no play in the rear end so just tramps and hard to get a decent launh out of it.
I will be raising it/changing suspension in the future

supakel351 · 12-12-2006, 11:25 PM

in my experiance the stiff rear is no problem ( better stiff on the strip, with heavy roll bar)) its the weight transfere form 90/10's that aid a little. that all said everyone will have a differing experiance

Craig · 12-12-2006, 11:32 PM

Quote:

Originally Posted by supakel351

in my experiance the stiff rear is no problem ( better stiff on the strip, with heavy roll bar)) its the weight transfere form 90/10's that aid a little. that all said everyone will have a differing experiance

I reckon your right but with a lowered car with standard shocks in the rear i reckon it's to harsh especially if you have hi-stall or tough clutch, diff gear upgrades. Stiff rears are ok if you have shocks to compenstate for it (i think).

I am still learning some of this suspension stuff. Where i come from we just vary the tyre pressures or put some weight on the clutch fingers or take power out of the engine.

Cheers CC

Doogstar · 13-12-2006, 12:10 AM

So from what I gather, if the rear is too stiff (as what happens when you lower it) the weight transfer to the rear on launch doesn't provide as much traction, as the rear wheels aren't being pushed down onto the track as much. Also by raising the front, you are helping the weight transfer to the rear.

So what about after the launch? The lowered car would be better aerodynamically (creating less drag) yes or no? So you should go quicker? I don't suppose that would compensate for the poor launch.

What does the 90 and 10 in 90/10 shocks mean?

I don't think I would want to lower mine now, but I would like to stiffen the rear suspension for everyday driving at some point. What effect would sway bars have on launch? or what else could you do?

Please forgive the stupid questions.

brenx · 13-12-2006, 12:25 AM

90 means fast up for weight transfer and slow down so you don't unload the rears. When the nose comes down it comes down nice and slow.

nugget378 · 14-12-2006, 05:23 PM

The 1/4 mile is won or lost at the 60',I have gained up to .3 of a second at the end for every .1 gained at the 60',although this comes down the faster you get.
For a street car from what I have seen,low=slow...

**Falcon Coupe** · 14-12-2006, 06:31 PM

Quote:

Originally Posted by brenx

Can't say my car being lowered was ever an issue for a street car on the strip. My XB is 2" lowered at the front and 3" at the rear. Fastest I've ever gone in my sig was in this config and totally stock shocks.

Supposedly raising the front, adding 90/10's and a traction bar (ie Oztraks in my case) is supposed to work better. I did the above apart from raise the front and I didn't go any faster than my PB. So? I don't know really. At this stage I'd say lowering has very litttle negative affect at all in my case. I've lifted the front left wheel before. Not much bit it did lift. The weight transfer couldn't have been that bad?

I'll be interested to hear from someone who had their car low and raced then raised it. I was told by the owner of frdpwr (also user name) that his car was slower when lowered. You'll find his thread in the windsor section.

Do you believe what you write ?
You saw what happened to mine low then raised.

nugget378 · 14-12-2006, 06:34 PM

Quote:

Originally Posted by Falcon Coupe

Do you believe what you write ?
You saw what happened to mine low then raised.

And wait till you get the big engine in it.
You gonna fit castor wheels to the rear bumper?

brenx · 14-12-2006, 06:35 PM

Quote:

Originally Posted by Falcon Coupe

Do you believe what you write ?
You saw what happened to mine low then raised.

You haven't been back to the strip with the same engine setup to compare no raised with raised. The only diff was you lifted the wheels. 1 combo was 12.9 and the second was 12.7. You'd even changed from drag radials to full slicks.

My times tell a story. As I did state street car not drag car.

**Falcon Coupe** · 14-12-2006, 07:35 PM

Quote:

Originally Posted by brenx

You haven't been back to the strip with the same engine setup to compare no raised with raised. The only diff was you lifted the wheels. 1 combo was 12.9 and the second was 12.7. You'd even changed from drag radials to full slicks.

My times tell a story. As I did state street car not drag car.

You commented that the change in setup didn't work, it was half done, if you had done the same as me you would have run a 10 IMO.

brenx · 14-12-2006, 08:08 PM

Quote:

Originally Posted by Falcon Coupe

You commented that the change in setup didn't work, it was half done, if you had done the same as me you would have run a 10 IMO.

Everyone had opinions prior to me running the car. The all had the same opinion as yourself but that didn't get me anywhere did it. As far as I'm concerned it went as fast as it could which wasn't a 10. In the planning stages I even stated what I wanted which was "a 10 in the car as is". Not screwing around with absolutely everything which go nowhere anyway apart from being all the poorer for it.

CAMS290 · 14-12-2006, 09:34 PM

I got my best 60' times running 90/10's in the front with BA XT V8 Springs, and only 2 leafs on each side in the back with caltracks.
the Caltracks kept the squat even.

Keeping the pinion angle correct saves the diff winding up on the leafs, hence what the caltracks achieve.

Quadcams · 14-12-2006, 10:23 PM

Quote:

Originally Posted by CAMS290

I got my best 60' times running 90/10's in the front with BA XT V8 Springs, and only 2 leafs on each side in the back with caltracks.
the Caltracks kept the squat even.

Keeping the pinion angle correct saves the diff winding up on the leafs, hence what the caltracks achieve.

A friend has some caltracs on his Ba ute noticed an improvement straight away on the street yet to fully test them on the strip, will be interesting to 315rwkw n/a.

nugget378 · 14-12-2006, 10:34 PM

Quote:

Originally Posted by brenx

Everyone had opinions prior to me running the car. The all had the same opinion as yourself but that didn't get me anywhere did it. As far as I'm concerned it went as fast as it could which wasn't a 10. In the planning stages I even stated what I wanted which was "a 10 in the car as is". Not screwing around with absolutely everything which go nowhere anyway apart from being all the poorer for it.

It didnt get you anywhere because sometimes your too pig headed to take advice..
There are NO guarantees in racing...
You either persevere and do it or you dont,as long as your happy thats all that matters...

brenx · 14-12-2006, 10:58 PM

Quote:

Originally Posted by nugget378

It didnt get you anywhere because sometimes your too pig headed to take advice..
There are NO guarantees in racing...
You either persevere and do it or you dont,as long as your happy thats all that matters...

I stated above under what situation/config the 10 had to be done in. What's so pig headed about being thousands of $ down and no closer? I spent $$$$ after the new engine was in the car. If it was enough I shouldn't have needed to spend any $ at all. I wanted a 10 in street config no adding 90/10's, Oztraks, fuel cells etc etc. My pb was done in street config and we know thats all it had in it. All the bits I added later didn't aid anything. As you found with your slide-a-links you gained nothing with them. It's all well and good for people to critise when they aren't driving the car.

No point getting into a debate over it. It's a low 11sec car. I can tell you it had no more in it. Nothing more, nothing less. I rung it's neck I can assure you. [edit]Yes, it'll go faster in drag config but I don't want a drag car. If I did? I'd have built one. It wouldn't have seats for 5 either.

If you want to chat about it more PM me.