Advice for getting off the line better

[RB Will]

Hi chaps

I did a Run What Ya Brung at Santa Pod last weeekend. Good fun (until the inevitable breakage, snapped a driveshaft).

I was wondering if you experienced guys had any tips for getting me off the line a bit better in future.

Car is a 2000 Impreza so awd and running normal street tyres and about 500bhp.

Using the launch control (5.5k rpm and about 1 bar boost) it was running consistent 12.3 @115mph.
The problem I was having was off the line it was juddering / jumping pretty much all through 1st and I think I'm dropping time here.
Vid of runs to show what I mean

https://www.youtube.com/watch?v=NjQO2W0DNbA&t=...

I figure I must be dropping a lot of time in the first 60ft as I found this video of a pretty similar spec Impreza and he is running 11.8 @ 116mph so picking up 0.4 sec on me at the start.

https://www.youtube.com/watch?v=9bBsVp5aRlk

So is there anything I can do to improve things without modifying the car, its for road use so don't want to start making drag specific mods.

I was getting a 60ft of 1.94 which was slower than my mate in his Challenger on drag tyres (1.82).

Thanks

Will

[Flying Phil]

It sounds and looks as though your tyres are tramping, so it might be worth dropping the tyre pressure a bit to "soften" the sidewalls? This would also tend to reduce the shock loading on your driveshafts.

[RB Will]

I knew there would be a proper term for it.
Any idea of a good starting point to drop them to? They run about 33psi in road trim

[chunder27]

You also are obviously aware they use massive amounts of traction compound at the Pod, and it will be still very soft from the Main Event I would think.

RWYB is perfect, just gradually drop the pressures by say 5psi every run, and see how you go, if you can do everything else consistently you should see a drop, and also you should be better 8th times obviously too.

[Jon C]

Make sure your traction control is turned off as well as dropping 5psi all round. Then try pre-loading the clutch against the handbrake (that one takes a bit of practice, lots of racers (me included) run a 'drift handbrake' on the front wheels to make this a bit easier. Its a bit easier on the drive shafts and, if you get it right, can shave a tenth off your 60' times.

[Camaro]

RB Will said:

Hi chaps

I did a Run What Ya Brung at Santa Pod last weeekend. Good fun (until the inevitable breakage, snapped a driveshaft).

I was wondering if you experienced guys had any tips for getting me off the line a bit better in future.

Car is a 2000 Impreza so awd and running normal street tyres and about 500bhp.

Using the launch control (5.5k rpm and about 1 bar boost) it was running consistent 12.3 @115mph.
The problem I was having was off the line it was juddering / jumping pretty much all through 1st and I think I'm dropping time here.
Vid of runs to show what I mean

https://www.youtube.com/watch?v=NjQO2W0DNbA&t=...

I figure I must be dropping a lot of time in the first 60ft as I found this video of a pretty similar spec Impreza and he is running 11.8 @ 116mph so picking up 0.4 sec on me at the start.

https://www.youtube.com/watch?v=9bBsVp5aRlk

So is there anything I can do to improve things without modifying the car, its for road use so don't want to start making drag specific mods.

I was getting a 60ft of 1.94 which was slower than my mate in his Challenger on drag tyres (1.82).

Thanks

Will

That does indeed look like wheel tramping, effectively where the wheel is jumping as it loses traction and then regains it and starts off a further cycle. I had this a lot in my car when I first got it, the key was getting more traction, so I had to then start lowering tyre pressures and performing a burnout just enough to warm them up.

From your videos I just want to say a couple of things, after your last gear change, I would suggest returning your hand to the wheel as soon as possible, sounds silly and I know about a second or so later you then do so once going over the finish line, but it's just one of those things that I'd suggest to anyone. A car at the top end is more like to go wayward and wayward quickly.

The second thing is on your last run, you did the right thing in getting off of it as soon as you noticed something was wrong, but in future, just pull up to the wall and stop. I can't tell in your video if you did, but this is the best thing to do, rather than potential idling down the track and dropping fluid or anything, it can all be contained in a small area. It could also save yourself further damage running the car any further.

Best of luck in curing your trapping!

[RB Will]

All points taken on board, thank you.