teknopete

Somebody help, my WRX is givin me grief

When I`m doing a launch anywhere between 2500 - 7000 rpm i`m gettin wheelspin
1 of my m8s woz watchin 4 it 2night and he tells me it`s the front wheels only. I`ve tried somethings 2 get rid of this but it`s still happening It`s gonna murder my 1/4 times.... Please help some1 must know how 2 solve this????

Cheerz Pete

Fullonloon

I wouldn't launch at 7k - seems way over the top...

Could be your clutch is slipping due to you wearing it out with such agressive launches?

Stef

What's wrong with a bit of wheelspin? It brings the boost up quicker and when the wheels finally grip you go 'whhhhhheeeeeeeeeeeeee'.
I've always had it when I got my best times at Spod. The front wheels are spinning cos the weights being transferred to the rear of the car, making the front lighter.

Stef.

ndouglass

Pete,

You could try strapping a moose to the bonnet, that would sort out your problem by keeping the front down but maybe a hinderance on aerodynamics.

Blackscooby

I'm with Stef on this one

There's no point in getting bogged down when trying to get a good start is there ???

When hillclimbing / sprinting I use about 5000rpm to ensure I don't get bogged down. These Scoob things are a nightmare to get off quickly and cleanly. I have to be VERY agressive to get it to go well

Mark

JohnS

iTrader: (1)

Racelogic do a traction control device, which I think comes with something called launch control.

Costs about £1k+VAT though. I think Falkland were selling them, but don't know about anyone that had bought one. They said it would be just for people who used them in competition.

Me, I'd look at the anti-lift kit, or stronger springs, which may help with the weight-transfer. Another alternative would be to fit stickier tyres on the front, such as moulded slicks (road legal), or even full slicks. Might be a bit hard to get these up to temperature at Crail though, as it's always freezing cold there, even in the summer

As Stef said though, a little bit of wheelspin isn't a bad thing, as it prevents massive shock to the drivetrain and helps stop the engine bogging down.

Chances are they are only spinning for a few 1/10ths of a second, during which time a large percentage of the available torque will be fed to the rear wheels. Unless you are getting wheelspin all the way through first gear and into second, I would have thought it would be costing you one or two 1/10ths at most. A reasonable compromise to pay for keeping your clutch, gearbox and diffs intact.

RB5SCOTT

9 times out of 10 my rear wheels spin(especialy in the wet) and sometimes i get a really horrible banging noise from the back, does anyone know what this is and if i'm doing any damage

Scott

sasim

rb5scott

The banging noise could be your exhaust hitting off of the bodywork somewhere, I get this sometimes

as for wheelspin, I have not managed to wheelspin mine yet even in the wet, I must be a *****

Stuart

teknopete

Cheerz for the input guys,

I jus realised that the post was lacking in details Jus 4 the record the "somethings" I`ve done are : had an AP racing cerimetalic paddle clutch fitted bout 6 month ago (so no slip there), full GAB top adjustable race suspension, whiteline uprated swaybar links, whiteline anti lift/dive kit(cheers John). Just seems to be since I had the AP clutch fitted and started running on 17" rubber the probs been worse I spoke to racelogic about their system an may do it as a last result but trying everything else first. Had a suggestion to try smaller (15")rubber any thoughts on that? As Stef & Mark say it`s useful my aim is now to minimise it an not get rid of it
Scott I used 2 get a bang from the back of it on high rev change ups / downs which was worrying till I found out it was a flameout from the exhaust

Cheerz again lads
Pete

cwal1

Pete,

A swap to 15 wheels and tyres could help as the greater flexibility in the sidewalls will allow some rotation between the wheel and tyre thereby limiting the slip.

Dragsters have large sidewalled rears for this reason - if you see high speed footage of a dragster launch you'll see the wheel rotate slightly without the tyre moving. This has the effect of acting as a form of damping on the torque output allowing the tyre to key into the tarmac without slipping.

Maybe worth a try especially considering the price of 4 2nd hand wheels compared to the Racelogic option.

Chris.

RB5SCOTT

My banging is not flames, and not the exhaust hitting the bumper. It is more of a mechanical sound and the car seem to shake when it happens, i think its something to do with the driveshafts.

cheers for the replys but its not either of them

Scott

WAYSIDERS

The noise you describe could be the rear diff moving vertically a couple of cm. It's possible to modify the mounting to stop it.

Call Roger Clark Motorsport on 01455 828610 for help.

A less obvious clonking comes from the mechanical lsd on type r's and ra's.

Keith

AndyMc

I can't believe nobody has mentioned the centre diff yet.It is there to stop the front wheels spinning as the weight comes off them when you launch.It sounds like you do a lot of emergency starts so you might have buggered it .

I got my mates to watch me launch on slippy tarmac and all 4 wheels spun at the same time(uk car),they did in the snow too.

Have you tried it with the suspension set to soft.My last car had adjustable suspension and used to wheelspin like crazy when it was set to hard.
I also used to be into VWs(before I saw the light ) and remember watching the powerfull cars trying to get off the line at GTI International.
The cars with big wheels/low profile tyres and ultra low rock hard suspension were crap compared with the standard cars,the tiniest bump made them wheelspin.

I think most people get the banging noises.If you look under the car the bushes that hold the front of the rear diff(under rear passenger seats) are very very soft,I reckon this is where it knocks.You can move the mounting a couple a cm's just with hand pressure.

I thought the worst revs to launch as far as breaking the box was concerned is at 3500-4000 revs when the engine is making the most torque?Mine whines like a metro if I do that.
Anybody know if that is true.

JohnS
Stiffer springs and the ALK do not have any effect on weight transfer,but they do change the effect the weight transfer has on the car ie it does not lift as much on a launch.Or roll as much in the corners

The only way to change the amount of weight transfer is to move the centre of gravity.Lower springs do this even when they are softer than standard.

One last theory for you.The reason wheelspin in the Impreza gives a faster 0-60 time is because when there is no wheelspin the clutch is slipped for much longer and so a lot of the engines power is transfered into heat in the clutch and flywheel.This is then unavailable to move the car.
When you do wheelspin the clutch is slipped for less time so this energy is now stored in the spinning wheels instead(flywheel effect) and so is available to accelerate the car.
Or to put it another way the energy lost as heat in the slipping clutch is more than the energy lost as heat from the friction between the tyres and the road.

Andy

teknopete

Cheerz 2 Chris & Andy 4 u r input ladz,

I`m gettin the mota up on the 4 poster 2morrow 4 a real checkin over. Will checkout the diffs / bushes n that whilst its up there. All the fluids r gettin changed 2morrow so I know they`re in top nick.
Need 2 get it setup 4 Crail this Sunday What we`re gonna do is a couple of 1/4s with the 17s on an a couple with the 15s an c what the difference is. This should check the sidewall ply theory.
Then we`ll fanny round with the suspension settings.

Like I said b4 cheerz 4 all the good input guyz.

Pete

Dave Brown

Can I suggest a change of driver, perhaps..

Gimme a shot at Crail, I'll launch the bugger

LOL

Dave
<who's had plenty practice>

teknopete

Dave,

I`ll let u play with mine, if u lemme play with u r s (ooer) ROFL

C u there m8

DJB

I think that the 'banging' sound mentioned above is the rear sub frame assembly (it probably has some other more accurate description) taking up the free play against its mounting on the car body. I get this clunking noise when I change from 1st to 2nd when accelerating hard.

D.

MorayMackenzie

Have you considered fitting a fron LSD to maximize use of the available front end traction? Mind you, some of the best starts actually start with 4 wheel wheelspin, slight throttle back to regain traction and whooshhhhhhhhhhh!

teknopete

Hey folks,

When I fitted the Whiteline antilift kit it made a hell of a difference

Got another prob now though, just on the subject of noises. Had a major clonk then a rattle and a judder to a halt at the weekend when at Crail. It was the sound of my gearbox fragging into millions of bits

S ok though new 1 getting fitted now.

BTW thanks 4 the lift home Derek.
A huge thanks 2 the rest of the lads 4 all their help u know who u r....

[This message has been edited by teknopete (edited 22 February 2001).]

Mike Tuckwood

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR>Originally posted by AndyMc:
<B>JohnS
Stiffer springs and the ALK do not have any effect on weight transfer,but they do change the effect the weight transfer has on the car ie it does not lift as much on a launch.Or roll as much in the corners[/quote]


This is incorrect, your own statement contradicts itself, the lift that the ALK prevents is weight transference. Reducing the lift also pro rata reduces weight transference.

Glad to see the ALK helped TP.

Gussie Cup

Pete - I've come into this thread a bit late to be of real help but I was also going to suggest an Anti-Lift kit.

You can feel the power going to all 4 wheels equally when you launch and its a lot smoother........

Sorry to hear about the gearbox though!

mutant_matt

This bang/thud from the rear when changing gear under hard acceleration has been discussed before but I a)can't remember the outcome and b)can't find it under search.

This happens in every Scooby I have been in but I'm fairly sure that the explanations given above were not the same as what was explained last time......anyone remember what I'm talking about?

Matt.

AndyMc

Hi Mike

I'll try and explain what I meant starting with the stiffer springs bit.

The amount of weight transfer on acceleration depends on three things
-The position of the center of gravity
-The acceleration
-And the wheelbase.

Say a car has springs with a rate of 200kg/inch which is accelerating fast enough to transfer 200kg of weight to the rear.Obviously the rear will drop by an inch and the front will lift by an inch.

If that same car was now fitted with 400kg/inch springs(of the same static height) and accelerated at exactly the same rate as before then the rear would drop, and the front would lift by only half an inch.

In both these examples the weight transfer is the same because the three variables above have not changed,however the effect that 200kg's of weight transfer has is now different.It seems like there is less weight transfer even though there isn't.

Springs that lower the car, change the C of G
so these do change the amount of weight transfer for any given rate of acceleration.

Now onto the ALK

When a car accelerates the front lifts due to two reasons.The first is weight transfer which is governed by the three things above.The second reason is due to the design of the suspension creating forces that produce lift.This second force is very small compared to the first in modern cars.

As I believe you are an avid biker I will use bikes as an example of how suspension design can affect lift.
On a normal bike the front forks are further forward at the bottom.If you pull the front brake then get somebody to push the bike from the rear the front suspension will compress and if you pushed from the front it would lift.I'm sure you would agree with this?

Now you need to use your imagination.If a bike had front forks that are further back at the bottom,besides being very difficult to ride it would now behave very differently in the above test.When you push from behind the front suspension would probably not compress at all and would probably lift.From this I hope you can what I mean about suspension design affecting lift.

Fitting the ALK is equivalent to changing the front forks on the bike in the above example ie it changes the suspension design which in turn changes the amount of lift created by the suspension.This is the reason the car does not lift as much on acceleration.It has nothing to do with weight transfer which remains very nearly the same.

The reduced lift due to the ALK does mean the C of G will be slightly lower so it will reduce weight transfer by a small amount but this is a secondary effect.

By the way I bought an ALK from you over a year ago and it transformed my car.The extra front end grip powering out of corners was very noticeable.Its a great product.

Andy