Don't have the engine running.

Seriously tho', why do you ask? If speed is your quest then driving at speed, quick starting and heavy braking etc are all violent acts.

To really go for a fast start, there is an almighty bang as the car takes off. Anything less and you are feathering the throttle/clutch and being sensible at the same time.

So, fast starting will cause the jolt. You could always get an auto!!!!

Regards

Ben

 

Come on guys, how do you let the clutch up quick without jolting the whole drivetrain?

 

Benny boy

In any gear, if u let the clutch up too quick then the drivetrain jolts. Now if you sprint/race whatever then you get to do quick gear changes but cant for fear of that horrible thud on each change!

Come on?

 

Sunil,

I'm afraid you'll have to modify your driving style a bit. It has taken much longer for me to adapt and be able to change gear swiftly(ish) and smoothly. Not a problem for anything other than the 1st to 2nd change.

As I mentioned in the lightened flywheel thread, there does seem to be a lot of rotational momentum in the drivetrain, so you will have to allow slightly longer for the revs to fall when changing up, and not just snap the throttle open and closed.

I think what is happening is that you're not allowing the flywheel enough time to loose enough speed to match the required revs for the next gear up. Unless you have the flywheel lightened, or slow down the change you are stuck with the clunking. Having come from a R5 Turbo with a 30% lightened flywheel, it seems to take an age for the revs to drop off between gears on the Impreza.

One (admittedly unlikely) possibility is that the springs in the clutch friction plate are knackered (weak or broken), reducing their cushioning effect. Another is that a slightly sticking throttle could also cause the revs to drop more slowly when the throttle is closed. I've had this before, and it can be harder to confirm than you think as the throttle may not stick unless you are holding it open for some time.

If it is a driving technique issue, the best way to practice smooth changes is to slow things down until the smoothness comes back, and then gradually increase the speed while maintaining the smoothness.

How long does a 1st to 2nd change take for you?. I don't think the car takes too kindly to be rushed thanks to the number of gears, shafts etc in the driveline. Any shunt will be more noticable than in a 2wd car.

Hope some of this helps.

Cheers,

A.

 

When I'm going for it...engage 1st, 4500rpm,slip clutch..2nd BANG..3rd BANG..

I have found that keeping the revs slightly higher than normal lessens the effect.

This (I believe) is all the torque winding up the drivetrain components.

 

Yup, think they all do it.

Down to 4wd & torque reversal & a lack of play in the drivetrain generally.

You can still change quickly but need to modify driving style to compensate.

D.

 

Diablo,

How can i change quickly, i.e. what driving style should i be using?

 

Has anyone heard of mechanical sympathy? I sold a WRX STI V4 Type R Coupe and the prospective buyer who approached the selling dealer was convinced that there was a fault with the gearbox (following the massive clunk and jolt experienced with every gearchange). The Dealer got straight to the point and told him that he could not f***ing change gear! Still not happy with the Dealer's response, an independent opinion from Lockyear Cars was finally obtained and a subsequent clean bill of health was obtained! Mastering the art of a quick gearchange whilst at full bore did take me several weeks to achieve. As suggested, start slowly first and then increase the speed of your gearchanges. Also, be warned of possible premature failure of the 2nd gear synchro if you insist on changing gear at the speed of light!

 

I'M GLAD SOMEBODY RAISED THIS QUESTION AS IT WAS A PROBLEM FOR ME TOO.OUT IN THE SCOOB TRYIN TO IMPRESS MY MATES AND 1ST **BANG##,
2nd ##*BANG**## ****.
IT ALL SMOOTHED OUT AFTER A COUPLE OF DAYS BUT I'VE STILL BEEN WONDERING IF I'VE JUST BEEN COMPENSATING A PROBLEM.MY MIND IS NOW AT REST.
IT ALL SMOOTHED OUT BY BEING JUST A BIT SLOWER ON THE GEARCHANGEAND BRINGING THE CLUTCH UP AT SLIGHTLY HIGHER REVS


PETE

 

Richard,

You don't need to slip the clutch to smooth out gearchanges. Once you are on the move, the clutch should only be in or out.

I read a good description of how to change gear smoothly on Mike Sheild's SPD USA site (

 

Cheers for that Alex - think I'll need to study that a bit more...

 

I found a good way to do it is to feather the clutch at the biting point a little rather than just dumping it when you change gear. Bit subjective but a mate of mine reckons it feels much faster when I do that as opposed to just throttle off, change, dump clutch, throttle on.

 

Yes, but have you noticed that extra use of the clutch to smoothen out hard-driving results in a nasty pong working into the cabin...

I would say that the drivetrain would take more abuse than the clutch. I'm told the clutch on the scoob is a bit small compared to the power output.

 

The only place I've noticed a smell is at the traffic light grandprix. And it lasted for days as well...

The only reason I do it is in the interests of smoothness - I'm not really considering any long term implications. I guess I'd (probably) rather replace the clutch than put any un-necessary strain through the transmission.

Also, it's the only way I could find to get around the jolting so I guess I kinda latched onto that and now that's the only way I do it.

Richard

 

I must say, in all the runs I did at Santa Pod last Sunday (surely a huge test for clutch and transmission) I only felt two 'THUD's.
Whether it's the car or my style I couldn't say, but it certainly wasn't a common occurence.
When I change gear at track days and on the strip I would say I was fairly gentle but precise, if that makes sense?
I think it's very much a matter of timing the application of the throttle with the release the clutch. In my opinion, you can only make the car accellerate so fast. What I mean is slamming the throttle back on hard won't make you go any quicker. As long as you bring it in to where the revs have dropped to, there should be a fairly smooth change without lack of performance. The drivetrain will only jolt if you apply too much throttle before fully releasing the clutch, or releasing the clutch too quickly.
I'm probably talking complete pants, but that's what I think.

Stef.

[This message has been edited by Stephan (edited 22-10-1999).]

 

Stef,

Not pants - absolutely right I think.

 

Stephan,

Completely agree, my car seems particularly responsive to gear changes when run on a track day. It seems to me that the harder I push the car on a track the better it responds.

Are you at Donnington?

Regards
Yex

 

Am I at Donington?
Are we all Scooby lovers?
I wouldn't miss it for the world.
Donington's my fav' track and I know this one's gonna be amazing, whatever the weather.
I'm looking forward to meeting all of you, well, those that I haven't already met of course.....but I suppose I'm looking forward to meeting all you lot again a well....a little bit...

Stef.