Car Judders when throttle off, Why ?

[RemarkLima]

Oh, just another thing I remembered, when I was racing at Pembray (BTW, we did give our cars absolute hell!), there was the final corner that it was better to just mash the clutch for... Basically coming at it in 4th full throttle, then just dump it into 3rd with no heel and toe, and bring up the clutch as fast as possible, this basically locked the rear wheel with the transmission just for a bit but meant you could back onto full throttle straight away

I\'d neven say do it to a car you like But as you can easily lock the driven wheels with the gearbox it shows how important heel & toe can be!

[Dr-Rotor]

Oh, just another thing I remembered, when I was racing at Pembray (BTW, we did give our cars absolute hell!), there was the final corner that it was better to just mash the clutch for... Basically coming at it in 4th full throttle, then just dump it into 3rd with no heel and toe, and bring up the clutch as fast as possible, this basically locked the rear wheel with the transmission just for a bit but meant you could back onto full throttle straight away
 
I\'d neven say do it to a car you like But as you can easily lock the driven wheels with the gearbox it shows how important heel & toe can be!

 
Hehehe...sounds like what I used to do on a paticular corner of a track going from 3rd to 2nd with no blip, locking the wheels for a few seconds as the car slid into the corner & you stand on the gas then bang your out of there and off down the straight. Now I just hold it in 3rd and hang on for the ride & hope it dosent slide out into the wall. HAHAhA....much faster way around this paticular corner as I have learnt. Racing teaches you some crazy ****.
 
About the clutch and bliping the throttle or heal toe, It dose not do a damn thing to it at all. How do I know for sure...well heres how. When I bought my car on 48,000km Id say it would have still had the same clutch as when it had left the factory. The car had never been moded, it was bone stock. Now as I was learing to drive my dad had shown me this method of gear braking to increase the life of the brake pads. So I practiced it with my car and discoverd that it drove alot more smoothley this way & also alot more interesting that the conventional method.
 
I drove it this way for 30,000km before I had the block removed & all the work done to it. When the rotary mechanic replaced the clutch with my new twin plate crabon D core from Exedy he said, "your old clutch has bugger all ware on it & can be used as a replacement for another car" I looked at it & saw it was still in pretty good nick, pretty much no heat marks or anything.
 
The only thing that free reving the clutch will do is work out your bearings. Aside from that & sharp blip to select a lower gear wont do a thing to the friction plates.

[probedb]

Mine used to do this quite bady, fitted an engine torque damper and it\'s all but gone! Really didn\'t expect it to do this but it did

[Dr-Rotor]

That will be because the engine cant move when you drop the gears & make the clutch play catch up...& as the car slows down it wont be abel to vibrate as much so it wont jerk your lighter gears around in the wrong rpm range.
 
As said before this can also be reduced with finer tuneing. This past week we have just done it on my girls car. The car will come right down from 3500rpm in 4th to around 1200rpm without jerking....but why the hell would you want to drive like that anyway. Also since the new tune it now revs alot quicker for the blip clutch change down....its lovely...soo smooth.

[gmogle]

Mine does this also, I find myself coasting a bit to stop it. Do try to do the heel and toe but it isnt easy as the pedals are close together and have to use the side of my foot. But its much smoother when shifting down.

Wil bear that in mind probed, tempted to get one at some point.

[Dr-Rotor]

You dont need to do heel toe to do this blip thing that Iv been talking about. More a matter of adjusting your driving style & beeing more aware of the distance you have to stop in. Yes you can do it heel toe but its not essential.
 
Hmmm ok let me put it this way....the way i drive is wired. I do not travel right behind people...I keep about 3 to 4 car lengths away. When I have to slow down I blip for the change down before I brake as I am not at the brakeing point so therefor no need for heel toe. If I need to slow down quicker I will still blip before brakeing, but brake harder and usualy just go to neutral if I have to stop.
 
Due to traffic I cannot always drive like this & do need to just slow down and have to wait for the right Rpm so I can change down. Sure you can heel toe but I wont take that chance of sliping off the brake and accelerating into the car in front.

[Timmy]

I think dr rotor is saying because he\'s not raceing he\'s slowing down well in advance without braking so he doesn\'t need to heel and toe. I often do the same.
Say your comeing up to a corner and you know you need to shift down you lift off well in advance and with your left foot on the clutch and your right foot covering the accelarator dip the clutch blip the accelrator and change gear all without touching the brakes and by than you\'ve lost enough speed to go round the corner.

[Dr-Rotor]

I think dr rotor is saying because he\'s not raceing he\'s slowing down well in advance without braking so he doesn\'t need to heel and toe. I often do the same.
Say your comeing up to a corner and you know you need to shift down you lift off well in advance and with your left foot on the clutch and your right foot covering the accelarator dip the clutch blip the accelrator and change gear all without touching the brakes and by than you\'ve lost enough speed to go round the corner.

Haaaa exactly what Im trying to say...thank you Timmy. :cool

[RemarkLima]

Ah ha, I see what you guys are saying now, and yeah I quite often do the same thing, if you only need a dab of brakes, or just need to lift off then just blipping the throttle is the way to go

Hehehe...sounds like what I used to do on a paticular corner of a track going from 3rd to 2nd with no blip, locking the wheels for a few seconds as the car slid into the corner & you stand on the gas then bang your out of there and off down the straight. Now I just hold it in 3rd and hang on for the ride & hope it dosent slide out into the wall. HAHAhA....much faster way around this paticular corner as I have learnt. Racing teaches you some crazy ****.

I think a big difference is that we were racing old Mk1 MR2\'s, 1.6 short-stroke NA engines, and with basically zero torque, so unless you were ringing it off the limiter they had no real guts to pull you out... We ended up doing the same thing pretty much as it was the only way to keep it right on song! Oh, happy days and good fun... Shame I ran out of money :/