FSAEracer03

hahaha, ouch... let's all be nice chillen' Well Z-Man, like I said... some prefer to use the engine too, some don't. I didn't mean to bring LFB into the picture just yet (but if you read my post, you'll see why it was in that thread). My boss is a former SCCA champ and Super Snake series champ. He still holds some track records. He raced in the Rolex Grand-Am series in '02 and was the fastest of the 3 drivers on his team... I think we can rest assured that he know's what he's doing (and though he doesn't heel-and-toe, as you'd read in that post, he does advocate earlier downshifting to use the engine to brake as well).

Now please no one get me wrong and take offense... i seem to get that reaction too much. I mean no harm by this, just want to point out that while some only use downshifting to select gears at the end of braking, plenty use it to aid in slowing down on the track.

-Kevin

Z-man

Kevin,
I don't mean to be a stick in the mud here, but can you elaborate on your claims? At this point, your boss is the only person I know in the 'racing scene' that advocates such a technique.

Oh, and I was just taking your left foot braking comment way out of context just to make a joke!

-Z-man.

Dsalillas

Ok ok, out of all the replies in this thread I think only a couple of people have attempted to answer my question. The rest of you guys flew off on some heel-toe downshifting argument.

Now, back to the question at hand. I looked at the reciept and it was a Sach's OEM clutch kit, so I'm assuming its a rubber center. Tifo said it's more prevelant in spring centered clutches but mine shakes the hell out of you. Anyone else with any pertinent answers?

Penz

don't assume, it might be the spring centered because you can also buy those.
One time I forgot to match the revs when I downshift and mine shook bad too. The clutch was almost bran new. The car is fine and their shouldn't be anything to worry about it. Just keep driving but blip the throttle to match the revs when you downshift.

Z-man

Dsalillas:
I apologyze for hijacking your thread. Sorry! Back to your original question:

This year, I got a new clutch for my 944S2: the old rubber centered clutch was replaced with a 951-type spring centered unit. After that, my car would often shudder if I slowed down enough to warrant a shift into second gear. Happens quite frequently, and I believe it's because the new unit is more 'grippier.'

One suggestion: feed in more throttle as you engage the gear. That seems to help my situation. And release the clutch pedal a little quicker.

Now, which one is the loud pedal again?!?
-Z-man.

Dsalillas

Not a problem guys, I actually wanted to ask about hee-toe shifting to learn. Myabe someone should start a new thread with some type of tutorial.

Thanks for the replies for my question. I feel better knowing that it's not really a major problem(as long as I match revs.) and that it's not only my car that does this.

RMills944

You should always try to line up RPMs when you're downshifting - it's very hard on the clutch when you slip it to dwonshift without lining up RPMs. Heel-toe is the best method for this.

Jay W

My 944S had the same shudder. I had found a thread a while back where a guy had the downshift into second shudder. He had just replaced the clutch, had it done two more times, replaced motor mounts, transmission mounts and I think CV joints too. After all that he still had the shudder. I looked at the last post on the thread and finally he figured out that he had an aftermarket exhaust that was not mounted to the car securely enough. He tightened it down and the shake went away (weight of the exhaust system vibrating was enough to shake the whole car). Anyway I went out and looked at my car and sure enough, the exhaust hangers at the converter and the resonator were NOT CONNECTED. I connected them back up and my shake was GONE too. Look at your exhaust hangers.

FSAEracer03

***double-post*** maaa bad

FSAEracer03

ohhh Z-man... we hijacked the thread like an eastern-religion extremest!! i apologize!

kennycoulter

hey, so in a real life situation.......everyone ive driven with in manuals, downshifts and engine brakes. i know engine braking is bad, but it seems my car pops back and engine breaks when barely lifting off the gas. in a situation, say someone has pulled in front of you when you were doing 55. they are going a little slower. so i let off the gas a little to slow down. i am now engine braking. then i check mirrors and glance to change lanes, while reengaging(real word?) the gas paedal. is even this bad? i always take the car out of gear when i know im coming to a stop. and only use the brakes. i also heard engine braking is bad on timing belts.

FSAEracer03

A bunch of shop customers use engine braking, Mike Canney, Sam Asinugo... more. I've noticed all the successful drivers racing SCCA at the Point use engine braking as well... in the pits you will hear the GT1 and GT2 cars as well as the AS cars the most... but pay attention to almost every class and almost every single driver downshifts earlier (many of the motors sound like they're in the 5-6k range!) in order to engine brake!

Also having attended (well, watched is probably a better word) a PCA event, I've noticed many more of the Porsche owners dont downshift until the end of the straight and halfway to the apex! I'm not sure exactly why they wait so long or who told them this, but the only ones I saw using engine braking were the guys that took their cars to race in SCCA, lol. I'm guessing you've attended some PCA events Z? Anyways...

Kenny, if you think of how a drivetrain works, everyone engine brakes somewhat. There is only a split second transition between accelerating and engine braking. You'll know this if you experiment with clutchless shifting sometime. The engine does work on the wheels (via gears, etc..) when you are on the gas and a second afterwards. For a split second they are both perfectly matched. Then the wheels do work in the engine; and thats engine braking. Letting off the gas and coasting, while having a little engine braking is good. If drivers made sure the wheels never did any work on the engine, our brakes would be changed every second oil change, lol... by the way, if you hear a term called "granny riding the brakes"... thats it.

-Kevin

Luis de Prat

Dsalillas, you didn't mention how many miles are on this clutch. Was it just installed, or has it been on the car over 50K miles?

Dsalillas

I'll have to go back and check the reciepts but I believe the clutch has less than 5k on it.

ERAU-944

i clutchless shifted once in my 944. from third to fourth. no grinding, i figured i did it once, and that was it, no more in the 944. tried in the napa work trucks a few times, sometimes successfully, sometimes not .

i also engine brake simultaneous with the wheel brakes. to each his own, some downshift only once, some engine brake. if you're just letting off the clutch to use the engine to brake, and not matching revs, thats most likely your shudder. just blip the throttle with the side of your foot while braking and downshifting. thats pretty much heel and toe right there, or how i do it anyways.

-Michael-