Mike 944

Ok, I got my transmission rebuilt and a new clutch put in before storing the car (clutch is a Sachs Power clutch with spring center). Now, I've been driving manual for 4 years and I want to know if I'm dumb, or if the car has a problem.
When I used to drive the 944 B4 I changed the clutch, I was able to do the following:
When driving in 3 rd gear doing 3000rpm, I would push the clutch pedal down, let go of gas, and lift the clutch pedal making the car slow down (when it passed the friction point). I wouldn't give gas.
Now, are you supposed to be giving gas at this point? I know it hardly happens that you wouldn't, but technically, shouldn't the car be able to slow down (making the clutch wear out quickly though)? I would sometimes do this when approaching a red light...once in awhile.
BUT, since I got my clutch/transmission work done, if I try to do this, I hear all kinds of noise coming from the back of the car. I don't know if it's the differential, or transmission, or what, but it sounds like my transmission is going to fall out, and that there's a bunch of rateling happening (loud)...like as if I am just learning to drive standard and making the car hop!
What can be causing this? It doesn't do it under low rpms, but only when I try the method explained above! My friction point is where all this happens. I called the mechanic and he says he tested the car well before giving it to me, and had no problems. I doubt anything happened while it was stored (humidity??).
So, can you guys please explain to me how you downshift, or what may be going on over here?
Thanks a lot,
Mike
84 944

Thaddeus

I can't really comment on your downshifting technique, but I follow one cardinal rule when clutching: do it as little as possible. Every clutch has a certain number of engagements and disengagements in it, and the more you use the sooner it fries. I spend every clutch engagement like a coin.

In coming to a stop from 4th gear, some people shift to third, then second, then to first, then sit there with the clutch disengaged at the stop. That's 3 clutch engagements. I do this from fourth; I disengage the clutch, use the brakes to brake, and keep the transmission in neutral in case I need to grab a gear and go. I leave it in neutral at the stop with the clutch OUT (especially on hot days) so the pressure plate will clamp the clutch plate down and it won't warp as it cools.

Thaddeus

icat

My take...
Using the "clutch" as you described is in reality using engine revs to slow down. Since brake components (pads, rotors, etc.) are far less expensive than engine repairs, I suggest using the brakes. As Thaddeus said, ther's only so much coinage in the bank, why waste it.

Now having said that, the noises you describe are not normal. You should be able to downshift and use the engine revs to slow the car without hearing any clinks or clanks from anywhere.

AndyK

I am with you Thad! Use the BRAKES for slowing down. The only time I'll downshift is AFTER slowing down on a turn, or to pass someone. Using the engine to slow down is fine, as long as you leave the clutch in...

For example, driving towards a red light in 3rd, I can let off the gas, and the car will slow down. I then step on the clutch (once), and throw the car in neutral, using the brakes to stop.

Like you said, wearing out break pads is better than ruining a $1600 clutch!

Matt O.

Samo - definitely use the brakes. I'll pop it in neutral at any speed if I see a light up ahead that's red and just coast. Like someone said, brake pads ~ $100. New tranny/clutch/engine, etc parts, $$$$$

-Matt

ERAU-944

i'm with these guys, i'll replace my pads/rotors LONG before i have to get under there and get a new clutch installed... since you just had it done, you could make it last a long time if you practice this, seems like you do what i used to do when i was learning, just letting the enging slow down the car through the clutch, thats just asking for premature failure. so i've learned, and if i DO downshift (usually de or autocross) and even sometimes on the street, i MATCH the rpm's so there is little or no strain on the transmission.

happy driving!
-Mike <img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

rfuerst

Mike I also have a spring centered clutch in my 944S and if I do not match the revs when down shifting I also get a chattering noise,but if I match the revs no problem.I believe what we are experiencing is one of the few down falls of the spring centered clutch,it does not absorb vibration as well as the rubber centered clutch.Just drive it and enjoy it and either match the revs or follow the advice of the others and use the brakes. <img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

Tremelune

I agree with Thad, icat, and co. Match revs when you downshift, and to use your clutch as little as possible. Never downshift or engage a lower gear for the sake of slowing the car down. The one thing I do differently is keep the car in a gear. If I'm slowing to a light in third/fourth, I'll just let my foot off the gas and slow down until the revs drop to "unhealthy" levels, then I'll push in the clutch, stick in first and leave it there, in case I need to scoot quick for some reason. If I need to get out of the way of something, I don't want to be in neutral. That said, I'll often just throw it in neutral at a light so I don't have to hold the pedal down.

Thaddeus, what's this about leaving it in neutral at lights on hot days? As I understand it, engagine the clutch in neutral has negligible wear because the plates isn't really rubbiung anything (much less with the weight of the car). Pushing the pedal in and out would put some wear on the springs, but I can't imagine that'd be so bad. I've only ever been in a car with a clutch so worn you could keep it in gear and not move...Most clutches pretty much kill themselves when they fail, right? And that's not the springs? I'm I way off on my understanding of clutches?

John Welch

Tremelune,

Along with using your clutch as little as possible, taking the car out of gear at lights uses the throwout bearings as little as possible. The only time I touch my clutch is to shift. Never do I sit with the car in gear and my foot on the clutch.

The downshifting method Mike 944 was using seems to me that it is like slipping the clutch in reverse! Instead of a fast spinning engine with slow spinning wheels, you have fast spinning wheels and a slow spinning engine. Either way, you are either slipping the clutch or chirping the tires. Both are bad.

I like to downshift through the gears so that I'm always in a useful gear. There's been a few times when I was in the wrong gear or neutral, and it took longer than I would like to get my car moving.

I had a passenger once ask me why he couldn't feel anything when I downshifted. Its because I match the revs, smoothly, and then left off the gas pedal to slow down. Smooth is the key.

Mike 944

Thanks guys for the response. I agree with using the brakes, and I usually do...but I want to make sure there is no mechanical problem with the clutch and tranny. I'll bring iot to mechanic and see what he says....and pass on the news.
Thanks again
Mike

Z-man

There's something called HEEL and TOE downshifting. It is an advanced technique that is used to match revs while downshifting. The purpose of heel and toe downshifting is NOT to slow down the car, but to smoothly engage the clutch when slowing down for a corner to save the clutch and to prevent the car's handling from being upset.

Heel and toe is commonly used in track applications, but many people (myself included) practise it on the street to become smoother drivers on the track.

If you are just slowing down at a light, and aren't practising heel and toe, there is absolutely no reason to downshift. Brakes are still cheaper than clutches, as stated above.

In days gone by, downshifting was used to slow a car down, but that was when brakes were crappy and the driver had use everything at his disposal to slow the car down. We do not need to worry about that anymore.

Just my $0.42.
-Zoltan.

Treiber

Hi. I am not a know it all, but I do know the correct way to shift. To downshift properly and smoothly, you must push the clutch pedal in, select the gear, rev the engine high enough for the lower gear and then disengage the clutch pedal. It is smooth and easy on the parts.

mouse

I am new to my 944 and manual transmission and this is a very informative post. If I hadn't read this, I would continue to downshift whenever slowing down, and I didn't even know to match revs...which makes sense to do. Thanks for the info! I love rennlist

-mouse

rihaa

Well this post is somewhat related to this topic. On my '91 S2 I would love to be able to use heel toe shifting for the times when I would want to but the pedal placement on the car doesn't lend itself to that at all. It seems like the brake pedal is both too far out and too low to be able to reach the throttle while braking. I do have reasonably large feet (11's) but this still seems like a poor set up for pedals on a sports car.

Do the other models have this similar problem and are there any adjustments/pedal sets that people have used to get around this at all?

Thanks ahead of time.