When you guys mean powershifting, are you talking about not engaging the clutch when you shift and jamming the shifter in gear?

 

I would like to know also. I don't know what powershifting is.

 

Hey guys- the definition of powershifting is to shift without taking your foot off of the throttle pedal but still use the clutch. Not using the clutch at all during shifts is called slamshifting :lol:

 

I grew up in the 60's and we powershifted everything that had a clutch. You haven't lived until you've powershifted a three on the tree :D Even the shop tow truck could be powershifted if you were determined enough. Mid to late 60's MOPAR's (Roadrunners, etc) had a bullet proof cast iron saganaw 4 speed with a long Hurst shifter. You had to shift it as hard as you could, (teeth clenched, pi$$ off hard, no holding back) or it would miss every time. I powershift my C5 everytime I drive it. With the BM shifter, it shifts clean everytime without brute force. The key IMHO is doing it without flinching. This would be a tough thing to learn, starting on a New C5. And another thing... Car & Driver has reported that John Heinricy was performing "clutchless upshifts" during the Supertuner test. I was somewhat skeptical about this, but this is the second time, second source I read this so there maybe something to it. I was thinking about this while out with the Vet today, so I tried it. It works. :eek: Before everyone declares my trans history let me explain. First gear, part throttle run it up to 4-5k rpm, lift throttle and apply firm steady pressure on the shifter towards 2nd gear. The second you lift throttle it will pop out of 1st and press up against the second gear syncro. When the rpms slow a match the speed it will drop cleanly into second. Repeat for the 2-3 shift and it works equally well. The whole gear change isn't as quick at a hard shift but as quick or quicker than a normal casual shift. I tried it a few times and it always work fine. It was ok with 1-2 & 2-3, but didn't like 3-4 as much. The C5 trans probable does this well because of the extra syncros. Disclaimer: doing this puts a bit of extra strain on the syncros and a stead diet of this would cause them to wear out prematurely. :blueangel:

 

I have heard some guys say they double shift. What is that????? Or is it called something else???

 

I think you might be thinking of double-clutching it. I think a lot of tractor trailer trucks have to do this. When you go to change gears, you push the clutch in to take the tranny out of the current gear, let the clutch out when it is in neutral, push the clutch back in and let it out once it is in the next gear.

 

'99Hardtop,

Most of the big rigs today use the clutch to but the tranny in gear.....from then on, all shifts, both up and down are done without the clutch. The shifts are done slowly and with rev matching and in no way are harmful to the drive train when properly executed. At least that was the way I drove rigs with 10 speed and 13 speed Roadranger trannies. I do remember driving an old 15 speed Eaton transmission which liked double clutching.

Power shifted my 64 and 66 Vettes but don't do it on my 2001. On it I double clutch my downshifts only. Should save the synchros, but the off set will be a little more wear on the clutch, pressure plate and actuator (slave).

Good luck.
Mark

 

Powershifting : shifting with the accelerator fully depressed, using the clutch

Double-clutching : clutch in to take out of gear, release clutch, push clutch, into next gear, release clutch when in gear

So what is Speedshifting?

- Charley

 

Shifting as fast as you can and blipping the throttle. Just fast shifting with a short ease of the gas.

 

I'll PS 1-2 and 3-4 when I am racing when I know the race is gonna be close.

Ben, you better be powershifting son, if you wanna keep up with me

 

Only if I decide to go back to drag racing on the track, haven't done it in over 29 years...

 

MDT, so basically, I have the right idea about double-clutching. I have never done it myself, so I didn't know for sure what it was. I just was told this by a friend who claims to be able to drive anything.

 

Don't think so :nono: I have had the Hurst for over a month and love it. If you don't believe me come on down and I will let you drive it! :yesnod:

 

C-5Vert, Well, how does it feel to have 1 of only 2, that I know of?????
That is/was the reason for my intemperate remarks
Get em' on the shelves, WHY aren't they out for GP consumption, if they are ready, and are SO good?????...................
Delayed release usually is bad juju.................hope not, as you stated..........I NEED a shifter, and both CURRENYT models have negative point's, and I would love to know there is an alt, that is BETTER, easier............ :D

 

You know, if I were in your position I would probably say the same thing. The fact is I just don't know what is going on with Hurst. From what Chris(the guy who set me up with the shifter) has said, they have other things on their plate. The shifter seems perfect to me. I can't understand why they just don't start cranking them out. I wish I could do something to speed the process, but I can't. Just take it from me, if you can wait, definately do it! My vette shifts like an F1 paddle shifter to me, smooth and never missed a shift. No complaints whatsoever!

 

I used to do clutchless shifting (up and down) all the time in my 85 VW Jetta. There is absolutley no harm to the tranny doing this. I would try to get where I was going without using the clutch at all. Coasting up to and timing red lights was the real biatch! :D You can do this in any manual car and it is a great way to learn throttle control, or at least rev matching and knowing what RPM your engine is at in any gear at any speed without looking at the tach. Damn, I actually miss that car now! Anyway, I know a Jetta's not the same as a Vette but since I don't have one yet it's the best I can do.

 

Daveg27,

Why do clutchless shifts? Because you can shift faster? I assume you just push the shifter towards the gear you want and don't touch the clutch....sounds like you could grind the gears fairly easily. What is the technique?

- Charley

 

You cannot "clutchless" shift under power (unless you have a special racing transmission, such as a Liberty. You must let off the gas to unload the gears (unless you are VERY strong). During that fraction of a second between being loaded under accel and loaded during decel, the sliders and synchros (those are what actually move in your tranny, not the "gears" themselves.....but that's a very long story!!) can be shifted. Bottom line is that as appealing as it sounds, clutchless shifts are 1) slower than normal shifts, and 2) impossible under power and 3) potentially dangerous IF you don't know what you're doing. It's not something to learn on your C5, put it that way.

I once drove a 340 Dart from West Virginia to Washington DC with broken clutch pedal linkage, shifting clutchless all the way. Started from a stop by putting it in 1st and getting going on the starter. No problem at all. However, the only clutchless shifting I do now is to sometimes slip the shifter to neutral from whatever gear, when coasting to a stop and feeling too lazy to move my left foot for a few more moments. I just take my foot off the gas and simultaneously slip it into N. I don't try to rev match to go into another gear....I'm quite aware that it can be done (did it), but I'm a little concerned about these double syncros and other delicate stuff in this trans.

I have successfully powershifted the car (I have a Kirban), but recently experienced severe clutch slip on the 2-3, so I think I'm not gonna do that anymore.

In my opinion, full-throttle powershifting a mostly stock C5 is worth between one to three tenths over good, clean, fast speedshifting, (depending on available traction and/or if you go up against the rev limiter!!!) but I have no personal track stats to back that up. Can anybody comment on that?

 

Tracy,

About that clutch slip on a 2-3 powershift there may be a simple cure. I experienced the same thing a few weeks back and thinking :cry new clutch. But at only 25k miles, it seems a bit soon. Then I remembered reading on this forum about someone having black crud in the clutch hyd. fluid. I checked mine and it was a mess. Lots of black slimely stuff in the fluid. It's a bit of a job to bleed the slave so I sucked out the reservoir with my turkey baster. Wiped out all the crud and refilled the reservoir. No more clutch slip. I'll bet sludge in the line slowing the clutch engagement has ruined more that a few C5 clutches.

PS I described the clutchless shift in some detail earlier in this post.


[Modified by Terry Humiston, 2:23 PM 12/6/2001]

 

Terry,

Yes, I've been hearing a lot about changing the fluid, and following different threads on the subject. At first, I dismissed it as mumbo-jumbo, because I can't really see how it can go bad in 15K miles, especially when compared to the brake fluid (which is still crystal clear when it dribbles out of a caliper bleeder, BTW). But............enough guys, including Steve Row, have told me about this, so I'm thinking it's worth a try. If it does work, it's a cheap fix. If it doesn't, at least it was cheap! :D

Now it seems the only decision is to do it the turkey baster way or the "right" way. I want to get that fluid out of the servo (slave), and I don't see how the turkey approach can effectively do that, as the slave fluid it basically trapped at the end of the line. Plus, it seems to me that the slave fluid is the worst. But then again, I haven't gotten the manual out yet to do a full study of the bleed procedure, so I'm just guessing here.

Is the bleeder fitting a significant biatch to get to, or is it just the whole prodedure of "pump it, hold it, okay. Pump it, hold it, okay" that is problem??

And yes, I read your discussion of clutchless shifting and argee that the technique you described will work. I just don't like it on the C5 tranny. It was easy on the old, more robust Mopar trannies. Plus, that rotating torque tube does put a strain on the clutch action of the syncros, unlike a "normal" clutch/tranny arrangement. And by the way, the Mopar 4 speed was a "Chrysler New Process 833", not a Saginaw. Sags came in low power Chebbies that didn't use the Muncie. I know that Mopar tranny all too well....I built dozens of them. They worked FLAWLESSLY if you did a little syncro tweaking, a little shift fork replacement (to steel) and totally rebuilt the crappy clutch linkage, using strong steel links, roller bearings and Heim ends. On some cars with very strong clutches, we had to brace the firewall, because it would flex and move forward (just a wee bit) when you pushed the pedal instead of disengaging the damn clutch!! It all feels the same to your foot, but what a difference it made mechanically!!

So, how hard is it, really, to totally change out the clutch goo? And wouldn't Castrol LMA (low moisture absorbing) be a good choice?