Just so i know incase my clutch goes out for SOME odd reason... how do I do clutchless shifting (for safety - limp-home)? No way i'm going to do this unless I absolutely have to, but I want to know how incase that time might come up.

 

It is a lot easier than you'd think. You want the car to be in a "glide" period when you do it. You don't want to be accelerating or decelerating. Apply gentle pressure to the shifter to to get it out of gear and then the same to get it into gear. On my car I can do this shifting at 10mph, 20mph, 30mph, and 40mph. I'm sure yours would be different.

 

Basically if you're moving you can knock it out of gear without the clutch, no big deal there. Then to make it fall into the next gear you need to match your engine speed to whatever your speed will be in the desired gear. Ideally you over rev that number just a hair and just kinda feel it into place as you let the RPM's drop into place.

Sounds pretty easy right? BULLpoopie! I can't do it and can't afford a new ZF while trying. Then there's the ever so interesting question of how you get it started again if you ever have to stop! I think I'll just have it towed if that ever happens. My dad can shift his 1946 without the clutch and it doesn't even know what a synchro is. It's just one of those things that you would get a feel for on the car after you've driven it forever, not something that can be just easily tought. If you decide to try it, good luck.

 

cool, thanks guys!

 

only reason i would do it is in emergency.. I figured it would involve matching the rpm's of the tranny and engine.. but i didn't know you could just push it out of gear and into another... :eek:

 

Yup, thats how it works. The synchros in your tranny do the same job. They slow the transmission internals down in order to match each other and fall into place. You are manually doing the job of the synchros.

 

any recommended reading on manuals tranny's & synchros? I know everything about auto's since i helped rebuild it, but i don't know much about the internals of the ZF

 

http://www.howstuffworks.com It's not ZF specific but it's good info. :cheers:

 

yeah.. howstuffworks is AWESOME .. but i'd like to see something more specific on the ZF :cool:

 

Just ease it into neutral and coast/apply brake to stop. Shut engine off, put trans into 1st gear, star car. It will slowly roll while cranking and start! Then you just procede to drive on. If you want to practice, you should, put car into first gear and go to a speed that is say 3000rpm(I'll use 15mph), now shift into second gear and go 15mph, look at your rpm(I'll say it reads 2200rpm), remember this rpm/speed, take second gear up to 3000rpm and check mph(I'll use 35) now shift into 3rd and go 35mph, check your rpm, and repeat this for every gear remember each gears rpm@mph. Now just drive in 1st gear up to 15mph/3000 rpm and apply light pressure on shifter towards second gear and ease off of throttle it will slide out of first, and if you allow the rpm to drop as it reaches 2200 it will slide right in to second gear! Keeep doing this through out you gears, and in no time you'll be doing it to impress your friends!! Down shifting is done the same way, say you're in second gear slowing down to 15mph apply pressure on shifter towards first, it will slide out as it does slowly increase you rpms as they reach 3000 it will slide right into first, and so on for each gear! Don't be affraid to practice, it is a good thing to know how to do, and if you ever need to use it, no problem. If you do not try to force the shift, you won't hurt anything! Good luck, have fun! :cheers:

 

Ahhhh, the joys of rev matching... I've never tried in the vette (don't feel like thrashing it), but it used to freak my friends out in my rx-7. I loved the nice little noise it made as it clinked into gear.

 

With the timing right, it shouldn't make a sound!!! It is fun to do with friends that have no clue!! :cheers:

 

I think I'll save practice for a rental or something, haha. :D

 

http://www.zfdoc.com There are a few good things to read in there.

If you get into a situation where you have to try clutchless shifting in your Corvette (highly unlikely it would just "go out"). Pull over, call AAA and get a tow truck because it will be a whole heck of a lot cheaper than any damage to the ZF transmission. The tow bill will probably be cheaper than just the freight charge in simply getting the tranny to a shop that can repair it.

 

 

:yesnod: :yesnod: :yesnod: k

 

On a related note, you will know when your clutch is heading it's way out the door when you can put it in a high gear (4th+) and at low speeds and rpm with you putting the throttle down, the RPMs will increase but the speed will not increase as much as it should. In this case, the clutch is slipping and will last probably another couple hundred miles depending on how you drive.

Chris

 

ok .. that was going to be my next question :D

 

Don't you have a clutch-starter disable switch? That will nullify this nifty method of starting off. I guess it can always be disabled though.

With regard to the original post, the ZF is a surprisingly robust transmission and I started doing this more out of playing around than anything else. It's not that hard to shift without the clutch. To start getting a feel for it I would suggest - while at speed - put the car in neutral and if you're going to shift up, angle the shifter towards the next gear and apply gentle pressure (not enough to grind) and when the revs drop enough (no gas pedal pressure), it should just slip in. A similar thing should happen if you try to shift down and just blip the throttle while applying the gentle pressure.

Jim

 

years ago, my first car died on the road. the tow truck operator showed up and towed me home...

I kid you not - this was a newer Chevy tow truck - used the clutch only to start.

the rest of the time he matched revs. smooth as silk. every so often it would hitch up, but it was still new. I was impressed.

I have done it. it is simply a factor of patients.... I did it on my prelude all the the time.

but never on the vette... ZF's are just too damned expensive.