Clutch / Shifting Questions

[Earlsfat]

I am asking these questions because I've so much BS lately that I'm starting to doubt myself.

1. When decelerating from any speed (let's say for example 55 mph in 4th gear) you are supposed to downshift through the gears, and let the engine help slow the car down, right. (?) (When I bought my 70, the guy who had it seemed shocked / concerned that I was downshifting when slowing to a stop.)

2. My clutch recently "exploded" and have to replace the whole deal. Could it be that the guy I bought it from new it was going and wasn't downshifting to make it last long enough that I'd buy the car?

3. 4th gear ground when I shifted from third ONLY when I kept it in third while cruising at slower speeds, (didn't grind when getting on it) and 2nd wouldn't hold unless accelerating, would pop out unles I held the stick back. Was that an indicator that the clutch was going? (A big hint that I missed ).

Thanks

[4onFloor]

theres a proper way to downshift without damaging the clutch. you want to push the gas to raise the rpm's before letting the clutch out on a downshift.

dropping the clutch and letting the vehicle speed raise the engine rpm's will shorten the life of your clutch and the transmission. i dont know if it's true, but i've been told that letting your vehicle speed raise the rpm's causes the piston rings to float and causes blow by. i dont know if that's true though.

i'm going to say that the bad clutch could cause your tranny to pop out of gear, but i dont know. it could be an internal problem

[drvngstorm05]

downshifting while decelerating is neither hurtful nor harmful, if anything it helps you stop faster... that wouldn't have anything to do w/ the clutch "exploding". if the car was being worked everytime it was drivin, that would have something to do w/ it, but not wether or not some1 used engine slowing or not...
on the other issue, there is a possiblity that u may not have been pushing the clutch all the way in when it was grinding... or maybe you are but the cable is begining to get worn out... 70's used cables as far as i know and not slave cylinders. if that is not the issue then u may be shifting from from 3 to 4 at too low of an rpm and the syncros weren't lining up... i can't give you a for sure answer, i could make a better observation if i was actually there while those things happened. hope i was of some help

[drvngstorm05]

oh, do u mean letting ur rpms drop and using engine speed to bring them back up? (resulting in deceleration). i thought u mean downshifting into another gear and just staying off the gas instead of putting in the clutch and coasting... because having your drivetrain connected will make u decelerate faster than just coasting. if you for say, take it out of 3rd at 1200 rpm, downshift into 2nd with the engine still at 1000-1200 rpm then you have the chance of wearing out your clutch if you let it slip too much, but there is no internal engine damage. its just that not rpm matching can wear out your clutch if you allow it to slip too much...

[Earlsfat]

For instance...
4th gear at 3500 rpm doing 60mph. Brake until slow down to say 45 mph at about 1500-2000 rpm. Clutch and downshift to third, no gas, and the engine bumps back up to say 3500 when I let the clutch out. Is letting the engine bump back to a higher rpm, without hitting the gas going to prematurely wear out the clutch?

Also, as far as the second half of my original post, is there anyway to tell if a clutch is going bad?

And while I'm at it, could the original clutch have been to light a clutch? Or is that what happens when a clutch goes... pedal goes to the floor, car won't come out of gear, and you hear/feel a big crunch?

PS: Storm, did you mean speedshifting down, not using the clutch at all??? Just jamming it from 4th to 3rd? I never really thought that was possible.

[cuda_dude]

I have always downshifted to slow my car (saves on brakes), if you double clutch it doesn’t slow you as fast, you need the high rpms if you want to slow yourself otherwise you are almost just coasting, but don’t get me wrong double clutching is a nice smooth downshift and when done right you shouldn’t even be able to tell you've changed gears...to answer your other question, yes speed shifting is possible but it involves the use of the accelerator and brake pedals....when downshifting hit the brake until u are in the low rpm range and push the stick into neutral, hit the accelerator and pop the stick into the lower gear.....

[Earlsfat]

Double clutching? I guess I sound like a REAL idiot now, I've heard of it but have no idea what it is.

[4onFloor]

like i said, there is a proper way to downshift. say your in 4th gear and your wanting to downshift to 3rd, push in the clutch put the tranny into 3rd gear, give the accelorator a little gas to raise your rpm's then let out the clutch. if your doing this to slow down, then let off the gas after your've downshifted and released the clutch.

releasing the clutch without raising the rpm's first WILL wear out the clutch. i know because i was told that it didn't harm the clutch at all, then i ended changing the clutch a year later. personally i think it's a little stupid to try to extend the life of your brake pads by downshifting. which is more expensive, brake pads or a clutch?

[Earlsfat]

Gotcha. However, my maro doesn't have power brakes. More often than I'd like to admit, I ahev to use the engine to help me slow the hell down.

I guess I really should be asking: What's involved in adding a power brake booster to a car when the engine's cam / lifter, etc don't provide enough vaccuum to run a regular set-up?

[cuda_dude]

downshifting without using the accelerator wont hurt your car enough to make a difference. the clutch is only involved a split second in the downshift....i personaly know people that have put hundreds of thousands of miles on their original clutch while downshifting reguarly......as long as you arent downshifting from excessively high rmps you will never have anything to worry about....but if you want that nice smooth shift and dont mind the hastle learn how to double clutch (clutch in, shift lever to neutral, clutch out, blip throttle, clutch in, shift lever to gear, clutch out)

[cuda_dude]

"Rods are under tremendous tension and compression during each and every stroke, it has
nothing to do with whether the engine is accelerating or decelerating. The stresses are greatest
at max engine speed, and fall off rapidly as engine speed drops. Engine braking doesn't harm
the engine in any way...it's just that brakes do a far better job of slowing a car down than engine
compression can ever hope to accomplish."