Is it really true that doing "Clutchless" shifts can wear out the synchronos? The trans in my Truck has 375,000 miles, all original, even the Clutch it's self. Drives perfect. 1990 F250 Diesel 5 speed.

 

I do it all the time,as long you synch / time, the shifts,no forcing or grinding,it will slide right in gear.
If you have 375k on your truck,you answered your own question
That's excellent.

 

As long as you don't grind it when you can't find it, it won't hurt a thing, there is a reason all of the truckers shift like that as well.

 

Alright then, cause some have told me that it wears them out. I didn't think so cause my dad has done that ever since he bought the truck brand new in 1990. Now i'm 16 and got my license so now it's my turn And some even say it's near imposible to do a Clutch less shift on a synchronized transmission, I acually find it easy. Since i've been doing that (few months) I only missed it ones from 2nd to 3th.

 

2nd to 3rd can be tricky from time to time on the 97 F250 I drive at the ranch I work for. Its got a very limited range of speed that it can shift, but I've just about got to where I've mastered it.

Now there are some tranny's are nearly impossible to do, my Dad's 85 tercel and and my old 1986 Corolla were impossible to shift clutchless.

My F100 with a 3spd on the column was also kinda tricky to shift clutchless but it could be done.

 

My sister's diesel ranger can be finicky with clutchless shifting (high miles tranny), but if I pay attention, I can still pull it off. That one doesn't like 1-2 or 2-3 very much. Driving automatic most of the time probably doesn't help my skill though.

I bought a 1996 saturn 4 door recently (also high miles) for a side project and after making it back to town, I played with it a little and was able to make it shift clutchless VERY easily. Was able to even float gears up and down for engine breaking deceleration. I was quite supprised how easy it was to shift clutchless on the first try considering it has a sloppy cable shifter.

If you read up on the mechanics of synchromesh manual transmisisons, you will find that the gear syncros work weather you use the clutch or not. What they do is line up the gears and shafts, the manual clutch and throttle control are what line up the engine RPM to the road speed. The only harm that is done is when you grind gears, so....don't grind them.

If it wasn't for the synchromesh transmissions, you would have to foat gears even when using the clutch to avoid grinding the gears during shifting.

 

Some good reading here:

Car Bibles : The Car Transmission Bible page 1 of 2

 

on my 86 with the t-19 4 speed 1st-2nd is easy but the rest are about impossible to get with out making her grind or clunk, but on my dads 89 with zf5 i can go threw every single gear and never touch the clutch and it shifts as smooth as butter