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View Full Version : Is it possible to "desync" a tranny



Luminatorz34
01-04-2009, 07:45 PM
i know this is a weird question. but me being a truck driver kinda raises curiousity to this...i drive a truck that is a 18 speed. big rigs do not have synchronized transmissions. meaning you have to either eev the motor to match the gear you want, or let the motor rpms drop to match the gear your going in also. after you get the hang of it, it is really nice. and super simple to float a gear. i know its not good to float gears on our normal day to day passenger vehicles. but would it be possible to take the synchros out of a standard manual transmission, and still be able to use it? or would it completly ruin the trans? any info would be useful, as im really just more curious than anything here

DustinsDuster
01-04-2009, 09:18 PM
one word: dogbox. any gear any time, no need to match RPM's.

black88gt
01-04-2009, 09:24 PM
passenger cars didnt have synchros early on, you could always go back. commercial trucks just ditched them to save weight, military trucks and vehicles that dont subscribe to weight restrictions have synchros a majority of the time

Scott
01-04-2009, 09:26 PM
yeah a Dog-tooth trans is similar to a Semi truck, it doesnt use friction material on the syncro's to match the shaft speed it uses rather large teeth on the sliders instead, it is stronger and faster to shift because you dont have to wait for the friction material to do its job "so to say" but its not as simple as just removing the syncro's because you need something to transmit the power and slide from gear to gear. Kinda hard to explain without a diagram or something

krustindumm
01-05-2009, 04:46 AM
you don't *have* to use the clutch on modern cars.

Ricky
02-02-2009, 02:35 PM
you don't *have* to use the clutch on modern cars.

yes but the question was.."does it hurt modern cars with syncros if you dont use the clutch"

derek072887
02-02-2009, 06:54 PM
actually he never asked if it hurts modern transmissions to shift without the clutch... he said "i know its not good to float gears in modern cars"

69gt4speed
02-03-2009, 01:31 AM
you don't *have* to use the clutch on modern cars.

yes but the question was.."does it hurt modern cars with syncros if you dont use the clutch"

That answer is yes if you have big physical gears as say a t56 or toploader or old muncie or the chrysler 4 speed. Trust me damage will result and cost dollars. T56 you will break a lil stamped key, chew the syncros and maybe chip a tooth, I've done it on a 3/4 shift. Little physical sized geared transmissions, low hp like bikes and they may be a dog /face tooth setup anyway do not need the clutch at most letting off the gas a bit is good enough. I never used clutch on my 400 tm suzuki, course they were made for such abuse.

These days you cannot switch back or forth, all those friction cones etc. take up space on the shaft. A t56 has a hundred lil parts. I said holy crap when I saw all the parts. x10 mo than a toploader 4 speed. Camaros, cobras have a crappy syncro system, new ones have a triple cone to make sync quicker at hi rpms. Think a dual disk clutch, it will lock quicker and sync the mass faster. But still no way close to facetooth/dogbox engagement at hi rpms. Or they would not sell them or make money doing it. Right?

Example: Why those 08 cobra jets went dog box 4 speed, u saw how crappy those guys shifted a triple cone t56. 2wks later week they had the g force dogbox .6 sec faster... Yes they work for racing.

Before.... triple cone, the damn thing won't shift 3/4 and slow on 1/2. 10.7 127
http://www.youtube.com/watch?v=tq5Q5ETQ_2o
After w g force 4 speed dogbox... .6 sec faster 10.1's hair over 130, he verified it to me.
http://www.youtube.com/watch?v=6CgJkKpUmYE

Scott
02-03-2009, 07:03 AM
Holy crap! I didnt know those cobra jet mustang were that bad-ass, low 10 sec times from the dealer?? damn!! anyway, yeah its not easy to get rid of the synchro's in a factory trans, if you eliminate them then a dog/face tooth "plate" has to welded in place of them in order to get the gear speeds to match or you would eat up the gears like crazy, then of course you have to do some type of heat-treating to the components. To my knowledge even with a dog tooth trans you have to remove torque from the input to shift gears, either tapping the clutch or letting off the gas to shift gears. So to answer your question, YES it is possible to DEsync a trans but its not easy or cheap to do it

krustindumm
02-03-2009, 03:04 PM
Like I said though, you don't have to take the synchros out. I blew up the clutch in my 240sx and drove it for a month without while I was waiting on the new one. Match the revs and shift it.

Ricky
02-03-2009, 06:29 PM
actually he never asked if it hurts modern transmissions to shift without the clutch... he said "i know its not good to float gears in modern cars"

yeah, and your mom is FAT!

TbTalon94
02-04-2009, 06:44 AM
Like I said though, you don't have to take the synchros out. I blew up the clutch in my 240sx and drove it for a month without while I was waiting on the new one. Match the revs and shift it.

Yea...how'd you go from a stop :yawinkle:

krustindumm
02-04-2009, 02:48 PM
shut engine off, put in 1st, start car. Had to push in the clutch to activate the safety switch. Mostly tried to avoid coming to a complete stop though.

Jappbox
02-04-2009, 03:41 PM
On my Dads Model A and 1926 Franklin you have to "double clutch" to get it into gears with out grinding. A Dog Box is streght cut so like said above can go into any gear at any RPM. a Semi Must have half streght cut gears if not using any syncros. On modern "normal cars" if you dont have syncros you would prob be locked out im guessing, when i had a bad syncro it was a hit or miss but 90% of the time I was locked out of the gear like a brick wall!

Luminatorz34
02-04-2009, 03:58 PM
well see on semis (big rigs) you dont need the clutch to shift..just simply let off the gas and wait for the r's to drop to grab the next gear...but they will only go into gear matched on speed..say your going 25 mph in 7th gear...you couldnt down shift to 5th to take off harder...it will just grind like its locked out of the gear unless u slow down slow enough for that gear. or rev the shit out of the motor to grab 5th gear. ill have to look into a dog box sometime then...cuz now i suck dirty nut sack trying to drive my talon now...let it be he clutch just disengages less thatn an inch from the floor...if i adjust it it might be a ton easier to drive...but its too cold for me to climb my happy go jolly ass under the dash and goof off till i can get the clutch adjusted

JJ240
02-04-2009, 04:26 PM
straight cut gears in a dogbox are terrible for the street. They howl like a motherfucker, and don't last as long unless you shift with the clutch normally which defeats the purpose of getting it.

69gt4speed
02-12-2009, 12:24 PM
Oh they have a dogbox w helical gears, a t5 replacement. Coarser helical teeth gears to take mo pwr. Developed specially for that nmra true street class w 30 mi cruises. Just $. Being a t5, fit gm, etc. also I suppose w right setup. It should shift real good and not be too noisy, don't know about popping out of gear w/o ur hand on shifter.
http://www.gforcetransmissions.com/tran_gt-5.asp