Please do, when you get a chance
Is a SMF bad for transmission?
- Thread starter vegas39
- Start date
Unfortunately, even though you have that worn syncro, there is no way for certain to know that it was caused by clutchless shifts for thousands of miles or just regular wear...or from bad clutching or from worn bushings on pins etc...list goes on.
only way to know for certain is to drive a truck clutchless for thousands and thousands of miles being the only driver doing clutchless shifting and same on a clutch shifted rig...YOU cannot compare them any other way IMHO.
Syncros are designed to do that synchronize two gears to mesh quietly at different speeds and become one.
However, the ability to match engine speed to gear speed and make the syncros blend more smoothly with or without a clutch is a skill worth having.
I for one do use my clutch and usually double clutching, however I also practice and do on a regular basis the clutchless shifting and I consider myself as adequate at doing so.
Bottom line..
Roll the dice..take yer chance..it's your truck, your money...do with both what you will.
Al
so AL...what is it? between post #17 and #32 it's either damn the torpedoes or use caution accordingly? imho, it sounds like more you're talking out of both corners of your mouth.
I'm all for a educated operator. understand what you have and use it accordingly.
I have no problem floating gears. Everyone should know how to do it when the situation calls for it. In the event of clutch hydraulic system failure, or throwout bearing failure, floating gears is a solution in "getting home"
Now here's the reason why floating gears should be done sparingly.
note the first pic. the syncros look like any other. but the second and third pics show the backside of the syncro where the friction material was supposed t be at. a healthy friction ring will have raised lines of sintered metal that has been electro deposited onto the inside of the ring. the metal is no different from brake friction material and it doesn't have a unlimited wear as the last two pics hold in evidence. it is true the exact length of time needed to wear the material off is unknown but it doesn't take a genius to know the unrestricted use of floating gears won't forestall matters. read up and make your own decisions.
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freebird01
Post Turtle!
i couldn't remember the specifics...i just know you posted pics of the knife edged splines on an input shaft many moons ago. wasn't trying to drag you down into depravity lol
YES I AM talking out both corners...do it if you want to...so AL...what is it? between post #17 and #32 it's either damn the torpedoes or use caution accordingly? imho, it sounds like more you're talking out of both corners of your mouth.
Be careful and know what can happen if you do....
CHOICE IS YOURS!!!!
K here is where I am, I have no way of proving that floating is NOT going to hurt the transmission, however showing pictures of a worn syncro does not convince me it does either. As I said, unless the transmission is floated from day one all it's life..not passed down from owner to owner, we just cannot tell 100%
My theory if you CAN float and want to do it, being able to should be a priorty skill to attain for those JUST in CASE moments. Hell I did it yesterday in the ranger for shitzngigglz just to see if I could, ya it's tricky, however not impossible.
If people want to float them cause they can do it and do it knowing that there could be potential dangers.
However I choose to drive is my personal business, and practicing clutchless is important to me enough to get good at it and maintain that skill. When I got my truck, it had a bad 3rd gear so I would double clutch all the time and some times it would take and others it would not. That trans was worn out and likely NOT due to shifting without a clutch, however being the second owner I've no way to tell how it was driven.
I see the wear and I'll reiterate that we have no way of knowing if the wear is from straight clutchless shifting the entire life of transmission or normal wear, or faulty part etc?
BE WARNED PEOPLE, CLUTCHLESS SHIFTING is not for meek of heart...do it at own risk, cause I sure as ***** won't pay for your repair bills or do your labour
PEOPLE LEARN TO CLUTCHLESS SHIFT it can get you out of a bad situation and help keep you moving to safety and get a job done!
There I've posted both ways outta both sides of my mouth...
Just wish there was a simple answer and there isn't..
Al
Dsl_Dog_Treat
I lost my face to the jaws of a poodle
Sent an email to ZF and this is what was sent and found.
icanfixall
Official GMM hand model
ZF kinda made a statement but didn't say what was asked. Floating gears gonna ruin the syncros or doing a poor floating gonna ruin the syncros AND the trans. A syncros purpose is to slow down the gears so they will ingage safely to the other clusters. They actually are a brake in doing this function. So how does a non cyncro trans operate.... My wifeys grandmother had a 1927 Rolls Royce with a non syncro three speed trans. I saw this car in the garage many times but never got to drive it..
She told me if she missed a gear it was over to the curb abd start all over again driving forward.. It was one of the first all american made cars and she had it delievered to the ranch in Texas on her 16th birthday. A gift from her mom and dad....
She told me if she missed a gear it was over to the curb abd start all over again driving forward.. It was one of the first all american made cars and she had it delievered to the ranch in Texas on her 16th birthday. A gift from her mom and dad....
RON thanks for kyboshing any misconceptions!
I still am of the nature that if the gears are matching speed wise properly no premature wear CAN occur...however if you don't match speed yes! I could be wrong and be doing damage but that's my theory and choice to make
Suppose it's from horses mouth...bottom line users choice!
Again
Thanks Ron!
I still am of the nature that if the gears are matching speed wise properly no premature wear CAN occur...however if you don't match speed yes! I could be wrong and be doing damage but that's my theory and choice to make
Suppose it's from horses mouth...bottom line users choice!
Again
Thanks Ron!
If road speed and engine speed are matched the syncros are NOT used.
Their one and only function is to change the speed of the shaft that it is shifting to enough to allow the shift to happen.
You can feel whether or not its right.
If it just slides but between gears with no effort great. If your off 100 rpm and it takes pressure your wrong.
Their one and only function is to change the speed of the shaft that it is shifting to enough to allow the shift to happen.
You can feel whether or not its right.
If it just slides but between gears with no effort great. If your off 100 rpm and it takes pressure your wrong.
jaluhn83
Full Access Member
Not sure why this has dragged out into such a long winded discussion, it seems pretty clear cut to me.
Assuming you can perfectly match rpms with the trans in neutral and no pressure on the shifter then slide it gently into gear, then no there *shouldn't* be any syncro wear. Problem is it's very hard to get this perfect in the real world. Anytime there's any pressure on the shifter and the gears are turning at different speeds there *will* be wear on the syncros. How much is going to depend on how much pressure and how much speed difference.
Remember that you've got something like a 30+:1 lever arm (estimating) on the shifter - that is 5 lb of force on the shifter (which seems reasonable for someone lightly pushing it in) equates to roughly 150 lb of force pushing the synchos together.
The other potential downside of clutchless shifting is that you have no shock cushioning - even if it's within 10 rpm, when that gear engages you're not locking everything together which means you're more or less instantly changing the speed of one or the other side of the gear train to match which is quite a lot of momentum.
That being said, I don't disagree that driving with out a clutch is a highly useful skill to have and good to practice enough to know you can if you needed too.
I wouldn't recommend driving that way all the time though - first of all it's a pain (at least to me), and then there's too much risk of wear/damage for what benefit? They designed the system with a clutch for a reason, and every reference I've seen says to shift that way - makes sense that to use the system the way it's designed.
Personally I double clutch 95% of the time - I feel like this makes things smoother and minimizes wear.
Given how long these units last with people abusing the heck out of them, I don't think there's any reason to really worry *that* much about wearing them out.
Assuming you can perfectly match rpms with the trans in neutral and no pressure on the shifter then slide it gently into gear, then no there *shouldn't* be any syncro wear. Problem is it's very hard to get this perfect in the real world. Anytime there's any pressure on the shifter and the gears are turning at different speeds there *will* be wear on the syncros. How much is going to depend on how much pressure and how much speed difference.
Remember that you've got something like a 30+:1 lever arm (estimating) on the shifter - that is 5 lb of force on the shifter (which seems reasonable for someone lightly pushing it in) equates to roughly 150 lb of force pushing the synchos together.
The other potential downside of clutchless shifting is that you have no shock cushioning - even if it's within 10 rpm, when that gear engages you're not locking everything together which means you're more or less instantly changing the speed of one or the other side of the gear train to match which is quite a lot of momentum.
That being said, I don't disagree that driving with out a clutch is a highly useful skill to have and good to practice enough to know you can if you needed too.
I wouldn't recommend driving that way all the time though - first of all it's a pain (at least to me), and then there's too much risk of wear/damage for what benefit? They designed the system with a clutch for a reason, and every reference I've seen says to shift that way - makes sense that to use the system the way it's designed.
Personally I double clutch 95% of the time - I feel like this makes things smoother and minimizes wear.
Given how long these units last with people abusing the heck out of them, I don't think there's any reason to really worry *that* much about wearing them out.
MidnightBlade
Shiftin' Smooth
And here we go again reviving from the dead One major difference between heavy duty and light duty transmission is the gear cut. A heavy duty trans has straight cut gears, while the light duty has a helical cut gear (smoother I think IDK 
) Naturally the straight cut gear is going to mesh a lot easier under a slight load or what not as opposed to the slant cut gears in the ZF. Sure theres more surface area which naturally is stronger but theres also the problem of them wanting to walk under high torque thus making them undesirable in the HD market.
But now back to the synchros... once the synchros are shot what makes it any different from a non-synchro trans?
One major difference between heavy duty and light duty transmission is the gear cut. A heavy duty trans has straight cut gears, while the light duty has a helical cut gear (smoother I think IDK ) Naturally the straight cut gear is going to mesh a lot easier under a slight load or what not as opposed to the slant cut gears in the ZF. Sure theres more surface area which naturally is stronger but theres also the problem of them wanting to walk under high torque thus making them undesirable in the HD market. But now back to the synchros... once the synchros are shot what makes it any different from a non-synchro trans?
I never use the clutch once moving in anything i drive. My truck,my jeep,customers cars etc. Just dont force it and its basically no different than using the clutch. Plus im saving my firewall! LoL! My t19 has a nasty rattle if ran at low rpm. Never knew what it was but it must be that trans noise you guys talk about.
My jeep has had clutchless shifting since i bought it new 145k ago. So far its fine. I put 360k on a t18 in a scout,never had to touch that trans.id rather rebuild the t19 in my truck than mess with a broken firewall. Its a tough trans and as long as i dont shove it into gear its not going to hurt it
My jeep has had clutchless shifting since i bought it new 145k ago. So far its fine. I put 360k on a t18 in a scout,never had to touch that trans.id rather rebuild the t19 in my truck than mess with a broken firewall. Its a tough trans and as long as i dont shove it into gear its not going to hurt it
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