Manual Drivers - No clutch once underway??

[GiesJ]

Ok – this is probably a real silly question but I’m going to ask away anyway. (By the way, I tried searching but just couldn’t narrow it down enough so if this is redundant someone please direct me to a related thread!)

I have a 98 24V 5 speed. I have been told that once I have begun motion (i. e. – used the clutch to start driving – usually second gear) that I can shift without the clutch from there on out. I have been able to do this and wonder if I am doing anything detrimental to my transmission. I don’t grind at all when I shift, it just seems to slide in place at the right time/RPM. Someone fill me in on if this is a good (save my clutch) or bad (hurt my transmission) idea. I have heard that TT drivers do not use the clutch once they are under way. As always, thanks in advance!

J

 

[RustyJC]

The NV4500 and NV5600 are synchronized gearboxes. They are not built for clutchless shifting. The loads associated with decelerating (in the case of upshifts) and accelerating (in the case of downshifts) the clutch, pressure plate, flywheel, crankshaft, etc. are being taken by the synchronizers when one shifts without a clutch.



Rusty

 

[Rob Thomas]

Semi's don't have syncros,we do, if you don't grind I wouldn't think it's bad,but yer not goin' ta save yer clutch any by doin' it,you don't "slip' your clutch while in motion,therefore it's not wearing the disk. I'm sure it's not the best thing you can do fer the trans,but I guess you'll find out.



Later, Rob

 

[BV]

Clutchless shifts

Like the others said plus you can ask yourself which is less expensive to replace 1. Clutch set or 2. transmission synchro set?

 

[GiesJ]

thanks everyone

Thanks for the input! Sounds like clutchless is more like clueless. I have a long way to go in understanding transmission's but this helps.



So I'll ask something related - when it's time for a new clutch, what has caused the clutch to wear out? The repeated starts? Cause it sounds like the clutch doesn't see increased wear say in a 4-5 shift (unless I'm cranking out some serious ponies and the clutch is slipping, right?)

Why do we have syncros and semi's don't?



Sorry if this is so fundamental and thanks again,

J

 

[Rob Thomas]

The clutch on a stock truck will last quite a while, I know two people who have well over 200,000 miles on a stock clutch and they're holdin' fine.



The problem is, BOMBsville, when you find yourself there,order a clutch, you'll need it.



Later, Rob

 

[dan_gilson]

I have a differing opinion... .



You pretty much can only get it into gear when you are at the correct (matched) RPM when not using the clutch. If you are not grinding, you should not be using the syncro's at all. Correct me if I am wrong here. I am always willing to learn.



When you compare this to a person who does not match well and uses the clutch and syncro's to do their work, you can wear out both in pretty short order.



The bad things that I can say about not using the clutch when shifting is that unless you are always good at matching you will catch some teeth and that is not good. Also you will put more stress on the rest of the drive line unless exactly matched. Also your shifts are slower so you need to rev more and expect a larger drop when shifting higher. And the opposite when shifting lower.



Yes, the semi's do not have syncro's. They also have straight cut gears that whine more but make it easier to shift without a clutch. Also their transmissions are engineering to shift at certain RPM's and it is pretty much always the same from gear to gear.



Clutching or not the BEST thing that you can do is match. The better you match the longer things will last. On my sports car most people got 80K from their clutches, mine was starting to go at 120K. And I drove that with and without the clutch. And I drove it very hard. I tried to exactly match every shift, in traffic or in the canyons.



Practicing without using the clutch when you out and away from things will help you better match even when using the clutch. Take your time at get to know what you are doing. Practice is a good thing.

 

[tazzen]

so anser this one someoneon the 5600 is there a lock out on reverse so it wont go in by mstake while moving forward?



ed

 

[csevers]

semi trans

big trannys are not all straight cut gears, the shift collors are straight and the are heavy duty BUT they do wear out also in time with good driver trans can go 500k to 1million without problems but with bad drivers grinding most to all shift ( there are a lot of then) I have seen trannys only get 250k before problems with collors or main shaft.

 

[dresslered]

I shift all my manual vehicles using the clutch, but I do use all three pedals to match the rpms--especially in the down shifts. I have never replaced a clutch with less than 100k miles.

 

[cmckinney]

Proper engine speed for shifting.

So gents what is the proper engine speed for flat unloaded driving in a 5-Sp?



Upshifts & downshifts.

 

[Sled Puller]

I can shift mine at 4000.





Without the clutch, the NV 4500 will burn a little bit of the clutch like material on the synchro every time you do that, even without grinding.



Beware of know it all truck drivers, they will cost you $$$$$!!!



Member, IUOE, Local 66, so I am biased against 99% of truckers.

 

[E7mack96]

clutchless

I just have to get in here. I have always shifted clutchless. Everything from my 88 ford ranger, 91 ford ranger, 97 neon, to my beloved Ram. Also my Big Trucks. While it may not be the best Idea, I feel that it has minimal long term effects, IF DONE RIGHT. I have put 15,000 hours on a Big Truck transmission in grueling off-road conditions, without the need of a rebuild. As far as our trannys, time will tell.



I do not claim to Know it All, Just what has worked for me.



Sled Puller, I hope I am not one of the 99%.

 

[Steve Campbell]

Two things about clutchless shifting...

... it takes some practice to get it right.



... If a person is making "good" clutchless shifts, it also follows that the person is actually kind of "babying" the drive train (no shock loads), which in itself will make things last longer.

 

[RustyJC]

Something to Consider!

In a synchronized gearbox like the NV4500 and NV5600, the gearsets are in constant engagement. What actually happens when you shift is that the two parts of the synchronizer, one linked to the gear, one splined to the shaft on which the gear is mounted, move into engagement. Therefore, when you hear "grinding" on a shift (clutchless or not), what you're actually hearing is the teeth on one piece of the synchronizer attempting to engage the slots in the other. The synchronizer balk ring tries to match the speed of the two parts before engagement to eliminate grinding.



So, what's my point?



1. If the gearbox doesn't grind on a clutchless shift and the engine/transmission speeds aren't perfectly matched, the balk ring is having to accelerate/decelerate some heavy stuff to accomplish the shift. There's a lot less friction material on a balk ring than on a clutch plate, so which is going to last longer?



2. If the gearbox does grind on a clutchless shift, it's because two pieces of bronze are chewing on each other. How long do you suppose those bronze teeth are going to stay on that synchronizer before they're rounded off or chewed up?



Hey, to each his own, but clutch discs are much cheaper than transmission rebuilds. Clutch discs are also built for the job of matching engine speed to transmission input shaft speed. Synchronizers were never designed to match transmission output shaft speed to engine speed (what happens on a clutchless shift) - they were designed to match transmission input shaft speed (including the clutch disc, but not the pressure plate, flywheel, crankshaft, engine accessories, etc. ) to transmission output shaft speed. Ya pays yore money and ya takes yore choice.



Rusty

 

[Okie-Go]

I think someone actually took apart a transmission that had been shifted wothout a clutch. Some of the parts were quite rounded instead af a square shape as a result of the clutchless shifting. To each his own but as for me I'll use the clutch.

 

[Lsfarm]

Rusty's got it right

Rusty JC has it right: the syncros are designed to match the couple of pounds of input shaft and clutch disc to the output shaft speed for each gear ratio. They are not designed to match the rotating mass and power of the Cummins [or any engine] to the rotating mass of the output shaft which is geared to the truck in motion.



A clutch disc IS designed to smoothly [in most cases] match the engine speed with the truck speed [output shaft speed x gear ratio].



The trans CAN be shifted without the clutch once in motion, but unless the driver is matching the engine speed to the road speed for the appropriate gear ratio, then the syncro ring will balk, or resist the gear [what we feel is the gear lever] from engaging. What is happening is the small surface of the brass syncro ring is being asked to do the job of the huge surface area of the clutch disc/flywheel/pressure plate. This will result in premature wear on the syncros.



NOTE: If the clutchless shift is accomplished with a perfect or near perfect match of the rpm's, then there is virtually NO WEAR on any components.



Over the road trucks have a much smaller rev range and power band than our ISB Cummins, and without syncros, the trans can be shifted without wearing anything by a skilled driver. It is easier to use the throttle pedal to get the input shaft speed to match the road speed than it is to try to engage the gears when the clutch disc and input shaft decelerates past the perfect matching speed [if the driver disengages the clutch].



So: a person can shift a syncro'd NV4500 or NV 5600 trans without the clutch, and it can be fun, because it takes some skill and practice, but if you get worn syncros out of the deal, this is much more of a PITA to repair than a clutch.



Just the nuts and bolts of the shiftless type



Greg L

 

[dan_gilson]

RustyJC: thanks for the good explaination! I understand the damage that can be done.