Double Clutching Vs. Floating a Gear

Some drivers think they float gears but in reality they just slam them in. Just watch some of them leaving a truck stop. If you can float gears smoothly keep on. I do not understand how you can damage your clutch by simply not using it. I don't double clutch and my clutch rarely needs adjustment. I believe floating gears if done properly is the way to shift.

 

I suppose my username gives me the credentials to comment on this.

I have driven for 34 years and never used the clutch once I mastered "floating"

Running my own truck, I clocked 640,000 miles on a single clutch, and I ran high horsepower and very heavy. When we pulled it, there were no burn marks on the flywheel or pressure plate. The discs had finally worn out. Ditto for drive-line componentry. U-Joint failure was not common in any truck I drove for an extended period of time.

If you can shift a truck without a clutch using 2 fingers on the shift lever, there is no way you will cause damage to the drive-line. "Slamming" or ""grabbing" gears is brutal on a truck, and the cowboys that do it are jack-wads.

On some newer self adjusting clutches ( Meritors ), you must occasionally double clutch at highway speeds to keep it in adjustment.

Shifting is an art. Too many of the steering wheel holders fail to grasp that. Give 'em an automatic and let them drool on down the highway.

 

Your instructor was probably talking about shock load that not only affects the input shaft but the transmission itself. If you've done enough double clutching and got the timing down you should be fine. If you haven't you may want to do that for awhile. The last truck I owned made it 750k before a spring fell out of one of the pates and ended its life. I have gone back to breaking a wrench so I've seen it from both sides. Have fun!

 

I'm not a driver, but I know many and I know their trucks. If you know how to properly float gears, it is a perfectly safe way to shift. A good skilled professional driver really only needs the clutch for 1st and reverse. I know plenty of customers that had over a million km on a clutch. They just have good shifting technique. Now, that being said, I also know some drivers who have been driving for years and they are total gear jammers and really shouldn't be behind the wheel of a big truck. Clutch manufactures just say stuff like that to protect their product from mis-use. When you are driving, it is obvious if you made a smooth shift or not. If you can successfully do that 99.99% of the time you will get good life out of your drive line. If you clutch every gear I think you will wear out the release bearing and fork prematurely anyway.

 

The manufacturers love to toss around terms like driver abuse or normal ware..... To get out of warrantee claims. And all they really care about is the lowest cost per unit and their almighty stock price.

But anyway , I've always double clutched. It's just what I like to do . When I sold the Last truck it had 680,000 on original clutch , trans and rears. I did replace all the u- joints just because that's how I roll... Current truck has 340,000 no problems yet. Both trucks did the same work hauling heavy, every load 107 thousand gross.

I haven't seen any excess ware from double clutching.
You can be smooth either way...... Or you can be a hack either way !

 

I'm sure your professor is a bright guy, but I can't see how not using the clutch will cause premature ware. If your two fingering the big stick there's nothing to worry about.

 

This is maybe why there are so many poorly informed, yet certified mechanics out there. Its no different from any other field of expertise. Its always the graduates fresh out of school that are the greenest around the ears when they start out. Take your training seriously, but take the opinions of your instructors with a grain of salt. I went to colledge many years after I learned electronics and had to hold my tongue in class every day, trying to ignore all the bad opinionated banter the instructors were spewing.

a follow-up to your question...

I have had my truck for 580k miles. My clutch is showing now 27% wear on its indicator from the 'New' mark. I have no wear on my input shaft, still looks new, and my clutch has never needed adjustment. I grease it every 25k miles, greasing the center bearing thoroughly each time, then wiping out the old grease and debris out of the bottom of the cover. I and my wife are the only drivers of the truck since new, and neither of us use a clutch above 0-mph,...ever. It still feels as new as when we got the truck. My front diff on the other hand, now has a bit of excess play and soon will need servicing, but that is because I run only 50-wt oil in it for improved fuel economy. Next home time, I will likely pull it apart and adjust the backlash of the input gear as per instructions of the rebuild manual.

 

Nothing wrong with not using the clutch my western star had 700, 000 miles on it same clutch had two clutch adjustments.

 

ask him how an eaton auto shift changes gear!