Double Clutching?

I have gotten pretty good at double clutching in my 95 YJ.. Especially going from 3rd to 4th when I get on the Interstate.. :)

Ben

95 YJ 2.5L

Ahh ...I see how it works now.

The T-5 in it's latest guises was only ever designed for up to 4,500rpm upshifts. It'll still shift at higher engine speeds, but will start to really baulk and can't be hurried (try flat shifting at 6,200rpm and it becomes really obvious). I was recently involved with "updating" this trans for a Ford of Australia performance vehicle program, and it wasn't a good choice for a turbocharged 4.0ltr inline punching out 320Bhp @ 5,500 and 330 ft.lbs. We've now replaced it with a T-56 with monster synchros. However, it's a great little 'box for understressed Jeep engines at lowish shift speeds. The synchros are tiny compared with more modern designs and lack capacity. Take it a bit easy and it'll last forever, gorrilla shift it everywhere and you'll burn out the synchros for sure, bend the forks and chew out the pads. Oil viscosity has a massive effect on shiftability (esp in cold climates) - my recommendation is to run a good quality synthetic ATF ("Castrol Transmax Z" or "Mobil 1" for example) as this gives better gear and bearing protection than mineral "gear" oils, runs cooler, more efficiently, and lasts longer. Remember that an auto has smaller, more highly stressed gears than a manual...

For general driving double-clutching isn't really required, but it's still a good idea if you want to skip down-shift (say 5-3 or 4-2, etc) as it makes the shift easier and faster, with less wear (and it's fun to do and satisfying to get just right). Also a good idea if you're down-shifting to

1st when still rolling at anything much over jogging pace. Also, take it easy on shift up-shifts (esp into 5th as the 5th gear synchro is especially weak).

If you've got a 'box like mine where the previous owner was a brain-dead gorilla, you quickly learn how to rev-match when shifting (esp as the synchros are completely gone on 3rd and not much better on 2nd and 1st).

Cheers, Clax.

Jeep only recommended the ATF for the first year of that tranny.

They then went back to recommending the proper API GL4 SAE 80W90 gear oil.

You really have to watch out that the oil isn't GL5 'compatible' and that it has no limited slip additive. If it is GL5 compatible, you will fast lose the syncro in 3rd, then 2nd, then reverse, then all of them.

If you switch back, the shifting will come back proper.

I am using a semi synthetic gear oil, only because it was 'all' the store had without the GL5 'compatible' or LS additive.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

Clax wrote:

Yes, it is something that is a throwback to back-in-the-day. Syncronizers have removed the need to learn to double clutch.

If you watch the old Steve McQueen movies, Bullitt in particular, he is driving around in his Mustang beign chased by the bad guys, and he is double clutching. The problem is, one would normally jab the gas pedal a lick on the downshift, not on upshifts. Another problem is, the Mustang he is driving came equipped with a fully syncronized manual transmission, and there is no need to double clutch at all, shifting either up or down. Having said that, one might want to jab at the gas pedal a lick on the downshift to raise the engine speed so the motor and the rest of the drive train are all going the same speed when the clutch is released, this little jab at the gas makes the downshift smoother, but is not required by the mechanical stuff, and does not require an extra cycle of the clutch pedal.

we won't explore the possible jokes that can go along with this one...

=)

-Steve 98 TJ

True on the matching speeds stuff. But on the upshift, one would want the speed of the motor to drop relative to the previous gear, so one would not be tapping the gas pedal between gears, and the fully synchronized transmission would completely eliminate the need to double clutch. On the downshift, on the other hand, a tap on the gas pedal between gears would be a good idea, and double clutching is not needed.

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Syncronizers