What makes a clutch last long or fail early?
03-09-2012, 11:22 PM
#21
JK Newbie
Join Date: Aug 2011
Location: OC
Posts: 97
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by JfK
Yes the transmission has synchros, but when you are downshifting double clutching will reduce any slip on the clutch. When the clutch engages it will act as a brake if the motor isn't going the same speed as the transmission. Braking is not the most optimal use of a clutch!
Double clutching is used to align gears in the transmission whether going up or down through the gears. It is a practice rarely used as syncros and beveled gears allow one to simply depress and the release the clutch pedal during the shift process.
Rev matching, most often accomplished through "heel toe-ing" is the act of depressing the gas so as to make engine speed match transmission speed when going down through the gearbox. Though one may double clutch in this process so as to allow a smoother mesh of gears, it isn't necessary as syncros accomplish the same thing.
So no, double clutching is not necessary, rev-matching however, does reduce strain on the clutch as it is not slipping to match speeds between the motor and transmission.
03-10-2012, 01:59 PM
#23
JK Junkie
Thread Starter
So I took my wife out today to see how she drive the JKU with the manual trans. It's been almost 20 years since her last manual. She handled it like a pro. I guess the jeep is a pretty easy vehicle to use the manual on. Just barely get it rolling and you can let the clutch completely out very quickly.
03-10-2012, 04:57 PM
#26
JK Enthusiast
03-10-2012, 05:06 PM
#27
JK Junkie
Thread Starter
I find myself. Of pushing it all the way until it bottoms out. Seems to work nice and smooth but wonder if I should try to get in the habit of pushing all the way down until it stops. May need to adjust my seat or get a longer left leg.
03-11-2012, 12:14 AM
#29
JK Super Freak
When it comes to the JK Wrangler, one of the biggest factors regarding the clutch to take into account is what diff gearing and tyre size you are running.
Chrysler gears these things very tall from the factory in order to get better mileage, so if you have a stock X/Sport/Sahara with the 3.21 gears and 32" tyres then it is very easy to slip the clutch too much, particularly in reverse (since reverse is higher than first). If the clutch was heavy duty then this wouldn't particularly be an issue however the OEM one is decidedly light-duty and very easy to smoke up & damage if slipped excessively. Running 32" tyres with the optional 3.73 ratios (available with the heavy-duty tow pack option) or the 4.10 ratios available on the Rubicons puts far less stress on the clutch components, and you'll find in the various polls regarding clutch longevity on stock vehicles that have been run here in the past that Rubis usually have longest lasting clutches.
I was aware from day one that my JKs diffs were way over-geared for the stock 32" tyres it came with so I have always been careful to engage my clutch carefully and at low RPMs to minimize slippage and heat build-up (and I will always change into 4-low if I need to reverse up an incline of any steepness); so far I have 45K miles on it without any obvious signs of wear. On the otherhand, one of the guys in my Jeep club went through 2 OEM clutches in 30K miles due to reversing his trailer up his driveway (installed his hitch after he bought it so didn't get the lower tow-pack ratios installed from the factory); he now has a heavy-duty Centreforce clutch installed and says the difference is night & day.
Chrysler gears these things very tall from the factory in order to get better mileage, so if you have a stock X/Sport/Sahara with the 3.21 gears and 32" tyres then it is very easy to slip the clutch too much, particularly in reverse (since reverse is higher than first). If the clutch was heavy duty then this wouldn't particularly be an issue however the OEM one is decidedly light-duty and very easy to smoke up & damage if slipped excessively. Running 32" tyres with the optional 3.73 ratios (available with the heavy-duty tow pack option) or the 4.10 ratios available on the Rubicons puts far less stress on the clutch components, and you'll find in the various polls regarding clutch longevity on stock vehicles that have been run here in the past that Rubis usually have longest lasting clutches.
I was aware from day one that my JKs diffs were way over-geared for the stock 32" tyres it came with so I have always been careful to engage my clutch carefully and at low RPMs to minimize slippage and heat build-up (and I will always change into 4-low if I need to reverse up an incline of any steepness); so far I have 45K miles on it without any obvious signs of wear. On the otherhand, one of the guys in my Jeep club went through 2 OEM clutches in 30K miles due to reversing his trailer up his driveway (installed his hitch after he bought it so didn't get the lower tow-pack ratios installed from the factory); he now has a heavy-duty Centreforce clutch installed and says the difference is night & day.
03-11-2012, 05:53 AM
#30
JK Enthusiast
Join Date: Apr 2010
Location: Wilmington areaa, NC
Posts: 326
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by pilosopo
Double clutching is not the same as rev matching.
Double clutching is used to align gears in the transmission whether going up or down through the gears. It is a practice rarely used as syncros and beveled gears allow one to simply depress and the release the clutch pedal during the shift process.
Rev matching, most often accomplished through "heel toe-ing" is the act of depressing the gas so as to make engine speed match transmission speed when going down through the gearbox. Though one may double clutch in this process so as to allow a smoother mesh of gears, it isn't necessary as syncros accomplish the same thing.
So no, double clutching is not necessary, rev-matching however, does reduce strain on the clutch as it is not slipping to match speeds between the motor and transmission.