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-   -   Grinding when down shifting into second gear. (http://www.wranglerforum.com/f210/grinding-when-down-shifting-into-second-gear-229427.html)

rwhitmore74 03-21-2013 07:27 PM

Grinding when down shifting into second gear.
 
When I am slowing down and shift into second gear around 15 mph it grinds with clutch in. If I put it into second at 10 mph or below its fine. Just to be clear this only happens down shifting at 15 mph. Everything else is fine.

jp2611 03-21-2013 07:29 PM

Full console? any BL or SL? How many miles? and which motor?

Patrick H 03-21-2013 07:44 PM

Are you matching RPM's? Try double-clutching..

kpla51 03-21-2013 08:15 PM

could be the synchronizer my buddy had the same issue shifting into 2nd and 3rd. they syncro is there so there is no need to double clutch. I'm sorry to hear that i know the sound is unpleasant

UFOtestpilot 03-21-2013 08:26 PM

As stated if you rev-match by blipping the throttle enough to raise the RPM's to what they're about to be in second gear as you shift you shouldn't have an issue. Usual suspects generally are synchros or selector fork. The fluid usually has excessive brass flakes in it if its synchros. I am also of the belief that double clutching only works on straight cut or non-synchro helical cut gearboxes.

Patrick H 03-21-2013 08:51 PM

Quote:

I am also of the belief that double clutching only works on straight cut or non-synchro helical cut gearboxes.
Double clutching has almost the same effect as RPM matching. When the clutch is engaged briefly as you pass through neutral, it causes everything on the mainshaft assy. to come to the same speed, reducing the RPM differences between the synchro collar and the gear before the dog teeth engage. Is double clutching needed on a synchronized tranny? No, but it helps, especially if the synchros are worn.

rwhitmore74 03-21-2013 10:46 PM

2 bb lift and inline 6 with 130,000 miles.

rwhitmore74 03-21-2013 10:47 PM

What is double clutching?

Patrick H 03-21-2013 10:50 PM

Quote:

Originally Posted by rwhitmore74 (Post 3536669)
What is double clutching?

You quickly let the clutch out and then depress it again as you pass the shifter through the neutral position a while giving the throttle a blip to match the engine RPM to the gear your down shifting to. I got very good at it driving early CJ5's with non-synchroed 1st. gears..;)

jp2611 03-22-2013 05:05 AM

Quote:

Originally Posted by rwhitmore74 (Post 3536662)
2 bb lift and inline 6 with 130,000 miles.


The reason I had asked the questions about BL and Sl and console and miles...has to do with my experience after my Jeep was lifted, 2nd gear was more difficult to get into, after both the SL and BL. (2 seperate occasions) about 2 years apart. Also because the mounting bolts for my console are "worn" it rides forward a little which interferes with the shifter.


I had my clutched replaced and it is a little better, (after it started slipping) I usually have the most problems when it is cold.

Even after all that SOMETIMES I still have trouble if I get lazy or am in a hurry with the shifting.

I had almost the exact same miles when I changed my clutch, on my '04 Sport with the 4.0 I6.


IMO the lift interferes with the "lines/ angles" of the shift linkage, and is part of the issue. It also puts the shifter against the console.

IDK if the double clutching will "fix it", but it will slow down your shifting to the point where it might eliminate the problem.

Hope this helps?

jtg51 03-22-2013 05:39 AM

Mine does same thing. I believe it is the angle that the transmission sits after the lift. I hear a slip yoke eliminator will help this or if a manual shift, slightly bending the shifter to compensate the lift. My lifts instructions actually recommended the latter. Hope this helps

Patrick H 03-22-2013 07:43 AM

No, double clutching isn't a fix, and shouldn't be necessary. It can make high speed or high RPM down shifts smoother. Double clutching doesn't "slow down" shifting, either.

Atthehop 03-22-2013 10:00 AM

If you try to downshift to fast you will override the syncros. Jeep transmissions are not like cars, they are more truck like and require slow and easy shifting.

KevinNJ 03-22-2013 10:06 AM

I had this grinding as well. While changing out the fluid isn't a guarantee, it solved 99.9% of my grinds (which was doing it close to 100% of the time prior to the fluid change). I went with the synchromesh from the local jeep dealer because I could find royal purple or redline. After I changed it out, still had some grinding for the first couple of hundred miles, but it is tremendously better now.


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