Clutch chattering in 1st...little help?

Hey guys, this is my first man. transmission vehicle, so I'm still learning...see if you guys can give a little insight.

I've had my 91XJ (93k miles, 35's, stock gears) for a few months. I still have the 3.07's and some 4.56's should be going in w/in a week or two. On cold starts the clutch seems to grab sooner than normal but also chatter/shake before catching all the way. It only does this for the first few 1st gear starts, and has only been doing it for the past week or so. The 35's have been on for about a month (i only drive the Jeep about 3 or 4 times a week b/c of school.) Is this being caused by the strain the 35's are putting on the 3.07's or is the clutch or some part of it going bad? Thanks for the help ya'll!
-Brent

It takes a lot of clutch slipping to get 31s rolling through 3.07 gears. That's the way my MJ was set up when I first got it. I've been driving manual transmissions for over 40 years, and this is the first and only vehicle I just cannot get started without clutch chatter. I think the kid who sold it to me probably slipped the clutch a lot and hot-spotted the flywheel. That makes it impossible for the clutch plate to grab uniformly, because the burned spots are either higher or lower than the plane of the flywheel.

I'm now running it with 3.73 gears, which is more gear than stock, and I still can't start w/o chatter (unless I'm very careful and very lucky).

flywheel, maybe

I'd venture to guess flywheel, like Eagle said. I replaced the clutch in my MJ (2.5L) last Thanksgiving, but didn't take the time to have the flywheel machined, and it chattered some when cold, too. Recently, I pulled the whole mess off for a different project and had the flywheel machined and a new pilot bearing pressed in. I can't tell you how smooth the clutch engagement is now....like brand new.
The flywheel wasn't scored, burnt, or grooved, but I guess after 140K miles, it just wasn't as smooth as it should have been.
Jeff

BrentNClemson said:

91XJ (93k miles, 35's, stock gears) for a few months. I still have the 3.07's
On cold starts the clutch seems to grab sooner than normal but also chatter/shake before catching all the way.
Is this being caused by the strain the 35's are putting on the 3.07's or is the clutch or some part of it going bad? -Brent

Click to expand...

A little of both. The 35's are putting an incredibale amount of strain on the clutch. Further..if the clutch is still original, it is getting worn. I would reccomend new gears, and a clutch job. I had 33's with 3.07's for a while so I have been where you are.


Rev

Thanks for the responses guys, I'm getting the new gears very soon...so we'll see how it runs then. If not, I'll look into the clutch and flywheel...thanks!
-Brent

I think you're going to be looking into the clutch and flywheel, I'd be surprised if you haven't scorched it badly.

Yeesh....... I ran 31s for a couple of months before I could regear from 3.07 to 4.10. I absolutely hated 3.07s and 31s. A couple of months later, I changed the clutch. I have no idea how you manage to run 35s on stock 3.07 gears.

The disc still had some meat left on it, but was definitely glazed. And the flywheel was scorched pretty well. I replaced the disc, pressure plate, throwout bearing, pilot bushing and flywheel.

I didn't seriously consider machining the flywheel due to concerns about engagement afterward. The FSM specifies something like no more tha 0.003" of material removal, and that it's apparently a profiled surface, i.e. not flat. Unfortunately, the only place I could get a replacement flywheel was the dealership.

Before anyone asks, I've never owned a vehicle with an auto transmission. I replaced the clutch again in May with over 60,000 miles on it. Almost no perceptible wear on the disc, and the flywheel still showed tool marks except for the outer 1"-1.5".