Drive line judder 1st gen 4Runner

I know it's not MotorSporty but this board has the best gearheads. My 4Runner is giving a bad shudder when I release the clutch. Here's the odd part, it does it when going from forward motion to backward or vice versa. In other words if I engage reverse it shake like a mother when I release the clutch. If I go ahead and back up a bit, stop and back up some more it's smooth. When I go back to 1st I again get severe vibration on clutch release. As long as I don't engage reverse again though, subsequent releases are smooth.
I have replaced the tranny mount. I have not done the engine mounts but they look OK and the engine does not move around.
Thoughts?

My thought is probably new clutch time. Possibly broken diaphragm spring or contaminated or worn disc/flywheel.

oldtin wrote: My thought is probably new clutch time. Possibly broken diaphragm spring or contaminated or worn disc/flywheel.

But why is it only when I change direction of motion? The clutch, flywheel and input shaft always spin the same direction. If I never engage reverse the clutch take-up is smooth.

Yeah if it was the clutch I'd think it would do the same thing over and over if you come to a complete stop. I'm thinking something driveline-related.

We need more info, try this: Stop on a downhill slope, put it in 1st and let off the brakes but keep the clutch in. When you hit idle rolling speed in 1st release the clutch. Try the same thing in 2nd. What happens? Do the same thing again but reverse a bit up the hill before starting the test. Any difference?

Oh and 4runners can be very motorsporty:

What about u-joints or driveshaft yoke - looking outside the clutch? Direction change would alter the stresses.

Well I dropped the transmission today to take a look. The shakes were really bad yesterday. I now have an oil leak. Anyway, the clutch looks fine. I just put it in Oct. 2011 so it should be fine. No broken fingers or springs, no oil on disc, pilot and release bearing turn just fine. I'm stumped. Could it be something internal in the transmission? I wouldn't think so since the problem is only on clutch release. Once in motion everything is tranquilo. There is a bit of play at the tranny input shaft. Not much, but I can wiggle it maybe 1/16 inch. Is that normal? U-joints seem fine.

Leaf spring hanger? U-bolt? Spring perch? I am just thinking once it vibrates or whatever, it gets into a tight spot and no longer is able to move (the rear axle I mean). Then reversing forces the movable axle to move the opposite direction until it finds a tight spot again. Can anyone SAFELY watch for axle movement?

I am thinking it is some mount.. if it were a rwd car.. I would say centre driveshaft support.

Check your suspension and diff mounts.. obviously, something is getting torqued to one side when you switch directions and then it takes a moment to get pulled back to the correct position

parker wrote: Well I dropped the transmission today to take a look. The shakes were really bad yesterday. I now have an oil leak. Anyway, the clutch looks fine. I just put it in Oct. 2011 so it should be fine. No broken fingers or springs, no oil on disc, pilot and release bearing turn just fine. I'm stumped. Could it be something internal in the transmission? I wouldn't think so since the problem is only on clutch release. Once in motion everything is tranquilo. There is a bit of play at the tranny input shaft. Not much, but I can wiggle it maybe 1/16 inch. Is that normal? U-joints seem fine.

Did you machine the flywheel? Clutches are exactly like brakes. You might not see warps or deposits but it could be clutch chatter. Did you buy the cheapest clutch like I do?

Its not internal in the tranny or it would be localized to one gear and it would continue after you were moving in some gears. If it only happens when you're engaging the clutch, its gotta be the clutch. Double check the pinion play and the U-joints, but you have clutch chatter. I guarantee it.

Hey here's a way to be sure whether it's the clutch or not: Reverse the truck and stop, then switch off the engine. Put it in 1st, hold on tight then crank the engine. If you don't get the same problem it's the clutch.

My big '65 F100 would have bad clutch judder going in reverse only. I checked every mount, u-joint, etc and had just about decided it was the leaf spring bushings when I wound up replacing the clutch because it started to slip. Sure enough, that solved the problem. Can't tell you why on earth it only did it in reverse.

I might want to add.. I was getting bad driveline shudder when going from reverse to 1st before replacing the engine mounts in my BMW

mad_machine wrote: I might want to add.. I was getting bad driveline shudder when going from reverse to 1st before replacing the engine mounts in my BMW

Thats funny because it looks like we are thinking along the same lines. My first thought was motor mounts. But I figured itd have to be both sides to do it fwd and rev but maybe not...

It was the clutch. Got it all back together yesterday. I replaced the flywheel as well. Last time I just did the pressure plate and disc.