rear diff shudder

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Nov 30, 2009 | 09:02 PM

#16

rpmfest

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I agree with 75F350 friction modifier goes a long way

Nov 30, 2009 | 09:34 PM

#17

benshere

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From: Longwood, Fl

I agree to a degree that a TracLock could chatter in a straight line, but there are a few problems with that in this case. If it is chattering because the unit is new and the FM was not added, then maybe slightly. I dont agree that straight away acceleration only will cause chatter. Chatter is a function of different speeds of the axles, regardless of acceleration or even deceleration It would chatter all the time if FM were the problem. True, tires frequently are not the same diameter, even though they say the same, but unless it is a significant difference, I dont believe it will be significant chatter. Yes, there are some other factors, but are not significant. He did not say he noticed chatter all the time, only when hard in it from a stop or maybe going up a hill. The tension against the clutch packs (2 on traclocks, 1 on the old style 8"-9" limited slips) is set by the "S" spring or Bellville springs and not by the amount of pedal. It would be much worse in a turn, but he didnt mention any of that.

I would not waste a bottle (they are not cheep for that small bottle---I have 2-3 of them laying around), especially if the unit is old and worn. Anyway, my .02 and not to say that other points are wrong.

Dec 1, 2009 | 12:32 PM

#18

helirich

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I would agree with Ben, straight line it will not chatter, even with differnt size tires. (I hope your not running 30" with 38's, LOL) One thing I will mention, the tension on the clutches is preloaded with the 's' spring. But it does increase with pedal. What happens is the spiders try to seperate with more torque and push against the clutches. Of course, if one tire is on glare ice, there may be no torque except excelleration torque. So you end up stumping it and the both tires will spin for a short time and then back to only one. This is why I dont like L/S.

My guess is it is in the driveshaft.

Dec 1, 2009 | 08:54 PM

#19

tazf250

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well i had the rear diff serviced and had friction modifier put in still shudders, since the tc is only $70 to replace i will do that next. i have the same size tires on all four corners and its not because of the crown of the road. it runs and drives smooth as glass unless you get on it hard from dead stop or rolling. and it is shifting hard.

Dec 1, 2009 | 09:09 PM

#20

benshere

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From: Longwood, Fl

Is tc "torque converter" or "transfer case ? If so, $ 70 is a good price. I really dont see any way the shudder could be the torque converter, because it does not lock the clutches at startup but could happen when rolling, after the thing is locked. I guess that if the converter lock sequence were screwed up and it was trying to lock when you floor it from the line, that would cause the converter to shudder, but doubtful.

With a 94, the Tq Cv almost surely needs replacing, expecially if it has done a lot of towing. My 93 was slipping at ~135K so I replaced it then. Depending upon your needs, I still think some of the other things mentioned here are the likely cause of the shudder.

Maybe you will get some more good suggestions--. LOL

Dec 1, 2009 | 10:14 PM

#21

tazf250

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well it doesnt shudder right off the line but after it gets rolling a few feet it starts to shudder. if you just drive it mellow it never does but it does shift hard easy or hard on the throttle.

Dec 2, 2009 | 11:08 AM

#22

Kemicalburns

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From: Bend,OR

have you pulled the diff cover and looked at all yet?

Dec 2, 2009 | 01:20 PM

#23

helirich

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I also wonder if TC is torque converter or Transfer case. Either way $70 is good. But changing the torque converter is no piece of cake. it probubly needs changing, but I still suspect the driveshaft. It wouldnt take long (and cost nothing) to remove the shaft and run it in 4WD and see if it still does it.