Drivetrain freeplay. Problem? Please Help!

[Diesel Freak]

I have a possible problem, so bare with me while I describe it. In the lower gears while accelerating lightly I have a slight nudge like there is some slack being taken up somewhere in the drivetrain. There is no noise, metalic clang or thud associated with it. I have checked all transmission and motor mounts, and even the transmission to transfercase bolts to see if there was something loose after the instalation of my South Bend Clutch.

When it happeds it is like a slight nudge that can be felt in your lower back. The transfer case lever jerks forward about . 5 inches and the gear shift jerks back about . 5 inches with constant light throttle. It is like there is a detent being engaged. That is the best way I can describe it without giving you a ride in the truck. is it possible that there is a broken spring in the clutch hub? or is the new clutch just making this "normal" occurance appear abnormal?



TIA



_cliff

 

[klenger]

Can't tell from your sig if you have a LWB, but on mine, the carrier bearing where the rear drive shaft splits blew appart causing problems. You might want to check that. It was real obvious on mine.

 

[Diesel Freak]

nope, I have a SWB... no carrier, and I have a one piece driveshaft.



on the drive back to portland fro seattle, it seems to be intermittent... . it did not happen all the time while driving through town

 

[Diesel Freak]

just for clarification, it is like a dull thud, but with no noise.

 

[Diesel Freak]

Is there an internally splined coupling between the transmission and the transfercase like there was on the first generation trucks with the NP205? My Dad had a similar problem that progressively got worse as the splines worked on eachother. I have eliminated the clutch and transmission as a possible problem since the "thud" becomes progressively less noticable with the higher gears, and it takes more torque from the engine to cause it. I have also eliminater the rear end since there is no related "clang" resonating from the driveshaft.





Any other ideas

 

[GotDodge]

Do you have a HD transfercase or is it the ST transfercase. I just installed my SBC 2weeks ago and ever thing is good. If I could fill or here it. I my be able to locate the problem. Send me a email if you need my help.

 

[Diesel Freak]

I have the standard case.

 

[tractoriden1]

diesel freak if you look back at some of my old posts you will see i had/have the same problem. dealer has over time replaced trans, tc, transfer case, entire dana 80, and i hope is now getting ready to replace hanger joint and driveshaft. i have laid under my rig and many others trying to find slack. i started comparing springs and the way they sat from truck to truck. i found many trucks with the springs loaded way down from the torgue on the u-bolts, however mine were not compressed nearly the same. believe it or not one socket, one breaker bar, one piece of pipe and 15 minutes later my thud, slack, freeplay problem was almost all gone. it all sounds like crap i know, but maybe it will work for you as well. there is always a definable amount of slack in the transmission slip yolk and in the ring/pinion combo but not enough to cause what you and i are experiencing. let me know if it helps.

 

[Lsfarm]

Check your driveshaft splines

You might want to check the splines on the driveshaft where the driveshaft slides inside the U-Joint yoke.



When stopping with brakes, the rear axle rotates slightly rearward, and the driveshaft lengthens slightly. Then if the driveshaft splines are sticky from lack of lubrication, the longer driveshaft has pressure on it when you stop.



then, when you take off from a stop, the rear axle pushes forward to push to truck, hard enough to overcome the friction of the splines, and this is felt in the drivetrain like a notch or detent as the axle jumps forward.



I've had this problem in several well used trucks, and it was cured by lubing the driveshaft splines with gear lube in a grease gun.



I hope this helps, Greg L

 

[GDouglas]

I agree with LSfarm. When I used to work for Ford, we periodically had some SWB 4WD trucks with a similar problem that you describe. It was more frequently found on the SWB 4WD trucks because they had the shortest driveshafts which inherently have more slipyoke travel than vehicles with long driveshafts. When the nose of your rearend rotates upward slightly when taking off from a stop, the slipyoke has to slide forward to make room for the lesser space between the rearend and your trans/trasfer case. Most cases were cured with a light blue colored special Ford teflon grease on the splines, but in bad cases it took a new slipyoke along with the grease to correct the thud felt on light throttle takeoff. Hope this helps.

 

[Diesel Freak]

I just checked the manual for my Dad's 1990 dodge and it says to torque the U bolts to 180 foot pounds I checked my U bolts and they were about half that... ..... I torqued them all to 130 FT*LBF... . time for a test drive

 

[Diesel Freak]

WOOOOOHOOOOOO I found the problem. The spline in the tailshaft was hanging up. I greased it and all is better.

 

[Lsfarm]

I'm glad that that was the fix!! A shot of grease is a lot cheaper than a broken mount or bad geartrain.



Greg L