Gears, Driveshafts, and trannys


Active Member
Apr 11, 2003
I seem to be having some issues i believe are coming from the rearend of my car.... a noice resembling a clunking in the rear while truning slowly(only when car is hot), and a vibration i believe to be associated with the rear. I have already replaced my u-joints and had the shaft rebalanced.

The vibration is less upon acceleration, but seems to worsen at cruising. light load applications. I was also thinking back, i have had a vibration for quite a while now. Even am starting to pinpoint it to shortly after the rear gears were installed. So i am thinking that the rear end is not set up right, and causing this harmonics type vibration........... Is this possible? I am pretty sure that i never had these vibration issues with the stock gears, and i have even driven a friends car with stock everything, just to see if the vibration i am thinking of has always kinda been there.... I know under acceleration, almost any t-5 with a shifter is gonna vibrate a little......

Please help me out with suggestions, i thought that the u-joints would cure all this.. Do you guys think it is possible for it to be coming from anywhere else..... i rule the D/S out due to the work that has been done to it. Would a new gear install with 3.73's and an alum. driveshaft cure all this..

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Maybe upper control arm bushings. Are the uppers stock? I had an annoying squeeking coming from a shot upper arm-to-diff housing bushing.

Perhaps you could put the rear up on jackstands and check the side-to-side play of the axles. Probably need to remove the calipers to get an accurate assesment, as they may hold the axles from moving like you are trying to test.

Good luck,
The clunking may be the cluches in the posi chattering. Was there any posi-additive put in with the gear install? If so maybe the clutches are going bad. You may could change the rear lube and add fresh posi-additive and fix that.

The viabration you are getting may be as simple as unbolting the drive shaft, rotaing it 90 or 180 degrees and bolting it back up for a fix of that problem. It may also be from the pinion angle being off if your rear has had a ride height change.
yes my car has had a ride height change.... it is very low... I installed the driveshaft according to the way it was pulled.....I may try rotating it a couple more times however just for the hellof it.....

I have newly installed lakewood lift bars for control arms....shouldn't be a problem..

I cannot remember if they put int he friction modifier, or told me to, i know i have never added any how bad would that be........ I have no idea about things inside the pumpking..... i am a newb at this gear stuff..

upgrade to an alum driveshaft as when you switched to 373's your rpm at highway speeds is greater which means the d/s is spinning faster and wipping more. the stock d/s with 273's has a critical speed of 148, when you go to 373's that critical speed is lowered dramatically, not sure exact numbers but enough to put the fear in ya when your really crankin it on the highway. in short buy the ford alum drivehshaft and it'll help out big time
makes sense.... but i don't think that is the only problem..... I plan on buying one after i get everything worked out with my suspension, i don't wanna be like someone else here whos car was low as mine, and it cut the driveshaft....
my car has been sounding horrible since the gear install. We made the collective mistake of not changing bearings and it sounds like my pinion bearing is shot. so looks like it goes back into the shop next week.

My car is howling on the highway, it is starting to clunk all over the place, it is just getting bad very quickly...

if you gears are real new take it back to the installer and take him for a drive. THat is what I did yesterday. And since it was a collectivve mistake he is going back in to change all of the the bearings cheap cheap... ($80 labor) and I am buying the bearing kit for $120 with new axle seals and all.

yep, i have vibration on the highway right now ans the soeed is slowly (or fast) creeping lower and lower. When they were first installed it started at 85 mph, not it starts at 65 mph in 800 actual miles.

I'll let you know how it is wed night.


I know the feeling I haven't really driven my car in about 4 weeks. I drove it the couple days after the gear install and a road trip to a buds house then jsut 3 or 4 times since...

I think this will do it as now the guy will have changed everything in the rearend. My new bearings and seals should be in for Monday so I can bring it down Wednesday to be worked on.