weird jerking when taking off
 

When I go to pull away, after the trucks been siting for a bit, it feels like the e-brakes on, then it jerks forward. The E-brake isnt being used, its not sticking, it rolls freely after wards.
I cant seem to figure out why my 94 p/u is doing this.
Here's the parts that have been replaced and fixed in the last month or so (copy pasted from previous post):

-new shocks
-new rear bearing /seals
-new endlinks
-new balljoint
-new idler arm
-treated, prepped, painted rims
-freebie PIAA fogs, to replace broken ones that were on it
-rock gaurded skid plate, hub caps, valence
-new windshield
-flushed rad
-adjusted ebrake
-installed alarm
-cleaned cleaned cleaned
-polished the not-so-great-paint
-new light bulbs in every orifice
-new signal lense
-installed new backup switch
-fixed spare tire winch
-topped fluids

Im not leaking any fluids, it drives decent on highway, nothing seems to be wrong.

This jerking at launch has happened before, but it didnt seem that bad. Last night it was a pretty rough jerk. Only happens when its cold or sitting.

Thoughts?

Is it an auto or stick? I dont fully understand the "jerk" that you are having. lol.

If its a stick it might be your clutch going out...

Its manual. clutch has no sign of typical slipping during driving, gearing, hard accel, downshifting etc.

I have had bad clutches before, and this doesnt feel like a bad clutch. But it definetly is stumping me.

Why do some 4runners sag in the rear?Ive got a 90 4x4 5SPD and it sits perfectly level.

5000lbs of truck with weak coils. That and lower cut rear fenders give the allusion of sag.

Are your brakes sticking? Sometimes in the wet my drums will kinda stick at a light, and it will cause my truck to torque up till it breaks free... Only happens in heavy moisture.

doesnt seem to have any sticking.

its been relatively dry here. and it never happens after being driven

Ok. so I drove the truck a bit again today. Seems like only when I brake really hard, that it sticks. but when i brake lightly to a stop, doesnt seem to.

wtf.

Also, while Im at it, it feels like my tranny may be moving a bit when i shift. I have driven stick for 20 years, including many high performance cars, and it seems it doesnt matter how I drive this truck, it shifts a little rough. The only time it doesnt, is at very low rpm shifts, like under 2500.

bad bushing on tranny mount maybe?

Maybe about the tranny. Depending on ur milage will determine if ur tranny is in need of attention. Probably not whats causing ur issue.

If you brake hard and it jams... and doesnt stick when you dont brake hard...thats a good indicator of your problem.

Im going to GUESS, only because its what i have, that ur back brakes are drum brakes. Just because ur not leaking brake fluid doesnt mean that ur rear drums are getting the right amount to work properly. They could be sticking...which would give a jerk?...but i agree..a jerk seems to be a hard word to diagnose.

Are there any noises that are present when your experiencing the motion?

And...when its jerking...you said its when your pulling away from a stop...does the jerk occur when ur clutch is being engaged to the tranny?... if so... not saying u havnt tried...but try slipping ur clutch a little longer with slightly more gas to see if it eases the jerk. if it does, your looking at clutch or transmission/drivetrain issues. possibly just an old clutch or tranny that needs some extra love when pulling away from a stop :)...

I let off on the clutch, tranny is engaged and it jerks with more rpm. the tranny and transfer are new within the least few years, and have no other problems with the clutch or the tranny. It definetly feels like a brake / rear axle issue, but I cant think of what it could be, as its not showing typical brake issues or axle issues.

No noises, and we just bled the brake system, properly, within the month.

man..i donno..sounds like brakes if u can manipulate the jerk with how you use your brakes. try new drums man...its spendy but dang..cheaper than a rear dif/axle

Yeah. Im going to my shop tomorrow, and am hopefully going to find some signs on why its doing this.

Warped flywheel or maybe it has hot spots?

Well get this....

Turns out I blew one of the ebrake drum lever springs. So my rear brakes werent fully unlocking at first, until it equalized between the two.

Lame.