Getting 'loose' on deceleration?

I let off the gas over 45 mph and you can feel the rear get 'light' and shift, it gets 'loose'. The shackles are stamped, stock YJ shackles. you get back on the gas and it tightens up and runs straight.

I am thinking spring bushings... I know they can't be in that great of shape. Would this cause it? IF so what would be a good vendor... I would be using the Poly ones because this vehicle will sit a lot most likely.

PROBLEM SOLVED ON PAGE 2

 

sounds like mine - I'd say its torque steer from the engine.

Mine has enough that it will throw you into the opposite lane if your not ready for it.

 

Could well be your bushings, a frame crack near a spring mount, loose lug nuts, etc, etc, but if you think the bushings might be worn out, they probably are. Replaced all of mine with some poly ones from energy suspension, big inprovement. Amazing.

My understinding of torque steer is that it is the force appled from the engine when you're in the middle of a corner when you accelerate mid turn with a front wheel drive vehicle. The torque steer wants you to go straight. Pretty much a FWD thing. As far a I'm aware, no such thing as torque steer on a RWD vehicle. I've nevere experienced what I know to be torque steer, even in 4WD. So bushings, mounts, frame, is where I'd be looking first.

 

you ain't rode in my Jeep, then! I can guarantee what I feel is what I said.
Ever feel a powerful engine tweak the frame/body when you 'goose it'? apply that to the suspension (especially in a SWB rig) and it WILL push the rig to one side. And when you let off the gas, it WILL push it to the other side.
A smaller weaker engine in the same chassis won't have that effect.
This is not a scientific explanation as to the hows and whys, but it IS there, and it does happen.

 

I forgot I have aftermarket springs... would the bushings be the same as the factory ones? I have no idea on the manufacturer

Torque steer is when you jam the gas on a FWD car, the wheel jerks back and forth as the front wheels search for traction. Farfle I think that is another version of torque steer though....

Packrat, you are probably getting spring wrap... may need to do some sort of traction bar, that shouldn't be happening even with a high HP motor if everything is setup correctly.

 

Just thinking outloud:
You've got 5.38 still? With a :v6:, is it possible the gears in an open diff are loading/unloading? One side gear, probably the pass side, applies more torque on accleration, the other wants to decrease torque on deceleration?

I know with my 4.88 I have to be very careful on pavement when letting out the clutch during downshifting.

 

Actually my diff tags read 3.73... I was told it had 4.88's... I need to pop a cover, I am thinking they are probably 3.73.

The only thing flatty is the body, radiator, seats and column. The engine is a '71 commando :v6: , and the chassis/suspension is all 1966 CJ5. I have the flanged 44 rear and D27 front.

This happens without touching the clutch..... IE letting off the gas in 3rd gear to slow down. Its almost like the rear end 'picks up' and 'shifts to the right,' Pulling the trailer loaded it was greatly exaggerated. When I jump back on the gas it shifts left again.

My mom's 85 corvette did this same thing because of worn bushings on the independent suspension in the rear (193k on it), but this is a totally different suspension setup... just trying to figur eout if I should be looking at other things too....

Edit:

My front springs look different then my rear, the second leaf goes eye to eye...

rear


Front

 

Are you kidding? do you have any idea what spring wrap is?
Spring wrap is where the tire's traction overwhelms the springs strength, turning it into an 'S' shape, then snapping back into shape.

http://www.carcraft.com/techarticles/116_0402_rear_suspensions_increased_traction/index.html

I can spin both tires on hard pavement,very smoothly. there aint no spring wrap there.

I may be calling what happens with my Jeep the wrong name, but there is nothing wrong with my suspension (its 1 1/2 years old). When I let off the gas, the removal of torque and the resulting weight transfer will loosen the rear wheels enough to steer the rig around with no input from me. which, funny enough, is what the original poster was complaining of.

 

I know exactly what spring wrap is... and if one side wraps more then the other under throttle you can get a shift too, whether it be a weak spring or something else. It does not have to be under WOT conditions either.

Either way if everything is tight then when you let off the gas under normal driving conditions it should not almost steer you into the other lane as you mentioned before.

Looking at my rear bushings closer one is deteriorated pretty bad, I may try to get some new bushings and try it as soon as I figure out which ones I need to order.

 

My cj-5 does the same thing when accelerating or letting off of the gas. I attribute it to the lockright in the rear. When you wind up first it pulls to the right then drops back to the left when you hit the clutch the back to the right when you hit second.

 

I use to have a older mustang that had a detroit locker in it. It would do the same thing, rear end shift, if the tires did not have equal air pressure. It would get quite shifty when you let off the gas at higher speeds.

 

I suppose you could have gotten lucky and a PO installed a locker. I had not thought of that. That being said, when I replaced my busings with poly, it made a huge difference in road manners...cheap (under $50, IRRC) but labor intensive. Well worth the effort. If you have one bad one, you can pretty much count on a couple of others being lame. They're something you're going to have to replace sooner or later, I would start with the bushing replacement and see what happens. I gurantee it won't make things worse.
The fun part is getting the old busings out. Lots of info on the forum about different methods to use...when its time, try search.
I tried a couple of different methods, and finally settled on the propane/flaming rubber and sawzall method. Seemed to be the most efficient for my circumstances/tools on hand. I mean, if you can't have fun with a propane torch, flaming gobs of smelly smoky rubber, and a sawzall, then you just don't know what fun is.

 

What you're describing sounds to me like a problem any high torque/light vehicle w/ a V(x) engine will experience. It's not torque steer or loose. Under acceleration or deceleration a V6, V8, or any number of V banked cylinders will experience an equal and opposite torque to the direction of the shaft torque. To prevent the engine from rotating it's bolted to the frame. In a light frame vehicle or a sub framed vehicle the entire car twists. If the engine produces enough (a dauntless will) torque it will push the car right when accelerating and left when decelerating (if normal rotation). Any looseness in the steering compounds the problem. Chaining the engine, subframe connectors, engine braces, boxed frames, and adjustable 4 links are used by the hotrodders to prevent this w/ varying success. Steering and being easy w/ the throttle is probably the only way to lessen it in a CJ, unless you want to go to the trouble of boxing in your entire frame.:v6:

 

The YJ shackles should be fine, they came off a heavier vehicle that I was running a V8 in, only difference is the spring width there. I will address the bushings though, they do look quite shot. IIRC the YJ shackles are very close to the same length as a CJ factory shackle, they were much shorter then what came off it too...

I have ~.5" body lift, everything is tight.

Shocks may be an issue... I don't have any on the back yet, they weren't there, and I figured they wouldn't help much. I rarely take the jeep over 45. The only reason I noticed this is I have taken the jeep to my parents twice in the last month and its all 55 road. Pulling the trailer of stuff to burn really exaggerated it. Other then this and the wandering I was getting (and just fixed finally) these are the only two issues I have had.

The rear cross member shouldn't be an issue either, My rear bumper is 1/4" thick C-channel welded directly to the frame, in the front I have welded 1/4" thick 4" angle iron behind the bumper to stiffen it all up there -- this is what fixed my wandering.

Tucked behind the bumper, this is going to be part of my winch mount


I can't find a close-up of the rear


Best close up I have


I am pretty sure I don't have a locker, if I do it would have to be some sort of lunchbox locker, I can spin the wheels opposite directions, I just checked the tire pressure last week, and they don't leak so it should be fine, I will double check though.

I will address the shocks and the Bushings it looks like.

I just cannot believe the V style motor would be the cause, I have never run iinto anything like this in the high HP cars (and the YJ) I have had with standard motor mounts, aside from the Corvette with the known bad bushings. Then again CJ's are a different animal, which is why I am asking for the stuff to check.

I will go over all of that and see what happens.

Any particular vendor I should use for the spring bushings?

 

I found out what was causing 98% of this feeling when I got off the gas. 98% of it was caused by the little cable from the bellhousing to the transmission crossmember was missing.

I installed the cable and adjusted it tight thinking it would help keep my clutch linkage intact off road, it has come apart twice. In the process The jeep tightened up and can run 60-65 easily now without scaring the hell out of me when I get off the gas. My clutch linkage also stayed together the last run out.

I am sure when I replace the front spring bushings this weekend (also shot) that will take care of the rest.

 

Congratulations! :tea:
I know how something like this can bug you. When you find the answer then you just want to celebrate!

 

I realized it when we were on the trail cleanup... I was pulling the trailer and we were driving between trails... the other guys didn't realize my jeep only went 50 (because of this) and it forced me to try to keep up. I let off the gas to slow down and it didn't do it, even with the trailer in tow. I was ecstatic. Tried all day to get it to do it and no dice. The only change I made to the jeep was adding the cable back into place.