Pulls to the Lt when I accelerate, and Rt when I let off.

[dabbrowne]

Hello Jeep People

I have a 73 CJ5 with a 360 AMC and 31" tires and some type of lift kit(2-3") from PO.

Jeep runs find however on the freeway if I'm going 50 and I punch it up to 60 it will shift lanes(pulls to the left). Then when I let off on the accelerator at this speed it will shift back to the right.

It feels like something is twisting during acc and unloading when I let it off.

At lower speeds this is still consistent however not as extreme.

I have checked the ubolts and they are tight. Frame is in great shape no rust. Steering is tight (15 deg slop), and it has a new steering box.

Any advice would be great. Thx

 

[Hedgehog]

My '75 does EXACTLY the same thing .... Our Jeeps are very much the same
360 .... 31x10.5's .... Tight U-bolts .... new steering box .... White wagon wheels .... Green

On acceleration it pulls right, pull off the power and she twitches to the right .... It sorta feels like the left rear is collapsing forward pulling the rear to the left which points the Jeep to the right. ....... Long and short of it, I'm watching this thread for the very same reason.

 

[BusaDave9]

yes, the rear axle is shifting as you accelerate. I had this same problem when I bought my CJ. It was loose leaf spring U bolts.

 

[Torxhead]

Or, something else loose in the suspension.

 

[tarry99]

Hello Jeep People

I have a 73 CJ5 with a 360 AMC and 31" tires and some type of lift kit(2-3") from PO.

Jeep runs find however on the freeway if I'm going 50 and I punch it up to 60 it will shift lanes(pulls to the left). Then when I let off on the accelerator at this speed it will shift back to the right.

It feels like something is twisting during acc and unloading when I let it off.

At lower speeds this is still consistent however not as extreme.

I have checked the ubolts and they are tight. Frame is in great shape no rust. Steering is tight (15 deg slop), and it has a new steering box.

Any advice would be great. Thx

New box but 15 degrees of slop? Need to address that first........with that lift you may also have some Bump Steer.......how much angle do you have on the drag link from the pittman arm to the front spindle? The flatter the better.

 

[DHugg]

I have a 73 CJ5 with a 360 AMC and 31" tires and some type of lift kit(2-3") from PO.

I have checked the ubolts and they are tight. Frame is in great shape no rust. Steering is tight (15 deg slop), and it has a new steering box.

Any advice would be great. Thx

Dab, I have an 80 CJ5 . My steering slop comes from no lower bearings in the steering column, worn tierod and draglink ends, and almost certainly some wobble in the front wheel bearings. I am attacking them in the order listed, soon as it warms up just a bit more than the 54 degrees we have today.

 

[Old Dog]

New box but 15 degrees of slop? Need to address that first........with that lift you may also have some Bump Steer.......how much angle do you have on the drag link from the pittman arm to the front spindle? The flatter the better.

Also check all u-bolts (even if they seem tight, check that the spring pad hasn't bent, maybe the spring center bolt broke, you get the idea, check everything that can move), spring and shackle bushings, motor and Transmission mounts.

 

[dabbrowne]

Hello Old Dog

Thank you for the advice. However I am not to good on ID of these things. Please tell me what is a:
1)spring pad?
2)spring center bolt?
3)shackle bushings?

I will check them however I don't know what they are. I have included a picture of my backend ubolts.

 

[Old Dog]

Hello Old Dog

Thank you for the advice. However I am not to good on ID of these things. Please tell me what is a:
1)spring pad?
2)spring center bolt?
3)shackle bushings?

I will check them however I don't know what they are. I have included a picture of my backend ubolts.

the spring pad (perch) is the piece that is welded to the axle that the spring sits on.
Spring center bolt is the bolt that goes through your spring pack to hold them togerher. it also sticks our and fits in a hole in the pearch to line it up.
If the bolt breaks the axle can move forward/backward
Your draglink looks good in the pic. so I don't believe the problem is bump steer anymore.
I had a perch bend and was letting the axle twist once.

 

[dabbrowne]

Hello Tarry99

Thank you for the response.
I don't have any bump steer since I tightened the front up, replaced the steering box and tires.
My drag link angle is very small, less than 10 deg.
My steering is tight. I can only rotate my steering wheel 10-15 degrees before I can see the wheels move.

I think it feels like it is in the back however Ubolts are all at 70-80 ftLbs.

 

[dabbrowne]

Thank you Old Dog

Thank you. I just verified that the spring pads and bolts look good and are tight. However they look very different than yours in the picture you sent. My ubolts are nuts down,(see picture) and yours are up.

Also I don't see any place where the ubolts would have slipped on the axle.

any other ideas would be great. Thx

 

[rufus1138]

Just for reference the standard practice for proper hardware installation in the aircraft industry is always inside pointing out, in this case the bolt head should be on top of the spring pack with the shank pointing toward the ground, in this application the bolt will hopefully stay in the spring pack if the nut backs off.

 

[mtnwhlr]

They came from the factory with the nuts on the bottem I was a little surpised to see that pic with them on top.

 

[mstar]

Old Dog has done some major mods on his jeep.From the description in your avator sounds like a hellava rig. I see no problem with that setup.actually have seen trucks done the same.Far as I know old dogs jeep doesn't fly so no need for aircraft specs. mike s.

 

[BusaDave9]

This is not the factory setup. You can't simply turn the U bolts upside down to do what OldDog did. The OEM U Bolts are curved to go over the axle tube. These square U bolts go around the plate on the bottom marked with the red arrow.
I don't like the gap where the blue arrow is pointing. That's what happend to my spring perch when the U bolts were loose. That could be your problem if yours looks like this. That could cause the axle to rotate. Sure the bolts may be tight but they would be fighting an uphill battle trying to hold still a rounded surface especially if the U bolts are round going over the top of the axle.
I assume OldDog doesn't have this problem. Because his U bolts are upside down he also has a plate on top. Is that top plate welded on the axle like another spring perch? That would surely hold the axle still even with the bottom perch rounded.

 

[johnbilt]

The suspension could be doing this I suppose, but I would expect something to be loose in an obvious way. But I could be completely wrong.

Have you considered a rear diff problem? I once broke a Detroit locker and it acted just like you are describing as only one wheel was being driven directly. It jumped harshly side to side under acceleration and deceleration.

My two cents. Best of luck

 

[Old Dog]

This is not the factory setup. You can't simply turn the U bolts upside down to do what OldDog did. The OEM U Bolts are curved to go over the axle tube. These square U bolts go around the plate on the bottom marked with the red arrow.
I don't like the gap where the blue arrow is pointing. That's what happend to my spring perch when the U bolts were loose. That could be your problem if yours looks like this. That could cause the axle to rotate. Sure the bolts may be tight but they would be fighting an uphill battle trying to hold still a rounded surface especially if the U bolts are round going over the top of the axle.
I assume OldDog doesn't have this problem. Because his U bolts are upside down he also has a plate on top. Is that top plate welded on the axle like another spring perch? That would surely hold the axle still even with the bottom perch rounded.

Dave, thanks for the blue arrow, that's what I was trying to show. My u-bolts were still tight even though this happened.
I do have my u-bolts flipped (with a kit) to gain a little better ground clearance.

 

[caveman]

Another area to check for rear steer problems is the spring eye bushings.

 

[rufus1138]

just giving simple hardware installation advise, if its good enough for airplanes it cant hurt on a jeep lol.

as far as the perches go i agree that the bottom gap is worrysome, better to have a flat bearing surface to ride on, better yet to have a plate on the top like mentioned for the u-bolts to ride on and have that gap shimmed or otherwise filled as well.

 

[mylittlecj5]

Sounds like a simple case of torque steer to me. You have a powerful engine in a small short lightweight vehicle. As you accelerate the engine is twisting to the left causing the frame to tweak the steering causing it to go left. As you decelerate the engine goes back to a nuetral position and the momentum relaxes and everything goes to the right (exact opposite).
My CJ had it as well. Just look at any drag race car and you can see it torque the car. Racers just tune the suspension to not affect the car so much.