new 31" s got that bump steering thang goin on-ideas?

[3jeepsdeep]

Sorry for long post

I just HAD to have 31" tires. and now my 77 CJ7 is SO hard to drive straight down the road.

Here's what I got:
77CJ7, 304 3speed, manual steering, new 31" tires (fairly open tread, not too aggressive), stock suspension / shackles, etc., 41k miles (yeah - that IS original), gas shocks 28 kmiles ago

Here's what I did:
new ball joints (rt side was worn/ broken), snugged-up steering gear lash, wheel bearings are snug, added a heavy duty steering damper, checked tie rod ends, had front end alignment done.

The 'bump' steering is somewhat better after adding the stabilizer - but here is something very curious and very annoying that I can't figure out...

In 2wd with front hubs disengaged, when I accelerate, the jeep will drift to the left, when I take my foot off of the gas, it will drift back right. This might have been happenin before the 31"s, but if so it wasn't noticeable.

Buddy of mine said he had installed a reverse shackle kit to address same problem and it worked. This is a head scratcher for me, anyone game to noodle on this or know if the reverse shackles help?


I drive it daily - and it DOES keep me awake trying to go straight.....or maybe it's the hedders that keep my eyelids open.......
thx
df

[pyagid]

when was the last time the alignment was checked? If you tightened up all the steering components, the alignment could be out of spec now. Also with the acceleration thing, Make sure your motor mounts, and tranny mount are in good condition. I have seen that symptom when the entire drivetrain is moving due to broken mounts.

My experience, the shackle reversal makes a much nicer ride on road, only problem is under hard braking it will nose dive. But i dont think this will be a solution to your problem

-Paul

[Mudrat]

Ditto the alignment - new ball joints will change geometry. Also check your tire air pressure. Had the left-drift problem in the wife's Chebby and turned out the air was 10lbs low on the rear drivers side.

Might also check the spring bushings - I had a similar issue with my 75 CJ5 and found the rubber was worn bad letting the springs wander.

Mudrat

[3jeepsdeep]

thanks for replies -- alignment was done recently after ball joints & everything else. I didn't think to check spring bushings, guess that's next. Air pressure in tires is good all 'round - higher pressure than old tires, tho -- these 31's run at 44 psi.......

will double chek engine / trans mounts, but all are relatively recent.
thx

df

[Lifted79CJ7]

Also check your steering box for slop - or maybe the u joints in the steering shaft. Those larger tires could have been just enough to show these problems. I developed a lot of similar problems after stepping up to 33"s in my 304 powered CJ7.
Just a thought,
Jack

[Goose]

I dont want to belabor the obvious here, but the drift left under accell and right under decell is "normal" it is the torque and the fact that you are actually lifting the left front a bit under accelleration and compressing it under decell..so if the steering box is mounted to the frame and the steering gear to the axle (as it is) when you move the two in opposite directions like that it actually "turns" the wheels as to why it only showed up after the 31" s added I don't know ..

[tufcj]

I had a Toyota that did the drift thing, it turned out to be that the centering pin in one of the rear leaf springs had sheared, and the u-bolts weren't tight enough to hold the axle still. The rear axle would shift front/back about 1", enough to cause a considerable "drifting" feel.

It could also be bad spider gears in the rear axle, but that would make noise when turning too.

Just another thing to check.

Bob
tufcj

[thejeepingoat]

i would lower the pressure some, 44 psi seems awfull high for such a light vehicle.

[Goose]

Holy cow yea.. Drop that tire pressure.. 44 psi is a bunch I run my CJ-5 at 30 psi.. the recommended pressure on the sidewall is for the maximum load rating of the tires (i.e. to get the load rating you must inflate to max pressure )

[rollen dean montoya]

you should never run the tires at max pressure. unless you are towing
or have loaded up like a pack animal you should run at 38 to 40 psi
in those tires.on the eagle i run my tires at 32 psi. the max pressure is 35
psi. the my dad has a 2004 grand cherokee with pirelli scorpions
235/75-15's the max pressure is 44psi and he runs 40psi cold 30psi for
snow,mud,and ice. as far as the steering problems, go back thru the list of work you had done and check everything. you may have missed something.
good luck, rollen