Relieving hard ride '80 CJ7 304 rock climber

[DHugg]

I have only a few months Jeep experience, and need some advice.

My '80 CJ7 with AMC 304 , AMC20 with new Superiors, lifted & on MT Baja 38X1250's has a hard, hard ride. The rear axle sits on 5-leaf springs under Pro Comp PS3000 shocks.

My immediate need is to soften and dampen the rearend hop that happens crossing the smallest road bump so I can get my young bride of 50 yrs to run the streets with me. So far she likes the Jeep, which makes my life a lot easier, and I'd like to keep her enthusiasm for top-down woods-running alive.

It looks to the inexperienced Jeep owner but long-time shade-tree mechanic that someone did a good job setting up the suspension and lift. But here along the Gulf Coast there are no rocks to climb, no crevasses to cross.

What should I do to get the ride down to something that folks with sensitive backs can survive? Any advice will be gratefully considered.

 

[Old Dog]

Do you have any idea what size lift it has. It's still spring under and you have 38" tires, that takes a lot of lift. And some pretty heavy duty springs I would think.
How about some pic's from the side.

 

[CJKrawler]

5 or 6 leaves is pretty normal for the number of leaves. I would look into the shocks, also, like Old Dog said, 38's wont fit on a CJ without a significant amount of lift in a spring under set up. The shocks may be too stiff for the weight, or, the tires themselves are too stiff, with extra sidewall protection. How much flex do you get just jacking it up?

 

[DHugg]

Gentlemen: I lied about my hard-ride CJ7 ..... it has 35's all 'round, not 38's.

Having said that, I went out and took pictures of side view as Old Dog suggested. The frame sits at about 23 inches Above Ground Level. The body is at 28 inches AGL, as the ruler displays on a close side shot.

So far, I have jacked rear axle to install Superior solids and overhaul both sides brakes. I jacked up both fronts to bleed steering box, a new AGR Superbox II. Didn't notice anything unusual as in flex or really anything I didn't expect. I am tickled with the steering (AGR box & Superpump, Flaming River EZ-install SS shaft). And of course I am delighted to have brakes again.

Here are some height comments I saved off this forum:
{=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=}
CJ7 UNLIFTED TUB HEIGHT
"I don't believe my CJ7 has a lift on it but I am not sure. I just recently got it and it measures 23" from the ground to the bottom of my tub, I am running 31 inch tires and have a ton of room. If anyone else can tell me what stock height is that would be great. I took the measurement under the drivers side of the tub."

"I'd be interested in hearing some measurements from known lifts. Just measured mine, and its 24 1/2", running 32's."

"mine is 27in with 33's and a 3in body lift."

"My 1979 CJ7 has I height of 21.5" and I am pretty sure that it does not have a lift."
{=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=}

Here are side shots as Old Dog suggested, and underside hardware views. Send me out again if you need a look at something else. Every time I back it out, I get to drive it around the block, the long way.

JUST AN ASIDE - yesterday I put tape across the tire tread width and drove about 20 minutes with 28 PSI in the 35's. The front tape had about 1/4 of the width unworn on each tread margin, and the steering was very sensitive and rapid. I dropped the pressure to 22PSI all around and retaped. Today, tape is worn evenly and completely across the tread, and the steering is smoother and not as jumpy. These tires seem to like 22PSI.

Thank you for the help I get from this forum. I must've read everything at least twice, saved about half of what I found. I intend to use it all over time and get this puppy in A-1 shape.

Denny

 

[Old Dog]

If they are 35's it's probally a 4" lift. It might just be a stiff set of springs.
Make sure the shackels are not to tight, and the shocks are good. Not much else you can do.

 

[DHugg]

This past weekend, I took off the PROCOMP 9000's and tried the ride... not as bad as with 'em in place. I will source a softer pair to replace the PROCOMPs. I read a lot of forum posts about PROCOMP being a bit stiff. Good thing if you're easing over rocks, but I'd have to drive 400 miles or more to find a decent rock !

Next, after the new shocks go on, I'll pull last-but-on (next-to-shortest) leaf from the five-layer springs I have, and try the ride again. Will remember to comment on how it comes out.

And yes, I see that the parking brake ( I was taught to call 'em Emergency Brake; we just 'parked' in the yard) cable is too short for the lift. I'll change it out as quick as I can get to it.

 

[chris insull]

Recommend checking tire pressures... 35" tires can support alot of weight; should not be aired to the max. Try about 25 psi and go from there; kind of a trial and error.

 

[smoothie]

The shocks look pretty compressed in the pics. Maybe it's just me

 

[CJ]

Ar you missing a body mount in this pic?

 

[Kane]

Cj that is a bracket for the OEM exhaust if you are refering to the tab that holds the e-brake cable.

 

[CJ]

Ahh, not familiar with the 80 yea, sure looks like there is a body brace right above it though.

 

[Old Dog]

I just noticed in the pics from 4-13 that your rear shackels are pointing in (toward the center of your jeep). Your springs can not work right like that. the shackels should be pointing out so they can move when the spring compresses. Heres a pic. so you can see what I mean.

 

[DHugg]

Good eye, Old Dog! Your explanation makes perfect sense from a physics standpoint. When the leaf spring compresses, it gets longer. To do that, the brackets have to flex rearward, giving you some of the shock absorbing cushion I'm trying for.

If the brackets point forward of vertical, when the bounce happens, most of the force is transmitted into the spring mount and thru that to the frame. I gotta fix that! Would you say either longer springs, or cut and re-weld the spring hanger bracket?

What is the accepted "school solution", the right way to correct this problem?

And again, thanks. This forum and the advice you guys offer up is worth a bunch to new Jeep owners like me.

Denny

 

[Old Dog]

Would you say either longer springs, or cut and re-weld the spring hanger bracket?Denny

If I were you I would try your idea of removing a leaf first, and see what happens. I might cure your problem. Or it might make the tires rub.

There has been chatter on the web of some springs being made to short mostly RC. Maybe you are one of the unlucky ones that got a set of these.
I would NOT move the spring hanger if they look to be in the stock postion.
The high dollor answer would be a set of RE 4 1/2" springs. You really need the lift with 35" and they are said to be a good riding high quality spring. The price isn't really that bad if you only buy the springs and not the kit.
Let us know what happens.

 

[fitzp20102]

DHugg,

New to the forum but not to Jeeps... The tire pressure everyone is talking about is probably your best option. I know with 36" swampers, I run 5 or 6 PSI on the trail because we weigh so little the side walls alone provide lots of support. But those are some stiff springs for sure.

 

[kicknjeep]

Two thing i would check is
1. Tire pressure, Can run chalk line across tire and roll over blacktop and see if you have an even contact patch.
2. check and make sure shackles are not overtightened.
If both are corrected and still harsh then move onto springs,shocks.....

 

[DHugg]

fitzp, kicknjeep:

I ran a tread contact check with tape across the width of the 35's. Started at 24, progressively cut down until the tape on the edges of the tire was wearing; even all the way across. That was at 18psi. But both bery, bery right..... tire inflation does make big diff in the bounce.

I will loosen shackle bolts and see how she feels. From the bend in the shackles, I'd suspect they are badly over-torqued.

I never have really liked air-ratchets for the lack of control. I'm just strong enough to tighten a bolt up to torque specs (except for AMC20 axle nut), and not strong enough to break one. I'll back off the bolts and let you know.

Thanks for your thoughts. I'll need all the help I can get to smooth out the ride until The Girl I'm Currently Dating (for the past 50 years) will be comfortable. She said she was worried about road noise bothering her, but the tires make so much noise she can't hear the other cars whizzing past. That's a good thing, maybe?

 

[Old Dog]

I will loosen shackle bolts and see how she feels. From the bend in the shackles, I'd suspect they are badly over-torqued.

Wow I thought we had checked this already, my bad.
If you have aftermarket shackels and poly bushings, use a nylock nut and tighten them down just enough to make contact with the bushings.
You should be able to turn the bolt with a wrench after you tighten the nut. All your really looken for is to take any side to side slop out. Also make sure they are greased good.

 

[DHugg]

Old Dog, I looked at the hangers this morning; I loosened the nuts that looked like too tight, and checked all the bolts for free-turn play.

I took the Jeep out for ten minutes in the neighborhood.... was it my imagination or did the rear end actually just bounce instead of jumping up like a scared jackrabbit?

Need more time on the machine to tell. I did notice that the front leaf springs are thinner that the rear, and have half as much bow as the rear. I'll take some measurements and post 'em after tomorrow's AM fishing trip to Lake Pontchartrain, 55 minutes away.

Thanks again for the keen eye, and the good advice.

 

[Nekator]

Fabulous CJ7 with great underbody... Wish my CJ looked as pristine as yours. I've a similar problem, It bounces a lot even when running over ants. Don't mean to brag but busty wife gets tired of riding on the Jeep after only a couple of minutes so I think I will try looking for smoother shocks as well. Problem is I don't know If I should start with the rear ones or the front (it's very unlikely I'll come up with the cash for the 4 this very weekend). Any suggestions?