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Jeep Rubicon wheel hop

4K views 34 replies 12 participants last post by  RRich 
#1 ·
Just bought the new Rubicon today.
Tried to climb a loose dirt hill my other rigs don't even flinch at. It wouldn't!
It'd get part way up, then the front end started hopping, losing traction.
Slow crawl, medium run, hard fast run ended up in the same place. That hill isn't that severe!

Now - what's the answer short of torching off the old Bronco type (POS) suspension and putting on a real one?

Wondering if the 9000 shocks with remote adjustable would help?
We used to double or triple, or quadruple shocks on the Bronco to dampen it, didn't cure it, just slowed it down some.

Anybody?
 
#3 ·
My buddy bought one of the Rubicons and took it wheeling one day. I watched it unlock its diffs at higher speeds. There is a fix for this that was in JP last month. It seems the diffs unlock past a certain speed. I think it is 10 mph.
This may be the reason why you are having a tough time.
Did anyone see if your wheels quit pulling?
Good luck, Ricky...seeya...
 
#4 ·
Not an unlock problem - but that too needs addressing. It's supposed to unlock at 10 MPH or above. Even unlocked but in 4 wheel drive it hopped. 2wd didn't hop, made it about the same.

Since it's just a Wrangler underneath I'm really surprised there aren't many complaints about it.

Maybe the way they lifted the Ford type suspension on the Rubi causes it, and it's too new for anybody to complasin about.

Yes, I bought it so I DIDN'T HAVE to work on it! It's touted as trail ready -- must mean a bike trail across a parking lot.

 
#5 ·
from what i understand, all tjs like to lift the left front under these conditions. it has to do with control arm length.

theres a guy with a tj that works at benz with my roomate. he has a tj that he just got lifted and he was in the parking lot showing off how it picks up the left front when he stomps it. i was like "yeah real cool buddy, think how useful that is when your climbing a hill and one of your fronts decides its not going to help anymore."
 
G
#6 ·
Do you have sway bar disconnects on there yet. If not, that is the source of your problem. The front bar is pretty stiff, and will not allow the front end to flex much at all. I would put on a pair of JKS disco's so you front tires can stay on the ground. They are pretty helpless until you disconnect the sway bars. Or just unbolt it and see if that fixes it. I'll but a dollar it does.
 
#7 ·
Disconnecting the sway bar didn't help at all.

The wheels still bounced up and down.
The hill's flat faced, so articulation isn't a problem - but that'll have to be addressed too.

I'm thinking heavy shocks with lots of rebound resistance is part of the answer.
Question - The Rancho shocks - the best? Or is there something better?

How 'bout the remote controlled Ranchos? The remote control - cables, air, hydraulic fluid? What does that system use to control the shocks?

And - the "Automatic" shocks - do they really work or is it just hype like Jeep did with the Rubi?

The hop isn't just on hills either, deep sand does it too - anywhere the axles have to pull hard - hop hop hop stuck!

So far I'm dissapointed in the Rubicon - it's not near what it's touted to be - it's a Mercedes with big tires - I'd bet a Mercedes with big tires would climb that hill better.

My old relatively stock Jeepster makes that hill without even trying!

Thanks again.
 
G
#8 ·
Huh.

The only time mine ever did something like that was when the whole thing was stock. Got a little bouncy crawling up a rock, with the sway bars connected it would lift the tires, and it would bounce when it only had slight contact on the lifted side. I pretty much put the lift in right away (3.5 RE and DT3000 shocks).

Not something I have heard about, and there are 15 Rubis in my club. Does it do it locked and unlocked?
 
#9 ·
Locked, unlocked, high tire pressure, low tire pressure, Hi or Lo range. 2 wheel drive actually does better!
It acts just like the older Broncos did - they had forward pointing control arms just like Ford trucks nowdays - a bad design. First attempt I knew what it was right off from my Bronco days. Got a friend to watch, he confirmed it - wheels don't stay down -- bounce like crazy!

Since it's just a glorified TJ I'm surprised that some folks have never experienced it.

Picture this - drag a broom handle around at an angle pointing downward - like the control arms - it goes over bumps fine - as long as you are dragging it.
Now push it over those same bumps - catches on everything. Going forward the rear's draging, front's pushing.

Dampening it with stiff shocks merely slows down the hop vibrations. We had to do that to the old Broncos - double, triple, quadruple shock on the front - didn't stop it, just slowed it down some.

Seems like a 30K "Jeep?" right out of the box should be able to go down a sandy wash and climb a hill that isn't that much of a hill.
So far I'm dissappointed - I'm wondering if it's worse than the H2?

My Chevy 4x4 truck, my Jeepster, my M38A1, my "built" Tracker, even my stock Suzuki Sidekick on 205's make that hill without difficulty.

Anybody try the remote controlled 9000's?

I'm about to take it back and throw it at them.
 
G
#10 ·
I pointed this out to some of the other Rubi owners down here, nobody has experienced this. Couple thought maybe a mech problem. Truth is, we can pretty much climb with anybody, but most have lifts/tires/shocks.

The only real difference between a Rubi front end and any other TJ front end is about 80 lbs and the high pressure shocks, maybe its the shocks, I dunno......

The guys with 9000's swear by them. One guy ground off the adjustment knob on a trail, but that is the only down side I have heard. The DT 3000s are OK. I may go to Bilstien 5100s.

You might post this up at the Rubicon board over at JU just to see if anyone else is fighting that.
 
#12 ·
The only time I've ever had any wheel hop is in deep packed snow that the tire physically could not "ramp up" to get over, so to speak (around 28" deep). The tire just formed a tire shaped curve that kept the jeep sitting in its own vertical rut. Backing up a few feet to get some momentum solved that ...but that's the ONLY time I've had wheel hop.

Something left unhooked from the factory? Maybe all four shocks are defective
 
#13 ·
I'm with Elusive....as usual....lol.

BTW--Theres nothing "bronco" about the TJ. If you're referring to Fords bright Idea called TTB, the TJ has a 5 link. Totally different animals.

Whgat I find hard to believe....is that some "engineer" at ford thought TTB was actually a good idea. Even better is theidea that his coworkers were cheering him on agreeing with him that it was great. Didnt anyone understand that camber is kinda important? The best part is that through the radical camber changes...the two sides dont even change equally...because the D/S arem is longer than the P/s. gotta love ford!
 
#14 ·
Whine? Trying to find a solution is whining? I'll remember that when someone asks a question I can answer.

The Rubicon is a 4 link - unless you count the Panhard as a link. You do know what a Panhard is, don't you?

Funny - the statement about the early Broncos - if there is ANY camber change on them, the axle housing's obviously broken. The early Broncos had a solid front axle, held in place by radius arms just like the TJ, but the arms were a bit longer so they worked better.
The race Bronco I was hired to run had 4 shocks on each front wheel, 2 on each rear wheel. Still it would hop on steep hills under hard acceleration. The shocks helped slow the rate, and keeping speed up got you through. That's why Stroppe eventually dropped the entire live front axle for a 2 wheel drive straight axle.
But I'll quit talking about it - even though I found the solution - I don't want to "whine" anymore.
 
G
#15 ·
so whats the solution. i got here alittle late to input my wheel hop problem with my Rubicon. when I first got my Rubicon, I turned onto on road out of the dealerships lot and attempted to see how bullet proof the axles are with a burn out and yea the was wheel hop that killed my rear end. I walked 30 feet back to the service office and asked for a tow and for a rear axle shaft to be installed. they were shocked that right off the lot they had a shattered axle on something I had got my keys on 2 minutes before, it made my day when they were so shocked. I wish I had brought my camera to show you all their faces, maybe next time


anyways I was lucky because while I was buying my Rubicon. there was a delivery truck unloading stuff tons of boxes. well one of them happened to contain axleshaft for the dana 44 rear in the Rubicon.

but back onto the topic how can I prevent wheelhop on my Rubicon?
 
#20 ·
In reply to:

i got here alittle late to input my wheel hop problem with my Rubicon. when I first got my Rubicon,

[/ QUOTE ]

Your profile lists yours as a '00. Have they offered the Rubicon package that long? I thought it was a more recent option.
 
#21 ·
It's interesting --
I presented the problem on several boards.
In sumation:

Lots of replies "never hear of that."
That shows it isn't a common problem - or those responding never get out of the parking lot. Take your pick.

A few replies "heard of it, never saw it." AHA, it's existed before, so it's not something unique to mine.

And a few responses "adding a lift kit cures it." Hmmm, must be something that got replaced in the process.

A few more "Try decent shocks, like 9000's. I know that will help some, but it covers up the problem, not cure it. I'd like to cure it first, then use heavy dampening.

2 said "it's the driver." I rather doubt that, considering my experience and the fact the rest of my 4 wheelers - 5 others right now - have no problem with that hill. Lost count years ago, but I've owned and wheeled somewhere around 25-30?

One guy has nothing better to do than count the number of Jeeps he's "seen" -- see above a few posts.

Another thinks getting innane responses with no suggestions, then posing the hop problem again is whining.

And the kicker - I referred to early Bronco suspensions - he must not have been born when the early Broncos were around - or under a rock. DUH!

The nitty gritty:
1. Have a look at the Panhard. Notice the ends are not at equal height above the ground when sitting flat. When the axle travels up and down, the panhard will rotate around the center where it's attached to the frame. As the Pashard travels up and down through it's arc, it pulls the axle with it from side to side. If it's flat - both ends equal - the arc it goes through pulls sideways very little.
But if the ends are not at equal height that arc is greater. That's the source of the bumpsteer -- I never even mentioned that! Try it on a paved road that's not perfectly smooth - at speed, like 80 or 90. You can hardly keep it on the road due to the bumpsteer.
It's very sensitive steering to start with - factory has the caster set too negative -3. I gave mine +2 - what a difference!
But the Panhard needs to be lowered at the frame end, or raised at the axle end. The Panhards are wrong at both ends of the vehicle. I'll fix that once I've lifted it a bit, probably going with 3" and a little body cutting.
That's part of the hop problem, the axles shifting sideways a tad. But not all of it.

Squat - Think about the front end. When under power the axle wants to rotate in the opposite direction from tire rotation - blame Isaac Newton for that. We all now a rear pinion wants to riase up under load, the front pinion, being on the rear of the axle, wants to rotate down.
But - since the axle cannot really rotate (wrap) like with a leaf spring, it pushes the radius arm(s) downward. On a flat surface with good traction you'd see the body get pulled down by the arm's ends. The body will actually drop -- or "squat." But another way to think of it, it's trying to lift the front wheels UP in relation to the body/frame.
Now on a hill - weight transfer lightens the front end anyway - making the following easier to happen. Under hard acceleration up that hill the arm pushes the frame down - think of it as the opposite - it's LIFTING the front wheels!
Simple - wheel lifts, loses traction (thus losing the reason it was lifting - Newton again) drops back to earth, grabs, lifts again - hop hop hop. It's the inherent design.
The upper links at a slight angle help some, better than the Bronco that didn't have them, but still it happens.
Longer arms and or a lower mounting point help reduce the squat a little. Notice those goofy looking Ford trucks that they lift waaaay up. The arms front and rear are next to each other and hang down way down. Otherwise hop's terrible even in a school zone.

And why mine was worse than most? I'm sure the broken factory weld that looked good on the arm's mount contributed quite a bit. That was a 5 minute fix once I saw it late last night. The weld looked OK, but it missed -it was next to the joint. Since it was so clean and painted there was no rust line to help find it. I was lying under it with TJ right next to it comparing angles and such when the light hit it just right.

The rear - same as the front but instead of Squat, it's called Anti-Squat. Get the front bouncing and the rear starts it - what a ride! You still see those rides sometimes in front of supermarkets, usually costs a quarter.

And - one more contributor - a coil spring has a fairly flat rate factor. In other words a 175 lbs spring takes 175 lbs to compress 1 inch. Another 175 lbs it'll compress another inch, or close to it. And another 175 gives another inch - it's a linear curve. That gives a nice soft ride.
Leaf springs are a progressive rate, adjustable by material, leaf thickness, width, length, taper, end taper etc.
A 175 leaf does the first inch at 175, but to compress it another inch it needs more than adding another 175 - maybe 250, then the next inch needs another 350 etc. So it's progressive. The progressive effect dampens the wheel hop problem to the point it's fairly uncommon - but - they wrap - an entirely different problem!!

Soo - check the welds veeeeery carefully! Replacing the rubber bushings with Urethane should help a little, takes the wiggle out.
Heavier coil springs - the Rubi's are light for a nice soft ride - as the service manager at my dealer says - "most Rubi's will never see the dirt."
Dampen the hell out of it with good shocks.
Add a little more positive caster.
Use tires with more sidewall flex, the stock 16's are stiff.
Lower air pressure to help dampen.
Get the Panhard flat.
I'd bet the reason the "D-44's" are hybrid D-44/D-30 is to keep unspring weight down a little - factory's aware of the hop. That unspring weight is a real killer.

And - ignore folks that think repeating a question is whining.

There are other things that could use improvent on the Rubi - but not as major.

 
G
#23 ·
In reply to:

Squat - Think about the front end. When under power the axle wants to rotate in the opposite direction from tire rotation - blame Isaac Newton for that. We all now a rear pinion wants to riase up under load, the front pinion, being on the rear of the axle, wants to rotate down.
But - since the axle cannot really rotate (wrap) like with a leaf spring, it pushes the radius arm(s) downward.

[/ QUOTE ]

Actually, no. The resultant force on the axle is to torque the opposite direction of the wheel. If the wheel is driving forward (force at the bottom pushing rearward), the force on the axle would be to twist the bottom of the axle forward and the top of the axle rearward. The control arms are mounted on the top and bottom (more or less) of the axle, so the force on the control arms is pushing in to the frame on top and pulling away from the frame on the bottom, force vectors coincident with the control arms (more or less).

I think you're gonna find that the broken weld was the problem, and that the hop is no longer an issue.
 
#24 ·
Thanks Babypoo, I thought I was having another sample dose or senility again. He has a lot of trouble keeping his stories straight, in one post, HE bought it, in another mommy and daddy bought it because he got good grades. So, do you think the box his came out of said Mattel or Monogram?
 
#26 ·
1. you come off very harsh with folks that dont have to take time out to read your post and make a responce. I thought so when you drove TR away (even though I didnt like him) and I am now convinced
I DO get out in the dirt... a lot, and a whole lot with tj's (the 2 I own and many others)

2.Lots of replies "never hear of that."
thats because your way off base with your assesment of the tj suspension, and this isnt a problem from swinging panhards.

3. I have changed my mind about posting #3 as it wasn't decent

4. That's the source of the bumpsteer -- I never even mentioned that! Try it on a paved road that's not perfectly smooth - at speed, like 80 or 90. You can hardly keep it on the road due to the bumpsteer.

so you commonly drive your jeep down bumpy roads at 90mph? I have done it, the tj was smooth and handled well. I recently drove one of mine 1800 miles...mostly at 70+mph towing a small trailer... amazingly I kept the death trap in my lane the whole way...actually.. my wife drove most of it. no bumpsteer.

5. factory has the caster set too negative -3
both of mine were at +4.5 from the fatory....unless the rubi 44 is different

6. But another way to think of it, it's trying to lift the front wheels UP in relation to the body/frame.
Now on a hill - weight transfer lightens the front end anyway - making the following easier to happen. Under hard acceleration up that hill the arm pushes the frame down - think of it as the opposite - it's LIFTING the front wheels!
Simple - wheel lifts, loses traction (thus losing the reason it was lifting - Newton again) drops back to earth, grabs, lifts again - hop hop hop. It's the inherent design.

this is where you are mistaken about the suspension design. the jeep will squat in the fron.. if you really want to see it, drive on just the front driveshaft...the entire jeep squats under acceleration. This is not the tires trying to lift and pulling the frame down, it's more a a weight transfer to there more weight could be used... above the front axle. Look at the bracket cars that have their suspension tuned well.. theyl squat when taking off. It transfers MORE weight to the driving axle. both the upper AND the lower control arms pull on the top and the bottom of the axle tube at the same time.(You keep trying to forget there are 8 control arms here) Therefore, on the rear, the top control arm is pulling and the bottom one is pushing. The front is EXACTLY the same..the top one pulls and the bottom pushes, but the arms are attached to nearly the same place on the frame. Once again thank newton, the forces are nearly equal and opposite on the nearly the same place on the frame.
I would estimate that If you were to really hammer a jeep it might compress the spring enough to cause them to bounce back;.especially since the engine would over-rev quickly in low range.
7.Something I agree with you on, I have seen many poor welds on the tj frames.

I notice that you have over 4000 posts, many are very helpfull, but a whole lot of them are you trying to be somehow "better" or "smarter" that someone else.

Read your post. You were sniveling " my $30k rubi doesnt climb well.......I wonder if the hummer is better...."
I know you'll retaliate with some long-winded responce, and you'll hate me forever now, and thats too bad... I dont dislike you... I disagree with you. Theres a difference.
 
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