Hopping (yes hopping like a bunny)

[Mr.Badguy]

I've not heard of this problem from any one else here, so i thought i'd finally ask this question and see what everyone's input is on this situation.

My VX hops. traveling at 50mph or higher on highways whenever i come to a bridge my VX hops across when you hit the shock of the bridge expansion seam. WHat do i mean by "hopping"??? well its a scary situation when the car quickly slides left or right or the rear end hops up and tries to switch places with the front end. Its very scary, and i've really tried to avoid highways because of it. I had to do some driving on RT 80 tonight, and though they are actually doing road construction as i write this on those bridge expansion seams its just a scary situation. Here is what i've done to try to fix the problem. lower air pressure to 32psi. raise air pressure to 35psi (no change), replaced shocks with the rancho 9000, which are currently set at 4 or 5. I do not remember the problem being so acute when i first got the VX 2 years ago, and had my stock wheels. but i quickly got rid of the stock wheels after i had my car 2 months (one wheel was bent and the chrome was flaking off all 4 wheels), and went with the AR 'Fuel' model. It was after that change that the car started to "hop". the shocks were at the end of their expectancy so i waited a bit to get the ranchos. they were installed in february of this year, and i haven't noticed an improvement. the only improvement i noticed with the ranchos were that bumps in the road were taken better, but under 50 mph. I'm at a loss of what to do. I usually do a lot of road driving, and i have a big trip planned for September. I don't remember having this problem in other states, as i've been through PA, OH, and KY several times, though not with the new ranchos, but since the wheel change. If anyone can help me with this, it would be greatly appreciated.

Thanks!

[Knigh7s]

That happens to me as well. I just installed the rancho 9000 a couple months ago, and it does the same as the stock shocks did. On the way to work there is this seam on the bridge that connects to the on ramp, and the vx always hopps to the left (right handed turn right over the seam). the first time i did it, scared the crap outa me, because i thought something broke underneath! But I have noticed that trucks infront of me hop to the left as well when they drive over it...

I dont know.. I sorta like "forcably" doing it!

[etlsport]

yeah i know what you are talking about.. roads in pa around me suck... like really really suck.. there are random lumps of asphalt as high as 2-3 inches on the highway next to jersey walls... potholes big enough to eat small children... bridges galore... and yeah my vx takes them with about as much grace as a sumo wrestler in stiletto heels.. ive gotten in the habit of bracing for that kind of stuff and almost always drive at 10 and 2 for better control esp at high speeds, i think its probably caused by the short wheelbase.. your front wheels dont have time to normalize again after a bump like that before the rear wheels hit so both front and back wheels are out of whack

speaking of driving onto bridges.. theres a bridge with a pretty steep uphill incline on one of my regular drives.. every time i drive up it, my tod engages violently when i hit the seam with my rear wheels.. scary at first.. kind of fun now

[VCrossfan]

Yes mine hops at times as well. My guess is the front shocks are bottoming out. I know when I installed my Rancho 9000's a couple years ago I noticed there's not much shock left for travel (sitting with no lift,torsion bars at original height) I'm going to look for a shorter bodied (cylinder) shock that will allow more clearance before bottoming out in normal road travel but will limit the total length travel (which I don't need) . The 9000's would work well if we cranked the torsion bars, but unless I install rear springs my stance is just right now, so I'll do some shock hunting. Anyone else have any thoughts or shock ideas, drop a line...thx

[Mr.Badguy]

I'm releaved that I'm not the only one that has this issue. Vcrossfan, if you do turn up any information on shocks, please let me know. I'm willing to try something new if it has good results. My mechanic also said that with the short wheel base that the rear end will want to replace the front end if i hit a bump.

Look forward to anymore comments or suggestions.

Thanks!

[VehiGAZ]

I don't have this problem (I have Bilsteins! Hahahah... ok, just kidding) but I wonder if it has to do with the alignment...

My engineer father told me never to get a thrust-angle alignment (which aligns the front wheels to compensate for & balance out any misalignment of the rear axle) because it would leave the car with an inherent tension in the suspension. What you guys are describing sounds a bit like such a tension being released when your rubber hits the slippery spot. (I made that sound dirty, huh?)

Diagnostic question - If you drive straight over a series of expansion joints, does the VX always hop to the same side?

When's the last time you had an alignment check?

[Mr.Badguy]

I don't have this problem (I have Bilsteins! Hahahah... ok, just kidding) but I wonder if it has to do with the alignment...

My engineer father told me never to get a thrust-angle alignment (which aligns the front wheels to compensate for & balance out any misalignment of the rear axle) because it would leave the car with an inherent tension in the suspension. What you guys are describing sounds a bit like such a tension being released when your rubber hits the slippery spot. (I made that sound dirty, huh?)

Diagnostic question - If you drive straight over a series of expansion joints, does the VX always hop to the same side?

When's the last time you had an alignment check?

I just recently, had an alignment done in June, but have no idea if it was a thrust-angle alignment. what sort of alignment should i get or ask for?

to answer your other question, most of the time it hops to the right, then to the left. it seems that whenever i hit the seams, the car hops up into the air (because the slide is so severe) and to the right. I have both hands on the steering wheel and try to keep it straight. if the wheel is turned any, the hop is worse, and goes in the opposite direction to which the steering wheel is turned.

I appreciate the input on this situation.

[BD-VX99]

Have Bilsteins, don't have the same problem. "-H0" back and front. My back end does bottom out on everything fun though because of sagging springs. I really wanted to cut down the bumpstops a bit but I think I'll wait until I lift next spring.

[SBC]

Sagging rear springs will make the axle bottom out on the rear bumpstops and cause it to bounce, Check those as you will see wear on them.......That was the problem in my case of it hopping and skipping!
Tim
www.streetboutiquecustoms.com

[VehiGAZ]

Well, IIRC, there are thrust-angle, two-wheel, and 4-wheel alignment methods (but the first two might be the same thing). Dino? Chopper? Anyone care to shed some light on that?

With thrust-angle alignments, they measure the alignment of the rear wheels and calculate the overall alignment of the axle, then set the front wheels to compensate for the angle of the rear alignment. It keeps the car going straight, but only because the opposing factions are equally matched. Imagine if the rear wheels were pointing the car 5* to the left (the thrust angle of the axle) - they would then align the fronts to point 5* to the right so that overall, you go straight, but as soon as the front axle hits a bump and goes light, the rear axle gets to push the car to the left.

I know that some vehicles can only be aligned by the thrust angle method, and I have no idea if the VX is one of them. Call an Isuzu dealer and find out or search the forum for "alignment" and see what comes up.

If you paid $59.99, it may not have been a 4-wheel alignment, though. 4-wheel is the best way to go - they get all 4 wheels pointing straight.

[VCrossfan]

VehiGAZ..Could you measure the body length of your front Bilsteins, and I'll check my Ranchos. If the Rancho peeps have this prob and Bilstein peeps don't I bet the cylinder body length is shorter on the Bilsteins which will give you more shaft length (now that sounds dirty) stick out of the cylinder body creating more shock stroke at a normal ride height. The longer cylinder will have more overall travel (for offroaders and lifts). It's like the Rancho's are a shock just waiting for a lift. I have new OME springs (913's so-so lift and nice ride) but I hate to looz my handling, it's just to much fun doubling off-ramp warning speeds and seeing sporty cars trying to keep up and there door handle dragging the ground and my Rancho 9000's set on 8. It's like the VX is on rails...

[VehiGAZ]

VCrossfan, my VX is still in the shop for the S/C install (due out today) and I leave tomorrow evening for vacation, so I don't think I can do this until the week of the 23rd sometime.

Nevertheless, I would be surprised if everyone is talking about the same problem here. A huge amount of spring & shock compression is needed to hit the bump stops, and you're not going to get that kind of force going over expansion joints like the guys above are complaining about (unless your VX was lowered maybe).