Rear end skips sideways on bumps

[ForOffRoadDriving]

i noticed that after installing the belltech 6400 shackles the side stepping decreased drastically, and even more so after installing the lock-rite. now ive got the idea of cutting the passenger side shock mounts off and making them both mount on the rear, damn you bobby!

 

[Tonka]

Are the axle tubes just made of plain old ordinary steel like black pipe or something? I would be wary about screwing with the temper of the steel by welding to it. But that is pretty stupid that they gotta be on different sides just for the exhaust. I mean, WTF couldn't they route the exhaust to compensate for the shock??

 

[alwaysFlOoReD]

AFAIK axle tubes are not tempered. People weld on axles every day. You may want to be careful so as to not induce warpage from excess heat.
I have had the impression from reading hot rod mags 20-30 years ago that the shocks are staggered to offset wheel hop .

Richard

 

[jesse93]

my buddy crashed his 91 from the same reason....i put both my shocks on the rear and it rides stiffer but i never had that problem in my 93

 

[Tonka]

I was hooking a trailer light harness up to my girlfriend's dad's 2010 Chevy Colorado and I noticed that it has it's rear shocks on opposite sides of the axle just like the Rangers. I asked him if it skips sideways on bumps and he said no.

 

[AllanD]

I'm simply not in the mood to teach you physics 101, but
moving the shock will not correct that problem.

There are two physical effects of simple newtonian physics, the forst is "axle wrap"
the tendency for the axle pinion to move upwards under load, but the one you are
missing is the tendency of the axle to resist driveshaft torque by "lifting" the right side wheel.

when that happens with an open differential the tire spins and you go nowhere.
With a positive differential you still get thrust from the drivers side wheel, but that thrust is off centerline and the vehicle tends to hook, or flip sideways.

Learn to drive around it, because there is little that will make it go away.

You swapped in a locker and there are dynamic consequences of doing so

 

[Earl43P]

So, I just installed a small diameter rear sway bar from a 90 4wd 7.5" onto my 2000 2wd 7.5 4.10 open. I already have 235/65-16 tires so it handles pretty good.

This is a direct effort (free parts too) to affect that skitter. I drove it to town and back and it handles better. I can't say the skitter is gone until Monday when I drive a certain route with a 30 mph left curve and a bump that ALWAYS makes mine skitter under power.

I have a question about the pre-load on the sway bar.

When I installed it, there is considerable leeway when tightening the clamps onto the axle tubes. What I settled on was pushing the center hoop upward, which made the clamps rotate upward and I tightened it that way. That hoop above the u-jont could easily be 3-4" lower than where I forced it to go. When I say forced, I'd guess 40-50 lbs pushing up with one hand while I tightened the u-bolts. It also made the vertical links to the frame "less vertical" with the bottom link toward the axle more (I tightened those frame bolts last). If I let the pre-load off, the links went more vertical. Will that affect the ride height and stiffness, because it seems to have done exactly that.

Seems to make it ride higher based on looking in the rear view mirror (I never move my power seat).

I'll try different levels of pre-load vs. ride quality and skitter in the next few weeks.
I wish this truck had a LS or locker....the sway bar test ride was let's say "enthusiastic".

 

[Earl43P]

Update: I drove over the 30mph curve with bump and it still skitters to the right under power.

The response is way different if I let off the gas pedal though. It none of that squirrelly diversion to the right and a much more stable feel. Overall, the ride is greatly improved with the rear sway bar.

I drove over it 4 times yesterday and once already this morning. Just for fun, I drove over it twice in 3nd gear and twice in 4th. You can feel the RR tire get airborne for an instant, then grab and skitter occurs. It's noticeably worse with the added rpm and torque applied in 3rd gear.



I am not a fan of the open differential. It is next to impossible to get the LR tire to spin, regardless of which direction I am turning "enthusiastically". When the LR does spin in a left turn, the whole rear end will drift like a LS for an instant, then traction resumes. There will be no drifting in this "old man truck". One wheel peel FTML.

 

[bobbywalter]

Are the axle tubes just made of plain old ordinary steel like black pipe or something? I would be wary about screwing with the temper of the steel by welding to it. But that is pretty stupid that they gotta be on different sides just for the exhaust. I mean, WTF couldn't they route the exhaust to compensate for the shock??

minor welding of shock mounts/perches are a non issue.

I was hooking a trailer light harness up to my girlfriend's dad's 2010 Chevy Colorado and I noticed that it has it's rear shocks on opposite sides of the axle just like the Rangers. I asked him if it skips sideways on bumps and he said no.

they certainly do skip..i have driven many types of those....but they are much lower slung and wt dist is different, along with the spring pack effective angle and actual shock setup. i really like the 5.3 versions.

my buddy crashed his 91 from the same reason....i put both my shocks on the rear and it rides stiffer but i never had that problem in my 93

i bet many trucks have been wrecked because of it.

I'm simply not in the mood to teach you physics 101, but
moving the shock will not correct that problem.

There are two physical effects of simple newtonian physics, the forst is "axle wrap"
the tendency for the axle pinion to move upwards under load, but the one you are
missing is the tendency of the axle to resist driveshaft torque by "lifting" the right side wheel.

when that happens with an open differential the tire spins and you go nowhere.
With a positive differential you still get thrust from the drivers side wheel, but that thrust is off centerline and the vehicle tends to hook, or flip sideways.

Learn to drive around it, because there is little that will make it go away.

You swapped in a locker and there are dynamic consequences of doing so

well i tried to explain this early on. there are factors with actual unsprung weight and location and corresponding torque application factors specifically because of that offset as well.

the pig is biased to the passenger side. the unsprung weight is not centered... it causes its own issues. 9 times out of ten if you rip the tires off with a limited slip or open diff, provided you have an engine that will do it, the passenger side usually is the one smoking.

pull the shock off one side and then the other and tell me shocks wont affect this situation.

setting up the shocks like i described helped the most when running unladen, i usually am laden enough to never have an issue though for the most part.

if you run unloaded, a centered diff and non staggered shocks will give you the best performance. its most definitely provable.

 

[85_Ranger4x4]

My '02 F150 has staggered shocks and my brother's '97 doesn't... as near as I can tell they ride about the same. Never felt either kick out to the side.

Mine is a 5.4 ext cab shortbox with a 9.75 rear axle, his is a 4.6 std cab longbox with a 8.8.

Mine has the tab on the axle to go either way though.

My Ranger has a nasty habit of it though, the shocks are shot beyond belief though and are pending replacement after get the Explorer springs and 8.8 in it this winter.

 

[Tonka]

My '02 F150 has staggered shocks and my brother's '97 doesn't... as near as I can tell they ride about the same. Never felt either kick out to the side.

Mine is a 5.4 ext cab shortbox with a 9.75 rear axle, his is a 4.6 std cab longbox with a 8.8.

Mine has the tab on the axle to go either way though.

My Ranger has a nasty habit of it though, the shocks are shot beyond belief though and are pending replacement after get the Explorer springs and 8.8 in it this winter.

Are you going to put an Explorer axle in it or just the springs? The Explorer axle has disc brakes, but requires you swap to the Explorer's master cylinder and you gotta cut the leaf spring mounts off and re-weld them on top. The leafs are on the bottom on the Explorer while on the Ranger they're on top.

 

[85_Ranger4x4]

Are you going to put an Explorer axle in it or just the springs? The Explorer axle has disc brakes, but requires you swap to the Explorer's master cylinder and you gotta cut the leaf spring mounts off and re-weld them on top. The leafs are on the bottom on the Explorer while on the Ranger they're on top.

Both, the truck already has an '88 ABS master so it shouldn't be an issue.

I am well aware of what needs to be done.