1990 FJ62 stock to parabolics fixing vibrations

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Joined
Feb 5, 2003
Threads
130
Messages
1,457
Location
Oshkosh, WI
Two weeks ago I took my FJ62 to the shop and pulled out thrashed 18 year old stock leaf springs and installed a set of parabolic leaf springs. I also put on a set of BDS shocks, anti inversion shackles and all new hardware. I netted six inches of lift and lost my 1/2" cruiser lean. Upon first test drive I noticed a vibration of semi epic proportions. I kept going knowing that I needed to get some settling out of the way so I went about 10 miles and then pulled back in to the shop. I recheck all my nuts and bolts and such, centered my steering wheel and called it a night.

Some back ground. The truck has nearly 150,000 miles on it. I bought it stock and have been treating it like a red headed step child for two years with 33x9.5r15 BFG's on stock rims. It rode and drove ok, no vibrations etc. I did 400+ miles including eight hours of trail the weekend before the install. My back hurt badly from the harsh ride of old crap and I developed a new clunk (ended up being a broken spring eye on the left rear spring frame mount side) when changing directions an off to on the gas on the highway. Since purchase I have completely rebuilt both axles with all new bearings and seals. I have all new steering except the box which works as intended. I have a lunch box locker in the rear. The tires have 5-6000 miles on them and have been rebalanced. I have all new precision universal joints in the driveshafts since the lift and the shafts are in phase. My angle finder shows equal angles at the rear t-case output and the rear pinion flange. I have tied up the LSPV rod to give me full rear brakes and adjusted the shoes properly. I have installed new calipers and pads in the front.

I have put almost 200 miles on the truck experimenting with correcting the vibration and have only made it worse. The suspension has settled to the six inch mark (three more than I wanted over stock but the ride is AWESOME) so I loosened all the bolts, greased all the shackles, springs etc (yep, bling hardware) and retorqed everything including u-bolts. I still have a bad vibration, it is shaking the WHOLE truck, not just the rear, not just the front. The truck runs great, shifts great and 4x4 high and low work as intended.

IF you read that much I appreciate it. IF I had hair I would be pulling it out but I don't have much. FYI I'm not a backyarder and know this should be a routine thing. I have searched and tested, checked, tinkered with all suggestions found on mud except shimming and/or installing a CV rear shaft which the suspension manufacturer says is absolutely not needed. He says there is no way I should need shims either. My angle measurements confirm this. Any help or suggestions will be appreciated.

I'll pay a years mud membership to anybody who hit's the proverbial nail in the head. Now, who is going to save a perfectly good FJ62 from getting drown in the river????


Thanks MUD!
 
Pictures
FJ62 lift project 003.webp
FJ62 right front corner after lift.webp
fj62 left front corner shot.webp
 
Sounds like a bad suspension setup. I will take the parabolics off your hands and give you my ome setup. It is original ome, not that dakkar stuff.

I am no expert, but don't people do a cut and turn when their suspension is that big, like going SOA?
 
A cut and turn is to correct pinion angle and more importantly caster angle. My caster and pinion angles are fine. It steers well other than some more pronounced bump steer. I have no stabilizer and with the increased drag link angle over stock bump steer is expected to be more evident.
Thanks
 
The first thing that comes to mind is the driveline. I suspect that your pinion angle has changed and that will cause some grief. The two flanges, T-case output and pinion, need to be at the same angle. For example, if the face of the t-case flange is 95 degrees from the ground measuring upward in a clockwise direction (the level ground being zero degrees) then the rear pinion flange would need to be within two degrees of that, and preferably two degrees low, not high, so as it rises with the torque of the driveline, it becomes equal. If you have a CV rear briveline, then the rear flange should point directly at the t-case out put flange and also be within two degrees. Make sure your slip yoke isn't buggered, just grab it and try to move it side to side. Once or twice I have raised the rear axle off the ground and placed a vehicle in gear with the engine running to check for driveline run out. Be carefull when you do this, but it was very revealing when I did it. Also, did you separate the driveline at the slip yoke? It MUST be positioned in the exact location in which it started. The yokes on both ends must align with each other and since the assembly is balanced all together, you should NEVER move those two parts around. Anyway, I hope this helps.
 
...have you checked motor mounts?
...checked trans/t-case mounting?

hhhmmm......I had an 'overall' vibration in my FJ40 with a bad tranny bearing....

you need some sucker to hang under the rig while you drive it.....glad i'm not in town....
 
The first thing that comes to mind is the driveline. I suspect that your pinion angle has changed and that will cause some grief. The two flanges, T-case output and pinion, need to be at the same angle. For example, if the face of the t-case flange is 95 degrees from the ground measuring upward in a clockwise direction (the level ground being zero degrees) then the rear pinion flange would need to be within two degrees of that, and preferably two degrees low, not high, so as it rises with the torque of the driveline, it becomes equal. If you have a CV rear briveline, then the rear flange should point directly at the t-case out put flange and also be within two degrees. Make sure your slip yoke isn't buggered, just grab it and try to move it side to side. Once or twice I have raised the rear axle off the ground and placed a vehicle in gear with the engine running to check for driveline run out. Be carefull when you do this, but it was very revealing when I did it. Also, did you separate the driveline at the slip yoke? It MUST be positioned in the exact location in which it started. The yokes on both ends must align with each other and since the assembly is balanced all together, you should NEVER move those two parts around. Anyway, I hope this helps.

Roger on the angle change. My rear flanges are 3 degrees off of perpendicular to the ground each, hence equal angles. I have not taken the opportunity to run the truck on the rack, that is next after this weekends busy events. Slip yoke has been checked and double checked. Yes it was separated to clean out all old grease, get a thorough cleaning and put back together EXACTLY the way it was. Hence the speaking of "in phase" I even took the thing out of phase to see if anything changed, that was kinda stupid since it had better change given the laws of physics.

I agree I need to get the rear off the ground and run it and look. That will be next. Keep in mind that I had NO vibrations before the lift and had vibrations immediately after. The driveshaft u joints and such came after the lift and first two test drives. Therefore the driveshaft work and new u joints are not suspect in my mind since the issue reared it's ugly head before the shafts were touched. A driveshaft does not go out of balance when a lift is installed in my mind however increased angles can make a previously non evident oscillation very evident post change. I'm also wondering, I'm measureing my angles static and the suspension is very soft. I'm wondering if there is enough wrap that the rear angles are leaving the "specs" under accelleration. However I can't coast at 50mph with out vibes.
 
........glad i'm not in town....
The sheep are happy too!

The motor mounts have me thinking. My P to D has been getting sloppy but not in the Mcnamara way. I need to get the hood open and look. Heck, i'll chain the beotch. I did put a prybar 4' to the trans/t-case mounts and am satisfied with them. Bad trans bearing + previous trans issues = bad deal to ugly to think about. The trans is working top notch though and the fluid in the trans and t-case is up to par (both new again) and free of contamination. I will exhaust all other possibilities before pulling that thing for a 5spd. I'll actually put a 700r4, centerted rear diff and some sort of atlas or other crawler box in it before a manual trans.

You've seen me drive. I can't imagine why no one will hang under it for me?!?!
 
Roger on the angle change. My rear flanges are 3 degrees off of perpendicular to the ground each, hence equal angles. I have not taken the opportunity to run the truck on the rack, that is next after this weekends busy events. Slip yoke has been checked and double checked. Yes it was separated to clean out all old grease, get a thorough cleaning and put back together EXACTLY the way it was. Hence the speaking of "in phase" I even took the thing out of phase to see if anything changed, that was kinda stupid since it had better change given the laws of physics.

I agree I need to get the rear off the ground and run it and look. That will be next. Keep in mind that I had NO vibrations before the lift and had vibrations immediately after. The driveshaft u joints and such came after the lift and first two test drives. Therefore the driveshaft work and new u joints are not suspect in my mind since the issue reared it's ugly head before the shafts were touched. A driveshaft does not go out of balance when a lift is installed in my mind however increased angles can make a previously non evident oscillation very evident post change. I'm also wondering, I'm measureing my angles static and the suspension is very soft. I'm wondering if there is enough wrap that the rear angles are leaving the "specs" under accelleration. However I can't coast at 50mph with out vibes.

Ok, you know as much as anybody about drivelines it seems. Are those U-joints OEM or something else? I have gone through hell with after market U-joints. Here's how it goes. I put them in, all is well. After a few days, things are vibrating like mad. Three times it happened and it was the same thing every time. The bearing caps migrate outward and the trunion was swapping around inbetween. It seems the clips were too small on all of them to hold the caps in place properly. Take a look and see if that has happened to you. Eventually I found a very savy driveline guy who actually found thicker clips to solve my problem. Now I have Spicer drivelines.
 
I am concerned about the u joints. They are Precision brand not OEM. The originals came out perfect and these went in perfect. The vibration was there before the u joints were changed and after they were changed. It is only now, after 200 some miles getting worse. I will recheck them though. I have OEM on order since Tuesday.

So far I'm going to: run the truck in the air and do a visual
Recheck the new U-joints
If the ujoints are as good now as they were when they went in I guess I'll have the shaft balance checked.

Has anyone else fought the battle of common sense before? I.E. No balance problem for two years, then a lift is put in and suddenly a shaft is out of balance? It's impossible. Or a trans or t-case that just did a 400 mile trip perfectly developed a vibration sitting on a hoist for two days? Obviously I'm missing something. I actually drove it to work on Monday (50 miles) and let it shake hoping that whatever was causing it would leave the truck while moving. It's an expensive way to diagnose things but it is rarely wrong! :beer:
 
I'm no expert but here's a stab in the dark. Sometimes lifting a cruiser actually puts the transfercase and rear pinion closer together, making the distance between the two effectively shorter. So sometimes what happens is the u joints,pinion bearings,tranferscase bearing's ect.. get smashed together destoying parts and causing vibration.The cure is of course shortening the drive shaft and replacing any ruined parts.I'm running Alcans(thanks pismojim) with about 6 or 7 inches over what it was(stock with AAL's? po installed) and mine is barely short enough.It's something that is easy to overloook so you might check it if you already haven't.
 
Good call HPD but no dice. I installed the driveshaft at full droop I have 2.5" of compression left and sitting on the ground I have 1.5" left and stuffed is plenty good due to the travel of the shackles.

Thanks 'Mud, keep the ideas coming.
 
I think this may be coincedence and not related to the lift as it seems you have checked all the variables. I'd take the driveline in and have it balanced. Maybe you threw a balance weight and never knew it. Maybe it's full of mud and/or water, who knows.
 
How about pulling the rear shaft, locking the hubs and driving the truck in 4H. This might at least help you see if the vibration is rear driveline related...

Nick
 
More ideas:

I know you said you got the tires rebalanced but do you have another set to try out to eliminate the tires causing vibs? To balance the drive shaft you could tap a hole, fill it with a little fluid (oil, tranny fluid, etc.) and plug the hole. This will help balance it when it's spinning. How about wheel bearings? Loose knuckle studs?

Are the vibs speed related or rpm related?
 
I think this may be coincedence and not related to the lift as it seems you have checked all the variables. I'd take the driveline in and have it balanced. Maybe you threw a balance weight and never knew it. Maybe it's full of mud and/or water, who knows.

In my post above it states that I removed it, cleaned it good enough to eat off it or out of it (slip) and then regreased and installed it. I am going to have it balanced though. I've been off to Missouri for a WSORR race with RidderFab Racing for a few days.
 
How about pulling the rear shaft, locking the hubs and driving the truck in 4H. This might at least help you see if the vibration is rear driveline related...

Nick

Been there too. Truck has a vibe in front wheel drive that IS isolated to the front driveshaft. Accelerated to 50mph then took it out of 4wd, vib is gone instantly. Rear is not the same, it has vibes with front shaft out and in gear or out of gear.
 
try looking at the sway bar links, i know with the ome setup, they send you new ones, its possible they are giving you some trouble

I have no front or rear sway bars hooked up. Sway bars have nothing to do with this issue. A, they are not speed related, b, they do not rotate.
 
More ideas:

I know you said you got the tires rebalanced but do you have another set to try out to eliminate the tires causing vibs? To balance the drive shaft you could tap a hole, fill it with a little fluid (oil, tranny fluid, etc.) and plug the hole. This will help balance it when it's spinning. How about wheel bearings? Loose knuckle studs?

Are the vibs speed related or rpm related?


I have 2 vibs, one is RPM related and one is speed related. Wheel bearings are new and have been rechecked since the lift at all four corners. Knuckle studs are new from this past winter and have also been rechecked. Neither of these items could cause a vibration such as this. Thank you.

I will update after rear shaft rebalance. I also have the alternative universal joints coming in today instead of the perfectly good Precision ones that I have in there.
 

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