Topic: Truck vibrations after new rear leaf springs and only when acceleration!!

[tyes]

Truck vibrates at 25-35 mph & 55-70 mph. majorities of vibrations is from the front end. ONLY happens when acceleration. STOPS when I let foot off gas.

I install new spring leaves in the rear and had to move my spring hangers 7.5 inches forward from stock and move my rear shackle mount 2 inches back. Everything looked right with a slight pinion angle issue. After reading 4Crawlers on “how to calculate degrees on pinion angles”, I calculated 23* off. I drove it like that for many weeks and it was horrible and annoying at all speeds. There was a bad vibration with foot on or off the gas pedal.  After getting new spring perches and correcting the pinion angle. All that went away except for the “25-35 mph & 55-70 mph” vibrations. My driveshaft is a custom made shaft and moving the springs forward allowed a 1 inch of play. Meaning, measurements from transfer case flanges to 3rd flanges is 39 1/8”, fully compress of the drive shaft is 38” in length. I took my drive shaft to a driveline shop and was told everything was rebalanced and that length would work out ok.

Check list:
Driveshaft: rebalance, no play from u-joints looks secure and tight
Tires: balanced 35x12.5x15 BFG KM2

What could be wrong? Need your expertice and direction guys. Thanks.

[laskt9]

Go to sears and get a cheap angle gauge with a magnet on one side. Recheck your angle and check your ujoints. If its coming from the front I'd shake it down. If it was a tire balance it wouldnt just be on accel

Sent from my HTC PH39100 using Tapatalk 2

[tyes [OP]]

Took off drive line and all u joints are tight and have NO play. but there seems to be a lot of play on the CV ball inside the double cardan joint. never seen this before. its very easy to rotate around. Its not very stiff like its use to be. I can carry it and that cv ball just swings round and round.. Anyone ever dealt with this issue..

[_HOIST_]

What year is it? Does it vibrate with the front driveshaft OUT?

[Rocksurfer]

When I lifted the rear of my truck I had a similar issue when decelerating or braking, I found that not only had my caster changed but my toe was also pitched in a little too much by almost 1/8 of an inch from what I generally set it at. So since I was going to lift the front I went ahead and did that, well that fixed my toe but the caster was still out so I shimmed the front and it went away.

[BirdDog]

I'm not trying to be a smart ars here. I know this sounds pretty basic but you never know.

Are the drive lines front and rear line up properly ? I'm sorry I don't know the proper terminology but both ends of the drive lines have yokes for the u-joints. These need to be aligned.

I had a friend that had a similar problem and his rear drive line was off. On his we had to pull the rear off and pull it apart and align them and it solved the problem.

[_HOIST_]

Are the drive lines front and rear line up properly ? I'm sorry I don't know the proper terminology but both ends of the drive lines have yokes for the u-joints. These need to be aligned.

Drive Shaft "Phase"

[tyes [OP]]

When I lifted the rear of my truck I had a similar issue when decelerating or braking, I found that not only had my caster changed but my toe was also pitched in a little too much by almost 1/8 of an inch from what I generally set it at. So since I was going to lift the front I went ahead and did that, well that fixed my toe but the caster was still out so I shimmed the front and it went away.

my front wheels are /\ but seems to run and drive smoothly before and after the lift...

[tyes [OP]]

What year is it? Does it vibrate with the front driveshaft OUT?

86 T4R, front driveshaft is never use, unless in 4x4. dont see that being an issue.

[BirdDog]

Thank you Stooges4x4 for the help. I had not heard it called that before.

[87toycrawlersbc]

It's probably either driveline vibration where the angle is a little steeper or something may be a little loose or springs soft and let your axle wrap up when u get on it and binding the u joint up. Usually if its driveline vibration though when u let off and it cruises w no load it will make a grinding sound

[tyes [OP]]

It's probably either driveline vibration where the angle is a little steeper or something may be a little loose or springs soft and let your axle wrap up when u get on it and binding the u joint up. Usually if its driveline vibration though when u let off and it cruises w no load it will make a grinding sound

I assume angle would be a little steeper since the axle was move forward 7.5 inches from original spot. Pinion angle was corrected and reduce the vibration by 75%.. Im so sure the CV ball joint area has something to do with it..

[4runnerRob]

its probably due to axle rap , when you accelerate the torque will change the drive line angle , i had a samurai with stock springs and an axle flip and it vibrated bad under acceleration because the stock springs were too weak , put an axle rap control bar on it and it was good , or you could change the pinion angle to acomadate for the rap , just my opinion with my experiences

[tyes [OP]]

its probably due to axle rap , when you accelerate the torque will change the drive line angle , i had a samurai with stock springs and an axle flip and it vibrated bad under acceleration because the stock springs were too weak , put an axle rap control bar on it and it was good , or you could change the pinion angle to acomadate for the rap , just my opinion with my experiences

dont the TG springs comes with that already?

[81_Toy4x4]

If the vibration was coming from the front end, you'd have to be in 4wd, have a bent wheel, or loose wheel bearings to cause that.

If you only have 1" of free travel from fully collapsed on the driveline with it in the mounted position and sitting normally, you could be bottoming out the driveshaft with suspension flex while running down the road. Maybe you could spray some paint on the splines on the male end of the slip yoke as it is sitting still, and then drive it and see how much paint is stripped off from the suspension flexing and shortening your drive shaft to see if your drive shaft is bottoming out in certain instances.

[tyes [OP]]

If the vibration was coming from the front end, you'd have to be in 4wd, have a bent wheel, or loose wheel bearings to cause that.

front end seems to be fine.. i took the rear shaft off and drove it in 4x4 with JUST the front shaft and everyting seems to be okay. no major vibing. Never got to 55-70 though.

[tyes [OP]]

If you only have 1" of free travel from fully collapsed on the driveline with it in the mounted position and sitting normally, you could be bottoming out the driveshaft with suspension flex while running down the road. Maybe you could spray some paint on the splines on the male end of the slip yoke as it is sitting still, and then drive it and see how much paint is stripped off from the suspension flexing and shortening your drive shaft to see if your drive shaft is bottoming out in certain instances.

i feel that might be the case too. and i agree with yout...but i had a talk with my local drive line shop and they said it wouldnt really matter... it shouldnt be vibing at those speeds. if it was the case, then it would vibe at everytime i acceleration....

[87toycrawlersbc]

The more I think about it it sounds like driveline vibration for sure. I put a 8 in lift on a short bed Chevy once. I bought a nv4500 for it and a adapter for a 10 spline 205 t-case. The lift was all spring a super lift kit no blocks no body lift mine acted like yours I woulda bet the farm the tranny was bad I lowerd the t-case 3 in messed w pinion angle it didn't change. I would drive it and stop get out and feel my u joints the pinion the back of the t- case to check for something hot it was always the back of the tcsase. I got a high angle 1 ton cv shaft and the problem was cured. If your getting a vibration something in your drive line will be hot. Drive it for 2-3 minutes at the speed it vibrates pull over make sure you have your gloves on and check those spots I mentioned above and also where you 2 piece drive shaft goes together one spot will b considerably hotter than the others then we can go from there. If u had a spare front shaft you could rig up a temporary cv joint rear shaft to see if that helped it jst lay it in a piece of angle iron and weld it up it won't be balanced but it will b straight and put the cv to the tcsase not the pinion. If it were mine that's how I would go about it. Throwing money at a high angle cv is very expensive if you are not 100% sure that's the problem let us know where you think the " hot spot " is. Good luck don't forget the gloves !!!

[tyes [OP]]

The more I think about it it sounds like driveline vibration for sure. I put a 8 in lift on a short bed Chevy once. I bought a nv4500 for it and a adapter for a 10 spline 205 t-case. The lift was all spring a super lift kit no blocks no body lift mine acted like yours I woulda bet the farm the tranny was bad I lowerd the t-case 3 in messed w pinion angle it didn't change. I would drive it and stop get out and feel my u joints the pinion the back of the t- case to check for something hot it was always the back of the tcsase. I got a high angle 1 ton cv shaft and the problem was cured. If your getting a vibration something in your drive line will be hot. Drive it for 2-3 minutes at the speed it vibrates pull over make sure you have your gloves on and check those spots I mentioned above and also where you 2 piece drive shaft goes together one spot will b considerably hotter than the others then we can go from there. If u had a spare front shaft you could rig up a temporary cv joint rear shaft to see if that helped it jst lay it in a piece of angle iron and weld it up it won't be balanced but it will b straight and put the cv to the tcsase not the pinion. If it were mine that's how I would go about it. Throwing money at a high angle cv is very expensive if you are not 100% sure that's the problem let us know where you think the " hot spot " is. Good luck don't forget the gloves !!!

thanks for the tip. i'll test that once i have the new cv ball install... i have apart now, and the cv ball is F*@$% UP....

[OOPS]

If the CV is that loose, it is worn out. Have fun replaceing that ball, I never could figure how to get the old one out!!!!

[tyes [OP]]

Took the whole thing apart and figure out the flang side of the cv that goes over and around the cv ball is broken. I think that's my problem... Also, seems to have 2 needle bearings inside hole where the springs goes into...Anyone in Fresno area has a double cardan DS?

[tyes [OP]]

since I can’t find a double cardan joint for the rear, can I just run and single joint up front? I have a TG dual case setup plate and my front drive shaft has a double cardan setup.. but my question is, would I have any problems putting a single joint up front and transfer the double cardan to the rear??

[Dingman.]

since I can’t find a double cardan joint for the rear, can I just run and single joint up front? I have a TG dual case setup plate and my front drive shaft has a double cardan setup.. but my question is, would I have any problems putting a single joint up front and transfer the double cardan to the rear??

Honestly, i know a lot of people who run cv's on the rear shaft, and non-cv on the front.
That is my setup and i have no vibrations at all.

If i were you i would go to pick and pull and see if you can't find an ifs front cv.  Keep in mind the bolt patterns are different between a 4cyl cv and a v6 cv.
As well as the bolt patterns are different between either cv and the non cv pattern.  So it would be best to get the same one you already have, unless you have multiple drilled flanges.

You could swap the cv off the front and onto the rear, but then you are going to have to pay to have a shop rework two shafts instead of just the broken one.

You can give my work a call and talk to Jesse.  I am not sure what our availability on cv's are but i believe we have some we could use.
If you wanted us to build your rear shaft, we could put a different cv on it/clearance it/etc.  Whatever you decide you want.

http://www.highangledriveline.com/

[OOPS]

I run a two piece with a CV in the rear, the front has two singles from IFS shafts (more angle) and it works fine. My front shaft is from Dave'z Offroad Performance and the long slip is beef!!!!

[tyes [OP]]

Honestly, i know a lot of people who run cv's on the rear shaft, and non-cv on the front.
That is my setup and i have no vibrations at all.

If i were you i would go to pick and pull and see if you can't find an ifs front cv.  Keep in mind the bolt patterns are different between a 4cyl cv and a v6 cv.
As well as the bolt patterns are different between either cv and the non cv pattern.  So it would be best to get the same one you already have, unless you have multiple drilled flanges.

You could swap the cv off the front and onto the rear, but then you are going to have to pay to have a shop rework two shafts instead of just the broken one.

You can give my work a call and talk to Jesse.  I am not sure what our availability on cv's are but i believe we have some we could use.
If you wanted us to build your rear shaft, we could put a different cv on it/clearance it/etc.  Whatever you decide you want.

http://www.highangledriveline.com/

guess thats gonna be it. im not too worry about the front shaft since i have extra parts laying around.. that double cardan is a hard piece to find. and at the end its more cost effective..

[tyes [OP]]

DS was balanced with a new double cardan joints, it was also shorten to give it some play, and grease up and still, it vibrate at the same speed just a tad to where you'll notice its there... i seem pretty happy with it from time to time... But long term, would it cause problems??? or what may be causing the vibrations???

[8D3TOY]

Are the locking hubs in good shape?  I had one locked all the time did darn near the same thing along with massive death wobble.

[tyes [OP]]

Are the locking hubs in good shape?  I had one locked all the time did darn near the same thing along with massive death wobble.

yes those are in great shape. i rebuilt them 1 yr ago.. issue has to do with drive shaft i sappos.

[tyes [OP]]

DL measure from flange to flange = 39”

Measurements from:

TC (transfer-case) = 6*

DL (drive-line) = 22*

Pinion = 71* -- converted ( 90*- 71* = 19* )

My calculations: 22* - 19* = 3*

“3* shim” is needed to tilt the pinion up to align with DL.

Are my calculations correct?

[3toys]

From what I have researched and been told by driveline shops:  if you are running a DC at the t-case side of a rear driveline, the rear pinion should point at the t-case flange, or maybe 1-2 degrees down to allow for pinion to rotate up on acceleration.  If you have a single jointed shaft, the t-case and pinion should be at the same angle.  So if the t-case flange is down 6*, then the pinion should be the same.  Basically the flange surfaces should be parallel if you were looking from a side view, make sense?

Again, this is what I've been told, not having experienced personally...