Driveline vibration after 6" Slee Springs install??? (1 Viewer)

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cc93cruiser

cc93cruiser

CRUZAHEAD
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Feb 2, 2004
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Hayward, Ca.
Hello folks, how's it going...I actaully just had a few questions regarding some drivline vibes I am now getting with my newly installed 6" springs. Before I purchased the springs, I actually thought that my cruiser already had the full Slee Suspension already installed into the cruiser(the guy I bought the 80 from had told me that it had every Slee's Suspension part installed-which it does, execpt for the rear upper control arms......needless to say I am not that happy with this.....)I just recently discovered after the 6" springs install that I have some really bad drivetrain vibes coming at only approx. 20 miles an hour. Before and after approx. 20 mph it drives smooth...The front drivshaft is a double cardon + I have the slee front control arms, so I doubt the front driveshaft is causing any bad vibes.. So I am pretty sure that the rear driveshaft is causing the bad vibes since I have NO upper rear control arms, NO double cardon rear driveshaft... Not having these parts would be enough to cause my cruiser to have these bad vibes at 20 mph, right???? The cruiser starts to shake at this speed pretty violently.....

Oh yea, knowing that I have to get these rear upper control arms to fix this problem, how do you adjust the arms.. Do you have to adjust them with them installed, or before you bolt them on to the rear differential? Typically when you guys install these 6" springs and the rear upper control arms, do you guys adjust the arms to be longer or shorter to fix the pinion angle??------thus eliminating driveshaft vibes...)
 
Dunno much about any of all that, but you can isolate the vibe, by pulling your front or rear shaft and locking the CDL.
Good luck,
Dan
 
It’s been a long time since I installed my suspension, but doesn’t the kit only come with one DC shaft which goes in the front?
Consequently, you will want to set up Slee’s upper rear control arms to be shorter than the stock arms. IIRC, the difference was about ¼”. Call Christo’s shop and ask. They’ll know for sure.
Have you checked to make sure that the tires are balanced properly as well?

:beer:
 
You have changed the geometry on the rear driveshaft which as a single joint shaft, is designed to run at -1.5 degrees difference between the output flange on the tcase and the pinion flange. I have seen trucks without the adjustable rears NOT vibrate because they are within the 1.5 degrees, but as Christo informs us, most likely the shaft will eventually. When you tilt the pinion up, you will have to run the Cardan shaft in the rear. They are designed to run with the cardan at the output shaft end taking all of the angle, and the pinion end being parallel with the pinion shaft. Your vibration being at such a low speed could possibly be patched by installing new Toyota ujoints because, the old ones may have a wear pattern in them from the previous height or it could also be that the slip yoke is worn allowing the shaft to rock back and forth in the receiver flange, but in the long run you will want to do the arms and cardan shaft. The arms are adjusted to be longer and need to be done on the truck. A simple straight edge is what I used on my truck to make sure the piion shaft is parallel to the driveshaft. I then measure the distance from the upper mounts to the frame to make sure each arm is the same length.
Gary
 
Last edited:
Waggoner5 said:
The rear upper control arms have adjustable collars welded in to allow you to lengthen or shorten the arms as necessary. It allows you to point the rear diff more directly at the transfercase, but in doing this you have now changed the geometry on the reardriveshaft which as a single joint shaft, is designed to run at -1.5 degrees difference between the output flange on the tcase and the pinion flange. ....
Gary
Click to expand...


I know that there are a lot of variables at work here but my truck has been vibe free for the past 20k miles without the D/C rear shaft and I don’t want to see people spend money that they don’t need. Why not just try the adjustable rear upper control arms to shorten the link thus moving the rear pinion angle down to make the two flanges more parallel? If that doesn’t work then pony up for the D/C rear shaft and adjust (lengthen) the upper rear control arms. That way you don’t end up paying for the D/C rear shaft unless you really need it.
 
That sounds like the best idea. Have you looked at the angle differences now? The last set of 6" springs that I installed the difference was only .5 of a degree. I drove the truck to 90 mph on an exceptionally smooth road and had 0 vibs. I don't like the angle of the driveshaft itself though. If you did any type of wheeling where the axle dropped out, I am afraid that the joints would bind quick, and I think thats what Christo has addressed with the new shaft and adjustable arms.
 
I just pullied the rear drivshaft off and drove well past 20 mph, and you guessed it, no driveline vibes....... The rear drive shaft is the one causing all the vibration underneath.... My next question would be, what should be bought first? The rear double cardon driveshaft, or rear upper control arms?? Or both???? What you guys think...Many thanks for the input guys :cheers: ...
 
I knew that was coming, oh well gots to spend a peso or two....
 
thanks Christo... I am going to have to call you in about a week and just most likely order both...
 
rear uppers

Waggoner5 said:
You have changed the geometry on the rear driveshaft which as a single joint shaft, is designed to run at -1.5 degrees difference between the output flange on the tcase and the pinion flange. I have seen trucks without the adjustable rears NOT vibrate because they are within the 1.5 degrees, but as Christo informs us, most likely the shaft will eventually. When you tilt the pinion up, you will have to run the Cardan shaft in the rear. They are designed to run with the cardan at the output shaft end taking all of the angle, and the pinion end being parallel with the pinion shaft. Your vibration being at such a low speed could possibly be patched by installing new Toyota ujoints because, the old ones may have a wear pattern in them from the previous height or it could also be that the slip yoke is worn allowing the shaft to rock back and forth in the receiver flange, but in the long run you will want to do the arms and cardan shaft. The arms are adjusted to be longer and need to be done on the truck. A simple straight edge is what I used on my truck to make sure the piion shaft is parallel to the driveshaft. I then measure the distance from the upper mounts to the frame to make sure each arm is the same length.
Gary
Click to expand...

The arms are adjusted to be shorter, unless you put in the DC then you lengthen them back out and Yes, it can be done on the truck. I have the exact same problem!! I have the rear arms adjusted/shortened all the way. WHICH turns out to be the wrong thing to do!! FAUK! Like they said get the rear arms first, the DC may not help if its really bad. or try adding some weight to it. If you had a few people in the back or a bumper it will make a ton of diff. I had some 10mm packers above them and took them out and it made alot of difference. still pretty bad tho at 20mph and when i let off the gas and im goin downhill. hope it helps
 
Last edited:
cc93cruiser said:
I just pullied the rear drivshaft off and drove well past 20 mph, and you guessed it, no driveline vibes.......
Click to expand...


You might want to replace the rear and pull the front. Some have reported that either shaft will releave the problem. Then it becomes a task in identifying which end is the cause.
 
landtank said:
You might want to replace the rear and pull the front. Some have reported that either shaft will releave the problem. Then it becomes a task in identifying which end is the cause.
Click to expand...

This is true, however since his front driveshaft is a double cardan I'm willing to put money that the vibes are his rear shaft. I could be wrong... but I'm probably not.
 
and I ask .. why some aplication need CV rear drive shaft and others no . ? the real lift ( plus rear bumper, tirerack, roof rack .. etc . ? )
 
I've got the Slee 6" lift, full kit, with no DC rear DS. No vibrations. Try the arms first. I did replace my U-joints at the time of the lift as PM.

-Spike
 
It is not a one or the other thing.

Dual CV shafts need the pinion pointed at the t-case output.

Shafts with a single joint at each end need the pinion flange and the t-case output parallel.

Gary had this covered, but pulling it out like this should help clarity.

Arms alone MAY do it.

Arms and shaft SHOULD do it.

Shaft alone will likely NOT do it.
 
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