K5 is back together.. driveline questions...

[POORBOYK5]

So I got my K5 all back together... took it for its first ride. What a Vibration! I never got to test drive it due to it having no trans....
My questions are


1. Is a new or lengthened driveshaft required with a 6" lift? I'm running a 700r4 with a np241. its just looks like wayyyy to much slip is hanging out IMO.
2. my blocks are angled and they angle the pinion up... should the shorter end be at the back to keep the pinion down?

 

[4X4HIGH]

That slip yoke is sticking waaay too far out. You will probably not get rid of the vibration until you do a SYE on the t-case and have a C/V driveshaft made. It will be a definate help though if you drope the t-case about 1" - 1 1/4" to help woth the driveline angle.

 

[POORBOYK5]

can I use those pesky spacers that gm put on the crossmember bolts? think those will be long enough?

 

[79-K5]

Aren't u-joints engineered to run at an angle? If so shouldn't the pinion not be pointing up as long as he has a non-cv shaft?

 

[4X4HIGH]

can I use those pesky spacers that gm put on the crossmember bolts? think those will be long enough?

Many people have moved those spacers around and put them between the frame and crossmember but that will eventually crack the frame. You need to make or buy the proper spacer which is one long piece of steel that is about 1 1/4" wide and at least as long as the crossmember is wide (front to back) so it doesn't stress the frame. Superlift used to make them and they are cheap ($20.00 or so).

 

[4X4HIGH]

Aren't u-joints engineered to run at an angle? If so shouldn't the pinion not be pointing up as long as he has a non-cv shaft?

Here is the problem. We are dealing with a short wheelbase vehicle and in order for a vehicle to not have a driveline related vibration two things must happen

(1) The t-case output shaft and the pinion must be parallel with each other (this can be achieved)

(2) A u-joint has a working angle of 3* or less before the joint will start to fail. In a short wheelbased vehicle you can achieve one or the other but usually not both at the same time.

If you have to sacrifice somewhere you are way better off to have the t-case output shaft and pinion parallel rather than worrying about the u-joint working angle. This way you generally won't get a vibration BUT the u-joints won't last very long.

The reason the t-case output shaft and pinion need to be parallel to each other is so that the u-joint angles at each end of the driveshaft are the same. As a u-joint goes through it's range of motion it is traveling in an arch which means that the u-joint speeds up and slows down and each end being the same angle cancels each other out and eleminates a vibration. If the angles are different they cannot cancel each other out and you will get a vibration.

 

[79-K5]

Yeah that is true. With a 6" lift and the short wheelbase the cv would pretty much be necessary huh?

 

[POORBOYK5]

Scott... Yet again, you save the day! I totally forgot about dropping the t-case. I'll do that tomorrow. That should also bring my slip yoke in a wee bit. I'll actually have access to a heated garage with a lift tomorrow Hopefully this will reduce my vibration and at least have enough slip to where I can stand to drive it! Cash flow wont allow for the SYE and CV shaft for a while...

 

[4X4HIGH]

Even if you can't afford a C/V shaft and SYE you will need to have that existing shaft lengthened. It is too short. It "might" be ok for street driving depending on how much spline engagment there is and also if the yoke slips far enough into the tailhousing bushing to keep it happy but the first time you tried to wheel it and got some droop say goddbye to the shaft as it will fall out of the t-case.

 

[POORBOYK5]

I getcha... I'm mainly just needing it to get back and fourth to work for now, The girlfriends mustang got banged up and will be at the body shop for a couple of weeks. So, she'll be driving my sweet little KIA Sorento. I cant live with just one car. I'll def be measuring the distance that the shaft goes in the tail housing. If it seems like enough, I'll use it.. if not, well then I'm F*%ked.... know of anyone that has a lengthened shaft they're not using??

 

[scrappyk5]

Definatly drop the t-case with the spacers, but if you can get some 1x1 tube that goes the full lth, it will be much betta. you will still need to lengthen the driveshaft or add the cv. as said before the driveshaft will either come out or even worse bind up and trash your t-case.

 

[tRustyK5]

I don't see shimming the pinion up 4 degrees being the end of the world in this case. It's pointing down pretty severely in the pic. I'd say drop the T-case a little, shim the pinion up a little and you may not have to lengthen the shaft at all.

Rene

 

[POORBOYK5]

Its actually pointed up towards the case.... I got some 1 1/4" square stock to drop the case some. That should get me pretty close on my driveline angle. Talked to a local driveline shop today, said they'd lengthen the shaft for about a $100 bucks.

 

[obijuan]

that slip is out about 4 inches too far!!!!
i would shim the pinion up a little further, maybe 3-4 degrees, dropping the tcase will help for DDing it and definaltey have that shaft the right length.
inspect and maintain the ujoints sorta like you change the oil.

 

[tRustyK5]

Its actually pointed up towards the case.... I got some 1 1/4" square stock to drop the case some. That should get me pretty close on my driveline angle. Talked to a local driveline shop today, said they'd lengthen the shaft for about a $100 bucks.

It needs pointing up even more. The pinion side of the driveline looks near to binding. Definitely do this before have the shaft lengthened. You'd be surprised how much the shaft will move when you rotate the pinion up.

Rene

 

[4X4HIGH]

If he keeps the slip yoke driveshaft he needs to make both the t-case output and pinion parallel to each other (whatever that entails, either pinion up/down or t-case down).

 

[diesel4me]

Could he gain the extra length he needs by adding a CV yoke to the transfer case end of the shaft??..that will help the vibe problems too along with getting the pinion angle corrected..

 

[scouthead]

Im on board with fixing the u-joint angles first, then seeing how the shaft length is. When I put the 4 inch lift on my Blazer, looked real bad...
T.C. came down 3/4 inch, pinion went up about 2 degrees, and upper and lower joint angles are within 1/2 degree at ride height. No bad vibes, and slip yoke went almost all the way back to the exact same place it was stock.

That was only lifting 4 inches though...

 

[4X4HIGH]

Could he gain the extra length he needs by adding a CV yoke to the transfer case end of the shaft??..that will help the vibe problems too along with getting the pinion angle corrected..

Yes but he said he doesn't have the cash for a SYE kit and the slip C/V is junk at best.

 

[POORBOYK5]

dropping the t-case helped ALOT! very slight vibration. still not in as far as I want it. I took it on a light wheeling trip to do a little flexing and inspect the slip while flexed. looked ok. Still wanting to do a SYE with cv. I hear people are running Ford Super Duty front shafts in the rear? I'm kicking myself now for getting rid of a TH350 style NP205 that I now know would have mated to my 700 with a little work....