CK5
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Dips
- Thread starter 90GMCJim
- Start date
Dips as in squats ? Rear spring settling, maybe the wye bushing are bad.
Any vibrations at speed ?
Any vibrations at speed ?
No vibrations. Yes it squats. I checked for anything to be loose and found nothing. Could it be the brakes? I have rear disc brakes…..
So just guessing here but the axle maybe rotating under power and when you stop the pinion drops, and allows the springs to flatten out. Or what some will call spring wrap
I think the disc brakes could be contributing to the squat
Is the truck lifted? You can get binding in the driveshaft slip. The vehicle naturally leans forward during braking and it doesn't take a lot of force to hold it there. It seems like a shock could get sticky, especially if it's dented.
While I was turning wrenches for a living this was a very common cause from a complaint like this and is worse when lifted on such a short driveshaft length with a slip yoke at the T-case.
It will happen on stock suspension but gets exaggerated with lift.
Check for wear on splines plus the tail shaft housing bushing - for diagnostic purposes you could put some grease on the T-case output shaft splines.
Completely cover all the splines part of the shaft - you’ll need to remove the seal ( so get a replacement one before hand ) to accomplish this correctly. If you don’t lubricate all the splines you won’t get accurate results.
Than put a little inside the slip yoke - not too much because if it has more grease than it can handle it could hydro lock under compression and ya’ don’t want that.
Don’t worry about a little bearing grease contaminating the T-case ATF - there’s nothing inside that case that can’t handle a little grease.
If doing this confirms the issue then replace the bushing inside the tail shaft housing and thoroughly inspect for spline wear and replace as needed.
Or, just add this grease treatment on the splines as a regular ongoing preventative maintenance type of thing and drive it till the wheels fall off.
HTH’s, Tom
Check for wear on splines plus the tail shaft housing bushing - for diagnostic purposes you could put some grease on the T-case output shaft splines.
Completely cover all the splines part of the shaft - you’ll need to remove the seal ( so get a replacement one before hand ) to accomplish this correctly. If you don’t lubricate all the splines you won’t get accurate results.
Than put a little inside the slip yoke - not too much because if it has more grease than it can handle it could hydro lock under compression and ya’ don’t want that.
Don’t worry about a little bearing grease contaminating the T-case ATF - there’s nothing inside that case that can’t handle a little grease.
If doing this confirms the issue then replace the bushing inside the tail shaft housing and thoroughly inspect for spline wear and replace as needed.
Or, just add this grease treatment on the splines as a regular ongoing preventative maintenance type of thing and drive it till the wheels fall off.
HTH’s, Tom
Be sure to mark the alignment of the two pieces. There may not be an indexing spline
Also sounds like this has been apart recently, if the u bolts haven't been retorqued since assembly they need it.
Just goin by his signature name I assume that ride ( ‘90 K5 ) has a rear shaft fixed yoke NP241 ( so no getting the joints outta phase ) and there should be no absent spline marker position on the T-case output shaft.
Unless things have been changed ?
It almost feels like the rear of the truck is unloading when you're stopping then it settles back down as if the shock is not doing it's job.
Are the shocks worn out?
Not trying to labor on a certain point but if the issue is slip yoke related bind and release just replacing a new driveshaft slip yoke does not address the possibility of output shaft spline wear or the tail cone internal bushing potential issues.
Well there's no replacement for a good physical inspection. Take a prybar to things that shouldn't move, put a wrench on bolts that have been apart recently and make sure they're tight. If it's driveshaft binding, the behavior should be different if you put the transmission in neutral before coming to a stop.
put a go pro under there and video the slip yoke and pinon in action.
So I lifted it up supported under the frame and let the rear hang with the wheels off.
Everything looked good. Put a torque wrench on the u bolts holding the springs. The driveshaft had about an 1/8th of play back and fourth. I did bleed the rear brakes. After I drove around I haven’t noticed the dip again. Will have to drive around some more
Everything looked good. Put a torque wrench on the u bolts holding the springs. The driveshaft had about an 1/8th of play back and fourth. I did bleed the rear brakes. After I drove around I haven’t noticed the dip again. Will have to drive around some more
