Driveline vibration

[frankenyota]

Need some help in diagnosing a vibration in the rear of my '83 Hilux.
The vibration seems to be worst at 95 - 110 km/hr, at that speed it is rattling the gear levers for the transfer cases.
At first i thought it had to be the rear tailshaft as it had single uni joints, so had a cv / cardan joint fitted and balanced. Then rotated the rear diff pinion to be 2 degrees lower than the tailshaft slope.
This seemed okay for a while but the vibration has come back?

It has a v6, auto with dual cases

Could the cv joint have gone bad or using an ifs cv not allowed for enough operating angle?
What is the optimal operating angle for these cv's?

Cheers
Matt

 

[jynx]

If the shaft and associated bearings are good then a quick check would be to give the pinion flange and transfer output flange a good shake. The tailshaft bearing or pinion bearings could be going down.

 

[2ndGenToyotaFan]

Check the condition of the motor mounts, specifically the Left hand side tends to fail first always... Have you had the tire balance checked?

 

[frankenyota]

Have some up and down movement in the transfercase output shaft, but it has always had some. From what i have read some play is normal.
Engine mounts are new, I will rotate the wheels to eliminate them.
it still feels like a driveshaft vibration.

If a track bar is fitted do you have to allow for a 2 degree difference from the tailshaft slope?

 

[EVILSPOTTER]

How much suspension lift do you have? On my 4Runner I used an old live axle style toyota double cardan joint to make my rear shaft. It would feel great until I jumped the truck, or did something to cause the rear suspension to drop out. After this nothing cold stop rear prop shaft vibration but replacing the double cardan assembly. I kept finding that the center trunion that holds the ball bent, but did not know why. I have since learned that exeeding the range of motion of a double cardan joint causes this.
Get a spare rear prop shaft made and if the spare feels good, diassemble your old DC joint & look at that center trunion. If it is bent, you may have too much suspension travel, or too much lift for that type of joint.

 

[EVILSPOTTER]

Driveshaft CV Modification for Increased Angle

This article from the FAQ says ifs DC joints are good for less than 25 degrees

 

[frankenyota]

The tailshaft slope is 16 degrees, 5 degrees at transfer output so the double cardan has a working angle of 11 degrees which seems ok to me, but maybe at high speed this is too much?

Have another double cardan so maybe a new shaft is in order.

 

[frankenyota]

Have done the mod to the IFS cv joint as it was at the max operating angle as Evilspotter sugguested.
The vibration is not as bad but still there?
I will run it without the wrap bar to see if that makes a difference.
I'm thinking that the wrap bar is working to stop all diff rotation, so maybe i need to rotate the diff to line up straight with the transfercase?

 

[bryan89]

.
Engine mounts are new, ....

what did you replace them with? mixing stock rubber with replacement poly mounts throughout driveline is generally not a good idea. they have different elasticities and can allow one half of driveline to deflect more than another under load.
so, i would make sure that engine and tranny mounts are both new, not worn out, and that they are the same material...

other than things that can cause it are:
pinion flange and trans output at different angles
out of phase drive shaft joints
un balanced / dented drive shafts
bad u joints
un balanced wheel
or under / over inflated tires.

if it aint one of those...you might have a bad bearing in the drive line somewhere.

 

[frankenyota]

Mounts were replaced with rubber replacements to suit the engine.
I run two transfer case mounts which are good.
Had the rear wheels rebalanced, which were slightly out.
Drive shaft in phase. Pulled the transfer to find the source of the movement in output shaft. Will strip and inspect.
Meanwhile i fitted another case i had with no play to test. Still need to drive it yet.
Is it possible for the shaft splines to be worn and cause movement?
Cause when i tried the flange on another transfer it felt much tighter ( without the nut on )

 

[bryan89]

i suppose its possible for a shaft spline to be worn, but i would be very surprised. (unless this truck has been beaten to within inches of its life)

when they are new, its a tight press fit between the gears and shaft, so there would be no way to develop wear (looseness) over time because there was no slop to begin with. its like one solid piece.
unless you seriously torqued this thing on the trail sometime...

my bet is that you have a bad bearing somewhere. the fact that you have one wobbly shaft and one not wobbly is testament to that