Half-shaft question

[padgett]

I have heard that there was a change in the transmission between 1988 and 1989 that resulted in a change to the half-shafts. Does anyone know ? Group 6.055 in the parts manual looks like the same halfshafts were used from 1988 to 1990.

[Guest TommyH]

i think the only difference was the splines or something.

[padgett]

That is exactly what I need to know. Can anyone say for sure ?

[Guest Greg Ross]

Padgett,

From my experience with Alterations the issue affecting half shafts is the Wheel Bearing. After '88 the wheel bearing was increased in size and was the same for '89 thru '91. Every time I've done a half shaft with the Getrag Tranny I run into the outer wheel bearing issue and we have to scavange outer knuckle parts to customize the Getrag/ W-Body half shafts. I've done it twice. Yours is an '89 right, you should be fine.

The next time I do one I'll replace the Wheel Bearing with '89 and after and keep the 1/2 Shaft as is. (find a used '89 Hub/ use new bearing)

[padgett]

Do you mean the spline on the CV knuckle that slides into the wheel bearing assembly is different 88-89 ? (Mine is an 88) But the splined opening in the transmission is the same ? Am trying to determine if you can swap transmissions between 88 and 89-90 or if a half shaft change is needed also.

[Guest Greg Ross]

Yes, the spline size thru the wheel bearing is the change from '88 to '89 , the tranny end will be the same. It's a bit of a nuisence but not terribly complex to disassemble the C/V Outer to blend parts and adapt the 1/2 Shaft.

[Jim]

Greg is correct on the shaft differences.

On the transaxle end the diameters are the same for all years but on the outer end, the '88 axles have a spline diameter of 1.116 inches and the '89-91 outer spline diameter is 1.413 inches.

I have good used half shafts for all years.

[Guest Greg Ross]

Jim,

With the change/ increase in the front spline from '88 to '89 I'm assuming the bearing is larger? is the Hub also different?

[Jim]

I went and visually compared an '88 knuckle and bearing assembly to an '89 and it looks like the hole in the knuckle where the bearing goes in is the same size. The part of the bearing race that meets the axle is thicker on the '88s to make up for the smaller axle. It looks like if a person wanted to put the larger splined axles in an '88 they would also have to add/use the '89-91 bearing assembly in their '88 knuckle.

I did see another difference between the '88 and newer knuckles in that the '88 has a bolt on aluminum piece to hold the ABS wheel speed sensor whereas on the newer ones this holder is cast into the knuckle.

[DAVES89]

I went on line at advanced auto parts .com and the drive shaft numbers for both right and left side are the same for both '88 and'89.