Front drive shaft is hitting

[John Reason]

Is there a spacer kit or special transmission crossmember I can get for my 83 K10. It's got the 700R4. My truck will shift into 4wd but makes an aweful racket and it appears to be the front drive shaft hitting the cross member. Been looking on line for he last hour and can't really find anything definite or I'm not asking the right questions. Need some help guys. Bought the truck already lifted and I knew it wouldn't shift into 4wd and now I'm starting to get the truck straight. I have attached a few pics from this afternoon.

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[84 M1008]

How high is the lift? That looks like an extreme angle on the front shaft, and I would imagine the rear shaft is as well. Looks like you need to fabricate some spacer blocks to drop the cross member enough to get some clearance.

 

[shiftpro]

How high is the lift? That looks like an extreme angle on the front shaft, and I would imagine the rear shaft is as well. Looks like you need to fabricate some spacer blocks to drop the cross member enough to get some clearance.

Look his cross member already has the spacers in between the frame and unit.

It also appears the rubbers are rotten and maybe that is allowing the the tail end to droop enough for contact.

 

[Customblue]

I had this issue when I swapped from the mm7 to the current trans, sm465. I cut the crossmember out of the way, just enough to clear the driveshaft and welded a plate to reinforce it
I'll try to post a pic later.

 

[CSFJ]

That may be the wrong cross member under it. Iirc, the later half tons got the asymmetrical trans mount, that dipped down below the front shaft, and went above the exhaust on the opposite side. That one looks like the one ton version.

 

[Jerry phillion]

Pull the drive shaft and see where it's been hitting. It'll be either the shaft or cross member. You may be hitting the balancing weights or a bad u-joint. If you have to drop the crossmember, you will have to put a like spacer under trans mount also, to maintain shaft angle. Also, ck for bad or loose trans mount.

 

[K201979]

X2 on the trans mount. Just went thru this with mine. Changed the chewed up mounts n no more racket. Good luck!

 

[bucket]

X3 on the trans mounts. Then grind some clearance if it's still needed.

That is the correct crossmember for an '83.

 

[Customblue]

CSFJ, was there a difference in frame widths between half tons/ three quarter vs one tons? If so, could one even bolt up a one ton cross member to a half ton frame?

 

[CSFJ]

CSFJ, was there a difference in frame widths between half tons/ three quarter vs one tons? If so, could one even bolt up a one ton cross member to a half ton frame?

all the cross members will bolt up to all the frames. The frames all shared the same width and footprint. The one ton frame rails were taller than the 1/2 and 3/4 trucks. They used a spacer arrangement to handle it from the factory. If bucket thinks that the one on your truck is correct for the year, he's more than likely correct. I've never really attempted to memorize which one came with what.

 

[bucket]

The "w" type was used in '85 and '86, the "s" type was used in '87-'91. They both used the short style t-case adapters with a single mount. 1/2-3/4 tons mounted below the rail, while the same crossmember mounted above the frame rails on the 1-tons. Military trucks were the exception, they stuck with the older style crossmember, using a tall adapter and two mounts.

 

[Customblue]

I didnt know that (obviously). Thank you for the info. I went from an 86 crossmember to an 81 and my front driveshaft was hitting but only slightly.

 

[bucket]

I forgot to mention that the '84 and earlier crossmembers did have a different version for the 1-tons. They looked basically the same as what's pictured above, but the ends didn't curve upward as much since the taller frame rails hang lower.

 

[84 M1008]

Look his cross member already has the spacers in between the frame and unit.

It also appears the rubbers are rotten and maybe that is allowing the the tail end to droop enough for contact.

Good observation.

 

[shiftpro]

Good observation.

Thanks. It's one of those cases where seen that-done that so it sticks with you. Driveline vibration that suddenly shows up... as the rubber gives up the ghost the tranny/TC slowly settles and one day starts to vibrate.