CUCV Driveshaft Length

[SquareBody]

Hey guys,

ran a search and came up with two threads about modified CUCVs. One guy got flamed and never followed up, so here I am.

I have a SRW pickup with factory drivetrain ( Th400/208 ) minus the 6.2–nothing has been moved from transmission back. I began experiencing a harmonic vibration that was noticeable above 55mph. I did the usual balancing of the driveshaft and replacing u-joints—still there. Someone suggested my torque converter even though it and the flexplate were brand new. I replaced both—still there. It’s worth mentioning that I have a new small block direct from GM, new factory serpentine setup, new front accessories, new motor and trans mounts, etc. The trans fluid was perfect when I installed the deep sump and new filter. The transfer case fluid was also immaculate, but I noticed my driveshaft looks short. I mean really short—3 and 1/8”+ of exposed yoke. Not the typical 3/4 to 1-1/4” that most experts on the matter recommend.

I’m having a driveshaft shop re-tube my driveshaft, which I believe is the factory unit. It has Spicer stampings on both ends and both yokes. I’m also replacing my tail housing bushing and seal. I hope this solves my issue. Otherwise, I’ll tear down the 208 for a rebuild with all SKF components and a cloyes chain since that’s the next cheapest link at $200 in parts. After that the only parts left untouched are the rear diff and th400. The TH400 shifts perfectly and the rear end and it’s oil looked great. Although, I do want to put an Eaton Truetrac in to give better drivability on icy turns.

Does anyone else suffer from a short shaft on these trucks? Maybe my truck’s shaft was bent and they put a blazer one in?

 

[richingalveston]

for a slip yoke, you have way to much sticking out. no way to get a blazer shaft in there, they would not reach the tranny.
most likely the drive shaft was repaired at one point and not done correctly. your vibration will probably go away once the drive shaft is repaired propperly

 

[SquareBody]

for a slip yoke, you have way to much sticking out. no way to get a blazer shaft in there, they would not reach the tranny.
most likely the drive shaft was repaired at one point and not done correctly. your vibration will probably go away once the drive shaft is repaired propperly

When I had it rebalanced and new u-joints installed they said it was perfectly straight and only barely out of balance. I’m hoping they paid close attention, as the same shop is building the longer one.

I blame myself, as I pulled the driveshaft and brought it in to the shop. I should’ve noticed the length issue then; before I wasted $130 on the balance and joint install.

 

[NDT]

Agree way too much slip joint.

 

[SquareBody]

Well I’m hoping this fixes it then. It’s been a long road restoring this thing. Worst case is what I’ve budgeted for, but I’d like to hold onto that cash for now.

Somebody local sells rebuilt TH400s for $995 plus $200 core. Is there anything special about the CUCV TH400 to make it worth paying the $200 to keep it or is it like all the rest? I’d probably hold onto it anyway to learn how to rebuild automatics.

 

[richingalveston]

the cucv has an HD case. not sure how it differs from regular th400's but there is an HD stamped on the case of the cucv TH400 that is not there on civy tranny's

 

[cucvrus]

NOT all CUCV's have that HD embossed on the transmission housing. I bought a new case in 1996 and GM must have know of a weakness in the tail flange section because the new replacement transmission case was twice as heavy in the rear flange section. And yes square body you have way too much slip yoke hanging out that transmission. M1009 Blazer shaft is only half as long as a K30 rear driveshaft. Good Luck. It needs re-tubed and balanced. Have a Great Day and Be Safe. I have a stock rear K30 shaft if you need a weld to weld measurement.

 

[NDT]

For sure have your transmission rebuilt. Likely just needs a few soft parts. It is special because of 4x4 tailshaft etc.

 

[cucvrus]

It may be the M1009 K5 Blazer that do NOT have the HD embossed in the case. But I have removed them from truck models also that the HD letters were not present. Not sure of the logic. But the last 9 of the VIN are on the ear of the transmission. It was a match for the vehicle I removed it from each time. This was a rebuilt transmission that I installed in my Mule M1009 in May 2015.

 

[SquareBody]

NOT all CUCV's have that HD embossed on the transmission housing. I bought a new case in 1996 and GM must have know of a weakness in the tail flange section because the new replacement transmission case was twice as heavy in the rear flange section. And yes square body you have way too much slip yoke hanging out that transmission. M1009 Blazer shaft is only half as long as a K30 rear driveshaft. Good Luck. It needs re-tubed and balanced. Have a Great Day and Be Safe. I have a stock rear K30 shaft if you need a weld to weld measurement.

That weld to weld measurement would be greatly appreciated!

If I remember correctly, my trans had HD on one side in raised letters and 39 on the other side. It’s been a while since I put it back in.

 

[SquareBody]

It may be the M1009 K5 Blazer that do NOT have the HD embossed in the case. But I have removed them from truck models also that the HD letters were not present. Not sure of the logic. But the last 9 of the VIN are on the ear of the transmission. It was a View attachment 787351View attachment 787352View attachment 787353View attachment 787354View attachment 787355View attachment 787356View attachment 787357View attachment 787358match for the vehicle I removed it from each time. This was a rebuilt transmission that I installed in my Mule M1009 in May 2015.

Nice and clean! Did you just use degreaser and elbow grease or soda blast it, etc?

 

[SquareBody]

So I got the shaft lengthened and was installing new bearing, bushing and seal in the np208 tail housing and hit a snag. I was using SKF p/n 18998 for the bushing/seal but the OD of the bushing is too small. The thickness of the bushing’s sidewall makes up the difference.


The old worn out bushing mic’s at .007

The new bushing ID is correct but OD is too small. It’s thickness is .0055




Old bushing p/n is F-23

New bushing p/n is RP775 CZ

Any suggestions?

 

[Chaski]

So I got the shaft lengthened and was installing new bearing, bushing and seal in the np208 tail housing and hit a snag. I was using SKF p/n 18998 for the bushing/seal but the OD of the bushing is too small. The thickness of the bushing’s sidewall makes up the difference.


The old worn out bushing mic’s at .007

The new bushing ID is correct but OD is too small. It’s thickness is .0055




Old bushing p/n is F-23

New bushing p/n is RP775 CZ

Any suggestions?

I ran into the same problem and long time ago. I could swear I posted about it on the forum, but I couldn’t find anything when I searched. I ultimately went with the “shotgun” approach and ordered several bushings from Rock Auto and one of them fit perfect.

Also- have you measured your driveshaft angles?

Motive Gear WT297-62 is supposed to be a good bushing part number for the NP208. Look it up and see what you find