88WHITE VETTE

I am in the late stages of the auto to 6 speed conversion.
Other day I installed the drive shaft and noticed "BIG" clearance betwen the output shaft and the yoke.
"BIG" means it moves slightly when I put pressure on it from side to side. Also I purchased the ZF6 from one person and yoke from another so it's not from same car.
I went to the one junkyard and found 2 more yokes and measured all of them and they all came same measurment ?!?!?
If any of you have easy exess, could you try to fit those two and see how they fit. Is it loose or tight.
I have my auto still in garage and that combination is nice and tight (when in, almost no play at all).
TIA

Ziggy

comp

do you mean loose on the spline's or loose in the seal /bushing ???

LD85

There is a big gap, maybe 1.0 inch or more, but if you get the new Federal Mogul ZF6 output shaft seal, it has a big rubber boot that covers that area.

88WHITE VETTE

There's no clearance on the output shaft from the trans. but "play" betwen the output shaft and the yoke. Seal fits fine around the yoke, it's just that "play" that worries me.

I am not sure if I am explaining my self clearly, but let me try again.
The output shaft has those long "groves/keyways" on the outside and yoke has same on the inside diameter. That's where the clearance is betwen those 2 when they are joint together.
Ziggy

LD85

So you think you have play on the output shaft/yoke splines?

How much radially?

88WHITE VETTE

That's the one!!
I have not measure how much, do you know what is the range of good and bad?
I looked thrugh my manual, but could not find anything on clearance.
Ziggy

LD85

Well I dont have the ZF 6 to check, but I just checked my 4+3 yoke and there is little to no play radially,

Is there a part number on the yoke? If so go to www.gmpartsdirect.com and type in that number to identify the part/year maybe

Mr6spd

The loose fit may be a problem. I recently had a custom driveshaft made with 1350 series U-joints. When I installed it, the transmission yoke definitely seemed to have a too-easy fit to it, and it went in about 0.25 inches less than the original.

Well sure enough, it resulted in a drive shaft vibration. I called Denny's Driveshafts (not the company who made the shaft), and ordered a long TH400 yoke (same spline as ZF6). I slipped this baby on the trans to check the fit (OK pushed it on), and needed screw driver to pry it back out. It fit's nice and snug. It's not overly snug, I just did not have much leverage to pull it back out by hand. What a difference. I feel a lot better about this one. I then determined how long I could have the slip yoke, while still being able to install the other end of the shaft into the rear axle yoke, and cut the trans yoke to that length. Then I took it to be computer balanced, and it needed no balance adjustment. I have not put it back in yet, but I hope this solves the problem.

pablocruise

My ZF is out right now.
Inserting the driveshaft into the tailhousing of the ZF and onto the splined output shaft, I have no play at all.
The rear seal is federal mogul part # 4334....(or is it 3443???)
I do know that the input shaft size changed in 92ish I think. Before that they are thicker.

LD85

Do you mean the pilot bearing end / hub is thicker?

h rocks

My guess is that you have 94+ ZF and an 89-93 yoke. The later ZF's output shaft is about .035" smaller than the "old" ones. Both are strong transmissions, but the "old" ones were officially rated to handle 450lbs/ft of torque, the 94+ rated @ 400lbs/ft. IMO, both are very conservatively rated. Just get the correct yoke and you should be fine. PS. make sure that you have the correct clutch also. Happy shfting!

88WHITE VETTE

From what I know,I have 93 ZF6. It also has the reverse lock on the shifter.
I was talking to the junk yard, and they said that all of them had same diamater output shaft. The diffrence in power rating was related with the gears cut not the size of the shaft. Again, I am new to ZF6 and glad that I found the "potentional live shortening" problem.
I will be calling Superior Chevy tomorrow to find out if there are 2 part numbers for the yoke betwen 89 and 96.

I opted for the McLoud street twin clutch package. So far it's installed and working fine (with car off and 20" of the ground). When I start the car than I will post more about it. Only thing that I did noticed, the clutch is very hard, I might be having some air in the MC butI will try to bleed it again after I drive for few miles.


Ziggy

88WHITE VETTE

I forgot, I went to local dealer and the only way they would sell the yoke is with the drive shaft and u-joints complete as 1 unit for almost $400. I was shocked so much that I forgot to ask about the part numbers diffrence betwen the years.
Ziggy
Just wenting!!

LD85

('89-'96) MN6 Drive shaft P/N 12557818
www.gmpartsdirect.com

GM PART # 12557818
CATEGORY: Propeller Shaft
PACK QTY: 1 CORE CHARGE: $0.00
GM LIST: $325.25
OUR PRICE: $185.39
DESCRIPTION: DRIVE SHAFT

h rocks

Ding, ding, ding, ding...If it has the OE shifter, it's the "older" (better) one.

Good move!

The yoke thing bothers me though. Need more info, or hands on. Good luck!

88WHITE VETTE

Thanks Id85,
So, acording to this, there's only one part #. I am scre....d!
Worst of all, non of the parts look like they are worn out.
I went to the garage again, and when the yoke is all the way in (until the rust spot) and move the yoke up to down or left to right, I am getting about 1/16" movement on the end of the yoke where the U-joint goes in. The OD of the output shaft is 35.01mm on top of the spline. The ID of the yoke is 35.48 inside the spline, diffrence of .47mm .When I take my 700R4 yoke and shaft, the diffrence is about .1mm in the same spot.
Ziggy

LD85

I measured my yoke ID, between the splines, side to side....35.5mm

This/my yoke fit nicely onto the 1992 Black Tag ZF I just took back, I will check out the new one I bougth when it gets here, problem is, GMPARTSDIRECT is where I got it so it could be a couple of weeks.

MarkBychowski

This one is really bugging me, Ziggy -- hopefully Chris at superior can tell you for sure if there are two different part numbers for the Yoke. Worst case, since I need to change the rear spring on my car, change the fluid, etc. (which I'll probably do at your place anyway ). While it's in the air, we can pop the driveshaft off and measure mine.

I really hope we don't have to yank the trans out again. If we do, I'm bringing over my trans jack and bigger jackstands!

scorp508

I have a ZF6 yoke I can measure at home that I bought on eBay. I forget what year it is from, but maybe I can find the site still.

scorp508

Well here is the auction, http://cgi.ebay.com/ebaymotors/ws/eB...tem=7908992434 ... so I'm going to guess it is an early model yoke since the guy says he has a black tag tranny for sale also.