I have a early 70's TH 350 Transmission , I am tying to slide the slip yoke on to the out put shaft. The yoke has 26 splines with one wider flat spline. So I ***ume this is a 27 spline. From looking at the posts this should fit. The output shaft doesn't have the flat space between the splines. The yoke slips on about half way before it starts getting harder to slide on . Any suggestions ? I also tired a yoke from a TH 200 with same results.
probably a buildup of rust/dirt/crud on the splines , either on the output shaft or in the slip yoke. if it will go halfway it can go all the way
At halfway it probably starts to enter the sleeve bearing in the tailshaft. Is the outside of the yoke clean with out any rust on it?
Two things. Dirt has been covered, down to one. The slip yoke in question is twisted inside the splines from either abuse or rearend failure. Part numbers for replacements. 2-3-6081x for outside snap ring 1310 series, 2-3-12051x for 1330 series like a GM pickup aluminum shaft 700R4 yoke. Neapco N3r-3-6081x for the inside snap ring 3R common stuff in Monte Carlo and larger GM cars 73 up.;
Almost has to be the output shaft from the description .Two different yokes- same problem. Also the bushing is right behind the seal. Wouldn't go halfway. I've seen some rusty stuff people have laying around, then try to use. Take your spare and tap on it with a br*** hammer. What's it gonna hurt? Either that, or take the tailhousing off and see what's going on.
You can eyeball a twisted spline by shining a light down the length of the spline in the yoke. Typically it's about half of a spline twist counterclockwise to the normal clockwise rotation of the shaft. Reverse drops, making J's, sudden differential ring & pinion lockup and failure, on the street. And if that twist is found, being a driveshaft builder, I would have the shaft checked for straight, because 8 out of 10 driveshafts ***ociated with this problem are twisted. Back to rust or dirt. You won't recover correctly from rust due to pitting and metal swell from the oxidation. Just as garbage as a twisted yoke.
The output shaft is a lot harder than the slip yoke. In my 28 years of dealing with driveshafts, I only saw one twisted output shaft on a Thunderbird Super Coupe, and the speedo had a reading because the break was forward of the slip yoke. ONE.
Typically a truck fixed yoke TH400 situation. The car slip yokes had a long counterbore to allow for the boss and o-ring on the output shaft that was larger than the minor diameter of the slip yoke splines. Meaning the points of the slip yoke splines are too close. The redneck cure for using a car type slip yoke in a truck transmission is to hog out the splines with a stone on a die grinder. I did this on the slip yoke for the Eastwood & Barakat sedan driveshaft in anticipation of problems. Mark, you are on point as always.
We always check the output shaft on any open drive trannies we rebuild, using a good slip yoke we keep in the shop for that purpose. I actually did have at least two twisted shafts that prevented the slip yoke from sliding on. First time was a "come-back" that the customer couldn't install a fresh slip yoke on. Second time was one we caught before trying to rebuild with it. Clean splines and no burrs.......just a slight twist. We ALWAYS check this now.
I know this is an old thread, but I've just run into something strange in relation to a Neapco N3R-3-6081x / GM 7812557 yoke I'm using in my V8 240Z with a BW W/C T5 with G-Force gears and shafts. I had to space the Sonic bellhousing off of the engine about 0.4" to get enough room in front of the RAM HRB for air space (0.200") between it and the back of a RAM Concept 10.5 dual disc clutch. This pushed the transmission output shaft enough to make the driveshaft too long. It would actually fit fine if the slip yoke were machined correctly. About 2/3 down the slip yoke, one side of the splines get wider by a large amount, keeping the slip yoke from sliding onto the shaft enough to install it. There's about 1.5" of splines in the yoke that can't be used. I'm not sure of the brand of this part, as it's been in the car for a decade or more. Anyway, sometimes part aren't machined correctly and it bites you in the ***. I'm going to order one, but I will be speaking with whoever I order from before hand to have them inspect the part to make sure the splines are fully machined. Seeing this thread, I wondered if the OP had gotten a poorly machined yoke like I have.
The Jalopy Journal
