Hey, is there a formula or rule of thumb by how much engagement the slip yoke should have on the output shaft of a transmission? i did a search but not finding anything would a distance equal to 2 output shaft diameter be adequate? M23 manual transmission with 1-3/16" dia output shaft, 550ish HP, 1330 hardened yoke, 3,320lb car empty (3,530 with my fat ass), 4Krpm launches with 12" wide m/t dot approved tire. thanks charlie
On a normal car 1" is enough. It depends on the rear axle movement and the angle of the drive shaft. A jacked up pickup truck with the shaft at a steep angle might need more. I put that in because your avatar is a jacked up Chev.
as much as you can get, and still not have it bottom out on bumps, or prevent you from removing the driveshaft. 3/4 to 1 inch slack is what I aim for.
Is this the Autogear trans? I thought the M23 had the larger output shaft (turbo 400 size), 1&3/8" dia.
If there is no stop inside the trans and the only stop is the yoke hitting the seal/end of the trans there are yokes available for use in circle track applications which are a lot longer since our rear suspensions travel a lot. We have even bought the longest ones and cut them for certain trans applications. Good luck.
1" is what my driveline builder says/recommends. He always has me insert the yoke 100% into the trans then measure center to center on the u-joint centers, he then subtracts 1" for a finished length. At least 6 drivelines now with no issues.
I'd go with the 3/4 to 1 inch. Too much sticking out and you will eat up the bushing in the tail shaft. That from personal experience the first time I took the 48 to an event with a freshly installed open drive setup.
thanks for the reply's guys, my issue is i buggered up my old drive line and had the shop make me a new one , same length but with new 1330 hardened ends (the last one was 1310...yeah, I know). so I get the drive shaft back and try putting it in Friday night and no way...its too long. I didnt measure the shaft length when i had them redo the ends, I just told them to do same length. So right now it's maybe 5/8" too long with the output shaft completely bottomed out in the tranny yoke. with the tranny yoke completely bottomed out inside the tranny, it's engaged on 3" of the spine. there appears to be more spine in the yoke but I cant get the yoke any more than 3" past the end of the output shaft. I'm gonna call A.G.E. tomorrow morning and ask them about that before I head over to the drive line shop. so my dilema is I need to have at least 5/8" of slop in the drive shaft to remove it from the diffy if I need to ( one half the 1-1/8" u-joint cap diameter). so 3" minus 5/8" leaves me with...2-3/8" of engagement if my math is right. the output shaft is 1-3/16. so if two diameters output shaft is the rule, then I'm pretty damn close. and of course all this happens the weekend before the march meet. I'm gonna be at the drive line shop first thing in the morning and hopefully they can shorten it while I wait. plan is to install tomorrow, test it Tuesday (supposed to rain here tomorrow), and trailer it to Bakersfield 5am Wednesday morning...if all goes well.
with the yoke bottomed out in the tranny I have 1-1/2" of yoke exposed. 5/8" of that has the output shaft inside it so Ive got 7/8" spinning unsupported?
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