Input Shaft Questions

[Mike D]

So it seems that my transmission/rear end problems are due to a possibly bad input shaft problem. This appears to have caused the shaft to move under load and the helix splines were disengaging from the input shaft splines. This ended up destroying the inside of the helix. I can change the bearing without much issue. What I did notice is that my input shat has some markings/scoring on it and a flat spot. For about 3/4 of an inch beginning behind the keyway on the shaft is a flat spot with marks/scores around the circumference of the shaft. At the end of this area is a ridge that you can feel with your fingernail. This ridge is not as noticeable all the way around the shaft. The tapered area has markings/scoring in almost a diagonal direction along the remaining length of the shaft from the flat area to the splines. Is this a normal shape for the input shaft, or is it improperly shaped? I also can't tell if the splines on the shaft are damaged. Some look as if they may be worn more than others. Is there any way to check these? I'm trying to decide if just changing the bearing is needed, or if I should replace the shaft as well. I don't want to destroy another clutch and helix. Any help is appreciated.

[Dave in VA]

Not sure how the shaft can move to cause damage. If the shaft is properly installed, there should be zero endplay. I had to take mine apart several times to get the end spacers correct. Maybe the nut holding the secondary in place was loose. From the damage you describe, it sounds like you will need a new shaft.

[smallblock450sl]

You didn't say what model car you have. If you have a G16 or G22 (dana transaxle), the splines useually dont go bad,but the circlip groove (that holds the spring seat) away from the transaxle housing goes bad, but there is a special toothed spacer for that. If the input shaft is damaged (out of round or gouged) were the sliding bushing rides, it's toast and need to be replaced or you'll be hearing growling and feeling a vibration when you drive it. If it is a Dana transaxle, Tom @ www.cartpartsplus.com , site sponsor has the best price for a replacement input shaft and it comes with a bearing/seal and gasket needed. Good luck!

[smallblock450sl]

Great pix's Dave You just forgot the one with only the spacer/collar slide on the input shaft

[Mike D]

I'm sorry for not posting the cart type. It's a 1999 G16. I've never taken the tranny apart, and this issue didn't start for a couple of years. When I installed the Plowman's hot set up this began to happen. I called Don and he told me that if the bearing is starting to have trouble spinning, it can heat up the input shaft causing it to turn incorrectly. He also said that under load the bearing may be worn just enough to have the shaft wobble. I think the increase in power/torque may have caused the bearing to start acting up. I had the spacer installed with the clutch. The markings on the shaft are from the clutch moving improperly. The splines on the shaft show some uneven wear I'm assuming from the helix engaging and disengaging under power. The splines of the helix were jumping in and out of mesh with the shaft splines. I'm probably going to replace the shaft as well because some of the scoring is deep enough to catch with a fingernail, and Don also said that scoring that deep may cause the sheave to move incorrectly. Now it's the matter of taking this thing apart and putting it back together correctly. Should I take it out of the cart or is it easy enough to work on with it still in the cart?

[Dave in VA]

Originally Posted by smallblock450sl

Great pix's Dave You just forgot the one with only the spacer/collar slide on the input shaft

Thanks, Dave--I've knew I had that one somewhere... These aren't the best--I didn't have one with just the spacer on the new shaft...

[Dave in VA]

Originally Posted by Mike D

I'm sorry for not posting the cart type. It's a 1999 G16. I've never taken the tranny apart, and this issue didn't start for a couple of years. When I installed the Plowman's hot set up this began to happen. I called Don and he told me that if the bearing is starting to have trouble spinning, it can heat up the input shaft causing it to turn incorrectly. He also said that under load the bearing may be worn just enough to have the shaft wobble. I think the increase in power/torque may have caused the bearing to start acting up. I had the spacer installed with the clutch. The markings on the shaft are from the clutch moving improperly. The splines on the shaft show some uneven wear I'm assuming from the helix engaging and disengaging under power. The splines of the helix were jumping in and out of mesh with the shaft splines. I'm probably going to replace the shaft as well because some of the scoring is deep enough to catch with a fingernail, and Don also said that scoring that deep may cause the sheave to move incorrectly. Now it's the matter of taking this thing apart and putting it back together correctly. Should I take it out of the cart or is it easy enough to work on with it still in the cart?

Just jack it up and remove the tire. You'll have enough room to work

[Mike D]

That's what I did so far. I think I have room to fix it in the cart. With the picture of the input shat with someone holding it (maybe you), I can tell you better where the scoring is. The area to the left of the thumb on the taper has scoring around the circumference of the the shaft. The ridge that I mentioned on the shaft is right next to that area closer to the thumb. To the right of the thumb is where I noticed the horizontal scoring along the length of that area of the shaft. That appears to be caused by the moveable sheave not sliding parallel with the shaft. I'm going to order the shaft kit later today, and contact Plowman's for a replacement helix and sheaves. They are all damaged.

[Dave in VA]

Yep, that's my thumb and broken shaft. Good luck with your project. The CCP kit comes with the case bearing and seal, a new key, and I think 4 end spacers. The spacers appeared to me to be of 3 different thicknesses. I had to experiment with different spacers to get the zero endplay. If you get it together and have to take it apart again, be mindful of the seal

[Mike D]

I was going to see if I could purchase an extra seal and gasket. I like to have more than stress out over having to take the trans back apart and damaging something. I was thinking of using the same spacer that was already in the tranny, but I guess I should put in a new one since I'll have the parts out. I'm assuming that I can measure the thickness of the original spacer with a micrometer, and matching that to one of the new spacers.