Magnetic transmission input shaft bushing

[Jeffrey B.]

I pulled my transmission because I was getting noise when the clutch was depressed. Eveything checked out including the throw out bearing which I had replaced last year when the tranny was rebuilt. The problem appears to be the input shaft bushing which I had forced in 3 years ago. the reason I say forced is because I found out later I had squeezed a standard size pilot shaft bushing into a powerglide crank which should not fit. I think it caused an early failure of the bushing. My problem is I just ordered and received a Dorman powerglide adapter pilot bushing that should be a proper fit to replace the failed bushing but it is magnetic. I've heard nothing good about using magnetic pilot shaft bushings on the post I read here. I hate to put that magnetic bushing into that crank if its going to fail prematurely, and I lay under my car on jack stands to do all of this work which is no fun for a 66 year old guy. I guess my question is why would they make these bushing with this material if they will fail early? Or are they OK to use? Any feedback would be greatly appreciated.
Thank You in advance.
Jeff

[Joe L.]

Re: Magnetic transmission input shaft bushing

I pulled my transmission because I was getting noise when the clutch was depressed. Eveything checked out including the throw out bearing which I had replaced last year when the tranny was rebuilt. The problem appears to be the input shaft bushing which I had forced in 3 years ago. the reason I say forced is because I found out later I had squeezed a standard size pilot shaft bushing into a powerglide crank which should not fit. I think it caused an early failure of the bushing. My problem is I just ordered and received a Dorman powerglide adapter pilot bushing that should be a proper fit to replace the failed bushing but it is magnetic. I've heard nothing good about using magnetic pilot shaft bushings on the post I read here. I hate to put that magnetic bushing into that crank if its going to fail prematurely, and I lay under my car on jack stands to do all of this work which is no fun for a 66 year old guy. I guess my question is why would they make these bushing with this material if they will fail early? Or are they OK to use? Any feedback would be greatly appreciated. Thank You in advance. Jeff

Jeff----- 1) How magnetic is it? If it's strongly magnetic, that's bad. However, if it's only very weakly magnetic, that's OK. 2) Notwithstanding (1), I believe that Dorman is the only manufacturer that offers the conversion bushing you require so, to say the least, "your options are limited". When someone has the "only game in town", if you want to play, you have to play their game. Quite frankly, I'm surprised that ANY manufacturer still offers this bushing. The sales volume at this point has got to be absolutely abysmal.

[Jeffrey B.]

Re: Magnetic transmission input shaft bushing

Joe, The magnet seems to stick fairly well, which it is a strong magnet. I had contacted Dorman as they still show the conversion bushing in their web site catalog. They would not sell to me direct, but did say the bushing was available from one of their product vendors, ROCKAUTO.com. I had to buy a package of 5, but that was not a big deal. My hope is that the bushing would work and last, as Dorman offers many of the standard size input shaft bushings in their catalog. Also, the car is driven only occasionally and not driven hard. The only other option I would have is to have a standard size all brass bushing turned at a machine shop. Not sure how difficult that process would be and where I could have it done in my area. Appreciate the feed back. Jeff

[Erich C.]

Re: Magnetic transmission input shaft bushing

Autogear ( www.autogear.net ) makes and sells the "true oilite bronze" pilot bushings. They have an 800 number: 1-800-634-3001 . If you go to the website, click on "what's new" to show the pilot bushings. They also have brand new gearsets and parts for the Muncie trans.
Erich

[Ray G.]

Re: Magnetic transmission input shaft bushing

I pulled my transmission because I was getting noise when the clutch was depressed.
Jeff

Is it screech, like lack of grease on the bushing ? Is it a gear related tick/clunk or gear rubbing sound ? Does the clutch disc slide freely on the input shaft ? Is there a normal wear pattern on the throwout bearing ? Is it an all steel throwout bearing ?

[Jeffrey B.]

Re: Magnetic transmission input shaft bushing

I have everything apart and the pressure plate, clutch disc, flywheel surface, throw out bearing and clutch fork all look fine. The throw out bearing is all steel. I rebuilt the transmission last summer. I'm fairly certain the problem is the input shaft bushing that I removed.

[Marco H.]

Re: Magnetic transmission input shaft bushing

Jeff,
I have never heard of a power glide specific crankshaft. Why would GM do that? It was my understanding that the only difference was that the PG cars had no pilot bushing in place. On the car I just finished I had absolutely no problem installing the supplied pilot bearing that came with the kit. (Car was converted from PG to M20).
It is essential that you check the crank center line against the transmission center line (Bell Housing alignment.) Any excessive misalignment will cause premature pilot bushing, input shaft bearing wear or drive train vibrations. The last car of mine was off enough for me to install offset bell housing pins. I used a specific tool that bolts to the flange at the crank shaft. Since I use this, I have no more issues of noises and vibrations.
Hope this helps.
Marco

[Jeffrey B.]

Re: Magnetic transmission input shaft bushing

Marco, This is a guess on my part, maybe the 327 crankshafts when forged would accomdate a powerglide transmission but needed to be machined for standard transmission pilot bushings when used in that application. There are I'm sure members in the NCRS that could provide the answer to that question. Thanks for your input. Jeff

[Timothy B.]

Re: Magnetic transmission input shaft bushing

Can someone tell me what the specs are for a powerglide pilot bushing. I wanted to share on my 327 crankshaft (4577) I had to have the standard 1.096 OD bushing turned down to 1.086 because the crankshaft bore measured 1.084.

[Jeffrey B.]

Re: Magnetic transmission input shaft bushing

The I.D. 0.593", O.D. 1.060", length .751", that is for the powerglide adapter bushing.

[Timothy B.]

Re: Magnetic transmission input shaft bushing

Jeffery,

Sounds like the hole was drilled but not finished lathed to the exact spec. On my crankshaft I remember seeing the drilled hole with a taper from the drill bit and then a small step where the hole looked to be finished and installing the bushing to the step located it to the correct depth for the input shaft to ride in.

I also agree to check the bellhousing alignment as was mentioned above.