Loose input shaft

nillle · Jul 4, 2006

Hi, I got the transmission, a 4 speed toploader, out of the car today and the input shaft seems to have a little play sideways. Not very much but it's not stiff.
I'm just wondering if that's how it's supposed to be?

ozstang65 · Jul 4, 2006

The front of the input shaft is supported by the spigot bearing in the end of the crankshaft when the gearbox is in place so a bit of play is normal.

zookeeper · Jul 4, 2006

A small amount of play is totally normal and also the reason a good fit on your pilot bearing is needed. I swap in a new pilot bearing anytime I do a clutch job in a manual trans car.

dennis112 · Jul 4, 2006

A little is OK. If you were able to touch the outer part of the throwout bearing retainer, then you have problems.

D.Hearne · Jul 4, 2006

If you ever take the Toploader apart, you'll see why that play is there. There's not much supporting it with it out of the bell and pilot bearing/bushing. The bearing retainer/throwout sleeve is holding the front roller (ball bearings) bearing in place and the inside of the gear behind the bearing rides on tiny needle bearings surrounding the tip of the mainshaft. As Zookeeper said, the fit on the pilot bearing is important in keeping things right. It's also critical that the bell housing's not so deep the pilot shaft doesn't reach up into the pilot bearing. Back in the 80's I had the stock big block bell crack on my 67 Stang. I swapped in a pickup truck FE bell. After breaking two input bearings on two different Toploaders. I then realized something wasn't right. I got "lucky" with the 2 replacement Toploaders I bought from local junkyards. Both were 390 specific Toploaders with short input snouts and nether reached up into the pilot bearing. Everytime I engaged the clutch, the pilot shaft was completly unsupported.

dennis112 · Jul 4, 2006

I learned about the short vs. long pilot shaft with a 200ci 3 speed to 4 speed toploader swap. My tranny was from a 390. Initially I couldn't downshift. Later took the tranny apart and discovered that I had ruined the case. The shaft MUST enter the pilot bushing/bearing.

Here is a new photo I took that shows the difference between a small block tranny and the big block tranny.

I should clarify that the bottom shaft is for FE engines. The 427, 428, and Boss 429 use the same length, but the other parts of the shaft are larger in diameter.

I've never messed with a 385 engined car so not sure which will be correct, although one report says to use the SBF one. Anybody have input on this?

D.Hearne · Jul 4, 2006

All the big block 1-3/8 inputs I've seen have the short snout.

nillle · Jul 4, 2006

Thanks alot! Seems like the play is ok then.
I didn't even know the pilot bearing existed
Is it pressed into the crank?

zookeeper · Jul 4, 2006

It's a bronze bushing lightly pressed into the crank, and it's usually easy to get out. They can be stuck pretty tight sometimes, but if you put a glob of grease in the center, then wrap a rag around a drift punch to seal the hole and whack the center of the hole (not the bushing) you can pop it out. You really need to wear safety glasses using this method, since that grease goes everywhere.

D.Hearne · Jul 5, 2006

You can either have a steel bearing back there or a bronze bushing. The steel bearings have been around for a while now. Instead of grease, I heard a better substance to use to force it out. Bar Soap. Hell of a lot cleaner (in more ways than one) than grease. Pack the hole with chunks of soap then pop a snug fitting dowel in there to force it out.

Martti Simila · Aug 23, 2017

D.Hearne said:
If you ever take the Toploader apart, you'll see why that play is there. There's not much supporting it with it out of the bell and pilot bearing/bushing. The bearing retainer/throwout sleeve is holding the front roller (ball bearings) bearing in place and the inside of the gear behind the bearing rides on tiny needle bearings surrounding the tip of the mainshaft. As Zookeeper said, the fit on the pilot bearing is important in keeping things right. It's also critical that the bell housing's not so deep the pilot shaft doesn't reach up into the pilot bearing. Back in the 80's I had the stock big block bell crack on my 67 Stang. I swapped in a pickup truck FE bell. After breaking two input bearings on two different Toploaders. I then realized something wasn't right. I got "lucky" with the 2 replacement Toploaders I bought from local junkyards. Both were 390 specific Toploaders with short input snouts and nether reached up into the pilot bearing. Everytime I engaged the clutch, the pilot shaft was completly unsupported.

Hi there,
I have 71 Stang with 429 engine and Toploader 4 tranny. Between them is D7...... casting bell house. Not sure if it differs from the original 71 casting in dimension but there is a doubt that the Toploader input shaft bearly reaches the pilot bearing ( the bronze one), so we made a new pilot bearing ab. 5 mm more support.
Now the concern is what is enough and is there too much dimension ? How much should it protrude into the pilot bearing.
My mechanic said that the crank should not get any pressure from the trannys side.
Can you or somebody give some guidence in this as now we have put 1mm shims between the tranny and the bell house - just for piece of mind but I would like to take them off ( and make a new pilot bearing with less dimension) as the hydraulic bearing ( Mc Leod 1300) apparently does not like it = clutch, too......

BTW should the pilot bearing be greased when assembled or can it run "dry" ?

Loose input shaft

nillle

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ozstang65

zookeeper

dennis112

D.Hearne

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dennis112

D.Hearne

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nillle

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zookeeper

D.Hearne

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Martti Simila

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Loose input shaft

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