Pilot Bushing in the Crank. Installation Technique

[zKars]

So. Seen a thread a few weeks ago on one of the face book groups about the proper way to install the  pilot bushing in the back of the crank. Actually I think it was about some trans noise the OP was trying to track down, then someone said it might be your pilot bushing, then others chimed in about that and it went on to how to install one. Then does and don’ts. You know how those discussions go.

Well a couple of questions have arisen from some of the comments I read, so I thought I’d ask this collective mind about them and see what you’re experience is.

Question 1. Some/several said you MUST grease the trans input shaft tip where it goes into the pilot bushing. Many of them are very experienced old timers with plenty of practical experience.  I never have, looking at the pilot bushings I have handled (plenty) they look like an oilite type bronze metal which typically does not require lube of any kind.

The FSM for 76 in fact says DO NOT oil. The 82 ZX FSM mentions nothing one way or the other.

The fit is also quite loose, i once tried every new bushing I had once (like 10) and they were all quite a loose fit, some worse than others, but NONE were anywhere near snug where you had to push it one by hand with some force.

[zKars]

Question 2. Bushing installation depth.

I usually to put them in until they were just even with the chamfer that is just below the surface of the crank face, may 2-3 mm in. I used to leave them flush, then when you put the trans back on, it would push it in to the exact depth it needs. 

Because of these questions and remarks in the FB posts i actually looked at the FSM about this for the first time, and found conflicting information.  The 76 FSM say 6.5-7 mm inside the face, the the 82 ZX FSM says 4mm inside the face. Quite a difference. I don’t believe the cranks are any different.

I sure don’t want it too deep and risk a really sloppy and barely engaged trans shaft tip. Recipe for noise and vibration I would think.  I’m not happy with setting it shallow and letting the shaft push it in, as it might leave the chamfer on the larger diameter behind the tip of the shaft still in contact with the face of the bushing.  Again source for noise. I suppose it might wear off quickly anyway.

What is your SOP on this?

[Patcon]

I set them at the back edge of the chamfer.

I have always lightly greased the tip of the input shaft. I didn't think it would hurt...

[zKars]

15 minutes ago, Patcon said:

I set them at the back edge of the chamfer.

I have always lightly greased the tip of the input shaft. I didn't think it would hurt...

I agree. Can’t see how grease would hurt. A Little.

Last question, how to install? I don’t want to pound on the face of it and deform it to reduce the ID. No way I want the shaft tip bound up in the mess I make installing it.

I have a bunch of real trans input shafts that i use for clutch alignment tools (HATE the plastic ones, WAY to sloppy). Seems like a natural for installing the bushings, but the ID Change is a chamfer not a nice square shoulder so that might spread the end making it too loose or hard to install all the way. Some are tighter than others.

I seem to need to make a nice driver tool with a double step. One to touch the face of the bushing, and the other 4mm (6.5-7??) back and large enough to stop the insertion at exactly the right depth against the crank face. 

Or just whack it with a punch……

 

Edited October 20, 2023 by zKars

[Captain Obvious]

I'm no engine builder expert, but I've always installed the bushing to even with the bottom of the chamfer like you and Patcon. And I greased them a little as well. With the same stuff I put on the throw out bearing collar. High moly I believe?

About installing... Block of wood and a mallet to get it started. Continuing like that until flush with the flywheel surface, and then tapped "gently" with an appropriately sized dowel (wood or plastic) and aforementioned mallet to get it down the the bottom of the chamfer.

[zKars]

So today I pulled out all my spare bushings again to compare dimensions. 

Generally they were all the “same”, nice loose fit on the trans shaft, not enough to make any play, just slip right on.

BUT the one thing that is VERY different is the material the bushings are made of. Half were bronze, half were steel! I had one Timkin in a box and it was steel (see magnet firmly attached to the silver ones in pics below). The others were (I believe) from Exedy clutch kits.

So regarding greasing or not, clearly to me at least, the steel ones would benefit from some grease. The bronze ones don’t “need” it but it won’t hurt. 

Going to keep doing the 4mm deep insert, which places it at the bottom of the chamfer. Even made an aluminum tool to beat it in without any fear of damage.

 

[grannyknot]

Those steel bushings must be soft mild steel, if you have a used one can you give it a stroke with a hacksaw blade to find out?

[Captain Obvious]

A reading from the Book Of McMaster:

High-Load Oil-Embedded Sleeve Bearings

Increased iron content makes these bearings stronger and more resistant to shock loads than standard oil-embedded bearings; however they operate at lower speeds. Startup friction causes them to release a thin layer of oil on the bearing’s surface. Color is silver because of the iron. These bearings are also magnetic due to the high iron content.

So I bet they are still oil impregnated bronze, but the high load variety with enough iron to be magnetic.

[kickstand80]

I have always put a couple of pumps from the grease gun into the end of the crank after installing the bushings. 

[zKars]

4 hours ago, Captain Obvious said:

A reading from the Book Of McMaster:

High-Load Oil-Embedded Sleeve Bearings

Increased iron content makes these bearings stronger and more resistant to shock loads than standard oil-embedded bearings; however they operate at lower speeds. Startup friction causes them to release a thin layer of oil on the bearing’s surface. Color is silver because of the iron. These bearings are also magnetic due to the high iron content.

So I bet they are still oil impregnated bronze, but the high load variety with enough iron to be magnetic.

McMaster carr comes to the rescue again! Well, you too Cap’n.    

So either way, officially, NO OIL NEEDED.  But feel free to grease’em up.