Excessive crank end float.
 

What problems are associated with excessive crank end float?

I have a crank that is in nice condition but when assembled up it has .020" end float. The motor starts up ok, I haven't driven it yet.

What, if any problems can I expect from this situation.

It is a French motor so has 59A type cam gears which thrust the cam towards the block and subsequently there is a forward thrust on the crank. This is the same direction as clutch release thrust.

So in this case would it be reasonable to think that the crank might tend to spend most of it's time at the forward limit of travel and not switch back and forth? Or do you think it would drift towards the rear location during acceleration?

I don't really have much choice as I want to run it at the weekend but I was wondering if excessive end float is more of a less than optimum thing or is it definitely a complete disaster.

Mart.

Re: Excessive crank end float.
 

I cannot answer your question, but what I've done in the past in this situation, is I've built up the thrust faces on the bearing with babbit and machined to suit.

Re: Excessive crank end float.
 

It may have a sound like a loose main bearing when going off and on load driving conditions. Spec is about .08 IIRC

Re: Excessive crank end float.
 

Hi Mart. At .020" end float I wouldn't expect any problems. Not optimal for sure, but not a disaster either.



Terry

Re: Excessive crank end float.
 

It is not going to last very long with that much clearance. You need to determine what the problem is first.
Is the thrust bearing worn? If so, possibly a new one will cure the problem.
Is the block saddle worn? If so, sleeving the side of the saddle will cure that.
Is the crank thrust worn? If so, it can be welded and re- ground.

Re: Excessive crank end float.
 

The thrust surface width on your nice condition crankshaft is worn so to reduce the end play a bit here's what you can do. Flare the thrust surface out just a touch on the main bearings. Wont take much to reduce the end play down to the max which is .006 according to the books I work from. It would take a long time before any wear is seen in the bearing if you decide to just flare the bearing thrust surface out a slight amount.
Ronnieroadster

Re: Excessive crank end float.
 

How is that done?


I've read here in the past that the bearing shell can be shimmed a few thousandths to adjust end play, is that a reasonable thing to do?

Re: Excessive crank end float.
 

My way of thinking is how does that much end play affect the rods with it thrusting fore and aft ? I’m thinking not good.

Re: Excessive crank end float.
 

.080"? You sure about that? That seems like a mile. That's just shy of 1/16".

Re: Excessive crank end float.
 

Ronnie, .006" sounds much more credible than the .080" that CAS3 posted.

Re: Excessive crank end float.
 

Same principal as if you were sleeving the middle of the saddle. You bore away about .080 from the area covered by the side of the shell, then make a flat curved piece to fit in the bored away area. Make the insert about .010 to .015 thicker than the finish thickness for the saddle.
Clamp the new piece in place with a generous amount of Loctite and drill 4, 1/8 holes evenly spaced across the piece. Take a short piece of 1/8 brass welding rod, coat the tip with Loctite and drive it in one of the holes till it bottoms. Do the other 3 the same way. Take the clamp off.
Using a fine tooth jewlers saw cut the excess brass off of the pins. Now peen what is left down till it is flush.
Face and bevel the insert to finish size.

NO, you can't shim a bearing shell and expect it to live.

Re: Excessive crank end float.
 

Thanks for that description Pete.


The shims I read about here were behind the thrust surfaces only, much like the inserts you describe. So you say that does not work? Is it because of lack of heat transfer?

Re: Excessive crank end float.
 

If there was some positive way to hold them in, they might work.

Heat is not a problem.

Re: Excessive crank end float.
 

So sorry...I left out one zero ! At any rate, I still think you will hear a knock like a main bearing, and agree with ken, rods won't like the thing moving around. I would fix, or not use it

Re: Excessive crank end float.
 

1/16th =.0625, .080 is over 1/16th
Bill

Re: Excessive crank end float.
 

Crank is low miles French military rebuild. Bearings are brand new. Saddle is not worn.

I think the French military might have ground the cranks oversize on the thrust faces and had access to oversize bearings to suit.

I have a crank with a damaged thrust face. Can someone give details on the welding process to build up the thrust face?

For example, what type of welding? Mig? Arc/ what type of wire or rod? Special gas?

If normal mig welding and wire I could try myself. Ditto if arc if I know what rods to use.

Thanks for the input so far..

Mart.

Re: Excessive crank end float.
 

Mart, What I've done a coupla times now is to build up the faces on the bearing. use a big iron and some whitemetal. easy peasy; the faces are already 'tinned' so to speak, just need a bit more of a build up each side. Then machine the built up faces to acheive your desired clearance. you say you've got .020" clearance. You only need an additional .007" on each face. In effect, you're making oversize bearings as you claim the French had access to.
Personally, I don't like welding cranks, can be done, but a lot of work!

Re: Excessive crank end float.
 

Hi Mart.. take the soft option. You could look at metal spraying the trust surfaces of the bearings. Then mill or sand them to suit. I like Brian's idea.
Just a thought.

Regards Kevin

Re: Excessive crank end float.
 

Crank can be welded and reground to reduce to proper Specification.

Re: Excessive crank end float.
 

Thanks for waking me up. Good grief!

Re: Excessive crank end float.
 

For the amount of money it would cost to weld/regrind the crank (and the time to drag it around) - I'm sure you could find either another crank and/or try the "iron a bearing fix". I like my crankshaft thrust to be between .004 and .006 inches.

Re: Excessive crank end float.
 

Crank welding is done in a crank welding machine by the submerged arc method. Basically it is an automated wire feed type where the actual arc area is submerged in a special granular powder while welding.
Pre-heat and controlled cooling are part of the process.

Re: Excessive crank end float.
 

I ran the engine for a few miles but have yanked it out as it does not seem happy. I'll have to look at it in more detail when time permits. Installing a plodder motor for the event this weekend.

I will look at adding babbit / white metal. I have no knowledge about it though.

Re: Excessive crank end float.
 

Mart, A talented man such as yourself will have absolutely no trouble building up the thrust faces. As I mentioned above, use a big soldering iron [more control that using a torch]; you don't want to damage the existing bearing material that the journal runs on. I use 'Fluxite' paste [made in England, so you should be able to source it easily], NOT an acid based flux [spirits of salts etc]. It'll build up real easy; like, the faces are already tinned for all accounts. Practice on an old bearing first? Good luck!

Re: Excessive crank end float.
 

Good advice Brian. An old guy in my model T club does this with the babet thrust on the poured babet to save an otherwise good engine. Finishes the face with a home made gizmo like a line boring tool

Re: Excessive crank end float.
 

Is Whitemetal another name for Babbitt? Would you just melt a blob off a bar with the iron or can Babbitt wire be purchased? I don't have babbitt scraps, only a couple bars of new material here of unknown providence.

Re: Excessive crank end float.
 

I think babbit and white metal are much the same thing. Just a lead/tin alloy. I think different grades are available, but I just use what I can find 'unknown providence'. I find it cast as ingots, normally it is melted in a pot and poured into a mold, but you can melt some off the ingot with the iron and apply. Basically, it is just like solder....

Re: Excessive crank end float.
 

Could solder be used?

Re: Excessive crank end float.
 

Mart, I think babbit has a much higher tin content than ordinary solder. possibly try here, they're in England; https://www.williamrowlandshop.com/a...itt-metals.htm

Re: Excessive crank end float.
 

Sorry Mart, to buy one ingot from that site will cost 53.12 Pounds? WR89A (BS3332/A) is their code for babbit. The stuff is available, ask around, someone into the repair etc of vintage cars should be able to furnish some. Good luck!

Re: Excessive crank end float.
 

Thanks Brian, I just got off the phone with another supplier, he will get me what I need. Thanks for the guidance.

Mart.

Re: Excessive crank end float.
 

Mart, I had this same problem with a French motor. When the motor was being reassembled we noticed the excessive end float and came to a stop. I sold the engine to Jim T and told him about the problem before we finalised the deal. I believe it is not uncommon on these motors and Jim has a solution to it.
Give Jim a call and see if he can put you straight.

Re: Excessive crank end float.
 

It sounds to me like they must have had a different (wider) rear main bearing in these French motors - especially since you said the crank is in great shape with no outward sign of thrust surface wear. I wonder if you can locate a new rear main bearing - the 'French Flathead width'?

Re: Excessive crank end float.
 

Dale raises an interesting point...Ford also provided rear main bearings with oversized thrust faces. The only listing for such in my Canadian catalogue is #81A 6331T which is .015 os on thrust faces, but .030 us on journal.

Re: Excessive crank end float.
 

Just a little input on this very interesting problem Mart.
I like the idea of building up the thrust surface of the bearing to restore the proper thrust, but I would do it a little differently. With your skills and tools you should have no problem using solder to attach a brass shim to the thrust surface, and machine as necessary. Tin the brass shim prior to soldering.
I personally feel the end result will guarantee a more durable fix.

Re: Excessive crank end float.
 

How about a thin shim BEHIND the thrust to force the surface out .007 on each side??

Re: Excessive crank end float.
 

Deuce5window.....The way the bearing fits the saddle would require the bearing thrust to be bent outward and then machined parallel to the crank thrust surface. I dont like the need to make the shim to properly backup the bearing thrust. Have i lost you........?

Re: Excessive crank end float.
 

Crazy question if you can't find an org thrust bearing that has the thicker thrust surface, if you have to do something to the bearing you have would it be best to do the work on the front side that it will just have normal thrust load and not the back where it has clutch pressure against it?
Steve

Re: Excessive crank end float.
 

Absolutely correct. The .015" or so that Mart needs would cause no problem if done as you suggest. :)



Terry

Re: Excessive crank end float.
 

No Russ, you didn't lose me (yet lol) but we are only talking .007 on each side and as far as straightening the side it could be done on a flat surface with sandpaper after the sides are forced out by the shims. Just tossing out an idea.