Babbett and Thrust

[jhowes]

If the babbetts are all good, can a babbett shop recreate the crankshaft thrust surface? Jack

[FRANK PKNY]

No the cap and block is re done all in one jig then machined to spec.

[jhowes]

Thanks Frank. Are you going to Hershey?

[100IH]

Yes, there are bronze inserts for that. Engines that are machined for insert bearings use these.

[FRANK PKNY]

I have never seen bronze inserts for a Model A I would think machine work would be necessary to use them. I have used a different cap from another engine , but that is only a short stop gap fix, because your only getting one half of the bearing thrust surface. You would also have to fit the cap and check the clearance. Personally I don't think any short fix is worth the time. I would do the job once correctly. JMHO And yes I'm planing on going to Hershey in the red field, I'll have a powder blue 1946 Ford PU there for sale and some miss. items mostly A parts.

[100IH]

Sponsored Links (Register now to hide all advertisements)

I believe that you are correct about the machining required to use the inserts. They are much tougher and are usually only on the cap, some shops may differ. You are correct in that short fixes often are not the best method. Is jhowes good babbitt good after removing most of the shims? We don't know. Is it loose and poorly tinned, we don't know. I expect that most shops would at least advise redoing the mains.

[jhowes]

I don't know the history on the babbett job but there is at least 2 shims on each side and they plasa-gauge to .0015. I don't know why the thrust is so looser and the engine doesn't make any objectionable noise when it is running. I thought that there would be some way to fine tune the thrust before I buttened it up. Thanks for your advise, I appreciate it. Jack

[wensum]

Check out Snyders thrust bearings. They have bronze thrust bearings in their catalogue. I have these with a Burlington crankshaft and shell bearings. So far, after some thousands of miles of reasonably hard driving, no problems. On second thoughts, not entirely true! the original crankshaft with welded on counterweights cracked and was replaced by the Burlington crankshaft. At that time it was discovered that two of the big end shells had suffered some sort of inexplicable damage. It looked like the bottom half of the big end bearings had been punished in some way (The motor is "improved")
With the Burlington crank, it now has all new standard size shell bearings ex Snyders.

[Synchro909]

Any half way decent shop that uses Babbet should be able to "dabble" some babbet onto the face required. I've built it up this way - it's like soldering. Once the babbet is put on, it can easily be adjusted to the correct thickness so your end play is right. I've seen a sanding disc, scraper, sand paper on a glass plate used - what ever is available. If you take off too much, simply dabble some more on and start again.
No need to machine the block for bronze inserts!

[redmodelt]

Synchro909, right on! It can be done. It may not be perfect but will be a lot better then not done at all. I did it with my Model T engine, put a lot of miles on it and it only has thrust on the cap. Hell all that needs done is a little babbitt added and if the shop has thrust cutter, eazy peazey!

[1930 coupe]

Originally Posted by Synchro909

Any half way decent shop that uses Babbet should be able to "dabble" some babbet onto the face required. I've built it up this way - it's like soldering. Once the babbet is put on, it can easily be adjusted to the correct thickness so your end play is right. I've seen a sanding disc, scraper, sand paper on a glass plate used - what ever is available. If you take off too much, simply dabble some more on and start again.
No need to machine the block for bronze inserts!

I agree, I also add Babbitt to the thrust surface and machine to fit when necessary.
You can poor Babbitt in a angle iron to make a filler rod, and I use a KRW cutter to machine the face after it has been built up.

[redmodelt]

^That is how we make our babbitt sticks for doing this kind of work.

[J Franklin]

How do you clean the old surface from oils to get good adhesion? I have an engine that could use a bit of thrust repair.

[FRANK PKNY]

I would agree 100% that the babbett can be repaired, and would possibly run OK for some time. It's a good bandage for a while. My concern is that babbett has a life span and will work harden with time. When you see that it has started to crack on the thrust bearing surface that is an indication it's reached it's life span. Your decision on how to do the repair would be made on the fact of how dependable do you want your engine? JMHO I have been fixing machinery for 60 plus years, I enjoy doing the job right the first time. Frank PKNY