Babbit composition

[Dave1]

I have recently acquired the tools and machinery to pour and size babbit, I am not professing to be an expert by any means.
However I have made some observations, it seems that the older engines I have disassembled which appear to have OEM Babbitt. I only “assume” these to be OEM, for example they would typically have cast iron pistons.

Regarding the babbit, I have never seen one where the babbit is cracked. Although the bearings typically show a lot of wear. Not uncommon to see all the shims have been removed. It could be that the previous owner did not change oil, or who knows how many miles were on that particular engine when it was parked.

As to the modern day re babbit jobs, it seems that failure of the bearings is common, even with relatively light use. I have seen examples of this from a number of rebuilders, not just one or two.

It could be that the guys pouring Babbitt back in the day were wizards and this is somewhat of a lost art….. or I am wondering if the composition of the Babbitt we have access to today is somehow different from the stuff Henry used, due to environmental factors for example?

[Dan Hatch]

Here is a link to some Babbitt.
https://stores.acrosales.com/sn86-sb7-c ... ngot-ford/

[Kerry]

If you are contemplating having a go yourself you can buy enough babbitt from the T vendors that is based on the same formula that Ford used, 86% tin 7% copper and 7% antimony. The T rods that you come across that have no shims could well be still original as Ford did not use them, you need to check that the caps are not over filed and still serviceable, Ford did use a shim on the main caps.

[BRENT in 10-uh-C]

If you are contemplating having a go yourself you can buy enough babbitt from the T vendors that is based on the same formula that Ford used, 86% tin 7% copper and 7% antimony. The T rods that you come across that have no shims could well be still original as Ford did not use them, you need to check that the caps are not over filed and still serviceable, Ford did use a shim on the main caps.

I have often seen that phrased used here, but exactly what constitutes "over-filed" or too thin? Now I realize that this can be a tad controversial however I think the fear instilled is generally unwarranted. And, I honestly believe this is one of those things that was once mentioned and someone else thought that sounded believable and so it became gospel. Me personally, I will pour and use a cap that has been filed less than 0.050" because it is the bearing in the rod that is taking the majority of the force. The cap only has any real loading 25% of every 2 rotations. A cap that has been filed/ground/thinned 0.030" or 0.040" is still very serviceable due IMO, -especially since most rebuilders stack shims under the cap anyway.

[Dave1]

That sounds reasonable. But I cannot imagine a circumstance where the cap would need to be filed .050”
Maybe over the course of many refits ?

[Kerry]

I have boxes of replacement spacers for filed T caps dating back to 1910, they are .070" thick. The early Dodge supplied rods had very thick babbitt so could be filed a lot, as Ford rods got better in being machined, by the 20's they had very thin babbitt in them, if the shim of today's suppliers doesn't replace the filing then a risk of hitting the metal when boring a STD size bearing, Some years ago Herm Kohnke posted that he would use 2 shims each side to salvage caps that would normally be scrapped. I will not do that for my re-built rods.

[John kuehn]

Failures in babbitt in todays rebabiting jobs could be because of how todays Model T owners treat the T engines. The aftermarket parts makers sold lots of outside oilers in the T era and any type of optional oiling system sure can’t hurt. Model T legend has a way of telling of how tough Old Lizzy was but that was in another time when going 40-50 mph was considered extremely fast in a T. But after a while that daily speed would eventually cause trouble for the average OEM T. Running around 30-35 will make a T run longer in the long run as lots of T owners find out. I know others will disagree and some T engines are built today to run a little faster and etc. Those engines will run a little faster for sure and we know that they are built that way.

[TXGOAT2]

Thick layered babbit may not stand up to higher speeds as well as thin-lined. A thick layer may tend to squeeze out under high loads.
A balanced engine with aluminum pistons, modern valves, and auxiliary oiling can stand up well to higher speeds when modern high grade oil is used, assuming everything is well-fitted. Babbitt was available in a number of grades and probably still is. I'd stay with what Ford specified.

[TXGOAT2]

Late 1940s Chevrolet babbitt rods had a very thin layer of babbitt metal. While a thicker layer might allow more re-fitting, the thick layer will not allow running loose rods and it will not accommodate a flat or tapered shaft. Low speed stationary engines often had babbitt sections of 1/2 or more, but they had bearings with a large surface area, larger than would be practical in an automobile engine, and they ran at speeds of a few hundred RPM instead of 1500-2000 and more.

[BRENT in 10-uh-C]

That sounds reasonable. But I cannot imagine a circumstance where the cap would need to be filed .050”
Maybe over the course of many refits ?

Exactly. So IMHO, no reason for a rebuilder to 'defect' a rod due to a shaved cap.

Failures in babbitt in todays rebabiting jobs could be because of how todays Model T owners treat the T engines. The aftermarket parts makers sold lots of outside oilers in the T era and any type of optional oiling system sure can’t hurt. Model T legend has a way of telling of how tough Old Lizzy was but that was in another time when going 40-50 mph was considered extremely fast in a T. But after a while that daily speed would eventually cause trouble for the average OEM T. Running around 30-35 will make a T run longer in the long run as lots of T owners find out. I know others will disagree and some T engines are built today to run a little faster and etc. Those engines will run a little faster for sure and we know that they are built that way.

John, it is my experiences that most cast bearing failures on the caps are due to Rebuilder errors where a cap was improperly tinned, -with a slight chance of them using an inferior material. Remember, the cap is only subjected the the weight of the Rod & Piston. There should be no outside forces against the caps.

Thick layered babbit may not stand up to higher speeds as well as thin-lined. A thick layer may tend to squeeze out under high loads.
A balanced engine with aluminum pistons, modern valves, and auxiliary oiling can stand up well to higher speeds when modern high grade oil is used, assuming everything is well-fitted. Babbitt was available in a number of grades and probably still is. I'd stay with what Ford specified.

Hey Pat, I have found that a bearing casting that squeezes out generally is one of two things ...which I don't believe it really has anything to do with the mil thickness of the Babbitt. It is my opinion that a rebuilder using too soft of metal composition can cause the casting to deform however the biggest reason comes from hammering the bearing which deforms it. The more it hammers, the more clearance it makes. The more clearance it has, the more damage the crankshaft can make against that bearing material.

In a nutshell, these excessive clearances between the journal pin and the bearing casting is because of poor craftsmanship. Many rebuilders struggle getting the journal pin round during the grinding process. (I know this because I grind our own crankshafts in-house and it is VERY difficult to grind T cranks accurately due to them being so spindly) Therefore when the Rebuilder sets-up the clearances on an improperly ground crankshaft, those clearances are generally tight in one area because the journal pin is tapered. Now with a small contact surface area, the bearing material is quickly compacted and moved around as the engine is being run. Now those clearances have become excessive which allows the hammering process to start. Had the Rebuilder actually burnished the bearings to fluidize the bearing material, it then could have flowed to conform to the actual shape of the journal pin and had a consistent measurement across the entire surface. At that point, the larger bearing surface area supports the forces and prevents squeeze-out. So in reality, IMO it was never the excessive thickness of the bearing material that caused the squeeze-out.