X or non X rods

[Terrye]

Just wondering if there are advantages of the x rods. I’m needing to order a set of rods for my 1915, just want to know to best ones to get.

[Norman Kling]

Originally they didn't have an X but if you have a hole drilled in the cap with a dipper on it, you will get more oil in the bearing, however you will also have less babbitt. If you don't have the hole with dipper, I would recommend no X on the rods.
Norm

[BRENT in 10-uh-C]

I offer lifetime warranty on my engines - however I won't give any warranty on the engine if the helical grooves are not cut.

While Mr. Kling is correct in that you have less surface area on the grooved bearing when compared to a non-grooved bearing, you also have less oil to lubricate the journal pin and the rod. Friction and heat are your enemy in this. If you have an old worn engine that is set-up pretty loose, and if you tend to operate the engine in the lower RPM range, then how the rod bearings were cast originally will likely be satisfactory however most engines in Ts today are operated at higher RPMs with higher compression ratios where tighter clearances and higher forces against the bearing(s) generally call for better lubrication.

[Joe Bell]

Some one asked this question a while back so one guy that has put more miles on a T than anyone should have the answer? Dean Yoder has driven a T with all kinds of things done to the rods over the years and has found out no grooves work the best!!

[SurfCityGene]

NoN Xed.... I measured a total of 1 square inch of Babbitt that was removed from those new Xed rods from the vendors. I paid to send them back... The X and holes make a nice path for the oil to escape and put more force on the surface that is left. The dipper does not see a puddle of oil with the windage around the crank only some mist, I believe.
Yup Dean and others have drove many many miles at pretty darn fast speeds and don't use dippers or X rods.

The relief at the mating points and a smooth rounded side is very important for the oil migration. It was explained to me about the pumping effect in the bearing journals as the piston pressure against the rod bearing surface is applied and relieved with each stroke.

YMMV

[Kerry]

Ford had a few teething issues when he released the first of the T's, water pump being the one every one remembers but along with that was X'd and dipper big ends, done away with that idea as well, today's oils are far better but it has still been proven over the years that
x'ing has a shorter milage to that of a correct swipe line bearing. X'ing such a small surface area as the T big end will relieve internal pressure, not enhance it. I do only T rebuilds, babbit and all, never had a rod fail and some drive their T's hard, I do fit dippers.

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[Kerry]

After the 08/9 fail, Ford did try it again in 1927, once again a very short life, the rods didn't even make it to the spare parts books.

[BRENT in 10-uh-C]

NoN Xed.... I measured a total of 1 square inch of Babbitt that was removed from those new Xed rods from the vendors. I paid to send them back... The X and holes make a nice path for the oil to escape and put more force on the surface that is left. The dipper does not see a puddle of oil with the windage around the crank only some mist, I believe.
Yup Dean and others have drove many many miles at pretty darn fast speeds and don't use dippers or X rods.

The relief at the mating points and a smooth rounded side is very important for the oil migration. It was explained to me about the pumping effect in the bearing journals as the piston pressure against the rod bearing surface is applied and relieved with each stroke.

YMMV

Gene, I am not going to say that is not correct because I do not know the situation however to put facts to this, Ford's print for the Model-A rod calls for a width of ³⁄₃₂" (-or 0.09375") oil groove. My grooving tool cuts about a 0.08 (⁵⁄₆₄" +/-) width likely because my cutter is getting worn. If my math is correct a ³⁄₃₂" wide linear groove cut in an X pattern will be about 2" long (-or actually less.) when calculated on a 1.250" radius. You would have 4 of those grooves if the cap and rod both are grooved. My calculations come up to about .184 square inches per grooved line or less than ¾ of a square inch when all 4 grooves are calculated. These 4 oil grooves comes in at about 12% loss of bearing surface over the entire bearing. And if you calculate the loss of material the hole for the dipper removes, then the grooves are less than 10% of the total surface area.

Ford had a few teething issues when he released the first of the T's, water pump being the one every one remembers but along with that was X'd and dipper big ends, done away with that idea as well, today's oils are far better but it has still been proven over the years that
x'ing has a shorter milage to that of a correct swipe line bearing. X'ing such a small surface area as the T big end will relieve internal pressure, not enhance it. I do only T rebuilds, babbit and all, never had a rod fail and some drive their T's hard, I do fit dippers.

Kerry, the irony of this is I'm not so sure that it has actually been proven per se' (-more likely just loud opinions ), but I also know that people tend to only believe what seems believable no matter what the facts are. Therefore if someone says it enough times that grooving shortens the life, ...then folks say then it must be true.

BUT with all of the above said, Ford engineers chose to continue with the same basic type of oil feed to the Mains & Rods on the Model-A as they used with the Model-As ....HOWEVER these Engineers did feel the need to add oil grooves to all the bearings, and integral dippers to the rods. So, if these oil grooves and/or dippers were unnecessary, -or that these oil grooves & dippers provided no benefit, then what is your opinion on why these Engineers felt the need for the added expense of tooling and labor to perform this grooving and dipper operation?

[SurfCityGene]

Brent, I'm glad you strickly limit the width of your X'es and also the size of the holes. Those brand new rods I referred to had excessively Large holes also adding to big loss of Babbitt! I couldn't believe it and had to check again my measurements!

You're right about when people see things over and over we tend to believe to be true. I think the Xing is something that most guys see as a great idea and an improvement to the original design. I know I did years ago and likewise drilled little holes with counter sunk funnels in the tops and scoops on bottom of my rods when I rebuilt the engine. I have since changed that idea and spend more time on the swipe line and removing any sharp edges on the sides of the bearings that act as scrappers.

I wonder if we will hear anything from some very experienced and expert rebuilders about the recent rod failure of the Ocean to Ocean car?

[Kerry]

Brent, nothing wrong with X'ing for the right size of surface area the bearing is working with, the fact is that the size of the T bearing is border line in area to be 100% successful.

[BRENT in 10-uh-C]

Brent, nothing wrong with X'ing for the right size of surface area the bearing is working with, the fact is that the size of the T bearing is border line in area to be 100% successful.

Kerry, I am unsure how you figure that the surface area is "border line". The Model-T Rod bearing has just under 6 surface inches (5.8905") whereas Ford's Model-B engine only has about 20% more surface area (7.605" surface) than the Model-T rod ...yet the stock Model-B engine produced over twice the horsepower and had nearly half again more compression. Then, -with all the era power adders and speed equipment bolted to those Model-B engines, the horsepower numbers often doubled to around 100 horsepower ....all with that stock Model-B rod!! Now I realize I am letting facts get in the way of these 'Forum Wives Tales', but come on guys, lets at least make it somewhat believable!!

[Art M]

I am willing to comprise on Xing the connecting rod babbitt and to follow the theory of hydrodynamic lubrication (HDL).
The compromise is:
X on the rod cap
No X on the rod

As I recall from 60 years ago, the theory of HDL involves a 7th order differential equation.

Art Mirtes

[Kerry]

Brent, I can tell you how I can "figure" it out, It seems you and I have different levels of education qualifications on the subject in question, mine being that of, The science of mechanical engineering, Motor Mechanical Engineering and Welding, for over 50 years. When a bearing area gets down to a curtain area size, then it requires correct way of lubrication, which Ford's Engineering team figured out a long time ago, swiping or Axial groove as it is called, has worked the best for 15,000,000+ T's with a bearing of that size.

[George Mills]

I'll chime in with opinion - everybody has one.

My held view is that the original boys just did what they knew how to do or what their professor at the Hungarian institute suggested they do.

In most cases it worked, but for the life of me all these other experts have never been able to explain to me why the grooved 716B bushing in the triple gear has a double helical twist that is axially asymmetrical and called out in a really weird degree minutes seconds of twist and not to any reasonable location. The ONLY logical answer is it worked on 15 million + units after trying it...why change?

It was then 'art' and they hit a magic combination that actually defies modern theory.

Didn't Ford itself attempt to design a new era theory transmission for the T-100 project? They all swallowed their transmissions in the first year...and all T100's have been changed back to original designs and set to clearances of the local club consensus.

So as mentioned by others, there are a dozen reasons why conn rods fail or have short life. Like everything else in this universe lube anything generously and you get the best life.

I hold opinion that Ford actually chose to use clearances and minor wobble to act as the needed 'pump' action to make flow happen. Who knows...certainly not us in the modern era.

[Kerry]

George, I don't know why no one cannot explain the oiling of the triple gear, it is so simple, when a bush is vertical and has 2 spiral oil axials, no matter on the spot it stops at, it will have a spot that is flat enough to hold a fraction of oil therefor giving it a lubricated start up.

[Norman Kling]

The rod will get more friction than the cap because it is pushing down when firing and pushed up when on compression. The cap is only dragged along by the movement of the rod. However by drilling a hole in the center of the cap with a dippper, it will pump more oil into the rod if it is X'd. The Model A actually had the dippers built into the caps, and the Chevrolet had the dippers bolted on like we do on our T's
Norm