Anyone have a rod bolt they could loan me or know their measurements?

Heath_h49008 said:

Who made the original bolts? That tooling could still exist in someones hands.

Possibly a similar bolt for a different application?

Click to expand...

How about a short stud/ nut?

just a thought, but a lot of ARP's products replace bolts with studs.

a reduced shank bolt doesn't provide any additional strength as the weakest point onthe bolt is in the minor diameter of the thread pitch.

why not have a grade 10.9 stud or threaded rod machined then use hihg grade nuts.

(edit: beat by a couple minutes)


or i bet that ARP has a plain 9/16-18 bolt of 2-3/4 or 3 inch length that could be used.

http://www.fastenal.com/web/products/detail.ex?sku=20872

yield strength specified for grade 5 is 92,000psi
for grade 8 is 130,000
for the grade 9 it is ~160,000


the spec sheet calls out 3 different possible grades of steel to be used
they have very different yield strengths
the 8640 is listed at 240,000 yield (I doubt this)
the 8637 is listed at 60,000 yield
and the 4140 is listed at 60,000 yield

However the information that i could find stated that 8640 was a cheaper grade of 4340 due to a reduced nickle content and the 4340 has a yield strength equal to 4140.
I have to assume then that the failed bolts are most likely within spec but are of the lesser 60,000psi yield strength (95,000 psi tensile)

if the info is correct the stock rod bolts are less than grade 5 and should be able to be easily replaced with a variety of available bolts (trimmed to max length if necessary)

Tractor rod bolt $15 each

HC40-1091706 - Connecting Rod Bolt | TractorJoe.com

As long as those are USA made replacement bolts, I think we have a winner.

It was re-torqued/reused bolts that were causing the problems if I recall.

Maybe my 1985 production non-rebuilt engine is looking better.

What to the White tractors use for bolts/studs on their connecting rods. Remember the thread about tractors having the "same" engines as deuces. I think it was a White 2-135 or something. I would think those connecting rod bolts/studs would be newer production if they are still available. Are surplus rod bolts still available for the deuce?

I was a little late on my last post.

If somebody can get me one that is in good condition I will send it off to our manufacturing center for a quote. I work for Fastenal and since it would be an employee purcahse I might get the cost down significantly. I'm not promising anything but I do know what we charge on the markup side on custom items. Just get it to me and I will go from there.

Russ

Excerpted from Oliver, Cletrac, Co-op & Cockshutt Tractors Discussion Board - Re: 2-155 cummins conversion I have NO idea if it is accurate. Maybe the tractors use a different rod bolt??

There are some differences in the 478 used in the Army trucks and the ones used in the tractors. The blocks are the same casting but the tractor engines have a few more holes drilled and tapped in them for the water pump. The heads are also the same casting but the two are machined a little different between the valves. The truck engines have a multifuel injection pump so the pump and plate behind the timing cover and the timing cover is different. Also the timing gears are different on the truck engines and the tractor with the roosamaster pump. Some of the army truck crankshafts are also different. they have two more counterweights on the crank and they are much larger. The rods in the truck engines are also lighter. The intake, exhaust and water manifolds are also different. The oil pump and oil pan is also different because the large sump on some of the army trucks is in the front instead of the rear. I believe the 2 1/2 ton trucks have the sump in the front and the 5 ton trucks have it in the rear. The tractors have it in the rear. The army truck engine can be made to work in the tractors. It just takes a little work. These army truck engines can be Hercules, White or even Continental. They are all the same casting. The truck engines are usually an LD-465 or an LDT-465 or an LDS-465. The 465 is not the cubic inches they are still 478 cu. in. just like the tractor engines.


__________________

spoke with my father who is a metalurgist - he confirmed that all 3 grades are about the same - could test a bolt if i had one to give him.



this means that the stock bolts are rather weak (~ grade 2) and even a grade 5 would be a major imporvement in strength. i would be pretty confident in taking a grade 9 bolt with a slim washer and trusting it to outlast a stock bolt, and they are significantly cheaper.

Atomic said:

If somebody can get me one that is in good condition I will send it off to our manufacturing center for a quote. I work for Fastenal and since it would be an employee purcahse I might get the cost down significantly. I'm not promising anything but I do know what we charge on the markup side on custom items. Just get it to me and I will go from there.

Russ

Click to expand...

this bolt:
9/16"-18 x 3" Yellow Zinc Finish Grade 9 Hex Cap Screw | Fastenal

in a flange head with a length of 2-3/4 instead of 3 inches would be ideal

after reading that, i want to see a side by side comparason between the tractor connecting rod and the truck connecting rod. Maybe because the truck engines (ours) have lighter rods is because they see higher RPMs than the tractor engines. less weight is better for RPMs. I know my truck works good and all, but if i ever had to rebuild a multifuel and could get a set of tractor rods at a good price, i might do that. I wonder if the bearings and wrist pins are the same. Another thing to note is that the tractors have spin on filters from the factory in addition to the same oil cooler as the truck.

Kohburn said:

spoke with my father who is a metalurgist - he confirmed that all 3 grades are about the same - could test a bolt if i had one to give him.



this means that the stock bolts are rather weak (~ grade 2) and even a grade 5 would be a major imporvement in strength. i would be pretty confident in taking a grade 9 bolt with a slim washer and trusting it to outlast a stock bolt, and they are significantly cheaper.

Click to expand...

True, but something made the designer choose the lower grade bolt. A bolted joint analysis could be done to figure torque vs clamp load on the O.E. bolt and the same at a grade 5 or grade 9. My gut tells me they weren't getting enough bolt stretch to maintain clamp load with higher grade bolts or they had fears of yielding threads at the higher torques required to get bolt stretch and maintain clamp with higher grade fasteners... It would be really nice to know if these failures are from stretching during use or from re-using fasteners during the rebuild processes which is just a definate no-no in a joint relying the fastener stretching to maintain clamp. Since once it is stretched, it is stretched.... Then again, I'm just a back yard hillbilly mechanic who wonders about such things.....

You guys are talking about all different bolts and even different lengths. I am not all that well versed on the multifuel but I have built a couple hundred engines in my years as a mechanic. Has anyone thought about the weight difference of the bolts and the effects of that on the big end of the rod? Any change in weight is going to unbalance the motor, I don't care how big and ugly it is. The end result will be about the same as what you have been getting. BANG!

Rick

rickf said:

You guys are talking about all different bolts and even different lengths. I am not all that well versed on the multifuel but I have built a couple hundred engines in my years as a mechanic. Has anyone thought about the weight difference of the bolts and the effects of that on the big end of the rod? Any change in weight is going to unbalance the motor, I don't care how big and ugly it is. The end result will be about the same as what you have been getting. BANG!

Rick

Click to expand...

Trust me, these things aren't balanced to begin with.

The balance on the LDS/LDT is a bit odd. They swapped solid vs hollow wrist pins and two different piston castings without changing the balance on the crank. VASTLY greater changes in mass than a swap of differing grade bolts...

But, I have no doubt that is a factor in the high-RPM failure issues these engines seem sensitive to. Velocity is the squared factor.

patracy said:

Trust me, these things aren't balanced to begin with.

Click to expand...

Neither are their owners.... Hey, I resemble that remark.

I'm sure they aren't, and at the RPM's they spin at the effects are probobly negligible.

barefootin said:

True, but something made the designer choose the lower grade bolt. A bolted joint analysis could be done to figure torque vs clamp load on the O.E. bolt and the same at a grade 5 or grade 9. My gut tells me they weren't getting enough bolt stretch to maintain clamp load with higher grade bolts or they had fears of yielding threads at the higher torques required to get bolt stretch and maintain clamp with higher grade fasteners... It would be really nice to know if these failures are from stretching during use or from re-using fasteners during the rebuild processes which is just a definate no-no in a joint relying the fastener stretching to maintain clamp. Since once it is stretched, it is stretched.... Then again, I'm just a back yard hillbilly mechanic who wonders about such things.....

Click to expand...

why do engineers ever spec out less than the best possible. cost. what is in there has lasted quite well for the most part. so cost vs life cycle their choice was a success.

getting the right clamping force definately is not an issue with higher grade bolts or ARP bolts grade 9 and up would not be the standard for high performance engine builds. when you start talking about stretch bolts you are talking about torquing a bolt to its yield point. most bolts are not designed to be used that way, usually only head bolts, and even then most manufacturers have been moving away from that.

Kohburn said:

spoke with my father who is a metalurgist - he confirmed that all 3 grades are about the same - could test a bolt if i had one to give him. this means that the stock bolts are rather weak (~ grade 2) and even a grade 5 would be a major imporvement in strength. i would be pretty confident in taking a grade 9 bolt with a slim washer and trusting it to outlast a stock bolt, and they are significantly cheaper.

Click to expand...

I have a hard time believing that anybody would spec grade 2 bolts for a con rod. Doing a quick google search yields this page which suggests that 4140 is grade 8.

Hex Head Cap Screws

"Made from 4140 steel, these screws meet ASTM A-354 BD, SAE J-429 Grade 8, and SAE chemistry and mechanical specifications. Available in coarse and fine thread, with zinc or black oil finish (class 2A threads). Stocked in diameters from 1/4" to 3" and lengths up to 30". Head markings for grade 8 bolts is most commonly 6 lines in some arrangement. See common head markings for hex bolt grade differences. "

This one also suggests that 4140 is grade 8 and that grade 2 is made out of 1018 (mild steel):
http://www.rbwmfg.com/images/HelpfulHints2.pdf

I also have access to a metallurgical lab and would like to have a few bolts to analyze, even broken ones. Maybe it would help if a few different metallugists look at the problem.
I'd also be interested in replacing my rod bolts if I could get better ones at a reasonble price.