Stripped Connecting Rod?

Tom Wesenberg

Tom Wesenberg

Well-known member
Has anyone had a stripped connecting rod and found a good fix? One of Mark's rods has perfect babbit, but one of the connecting rod studs has the threads pulled off from overtorque in the past. I was thinking of a couple of possible fixes. Add a thin layer of brazing and rethread it, or cut the stud flush with the rod, then drill and tap for a new stud.

Any ideas or fixes? Thanks
 
Tom Wesenberg said:
Has anyone had a stripped connecting rod and found a good fix? One of Mark's rods has perfect babbit, but one of the connecting rod studs has the threads pulled off from overtorque in the past. I was thinking of a couple of possible fixes. Add a thin layer of brazing and rethread it, or cut the stud flush with the rod, then drill and tap for a new stud.

Any ideas or fixes? Thanks
Click to expand...

Rod to replace bad Rod 60.00?? A failed fixed rod, o, Hole in block from failed rod?? Taking big chance Mr. Tom, Herm
 
The rod cap has little force applied to it when in use, mostly on deceleration. I would add weld and rethread, use the castellated nut with a good cotter pin. I like the metric cure above also.
 
A special nut, made to use the entire length of the stud, drilled at the location of the original cotter pin hole after torque , with a tight fitting pin -peined over (to make use of the few threads the other side of the cotter pin hole that are probably still ok)

As Herm said ---another rod is the proper repair.

How about a grade 8 cotter pin ???
 
Herm has the RIGHT answer.

The other remedies are as MICKEY MOUSE as the one I had come in one time.
The cap had been tig welded to the rod after assembly.
 
Last edited:
Kurt in NJ said:
A special nut, made to use the entire length of the stud, drilled at the location of the original cotter pin hole after torque , with a tight fitting pin -peined over (to make use of the few threads the other side of the cotter pin hole that are probably still ok)

As Herm said ---another rod is the proper repair.

How about a grade 8 cotter pin ???
Click to expand...

The castle nut is the full length of the stud and there are no usable threads left at the end.
 
A new rod with re-poured babbit is cheaper than replacing a block after a temporary repair has failed.
Question for Pete; does mickey mouse mean a dodgy/bogus repair because in Australia something that is mickey mouse means it's squeaky clean.
 
I've found rods that have had the studs rethreaded for a smaller nut. Not a metric nut, a significantly smaller SAE nut. One each stud on two out of four rods. The babbit is good and the engine has been down the road ... but now it is on my (borrowed) engine stand waiting for some funds or for that perfect rod from a donner engine.
I'm hurrying, Phred. Just don't know which way to hurry!
 
dave in australia said:
A new rod with re-poured babbit is cheaper than replacing a block after a temporary repair has failed.
Question for Pete; does mickey mouse mean a dodgy/bogus repair because in Australia something that is mickey mouse means it's squeaky clean.
Click to expand...

Yup Dave - Mickey Mouse here means really poorly executed and probably won't last.
 
Don't fool with it Tom. Get a hold of Bill Barlow, and he will fix you up with a re-furbished connecting rod that will fit perfect. You may have to finish it to the wrist pin, but that would be all. He can have it in the mail before you can get turned around. I received a set of main bearing caps finished to exact size required, shipped to Canada, within one week.

Bill Barlow - 20378 Pine Vista Drive, Bend Oregon, 97702
(541) 389-2694
 
da40233b.jpg


I brazed a layer on and ran a die over it. It's now installed and torqued down. It was my first thought on how to fix it and it didn't take long to do. Mark put on 5,200 miles last summer since he got the car, and the nut was loose due to pulled threads, so this has to be much better, and I can't see it giving a problem.

Now I'm lapping in the valves and hopefully no more problems will slow down progress.
 
Looks good, Tom. Rod torque is relatively low, so the brass may have enough shear strength to hold up.

I suspect if I had done the brazing, all the babbitt would have been in a puddle on the table. ;-( Did you use heat-absorbing putty or some other trick to isolate the heat?

Joe
 
JoeWay said:
Looks good, Tom. Rod torque is relatively low, so the brass may have enough shear strength to hold up.

I suspect if I had done the brazing, all the babbitt would have been in a puddle on the table. ;-( Did you use heat-absorbing putty or some other trick to isolate the heat?

Joe
Click to expand...

No, but I should have! I did loose a couple drops of babbit near the bolt, but not enough to bother.

Now I'm installing the double nut adjustable lifter and the smaller diameter of the lifter is what bothers me. The original tappets are 1.119" and the double nutters are .985 to 1.000"
 
I know this is a very old thread, but I was wondering what the outcome of Tom's brazing fix was. I just found a stripped stud on my #3 rod and am weighing my options. I would like to keep my current engine in service until I can get my rebabbited spare put together.
 
It worked fine to hold the torque. But Mark bought another engine within a year from Antique Engine Rebuilders because he puts on a lot of miles every year, plus he wanted more horsepower. Mark also added an overdrive.
 
Bad threads is the reason that I don't use castellated nuts, they only have about 4 full, useable, threads. I use aircraft, or grade 8, or Caterpillar, or ARP nuts. ARP are now my favorite. No cotter pins are needed, just torque them down.
 
You must log in or register to reply here.
Back
Top