Refurbished connecting rods- does this look ok

[herman maire]

Could use some advice, I had a set of connecting rods refurbished by a reputable
Shop so I’m hoping it’s ok/normal but I’d like to hear from some more experienced builders. My concern is the upper bushing.

4 connecting rods have a nice evenly sized upper bushing but 2 look like there not perfectly round as when they sized the upper bushing it looks like it didn’t evenly machine the upper bushing.

Also some look like they were machined a bit off center. Not sure if that’s critical. Im thinking yes ��

Really appreciate some opinions


Vs this

[bpu699]

That don't look right...

[herman maire]

Originally Posted by bpu699

That don't look right...

Not what I was hoping to hear but pretty much what I was
Thinking. Thanks for the reply.

[flightlead404]

Its hard to tell what the issue is from the pics and description. Are you saying the bore is offcenter in the bushing? ie The bushing is thinner one side than another?

In my limited experience that actually used to be (still is?) a way to increase stroke slightly.

Regardless, the dimension you really care about is the distance between the center of the bores on the crank end and piston end. Possibly they were bored slightly off center to achieve consistency between your rods?

Did you discuss with the vendor?

[herman maire]

Hi, no I wanted to see if it’s normal before I contact the shop.
The area I’m concerned with is marked in the picture. It just makes me think
There is a hollow section Since it does not have a nice
Consistent machined surface.

[mikedsilva]

Plenty of experts here, I am not one of them. Your shop should rectify and re-bush. Not hard for them.

[Rosco_NZ]

They need to be honed to size precisely for each pin ..

[Walt Fricke]

Find a post from Craig Garrett (cgar is how he names himself here)and figure out how to send these pictures to him. If, like me, you can't figure out how to attach a photo to a private message, just ask him to look at your post here with the title you gave it and your name. He's an experienced machinist who, among other things, rebuilds/resizes/rebushes 911 connecting rods. He could give an answer based on more than theory and supposition.

But here is my supposition: It is common knowledge that the rod big ends can get distorted, and when machining to get that corrected you have to deal with restoring the stock center to center dimension. Offset machining/honing new small end bushings seems to be one way to do some of this. If repairing the big end makes the rod too short, you'd offset bore the little end bushing toward its end, and that might mean that your tool never touched the big end side of the little end new bushing? One might suppose the cure for this would be a thicker bushing before machining?

But you are right to wonder, and contacting the machine shop would be a good first step.

[herman maire]

Thank you for the replies. I will message the shop and see what they say. Hopefully its fine.
Thank you

[dannobee]

Walt has it right. The center to center length check/correction is usually one of the last operations performed when rebuilding rods. Although the center to center length differences don't usually cause problems, having them all the same length will help getting the deck heights closer to where you want them. (Rod length has NO effect on the stroke, that's the job of the crankshaft).

Call the machinist and ask.

[mikedsilva]

I sent the photo to a friend who is a machinist.. this is what he said:
"Hi Michael,

What you have there is either a worn out bush, a poorly made bush, assuming the hole is the right size.

The coppery coloured material is the actual bearing material, it is Cu Pb. The silvery patch is the steel backing material, (or possibly the bonding layer, if it is soft).

It is a rare occurence, but I have seen it before. Very fixable with a new bush. If it had been not in the lower half, it would be fine."

[cgarr]

I wonder if they reamed the bushings before honing them? The new shells are semi, about .010 small which is a lot to just hone but it does keep them straight by just honing them. Its hard to ream them straight. They apparently went through to the steel shell it looks like?

[Neil Harvey]

Could I ask if you have 22.00mm pins?

Wonder if bushings fitted for 23.00mm pins and sized for 22.00mm pins? Reason, the tell tale sign is the split line is still visible? Always disappears once bushing is sized to pin.

[flightlead404]

Originally Posted by dannobee

(Rod length has NO effect on the stroke, that's the job of the crankshaft).

right, not stroke. I misspoke. Compression is what I meant to say. The stroke remains the same, but by offset boring you can move the top (and the bottom) of the stroke slightly further up the cylinder bore.

[Sboxin]

Agree with others - doesn't look right; for unknown reasons . . .

We had an upper rod bushing edge break off and ended up in the oil drain . . . photos
We replaced with Clevite one piece bushings sized to piston pin and cut to same width as rod end to prevent further failure . . . 3.8L 964 race engine . . .

If it were me - send rods to Cgar for repair/reconditioning . . .

Regards,

[herman maire]

Sorry about the delay in following up. Thank you again for the replies, I took your advice and emailed the shop, they promptly gave me a call back. They said if I had any concerns to send them back and they will redo/verify all the connecting rods.

As far as piston pin size they were machined for, I did not measure them but perhaps I will. They should be 22mm since its a 2.7 connecting rod. I believe the 3.2 and 911 turbo had the 23mm pin.

Still somewhat disappointing to have to mail them all the way back to arizona as I have to pay shipping both ways. I know its minor though at the end of the day.

I will for sure keep cgar/craig in mind in the future.

Are the Clevite one piece bushings better than what was installed in my connecting rods. The shop did not give me any options.

I dont rebuild enough of these engines to know.

[Sboxin]

Originally Posted by herman maire

Are the Clevite one piece bushings better than what was installed in my connecting rods. The shop did not give me any options.

We were advised by our engine builder and contacts at EBS the Clevite one piece are
better quality - Clevite makes the NASCAR engine bearings . . . others may have better
information on bearings/bushings . . . our engine lives in the 5K - 7K RPM range and is
doing fine after the refresh - but we also use Amsoil race oil, something not to be
taken lightly . . .

I'm curious about which shop in Arizona is doing your work?

Regards,

[dannobee]

The absolute best bearings that we ever used in our little nascar fleet were Vandervells. Then they were taken over by Mahle and our source pretty much dried up (for our applications). Only then did we go back to Clevites.