Official S65 Rod Bearing Condition Example Thread

[GearKid]

Originally Posted by Assimilator1

I wouldn't have thought it'd be a good idea to re-use an OEM bolt, they are stretch bolts, so once used I wouldn't think they'd yield anymore which could lead to over torquing?? Not a 100% on this though!
And, if he truly only did the 20 Nm stage then noway would that strip the threads. All very odd.

Btw, instead of buying a stroker motor (unless you really want to), how about buying a new rod and then having all the rods balanced? (still would need to strip it down of course).

If anyone with spare rods would be willing to experiment with over torquing the OEM bolts that might be helpful to the community. My situation can't be the only one.

[Helmsman]

Originally Posted by Assimilator1

I wouldn't have thought it'd be a good idea to re-use an OEM bolt, they are stretch bolts, so once used I wouldn't think they'd yield anymore which could lead to over torquing?? Not a 100% on this though!
And, if he truly only did the 20 Nm stage then noway would that strip the threads. All very odd.

Btw, instead of buying a stroker motor (unless you really want to), how about buying a new rod and then having all the rods balanced? (still would need to strip it down of course).

I believe if not most at least many shops have reused OE bolts when replacing shells back in the days. For instance one of the shops I chatted with, went with another thought. So no, I can't imagine that they would break by being re torqued.

[Assimilator1]

Back in the days, as in older cars? If so they probably didn't have stretch rod bolts.
Depends when you mean and what cars

[Helmsman]

Originally Posted by Assimilator1

Back in the days, as in older cars? If so they probably didn't have stretch rod bolts.
Depends when you mean and what cars

No, incl S65 and S85. Mentioned local shop I mentioned are viewed as ///M experts in the Stockholm area. Didnt use them though cause didnt feel comfy.

[Assimilator1]

Ah ok, interesting. I always thought re-using stretch bolts was a big no-no!

[pbonsalb]

You are not supposed to reuse TTY rod bolts. I reuse some bolts that have angle torque specs like those for the front aluminum plate that stiffens the suspension, but I would not take the risk with rod bolts. If you were going to do it, you should measure for stretch against a new stock bolt.

[Green-Eggs]

You can't measure rod bolt stretch on OEM rods.

[Assimilator1]

I assume you need a hole in the rod on the threaded end to place the gauge to the bolt?
I don't suppose you've got a pic or link to hand to show how it's done? (never seen it done myself).
And assuming you could measure OEM rod bolts in situ, would you reuse stretch bolts?

[Green-Eggs]

Originally Posted by Assimilator1

I assume you need a hole in the rod on the threaded end to place the gauge to the bolt?
I don't suppose you've got a pic or link to hand to show how it's done? (never seen it done myself).
And assuming you could measure OEM rod bolts in situ, would you reuse stretch bolts?

https://www.m3post.com/forums/showpo...5&postcount=74

I would think measuring stretch on a previously used rod TTY (stretch) bolt would be pretty meaningless because the bolt has already been to the point of yielding.

[Chris_PDX]

'12 E92.

Just replaced. As far as I know these are OEM, I bought the car in 2014 with 40k on the clock. Now at 95k. Includes around 40+ track days since 2014 and I changed oil every 5k miles.

[G80indy]

Encouraging for that OCI !

[DLam]

I just got my rod bearings replaced. Replaced with BE bearings and ARP bolts, BW performance motor mounts.

2008 E90 6MT
97k miles
Bought the car in 2015 with 51k miles. Car has only 3 track days.

[Assimilator1]

Originally Posted by Green-Eggs

https://www.m3post.com/forums/showpo...5&postcount=74

I would think measuring stretch on a previously used rod TTY (stretch) bolt would be pretty meaningless because the bolt has already been to the point of yielding.

And that's why I was thinking re-using them would be a bad idea.
Thanks for the link btw, excellent quality photos!

Originally Posted by 330indy

Encouraging for that OCI !

More likely down to the luck of the S65 lottery, that and LCI bearings generally coming out looking better than the earlier type.

Originally Posted by Chris_PDX

'12 E92.

Just replaced. As far as I know these are OEM, I bought the car in 2014 with 40k on the clock. Now at 95k. Includes around 40+ track days since 2014 and I changed oil every 5k miles.

Do you still have your old bearings? And if so, would you be interested in doing a little experiment on one of them?

[Chris_PDX]

Originally Posted by Assimilator1

A
Do you still have your old bearings? And if so, would you be interested in doing a little experiment on one of them?

I'll have to check the garage, I honestly don't remember if I tossed them or not yet lol.

[jamabdi]

Went with BE bearings, and BE ARP bolts. The car has had two previous owners before me. Original owner changed oil every 5k miles, and sold it to carmax with 12k miles on it back in 2016 I believe. Second owner bought it in 2016 with the carmax warranty, did oil changes every 6k miles, and took it to autocross and track days. I bought this car in January of 2021 with 42k miles. Decided to get them done now since the warranty is coming to an end this april.

2013 e92 m3
6 speed manual
45k miles today.

[drrust]

Saw this from FCP Euro where a 300,000 Mille Volvo motor was torn down. Bearings looked better than just about every set in this thread.

[Helmsman]

Originally Posted by drrust

Saw this from FCP Euro where a 300,000 Mille Volvo motor was torn down. Bearings looked better than just about every set in this thread.

Its a Volvo mate, built to last...

[Davisca455]

Originally Posted by Helmsman

Its a Volvo mate, built to last...

Yep.
Just look how wide (heavy) that rod assembly is at the big end.
Lots of area to help the oil film do its job.

[ol doc gully]

rod bearing change on a new to me 2008 at 122k

had a big scare at first with what appeared to be chunks in both oil pickups. turned out to be a dye, thankfully. still very interesting how exclusive the wear was to the top front shell halves.

[Bubbles]

Originally Posted by GearKid

It has all of us puzzled. The shop is legit as is the tech. He was explaining that he used the OEM bolt in order to get a clearance reading. Old bolt was tightened according to the procedure which worked fine for the previous 7 rods. This was #8. Claim is the bolt yielded right around 20N-m so it never had a chance to be over torqued.
This implies a pre-existing condition, which is saying that rod cap remained perfectly in place for 78k without any strange bearing wear. With the new APR bolt the tech was able to grab just enough thread to torque it down to 50ft-lbs but I'm not about to start it up and roll that dice.
I'm curious if anyone has experienced a rod stripping or if anyone with spares to experiment with can try to force one to strip. It would be really good to know if retorquing the old OEM bolt using the BMW torque procedure could cause this .

Did the tech use the same pair of bolts for each test fit?

[Assimilator1]

Wow! A couple of your shells were really bad! (Was their any lead left on them??) 1 and 5 uppers, curious it's on the same pair....

Oh and all your close ups of the oil pick up are out of focus

[kevin @ eas]

84k just taken out and replace with BE bearings