Rodbolts, loctite - correct torque ??

[Roslin]

I wayne's i read that if you atemp to use the st. rod bolts in a Porsche engine, they should always torqued with Red Loctite 271, but how can you reach the correct torque ? does the Loctite
have the same anti friction efect .. like oil or asm. lube ?

Did the factory use Loctite ?

Regards Roslin

[David E. Clark]

This Loctite technical data sheet should answer all your questions about Loctite 271. Hope it helps.

[Jeff Alton]

A quick search in the engine rebuilding forum will yeild a thread where is debated a fair bit.

Cheers

[911pcars]

You don't want the big end to loosen, yet Loctite is not an approved thread lube. Check the archives for a thorough discussion. In the meantime, I would torque with antisieze and fresh fasteners, then dribble some green Loctite into the threads to provide some (nil?) measure of backup. If the engine over-revs and the rod bolt stretches, than the equation goes out the window.

Sherwood

[88911coupe]

I've read the long thread on this issue and knowledgeable people seemed to disagree as to wet vs. dry torque issue which to me is the critical point of contention in this whole issue. My main concern is that I, following Wayne's book, used Loctite and torqued my con rod bolts per instructions, which is torque to some setting if foot/lbs then 90 degress or whatever it was. Have I overtorqued my con rod bolts since I used loctite...?
BTW, I can't seem to find anything addressing this issue in the loctite sheet, however, one I found for Permatex specifically said no adjustments needed to be made to torque values.

[JFairman]

The factory uses oil on the threads of the rod bolt threads, not loctite.

Here is a video on you tube where you can watch 911 motors being assembled at the factory and they do it quickly.
Halfway through this video you can see the guy pick up an oil can and squirt oil on the bearing shell, put the rod on the crank, more oil, then the rod cap, then he squirts oil on the rod bolt threads, then thread the nuts on, the video skips where he torques the rod nuts, then 2 guys pick up the crank and set it into the case half with 3 rods down while another guy holds the other 3 rods pointing upwards.

It's cool to watch these old videos.
http://www.youtube.com/watch?v=JPWoSOgXRf0

Use new bolts and nuts, unless you're using ARP or Raceware rodbolts. They can be reused.

[RWebb]

re green Loctite... nil

Loctite says somewhere that the green (which wicks in) is about as strong as blue.

as to the answer to the question ... who knows?

[MattAlpha]

Its amazing how many questions can be answered just by watching someone perform a task (like building an engine) that would need hundreds of pages to properly describe. A video is best so that you can re-watch it to learn more each time. Though multiple angles would help

[88-diamondblue]

On my rebuild I used ARP rod bolts since I have a 88 Carrera, smaller factory rod bolts than for the SC. After reading all that I could find on the rod bolts I decided to use the ARP lube and use a stretch gauge to install the bolts. No thread locker even though I was going to use red loctite when I was planning the rebuild. Even if I used factory rod bolts I would not have used thread locker. JMHO

[Roslin]

My threats on flywheel bolts and con rod bolts are torqued with no use of Loctite, just oil as from the factory. I havent heard about factory cars with failure because of lubricated threads ! so no loctite on these components here.

Merry christams.

Roslin

[Scott R]

Originally Posted by 88-diamondblue

On my rebuild I used ARP rod bolts since I have a 88 Carrera, smaller factory rod bolts than for the SC. After reading all that I could find on the rod bolts I decided to use the ARP lube and use a stretch gauge to install the bolts. No thread locker even though I was going to use red loctite when I was planning the rebuild. Even if I used factory rod bolts I would not have used thread locker. JMHO

Your rebuild was an inspiration for mine, after watching you I also did the ARP bolts and I'm very happy I did. I never think twice about them actually.

[911pcars]

Originally Posted by JFairman

The factory uses oil on the threads of the rod bolt threads, not loctite.

Here is a video on you tube where you can watch 911 motors being assembled at the factory and they do it quickly.
Halfway through this video you can see the guy pick up an oil can and squirt oil on the bearing shell, put the rod on the crank, more oil, then the rod cap, then he squirts oil on the rod bolt threads, then thread the nuts on, the video skips where he torques the rod nuts, then 2 guys pick up the crank and set it into the case half with 3 rods down while another guy holds the other 3 rods pointing upwards.

It's cool to watch these old videos.
http://www.youtube.com/watch?v=JPWoSOgXRf0

Use new bolts and nuts, unless you're using ARP or Raceware rodbolts. They can be reused.

Using a 50 year old PR film to establish optimum assembly techniques might limit the scope of one's rebuilding procedures. While threadlockers were invented sometimes in the 60's, I'm not sure Porsche would have strayed too far from their traditional methods of manufacturing for a new and more costly assembly technique.

This is neither condemning or advocating the use of a threadlocker in these applications.

Sherwood

[RWebb]

good point

what do they use now...?

[diverdan]

Really Old School. I had a 50s race car back about 40 some years back and the con rod bolts were safety wired. Anybody still do that?

Diverdan

[T77911S]

just talked to a guy i work with that use to race dirt track. he built his motors, about 6-700 hp, he said he tried both ways, never had one fail either way.

[db_cooper]

I was a Porsche tech back in the early 80's and attended many factory training schools. One was 911 engine rebuilding. Official guidance was to assemble the rod bearings and torque with oil.

I never heard of any rod bearing caps coming loose using this method. Not an issue and I would not recommend adding safety wire or locktight.

Done correctly, they go 250k or more, without a problem, as we know.

[T77911S]

wouldnt safety wire negate any balancing that was done?

[Quicksilver]

Originally Posted by db_cooper

I was a Porsche tech back in the early 80's and attended many factory training schools. One was 911 engine rebuilding. Official guidance was to assemble the rod bearings and torque with oil.

I never heard of any rod bearing caps coming loose using this method. Not an issue and I would not recommend adding safety wire or locktight.

Done correctly, they go 250k or more, without a problem, as we know.

When rod bolts loosen up it is always from bolt stretch from over revving, stresses from a failed rod bearing, incorrect torquing during installation, or materials failure from a bolt defect.

Oh, and if you see a failed rod bearing it is often not the cause but a symptom of a stretched rod bolt...

In other words: Oil.