Con rod nuts

Kiwi Landie · Jan 29, 2020

Rebuilding 1976 S3 engine. Installed pistons and was about to reuse the old con rod nuts when I saw in the manual that they say to use NEW ones (their emphasis - so probably worth taking note of!).

The ones I took out were Nylocs, perhaps a little taller (more thread) than ordinary Nylocs, but Nylocs just the same. Photos on the web appear to show the new ones ETC 5155 as ordinary nuts.

Now 3/8 UNF plain high tensile nuts and ordinary Nylocs are easy to come by here in NZ, but taller Nylocs are a bit tricky. Can anyone please explain what the original equipment is and whether plain grade 10 nuts and a bit of Loctite would do the trick? Obviously I can go to Paddocks and get some new ones, but they want 15 quid for the postage out here which seems excessive for eight small nuts.

Thanks in advance!
Andrew

Colthebrummie · Jan 29, 2020

I wouldn't take the chance, never reuse old nyloc nuts. £15 for postage is a lot but what price piece of mind.

Col

jamesmartin · Jan 29, 2020

Kiwi Landie said:
Rebuilding 1976 S3 engine. Installed pistons and was about to reuse the old con rod nuts when I saw in the manual that they say to use NEW ones (their emphasis - so probably worth taking note of!).

The ones I took out were Nylocs, perhaps a little taller (more thread) than ordinary Nylocs, but Nylocs just the same. Photos on the web appear to show the new ones ETC 5155 as ordinary nuts.

Now 3/8 UNF plain high tensile nuts and ordinary Nylocs are easy to come by here in NZ, but taller Nylocs are a bit tricky. Can anyone please explain what the original equipment is and whether plain grade 10 nuts and a bit of Loctite would do the trick? Obviously I can go to Paddocks and get some new ones, but they want 15 quid for the postage out here which seems excessive for eight small nuts.

Thanks in advance!
Andrew

use the old ones with loctite,previous they were just tall plain nuts,replacements tend to be of lower quality

discool · Jan 29, 2020

Colthebrummie said:
I wouldn't take the chance, never reuse old nyloc nuts. £15 for postage is a lot but what price piece of mind.

Col

A quick search with UKs Royal Mail to send a 300g small parcel, tracked to NL as below, but then there would add a small admin charge possibly.
https://www.royalmail.com/business/price-finder

Moron · Jan 29, 2020

Is your rebuilt engine worth 15 quid ?

rob1miles · Feb 7, 2020

I would tend to inspect and re-use the orginals with some loctite. I'm suspicious of the quality of some of the new replacements. Fine of you can get OEM, old stock but I would be wary of standard nylocs. Have you tried a fastener specialist?

Kiwi Landie · Feb 7, 2020

rob1miles said:
I would tend to inspect and re-use the orginals with some loctite. I'm suspicious of the quality of some of the new replacements. Fine of you can get OEM, old stock but I would be wary of standard nylocs. Have you tried a fastener specialist?

In the end I went to a local fastener place here and got myself some 3/8" UNF high tensile grade 10 nuts, which I then installed with Loctite. It turned out the originals were of two (very, very slightly different) patterns, so probably not OEM. They looked to be in good nick, but the new HT nuts were better. I source from this fastener supplier regularly and have confidence that Grade 10 nuts from them are actually Grade 10 and not Plasticine. I did check out regular Nylocs but they have quite a bit less thread than the nuts I eventually got, and of course are not available in high tensile.

Thanks for all the advice guys. It's oil pump, timing chain and tensioner today, so there may be further queries!

rob1miles · Feb 7, 2020

Sounds like an excellent fix

Con rod nuts

Kiwi Landie

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