Nuts - I’ve looked all over and... nothing. Germany?

looking for:

PN: 163534

M12x1.25 DIN982 Class 8 Nylon Locking Hex Nut - preferably in a yellow cad finish

This is the tall nylon lock nut that secures the rear subframe to the chassis. Newco products carries it in a Class 10, but a Class 8 is needed for this application.

Perhaps a German Supplier?

Any help appreciated.

 

Good tip - many thanks:

I just shot a note to them in order to confirm the Class and DIN
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As a side note... if folks have interest, here is why these nuts should be replaced at each service and why a Class 10 (harder) nut from Newco cannot be substituted for a Class 8. This also demonstrates why the ‘tall’ DIN 982 nut is required.

Check out the last few paragraphs.

 

BTW:
These vital chassis nuts are rarely if ever replaced during a typical engine out service. Note the second to last paragraph and ask yourself... “do I really want to go 180mph in this 30 year old car.”:

It reads:

On a demonstration with a ½-13 zinc plated SAE J429 Grade 5 hex cap screw and zinc plated SAE J995 Grade 5 hex nut with an installation torque of 70 ft-lbs to obtain a clamp load of 9000 lbs (without any added lubrication). On the second installation, this torque had increased to 95 ft-lbs to obtain 9000 lbs. By the fourth installation, we required 145 ft-lbs to reach a clamp load of 9000 lbs.

 

The guys at Superformance answered my email.... based on their info, the nuts they sell are DIN 985 Class 8. The OEM nut is DIN 982. Below is the dimensional info.

Their M12 nut is 2mm too short. I’ll need to do more research to see if it is an adequate substitution.



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EU DIN nuts are marked with their grade number stamped on their bottom mating surface. The most typical values you’ll find on a TR are 8 (mild steel) and 10 (hardened steel). Here are the specifics.


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Here is a stress strain curve to illustrate Proof Load. In essence, it is the maximum safe load to ensure that the fastener does not permanently deform



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That sounds like a good PhD thesis subject. I suspect the short answer is ‘it depends’.

 

With some 28 or so main bolts securing the subframe it is an attestation to Ferrari’s robust engineering. That said however, it is well documented how nuts loose more of their ability to properly secure a joint with each reuse.

I hear your point however - it is a trade off. How much $ does the new hardware cost compared to the cost of failure. If it is a critical joint on the space shuttle - use new hardware each time. If it is a Ferrari structural component.... perhaps every 30 years (7 to 10 or so remakes) makes sense.

The need and timing for replacement is arguable... even amoung experts.

 

Exactly right. I got a chuckle seeing the timing belt cover nuts (M10) being a Class 10 and the chassis nuts (M12) being a Class 8. No doubt it is because of the very reason you cite. Ferrari definately overdesigns!

Just to be clear.... I am using the DIN version of ‘Class’ and not the SAE version of ‘Grade’. Regardless, your point is equally valid.

 

For the most part, just the nuts ‘may’ merit replacement. The trick is knowing exactly what you need and then finding a supplier. If it adds $100 to the price of a major, I’d be surprised. Even less if a plain silver cad is acceptable rather than the Ferrari yellow.

Example - these M6 Class 10 nuts are commonly used on the Testarossa and they cost only 17 cents each.
Yup, I have more than I need! Every shop should have these on hand as well.

Besides... fresh yellow cad hardware makes the engine compartment turn into eye candy when compared to 30 year old, corroded nuts that have lost most of their cad plating over time.

 

agreed!

 

Please read the enclosed pdf shown in post #4.

There are many other sources on the internet that document how nuts lose their effective fastening strength with each re-use.

Here is a quote from the pdf:
“On a demonstration with a ½-13 zinc plated SAE J429 Grade 5 hex cap screw and zinc plated SAE J995 Grade 5 hex nut with an installation torque of 70 ft-lbs to obtain a clamp load of 9000 lbs (without any added lubrication). On the second installation, this torque had increased to 95 ft-lbs to obtain 9000 lbs. By the fourth installation, we required 145 ft-lbs to reach a clamp load of 9000 lbs.”

Let me rephrase that quote:
1st torque - 70 ft-lbs to reach the designed 9000lbs of clamping force
2nd torque - 95 ft-lbs to reach design
4th torque - 145 ft-lbs to reach design - MORE THAN TWICE THE ORIGINAL TORQUE

Unfortunately, a tech can’t just keep upping the torque levels to get the designed clamping force. He cannot typically even measure the clamping force! He has no idea how many times the fastener has been retorqued. He has no idea on how much torque he needs to apply. If he always applies the workshop manual’s specified torque.... the CLAMPING FORCE is reduced with each re-torque of the fastener.

Effectively, the joint remains ‘loose’ even if it is torqued to spec.

Connecting rod assemblies routinely fail in this manner. This is why engineers have developed new techniques to more accurately measure “clamping force”:
http://www.performanceenginetech.com/connecting-rod-bolts-stretch-vs-torque/

Remember:
The engineers calculate their “designed clamping force” and then cite the ORIGINAL fastener and torque levels to achieve the required clamping force.

So, in layman’s terms - nuts DO IN FACT ‘wear out’. It is a proven engineering fact.

BTW:
Please do not misunderstand my intent. I do not in any way suggest that fasteners be changed out with something ‘different’.... but rather, just ‘new’ versions of the identical OEM fastener.

I hope that helps.....