7 replies to this topic

[HUBBA.HUBBA]

As above. Are they torqued down more?

[kappa]

I would like to know this aswell

[Tupers]

I know they're made from Cro-Moly a better quality steel than standard ones meaning that they will hold the torque better and be less prone to stretching. I don't know if they're torqued up tighter but it would seem unlikely.

One interesting thing that was pointed out to me by a local engine builder is that the ARP nuts have a considerably smaller footprint than a latter A+ nut. This means that although ARP studs may be able to take more force without stretching they're actually spreading that force through a smaller area which isn't necessarily a good thing.

[HUBBA.HUBBA]

I know they're made from Cro-Moly a better quality steel than standard ones meaning that they will hold the torque better and be less prone to stretching. I don't know if they're torqued up tighter but it would seem unlikely.

One interesting thing that was pointed out to me by a local engine builder is that the ARP nuts have a considerably smaller footprint than a latter A+ nut. This means that although ARP studs may be able to take more force without stretching they're actually spreading that force through a smaller area which isn't necessarily a good thing.

So they are torqued down to the standard amount?

[Cooperman]

When you buy the ARP bolt & nut set the torque figures ae given on the data sheet. They quote figures for 'dry' and 'greased' assembly and a small supply of the correct grease is supplied.
For normal road use they are probably over-engineered, but for competition use they are quite simply the very best.

[Ethel]

Standard A+ bolts are pretty good.

Bolts behave like coil springs under tension, it's their elastic qualities that squeeze the head and block together. If they are too near their upper limit they'll stretch permanently and no longer clamp, but if they are too stiff they won't share the forces as well between them and they will fatigue and fail quicker because the lack of "give" will make the instantaneous forces much higher. A+ bolts are thinner in the middle to make them stretchier. You need to use flanged nuts or washers of equal quality.

[The Matt]

They're also used in engines that are likely to be stripped and rebuilt a lot. Threaded fasteners are prone to stretch (as explained above by Effel). IIRC they are torqued up higher on the A-series kit. Can't remember for definite so don't quote me on that. I know my Minis big end and mains bolts are ARP ones and are torqued higher than standard, but it's not a proper mini engine.

[The Matt]

Nope, use factory torque setting:

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