Pressure plate bolts.

[John S]

Which bolts would you use for pressure plate. Grade 8 bolts or ARP bolts factory manual says 35 foot pounds of torque for pressure plate. ARP says 45 ft lbs. for their bolts with their lube. Tell me what you think. If the ARP are better I’ll get them.

John S

[Marks71]

Can’t go wrong with ARP.

[MC1of80]

ARP bolts are always better. The price, not so much. 

If you plan on "playing" a little, then you can't go wrong with ARP. 

But also remember, the factory bolts are plenty strong also. 

[John S]

1 hour ago, MC1of80 said:

ARP bolts are always better. The price, not so much. 

If you plan on "playing" a little, then you can't go wrong with ARP. 

But also remember, the factory bolts are plenty strong also. 

It seems unusual that both bolts are 3/8-16 but one is torqued at 35 foot pounds and ARP at 45. Seems like a lot of torque on a 3/8 bolt.

[MC1of80]

20 minutes ago, John S said:

It seems unusual that both bolts are 3/8-16 but one is torqued at 35 foot pounds and ARP at 45. Seems like a lot of torque on a 3/8 bolt.

They can take way more torque than that. As a "wee one" 17 yr old working at a transmission shop we used to install all pressure plate and flywheel bolts with 1/2" air impact guns. Never checked torque and thankfully no failures. 

Didn't know or care about "torque" specs. Back then. Know better now. I guess... 😂🤣😂

[jft69z]

I'd go with whatever torque ARP recommends for their products. They would know best what their product metallurgy is capable of, in terms of stretch and clamping load, vs a standard grade 5 or grade 8 bolt.

 

https://arpinstructions.com/generaltorque.html

https://arp-bolts.com/kits/bulk-list.php?PL=1&M=1&W=*&D=*&P=*&WS=&Set1_page=8

 

https://crafter.fastenal.com/static-assets/pdfs/Torque-Tension_Chart_for_A307_Gr5_Gr8_Gr9.pdf

[John S]

I will set it up as per their torque specs. Thanks for the help a lot of people on this forum work with this stuff a lot more than I do so I value your input, again thanks. Also, back in the late 70s and 80s working in auto shops we used to follow More’s law if tight as good tighter better and too tight is just right.

John S

[DragCat]

I usually follow manufacturer specs on torque, except on aluminum pieces. But I always use that silver crap that gets all over everything when I bolt into alum 😮

[cbolt]

Working on aircraft my whole professional career the torque specs were always followed to the letter and witnessed by a quality inspector. That habit has always carried over to vehicle maintenance for me. 

 

Having said that in this case I would go with the higher torque spec as well simply because the danger from over torque would likely be stressing the bolt itself so you would need to replace it in the event you have to remove it for maintenance, which most folks do anyway just like cylinder head bolts. Under torque could cause the bolts to vibrate loose, which is much more trouble and something I have seen over the years.