TR4/4A ARP Bolt Torque Specs

[ghawk16]

OK...I'm planning to call TSI tomorrow to see if they have the torque specs for the kits they sell for ARP main, rod and flywheel bolts for my TR4 but figured I'd ask here first to see if anyone knew or had some feedback. I know, I know...I'm sure the bolts are overkill for the TRactor engine but I figured why not while I was in there. But does anyone know if the torque specs change on the flywheel, main bearing caps and rod bolts when using ARP products. I'm sure the cylinder head kit will come with torque specs since it was made for the TR4 and listed on ARP's site. Thanks

 

[Sarastro]

I don't think it's overkill--there was a recent posting in the MG forum where a newly rebuilt engine was destroyed because a bolt for a rod-bearing cap broke. I think that using the best bolts you can get is wise.

Wouldn't they have the same torque as the ordinary ones? I'm having trouble imagining why they should be different, but maybe I'm missing something.

 

[TomMull]

If they are "stretch" design, they may be torqued differently. This might help:

https://arp-bolts.com/p/instructions.php

 

[ghawk16]

If they are "stretch" design, they may be torqued differently. This might help:

https://arp-bolts.com/p/instructions.php

Yeah...I saw that Tom, but the problem is these bolts for the flywheel, rods and mains aren't a "kit" for the TR4. They are part numbers that TSI put together that fit the TR4. So I'm sure they did their research and found out the torque values. The head "kit" that ARP sells I'm sure will have the torque values in them as a lot more people of have used those. I'll give TSI a call shortly.

 

[Sarastro]

Hmmm...just as an example, I took a look at the ARP head studs, and they recommend 110 lb-ft. The shop manual spec is 100-105, which is, for all practical purposes, the same. My thinking was that the ARP bolts have greater tensile strength, but the amount of stretch for a given loading depends on diameter and elasticity, which should be virtually the same.

Best to contact the people selling them, of course. It would be nice if ARP produced a set specifically for TR4/4A rods and mains, and supported it with the kind of instructions they provide for their other sets.

 

[Mickey Richaud]

I just received rod, main, and head studs and bolts from ARP for the MGB engine I'm building, and they provide all info for torque specs and how to fit them with each set they sell. They also sent me a catalog and tech guide for all their current products. You can also go online or call and ask questions about any of their items. Great support.

 

[ghawk16]

Hmmm...just as an example, I took a look at the ARP head studs, and they recommend 110 lb-ft. The shop manual spec is 100-105, which is, for all practical purposes, the same. My thinking was that the ARP bolts have greater tensile strength, but the amount of stretch for a given loading depends on diameter and elasticity, which should be virtually the same.

Best to contact the people selling them, of course. It would be nice if ARP produced a set specifically for TR4/4A rods and mains, and supported it with the kind of instructions they provide for their other sets.

Yep I called ARP on Friday and the customer support was awesome. And...you can buy directly from them which is nice. I got my flywheel bolts and main bolts and washers using TSI part numbers from Summit Racing and then ordered the rod bolts straight from ARP. Now after talking to support this is what they said and hope this helps in the future.

Bolts/Stock Torque/ARP Torque:
Flywheel Bolts (#206-2802)/42-46 ft lbs/55 ft lbs (so close enough...and ARP said it wouldn't even hurt to go with the stock value or go somewhere like 50 ft lbs as it's so close)
Rod Bolts (#4AP1.850-2U)/55-60 ft lbs/75 ft lbs (recommended looking at stretch after torquing using a rod dial gauge and they should go to about 3.5-4 thousandths)
Main Bolts/Washers (#HAR3.500-5)/85-90 ft lbs/100 ft lbs (ARP said 90 ft lbs would be perfectly fine with these since they are main bolts)
Head Stud Kit/100-105 ft lbs/110 ft lbs (Follow ARP torque values)

Be curious to see the difference in torque values on Mickey's MGB kits since the only "kit" for the TR4 is for the head.

 

[Grantura_MKI]

There is a dry and wet torque setting?

 

[Mickey Richaud]

Be curious to see the difference in torque values on Mickey's MGB kits since the only "kit" for the TR4 is for the head.

All my stuff is at the machine shop at present; not sure when they'll finish up, but will check back in when I get everything back.

 

[ghawk16]

So called ARP back and sure enough the torque values are wet values utilizing their lubricant. Also, for the main bolts the washers must be used due to length. So I asked ARP if this was OK and they said that the 200-8533 washers were OK to use with them. So...give them a shot and see what happens!

 

[TBU_Triumph]

A few basics to remember with bolts and torque.
1) Torque is an approximate way to measure tensile load (stretch) in the bolt.
2) All bolts of the same size stretch at the same rate up to the elastic limit (strength) of that bolt.
3) The primary difference between the stock bolts and ARP bolts is that the elastic limit of the ARP bolts is higher. They will stretch further without permanent deformation.
4) The key limit is what the overall joint can handle. That is why the torque for the ARP bolts is essentially the same as the stock bolts. For example, the internal threads in the crank flange cannot take a higher tensile load just because the flywheel bolt is stronger.

So when you torque an ARP bolt to a given torque and a stock bolt to the same value you have the same clamp load. The difference is that if some load tries to separate the joint the ARP bolt will stretch further without failing.