Those of you who have used these. Did they affect the main bore at all?

Sorry for repeating myself. I figure this question merited a separate thread from my original post.

 

Why would they make a difference? There are dowels to keep the girdle placed correctly. The bolts are just a clamping force.

 

If the clamping force is greater in order to get the correct stretch of the aftermarket studs I would think it could possibly cause a few 100th. of a mm distortion?

 

It's not the studs. It's the clamping force.

If your clamping force is different with the Raceware studs, then yes... you will have to check it and possibly correct for distortion.

TonyG

 

The whole point of the Raceware products are to get the correct clamping force without creating distortions.

Check out this link: http://raceware-fasteners.com/german...er-not-better/

 

eh.... not entirely true and very vague.

The bottom line is that you should have the block checked no matter. It's cheap to check it and correct it if necessary.

TonyG

 

First of all it is not cheap to send the engine block of to a machine shop where he lives, it is very expensive, it would probably run close to 400usd or even more. The better safe than sorry approach doesn't answer his questions. He is probably better of asking Raceware than on this forum.

 

There's no first of all...

If you change how **** is torqued, which includes changing the type of fasteners, you need to check it to verify the distortion under load.

If it's too much much of a hassle or expense to check the crank mains for straightness.... then you have no business ****ing with the fasteners. Put the stock parts back in and follow the directions and be done with it.

TonyG

 

The OP had problems with rust on his studs and he has already done align honing on the block (when the main bolts where not rusty). That is the source of this question. My experience with Raceware is that they keep to factory spec torque, so no need to redo the alignment.

 

If the fasteners became rusty after the block was machined, then replace the fasteners with the same fasteners and you're fine.

Change the fasteners, and you need to put a load on it and remeasure.

And yes... I have used a lot of aftermarket fasteners... including Raceware.

TonyG

 

Tony. Do you have a source for OEM B.E fasteners? I can't find any.

 

This is the basic formula for axial load. As you can see from this formula with bolt diameter and torque being the same the only variable is the c, which may vary slightly. Still the clamping force won't change much.

Equation T = c D F

T = Torque required (inch pounds)
F = Bolt tension desired (Axial Load) (pounds).
D = Nominal bolt diameter. (major dia.)
c = Coefficient of friction constant
Steel and/or zinc plated threads = .2
Cadmium threads = .16
Lubricated threads = .16 to .17

 

Thanks mate.
Can anyone confirm the torqueing procedure for the RaceWare studs?

By the way, isn't part of the point of high spec fasteners the ability to use higher, thus more secure, clamping forces and still be safely below the yield point?

 

They have higher tensile strength and will stretch less under load. From the formula you will see that everything else being equal, increased tensile strength will give a smaller change in bolt change length. Torquing the bolts more wont necessary give you any benefits, as the part may start to deform.

EDIT: Tensile stress area is affected by number of threads pr/inch, and can also be changed do decrease change in bolt length

dl = F L / E A

where

dl = change in length of bolt (inches, mm)

F = applied tensile load (lb, kN)

L = effective length of bolt where tensile strength is applied (inches, mm)

E = Young's Modulus of Elasticity (psi, N/mm2)

A = tensile stress area of bolt (square inches, mm2)

 

If a stud is not torqued to a value which will exceed the yield strength of the material, then the only variable in determining the difference in elongation is the modulus, which for any conventional (i.e. any steel) material is going to be basically the same. This assumes you have kept the same stud diameter, pitch, and tension (torque) values.

So unless the tension in the stud produces stresses in excess of yield, there will be no difference in the resulting lengths of two steel studs of identical geometry, torqued to the same value.

It would be easy enough to compare the torque procedures and thread/stud geometry between stock and Raceware offerings to calculate ballpark tension values...