banzaitoyota

mmmm



Guru's Kit and 1Revvins kits are apples and oranges

Cheers!

Hrm... looks like over the years nothing changes and the same arguments continue on.



I still stand by my 1st position that any aftermarket stud is a waste of money.



Some of the reasons behind my opinion:



-These long studs no matter what material you make them from will deflect when you apply a cantilevered load to them. It is actually better to use shorter bolts so that when you cantilever it at the furthest two ends the bolt won't interact with the other 1/2 of the engine.



-Bolts create clamping force and maintain clamping force by elastically yielding in tension to create this clamping force. If you ever get a chance to look at custom aerospace bolts you can see they are somewhat butted on both ends. Meaning the diameter tapers slightly in the middle. The strongest part of the bolt is at the middle far away from the threads and the top head. You want all your elongation to happen at the middle of the bolt elastically.



-Another important factor is the type of thread you have, and the tolerance on these threads. Ideally the threads are rolled onto the blank as this cold works the threads and increases their strength.



-If you want to have true perfect even tension each time you should not be using any fancy or unfancy bolts at all on the tapped cast iron. The threads from the cast iron front plate is no where near as strong as any decent bolt. What you want is to drill each of those holes out, and install stainless locking helicoils.



Regardless if it's 1revin7 or Guru or anyone who is making stud kits, I think you are better off spending your efforts else where than on tension bolts. The engine's torsion is reacted by the dowel pins. You should focus on adding additional pins with greater hardness and stiffer. That would prevent engine torsion more than using fancy studs instead of mazda tension bolts.



Also a tapped hole is never as strong as a through hole with a bolt/washer/nut combination. I wonder if it is even possible to drill through the front housing. Make new long bolts, and use a washer, bolt setup. That way it would be somewhat possible to measure the before and after length to determine the preload on each bolt.

ColinRX7

From their website? Horses mouth?

j9fd3s

on particularly the fd engines you could drill em thru, the bosses are there from the 20b, which uses tension bolts that go forward on the front rotor.



so i'll bite, why do piston people use head studs?

ColinRX7

Elliot knows what he is talking about.. Better torque distribution..





But keep in mind the application dictates the importance of the fastener. A cylinder head takes abuse from the piston compression and fuel ignition, think of the direction of the bolts and the piston travel. They are parallel.



A rotary engine has the bolts positioned different.



But, better torque distribution is better torque distribution.

mazdaspeed7

Arent studs more accurate with torque numbers because bolt twisting and thread friction dont have as much effect as they do on a bolt?

banzaitoyota

Might I suggest reading: Carol Smiths: Nuts bolts and fastener handbook. AKA "Screw to Win"

Lynn E. Hanover

There is more than one advantage to using studs vice bolts.



The aftermarket stuff can be very much higher quality than the OEM stuff. More a Ford problem than A Mazda problem but now that Ford has a big piece of Mazda, ???????



I used to overhaul Ford inline 6s for a local heating company. The fords had the most horrid machining I had ever seen. The fasteners were absolute crap. Differing diameters, heads cocked and only touching on one side. Threads run at angles. It was more like they only used crap that failed inspection from another MFR.



In torqing up a stud installation, the resistance you measure is between a real good nut and a real good stud with rolled threads. Instead of a bolt and cast iron junction. So the torque idea is valid.



In situations where a tension figure is critical, a stretch value is published, for the properly tensioned fastener. High quality aftermarket rod bolts have a dimple at each end. A special micrometer with either pockets for small bearing ***** or a pointed anvil and stem is used to measure the bolt length, and the nut is torqued until the bolt has achieved the specified length. It may be different for different bolts and studs of the same diameter. For example, some rod bolts will be correctly torqued at 47 pounds, and others at 51 pounds. The amount of stretch is what you are after.



Lynn E. Hanover



The picture is a Lexus (Toyota) from a Daytona Prototype.

kuhnke

ok then to get more ridgetity in the motor would you dowl pin the motor.

the problem i have with that is in the rear iron you take away threds for pin holes.

j9fd3s

it would appear, that adding dowels really doenst work, weather taking away material from places makes it weaker, or machine shops not being about to machine something like that accurately. or b, the factory bolts stretch. i'm looking for the reference to that, lol