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-   -   Intake Manifold Studs (https://www.miataturbo.net/race-prep-75/intake-manifold-studs-76353/)

Leafy 12-02-2013 11:09 AM

Intake Manifold Studs
 
I was finally bitten. When pulling my intake manifold off one nut just fell off with the half stud in it. What are you track people doing for intake manifold studs? They seem to fail left and right for the auto-x people, the csp car ended up replacing an entire set worth this season IIRC. They're m8x1.25 I need to pull a good one to get the length. Do we just replace with OEM as the break or have an upgraded option? Mcmaster doesnt have 10.9 studs, but they do have 4140 for pressure bolted connections in high pressure systems. Minimum tensile strength of 124,000 psi and max hardness of Rockwell C35, which is in between class 8.8 and class 10.9 for both strength and hardness.

Seefo 12-02-2013 12:03 PM

I haven't had any issues with mine. Are you maybe overtorquing them? I remember them having a pretty low torque range.

Leafy 12-02-2013 12:07 PM

I tightened them with a 1/4" drive ratchet so I doubt I yielded it. The failure looks like fatigue, it didn't look over torqued.

Preluding 12-02-2013 01:42 PM

...maybe the intake manifold brace serves a purpose after all...

mx5-kiwi 12-02-2013 07:39 PM

I have been racing mine for the past year and previous owner for 4 years with out any problem..

This is WITH the brace...1600cc motor, though I doubt that makes a difference....

Now the exhaust manifold, thats a different story!

Leafy 12-02-2013 07:45 PM

Yeah, I've been looking some more and it looks like this is just an issue that us cone dodging, weight weenies that rev the car to the moon and back have to deal with.

codrus 12-02-2013 08:02 PM

Quote:

Originally Posted by Leafy (Post 1078799)
rev the car to the moon and back have to deal with.

I suspect the revving is the culprit.

I've done about a hundred autoxes on mine, with nary an intake manifold stud problem so far, but I don't rev it above the stock 7200 (here's little point with a a 2560).

--Ian

mcfandango 12-03-2013 09:44 AM

So bust out the sawsall, grinder and other associated metal removal tools and make the intake lighter! :giggle: Less mass means less torque on those studs.

Leafy 12-03-2013 09:48 AM

Quote:

Originally Posted by mcfandango (Post 1078954)
So bust out the sawsall, grinder and other associated metal removal tools and make the intake lighter! :giggle: Less mass means less torque on those studs.

The thing is freaking heavy, its also borrowed. :giggle:

shlammed 12-03-2013 09:49 AM

tap the bolts out for a larger size- best option, not easy to do properly in the car.
use higher grade bolts (not as ductile though in most cases, so it likely wont help)
use the intake manifold bracket - if your a weight weenie for the 1/2 lb that the brace isare, drill some holes in it in the middle of the web, leave the outside of the web for strength.

mcfandango 12-03-2013 12:38 PM

Then I'd vote for bracing. Just like on the turbo/exhaust side of things. I actually had my turbo come off the manifold recently because of a broken exhaust hanger in the rear.

Sucks to add weight but it might be necessary. Also you can probably fab up something lighter and just as good than the factory brace with a swaged rod or turnbuckle.

Leafy 12-03-2013 01:14 PM

But the turn buckle wont work, too many axis of movement, it just becomes a point for the manifold to rotate around. It needs a solid connection if its going to have a brace.

I took a look back at one of the old engineering texts, my failure may potentially be an under torqued fastener, or just a lack of yield strength in the fastener. I'm going to find some class 10.9 studs, and actually use a torque wrench. And probably re-calculate the actual torque spec to be 60% of yield for the new studs.

mcfandango 12-03-2013 01:40 PM

If you are recreating the factory type brace, I don't see how a turn buckle would have too much motion. Lock the buckle into the length you want. I'm not saying put rod ends on it.

Leafy 12-03-2013 01:46 PM

Quote:

Originally Posted by mcfandango (Post 1079147)
If you are recreating the factory type brace, I don't see how a turn buckle would have too much motion. Lock the buckle into the length you want. I'm not saying put rod ends on it.

That seems more expensive than just drilling a bunch of holes in the stock brace. :giggle: Or just running stronger studs with a re-calculated torque spec.

Seefo 12-03-2013 02:30 PM

Quote:

Originally Posted by Leafy (Post 1079152)
That seems more expensive than just drilling a bunch of holes in the stock brace. :giggle: Or just running stronger studs with a re-calculated torque spec.

just don't bottom them out in the head, not really sure how much space is back there. that won't be fun to get out...

btw, are you running a phenolic intake manifold gasket by chance?

mx5-kiwi 12-03-2013 02:31 PM

How much does the stock brace weigh?

and is the weight cost REALLY worth the hassle?

Leafy 12-03-2013 02:34 PM

No stupid plastic gasket. I havent weight the brace and associate fasteners but it must be around 5 pounds. Its also in the way of where I want to put my power steering pump maybe.

mcfandango 12-03-2013 02:37 PM

:dunno: I have a piles of unused parts from all sorts of stuff. This would be nothing to scrounge up something to create it. Cost? You must not value your time very much. Taking much weight out of the factory brace is going to take a while even with a drill press.

Even cheaper? A piece of square or round tubing could be abused in pretty quick fashion for this and probably still lighter than the abused factory one.

It looks like Dorman has some M8x1.25 10.9 studs.
Dorman Products - Double-Ended Studs Class 10.9

Seefo 12-03-2013 02:37 PM

Quote:

Originally Posted by Leafy (Post 1079185)
No stupid plastic gasket. I havent weight the brace and associate fasteners but it must be around 5 pounds. Its also in the way of where I want to put my power steering pump maybe.

5 lbs? you are crazy. that brace is no more than 1.5 lbs with the 3 bolts it needs.

FrankL 12-03-2013 02:58 PM

Solution, a lighter intake that is also *SP legal. Coming soon.

OP question, check with ARP, they make all kinds of products that don't have a specific application.


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