They're gonna have to have an engineer call me back with the load/deflection data.
But they have this info:
"No deformation or fatigue under normal loads, long service life.
Chrome Vanadium Spring Steel."
Stephanie

 

Make me number 5 but I'm sure there are many more. I'd been putting up with it. I thought having to regularly tighten the mani/turbo, turbo/dp bolts was SOP with aftermarket turbo kits. I have a mani being ceramic coated to help reduce the need for heat sheilding that's in the way of tightening everything.

I'm hoping a better stud material, combined with Bellevilles, will reduce the problem considerably. It doesn't have to eliminate it for me completely to be happy, just knock it back. If I only had to retighten bolts every few track days I'd be fine.

 

Oh, I'll totally borrow someone's car and thrash on it on the track. And I will also be testing those studs which hold the bumpers on, free of charge. :-)

Kudos to you guys for doing it. Certainly not trying to rain on anyone's parade. It just seems that it's not the most likely to work.


For that matter, I mentioned I had my turbo falling off constantly, I'd had studs shoot out and hit the far fender, broken at least 8 studs and lots easily as many nuts. I shared what worked (and continues to work) for me, and I'm glad to see what other people are doing. That said, Travis' set up sounds like it'll cost less and work better in theory, no?

One data point, on the FM-II and compatible manifolds, it'd be fine. Will make it even harder to get it assembled (as it is I rock the motor over on it's mounts with a 4' prybar to get the turbo on) but I think I could just live with it.

Certainly that's a good way to match up CTE...

 

Bellevillesprings.com has force/deflection info

Belleville Washers

M8 washers will deflect to 60% of max, with 700N (150 lb) of clamp force, leaving about 0.17 mm of remaining deflection.

10 ft-lbs of torque on an M8 nut will clamp at about 1800 lbs. That's 12x what would nearly flatten the bellevilles. In addition, the above M8 belleville is 18mm outside diameter.

I don't think bellevilles will work.

 

What about when you heat them to 1200*?

 

FWIW they have hi temp material which is good to 500 or 700*C, which would have been good enough.

See "heat resistant steel"
http://www.bellevillesprings.com/dis...lications.html

 

they will if you stack 12 of them!

 

LOL it'll be 10 mm thick.
If you had that much room, may as well add an extra spacer/flange between the turbo and the manifold.

 

So far it looks like we have a few possible solutions that need to be tried:

stud material:

1) 316 SS - 316 is stronger than 304
(spookyfish has tried 304 SS successfully so far, but with nuts tack welded.)

2) Inconel - JKav says it's a known solution - Savington will test (cool!)

3) Boundary Engineering's super special stud material - problem is price and size of group buy needed

All the above materials appear to withstand high temperatures better than the regular stuff - it won't corrode and creep / microyield / crystallize (?) like the regular stuff may be doing.

Although SS has a lower yield strength than regular steel, it has a higher CTE (coefficient of thermal expansion), so as the whole assembly heats up going down the main straight, and (as Boundary's thermal sim shows) its temperature lags the rest, it can lengthen more than regular steel to accomodate flange growth due to temperature rise.
In addition SS has a bit lower Young's Modulus at high temperatures, which means it can stretch to accept more flange "growth", before yielding:
http://www.engineeringtoolbox.com/yo...lus-d_773.html

NUT fixation
1) Torque to 10 ft-lbs so studs can "stretch", and use Resbond to keep them in place - this is what 034 motorsports recommend

2) 034 have some pricey nuts which they think are better than most - perhaps they have good hi temp capability
Aircraft Quality Turbo Lock Nut, M8 x 1.25 - 034 MOTORSPORT They recommend 10 ft-lbs + Resbond.

3) safety wire

Others:
1) through bolts so that the length of shank that stretches to accomodate flange growth due to temperature is longer
2) spacer flange between mani and turbo for the same reason

 

Good summary, now close this thread, start a new one with that as a FP

 

Glad someone did a summary, and I agree with most of it IIRC, but...

A lower Young's Modulus than what? Any steel, be it 304 SS, 316 SS, mild steel, A286, whatever, has a Young's Modulus (also known as Modulus of Elasticity) of about 30 ksi, with minor variations, say +/- 5%. The main thing that varies between alloys and heat treats is the yield strength, the ductility, and the ultimate strength.

At least you did not use that "stretchiness" term

 

That looks like a moly-coated steel Jet Nut, which is also available from Coast Fabrication for a little less money, and in both M10 pitches if you back up a level.

"Available in steel (450?F maximum temperature) and stainless (900?F maximum temperature)."

I notice they don't have stainless listed on the site for easy ordering. Might take awhile to special order.

I've requested the catalog to get their tightening recommendations.

 

FYI, I'm using the 034 nuts with resbond @ light torque. On my first track day with this setup they seem to work well. Six 30min track sessions and only one of the nuts loosened a bit. Then again, I'm not turning studly savington lap times.
The nuts themselves are a one-time use item as locknuts. I pulled the DP and turbo while replacing the transmission so I had to remove the nuts. The small wrench size makes them way easier to install than a standard nut. But after removing and reinstalling they go back on significantly easier therefore the locking effect is pretty much gone. I put them back on with resbond so I'll find out shortly whether resbond alone will work or not.
I'd recommend these nuts for the ease of installation alone.

 

I dont think it's the same nut. The 034 nuts are actual locknuts. The non-flanged side of the hole is kinda triangular in shape.

 

somebody sell me something quick! mines getting worse. instead of one bolt loosening, 2-4 are and my turbo is hanging off! i need something stat and can test at ecr, tws, and hhr next month. if not, i'm gonna weld this bitch together, **** it.

 

What stud material are you using? If you're still one some standard steel, you're in the failboat still.

 

Bryan, you were no slouch either. What were your times?

 

Seriously, the nuts I used have worked pretty well. I'd say someone else should try them, EVEN if they don't like my studs. I've NEVER seen anything work half as well as these.

From their pictures, their nuts don't have the triangular pattern I've seen on most of the locknuts. That's why I find them interesting. Also, a flat finish on the bottom. Are you sure it's the same nut?

 

See edits to summary post
https://www.miataturbo.net/forum/t35874-37/#post454419

 

Instead of dicking around with those pricey nuts, you might as well slap on some Stage8 locking nuts.