Track crew- Studs/nuts is the mani the weakest link now?
 

I got these studs which have a Minimum Tensile Strength of 124,000 psi
McMaster-Carr

Matched with stage 8 10mm locknuts
Flyin' Miata : Turbochargers : Parts and upgrades : Stage 8 locking turbo hardware (10mm)

Now, for the track guys/engineers or anyone who can shed some insight.

I am going to guess that now my begi cast mani is the weakest link here. My question is, how are the threads inside the mani going to hold up? Will i be screwed from having the stud shear the female threads? I will of course re tighten them after they heat cycle a few times.

If this doesn't work, what will?

Since everyone like pics, here is one i mocked up while i await my motor to be completed:
Attachment 205443

I would say that on the street you are fine. On the track this 10mm stage8 will still loosen or break. The manifold should be ok as that has 9 nuts over 4 here. That is 125% MORE nuts.

My apologies for not making this clear.

On track, will this hold up? I am talking about the studs threaded into the mani. Not the studs on the head holding the mani to it. Think the stage 8s aren't strong enough?

To make this even more clear, the 4 studs in the picture above.

@thesnowboarder: I have not tried stage8 myself but others have reported that nothing holds up at the track once you drive hard enough.

remember that the studs (when tight) are primarily in tension. there is very little shear on them. the shear force is carried by the material interface of the manifold/turbo mating being squeeeeezed by the tight studs. so as long as they stay tight, they wont shear.

i think the stage 8 hardware will be fine. it's in a low load situation other than the nuts themselves, right?

The problem is not lack of strength, it's that they loosen, which the stage 8 stuff will address.

All,

I just tried the Stage 8 system on a Miata Turbo over 4 track days. The nuts remained on the studs (M8 1.25). However, the studs stretched/backed out themselves. Tension was lost. So, at least I didn't lose the nuts and the fancy retainers, but the I could rock the nuts back and forth about 3 degrees with my finger (once things cooled down). These were fancy-pants ARP exhaust studs, by the way, that promised a tensile strength that "far exceeds grade 8 bolts."

These Stage 8 fastners did keep a small exhaust leak between the turbo and manifold from becoming a big exhaust leak. However, even after retightening when warm (just try to get the locking hardware off of a hot turbo sometime. The lower right nut, ouch!), the nuts still lost tension the next day after a single 20-minute track session.

I was still making full boost, and the gap shrank when warm, but I could have slipped a feeler gauge in there when cold.

So, even though these worked, the stud to which they attached still let the overall system fail.

Phil


Has anyone tried simply welding the studs in? Or using high-temp epoxy? Anyone?

I have a begi s5 manifold.

I've had the same problem with studs backing themselves out. I tightened down the locking nuts on the studs really hard but the stud still backed out. The nut didn't move at all. This was with street driving.

I too would like to know a way to keep the studs themselves from backing out.

Drilled studs with a castle nut safety wired.

MX-5 Miata Forum - View Single Post - Calling Black Jesus...

Thanks for the link, but I don't understand. Wouldn't this just lash the nut to the stud and keep the nut from coming loose? The only way I can see this working is if you're lashing a nut onto both sides.

The stud is drilled, you safety wire the studs, it keeps the studs from spinning. The castle nut allows the safety wire to pass through, also retaining the nut.



http://www.tpub.com/content/aviation...4014_116_1.jpg




I assumed it was implied, the cotter pin mentioned is not used, you replace that with safety wire.

I dont know if you have room, but i use 3/8-24 nut and bolt. been on there for almost 2 years and have never messed with it since. There not even anything fancy maybe grade 5. or go 7/16 NF, but again you may not have the room for that size bolt/stud.

How much track time?

2 days @ Streets of willow and 2 days @ Spring mountian in NV. and 13K miles on the street. would like to track it more often, but the economy is not allowing it.

What are you using to keep the nut on?

I agree a larger size with more thread area is needed for most of us. But I think your setup will eventually loosen.

The nut itself is an OEM exhaust nut, i cant remember for what car, but i will find out for you all, its just been so long since i put it on. Anyways I remember the threads inside the nuts have a little wave in them right at the end so they go in a bit tight at the end of the nut. Basically they spin on real nice then when you are tighting the nut it kind of feels like your cross threading it cause it get tight, but it does not cross thread.

Opppss, correction i have a 10mm x 1.5 nut and bolt, not 3/8-24. holding the turbo to manifold. My mistake. The nut from what i gathered from everyone i ask said they think it was most likly porsche 944 turbo, but that may not be correct. obscure details, when it happened so long ago. dang it :(

safety wire. I saw it on a few cars last weekend, but v-bands are the answer. I'm going to try the safety wire and if it fails I'm getting the check-book out and getting a tial turbine housing w/gate, begi s4 manifold and dp with v-bands and never looking back. Gotta pay to play. There's a reason every car in competitive racing runs v-bands.

hustler, you gotta figure out how to do v-bands on the head flange.

Nah you can use explosive welding to join aluminum and steel so just do that for the head-to-mani joint :bigtu:

I had the front 2 studs break last weekend, whilst at the track. I run about 10psi boost. This is the second time this has happened so my mechanic has said he needs to build a turbo brace, to support the turbo. He thinks it's the weight of the turbo snapping the studs.

Would firmer engine mounts help, by stopping the engine moving around so much? Just a thought before anyone shoots me down! I thought maybe the engine/turbo is moving as the engine revs, but the exhaust could be too rigid/fixed, putting extra strain on the bolts.

Is it an unusual problem or does it happen to most cars with a turbo system? If so, how do firms like FM sell their turbo systems without more comment/noise about this problem? Does it happen to everyone or is there something different about our set-ups?

Nope, we've tried that. Have also braced the downpipe to the transmission to try to limit any turbo/manifold movement, without success.

They sell their setup without addressing this issue because they don't drive their cars very hard, and the majority of their customers don't either.

You could weld 4 v-bands onto the head itself, but it would make manifold construction a bitch and it probably wouldn't be worth it. I've never had trouble with the head flange coming loose.

If I were sticking with flanges, what I would probably do is new studs with roll-pins pressed into place, and then nuts that have been drilled in a few places so they can be tightened when necessary. Drilling through the nut and stud means you can never tighten it - and you will have to tighten it.

V-Bands are the answer. Who wants my manifold, DP, and turbine housing?

Sorda on topic.... I dont plan on tracking it any time soon, but i was thinking of using these

http://ep.yimg.com/ip/I/yhst-1164098..._2054_65883610

They were stock on my SR20 and My turbo to mani nuts never once came loose. worth a shot?

Yeah worth a shot for sure IMO. That is easier than using the individual bend-up-tab type and safety wire. I have seen them sold somewhere before but cannot remember where. Anyone know where to get them for T2 flange spacing?

Hell I might try that and safety wired socket head cap screws on the DP flange. That is unless there is a similar product as above for a 5-bolt flange.

they are sold locally from my friend jeff at 240sxmotoring.com. They are for the T2 flange. Stock on all sr20det's. They do wear out. my first ones that were on the car originally did fail. put new ones on, never ever had an issue!

Excuse the ignorance - how does it work?

Does he make them for t25s?

The problem isn't the nuts or studs spinning though.... Safety wire solves that problem easy enough.

Have you ever seen the front sprocket on a motorcycle? Same kind of deal.

The plate goes under two of the four turbine inlet flange nuts. The fact that it is over two studs keeps the plate from spinning. Once the nuts are tightened, the two tabs protruding out next to the two holes are bent upwards against the flats on the nuts. That keeps the nuts from rotating.

Yeah sorry I should have said T25 according to the way Garrett identifies the turbine inlet flanges on the T25XX and T28XX series turbos.

I think if stainless studs and nuts were used to match my stainless exh mani flange, and the DP flange, then they should expand the same amount when they heat up since they will have the same TEC (thermal expansion coefficient - I am ASSuming that since they are is such close contact, their temperatures should be pretty close to the same). Therefore, they should not stretch, at least not to the point of yielding. If the nuts/bots/studs/whatever are kept from spinning, that should take care of it loosening. Or, am I missing something here?

How does that work exactly?
Spring pin - Wikipedia, the free encyclopedia
Is there an oval slot in the stud?

Mine has no room for that, I doubt the studs on the hot side can be made any longer:
https://www.miataturbo.net/forum/att...6062009034.jpg

what about this nuclear shit???
Extreme Temp Thread Locker, Turbo Rated - 034 MOTORSPORT
http://www.034motorsport.com/oscthum...OCKER2100F.JPG
it says 2100*

I'd be a little worried about getting this shit out of the manifold if something bad happened.

just ordered the Resbond thread locker. I talked to the guy on the phone and he said they use it in racecars with cast iron, horizantally mounted turbos and its worked without failure.

Great, hope you found a gem there.
Using it on the nuts only and not on the stud end that goes in the manifold?

why not use it on both ends? The guy told me I could just "double-nut" the studs and they will come out. However, he said to only use one line accross the threads becuase using too much will make extraction seriously dramatic. It sounds to me like this shit is pretty hardcore.

Apparently they use it on several turbo VW racecars and he claimed that they've never had a failure with it. I should have my next track event in 3-weeks or so at Hallett. Fingers are crossed...now I just need someone in Little Rock to let me borrow a drill so I can extract the broken stud.

Good luck with that stuff Trey; I hope it works. I'll be waiting to hear the results. Hallett in June should be a good test.

BTW I found another threadlocker made by Aremco, Ceramabond 671, good to 3200F. Holy crap...
http://www.aremco.com/PDFs/Aremcocat2008FIN2.pdf
From matweb.com
http://www.matweb.com/search/datashe...63bbbbef74aad6

I ran across something while flipping through an old Summit catalog the other day. Not sure if they're available in the right size for us, but it's at least an interesting concept:
http://www.jegs.com/images/photos/700/760/760-2xxxx.jpg
Available here and here.

Tech linky...

The story on these studs is that, once you've got the flange over the studs, you tighten the nuts...and then tighten a little set screw that's inside the stud end. This widens the diameter of the stud, making the nuts unable to loosen.
Given the issue at hand, I'd then have to wonder how secure the little set screws would be. However, it's another option to consider.

034 is local to me, ill put this shit on my studs before my event on the 20th matched with stage 8s.

Will report back.

I like that idea a lot, but they don't make them in 10x.125 and there is no way you're going to get a box wrench over the bolt head in any turbo housing. The could have done something more simple but they chose to make it pretty instead.



I'm trying it on the stud and the nut so I can see if it actually works. Then, I'm trying safety wire. Then, I'm going v-bands.

10x1.5?


I think ill put it in the stud, let it all heat cycle a few times, followed by putting it on the nut WITH the stage 8 locker thingy. Ill let it heat cycle without the locker thing.

I'm going with thread locker on both sides and very little torque on the nut. Hopefully that will let the cast iron shit expand and not break hardware.

Are you breaking shit? I am yet to break anything from actual track abuse. My only problem is loosening hardware. Think that goo you posted will keep it from loosing? That matched with the stage 8s should do it.. Lets hope.

I'm skeptical by nature or everything at this point, but it would be illogical to try considering I have more power than I know what to do with at this point. I've only done one track event and I've broken nothing. I still need to hook up the brake ducts and work on oil cooler ducting. I want to take my car to Boost Logic for sheetmetal work on the heat exchangers and be done with this shit and just drive it.

:drama:
I hope someone finds a cheap way to do this too. My studs were backing out too with locking copper nuts. Pain in the ass.

That crazy threadlocker sounds promising though. Is there a preferred stud to use with the threadlocker?

The strongest ones you can find, i posted the strongest ones i could find on the original post in THIS thread. If you find something stronger post it here.

40mm is as long as a t25 will fit with the begi cast mani.

Nick, I'll go halves on a bottle of resbond with you.

I don't know that the strongest is wise...we don't want a brittle stud, we want one to expand and contract. Then again, I'm talking out of my ass and going to try it with the shit I ordered from BEGi today. I'm replacing everything and putting Resbond on it. If this works, I'm going to shit my pants and run.

Sounds good. Think you will be around 034 area?

For anyone looking for the RESBOND it can be found here:
http://www.034motorsport.com/product...roducts_id=609

Im hoping to have my motor going in this weekend. Let me know if you will be able to swing by there otherwise ill order it tomorrow. (I wont be able to make it over there i have a busy week)
My engineer friend told me stronger would be better.

Locking Tab, M10 or 3/8", Turbo Nut - 034 MOTORSPORT

Saw this...kind of interesting. Similar to the other one posted earlier in this thread. Would probably work great with bolts and an easy diy.

http://img.photobucket.com/albums/v3...2090037jpg.jpg

lol

edit: 10mm

is that 10 or 8mm sav?

Yeah, I'll pick it up.

Oh no, you'll never be done. You'll want your bushings replaced, your final drive changed, an engine brace, a wing, splitters, the works.

Its a street car.

Another thing that will change. That's how I started too.

Don't derail the thread.

I love driving it on the street too much to gut it and only drive it once a month or less. I really like taking a street car to the track, then driving it home...I also really like taking it with me on business travel so I'm not trapped in a Hyundai for 6-months at a time with racetracks close by. I have another miata that will be a racecar before its done with lots of aero.