Keeping your hot nuts tight

[davedave]

Driving home from work last thursday, I thought I had sprung a fairly major exhaust leak (probably just one of the muffler flanges I thought). Anyways, as I drove on, it got louder and louder and in the end, I wasn't able to boost above about 1PSI (shit, I've torn my manifold a new one).

I finally had the time last night to check it and all 4 bolts had come out of the manifold-turbo flange?!?!?!
One bolt it still in the flange (whose nut was no the bottom) and one bolt is on top of the turbo. The other two maybe be as south as Bendalong, as north as Port Macquarie and as west as Cootamundra.

The two bolts that I still have, seem to be ok (not snapped), so I assume with the heat expansion and contraction of the two flanges, the nuts have worked themselves loose.
Which is a bit strange, because they were done up almost to breaking point.

Is there a lock-tight product that will help grip my nuts?

Thanks in advance,
Dave

[RobertoX]

Hi Dave,

On the factory turbo installations that I have taken apart there has been a metal plate that goes between these nuts and the flange, on the plate there are some tabs that you bend up around the nuts once you have them torqued. The tabs are to stop the nuts coming off, did you have one of these installed? If not maybe you should find one for your turbo, if its a common sort of flange they shouldn't be too hard to find, or you could make your own pretty easily.

[davedave]

Not sure I understand what you mean about the tabs that wrap from the plate (along side the gasket?) around the flange.

Here is a picture of my standard manifold and old CT26 turbo

As you can see, there is a thick metal gasket and just nuts on the studs.

Now the system I'm using is with a manifold I made (without studs)

I have the same (but new) thick OEM metal gasket between my aftermarket manifold and the CT20B (CT26 like) turbo, but now I have just high tensile 35mm bolts and nuts binding the flanges.

[-==L=a=N=c=E==-]

I had the exhaust same problem on my GT4.

The way i got around it, was use longer studs, and using 2 nuts per stud. Like a locknut. They havn't budged yet.

I got the car hot, and did them up while it was going. So hopefully that will account for the heat expansion.

[RobertoX]

What I'm talking about are more like a washer that goes under the nut but with a tab that sticks out the side which you can bend up around the nut.

The locknuts are a good idea but sometimes the space around the turbo flanges can be a bit limited, if you have the space then this might be the way to go.

[davedave]

I have only enough space for about 1 extra thread above the nut on one hole and 3-4 threads on the other three. The bolts can only go in one was due to this, three up - 1 down. In hindsight, I should have paid a bit more attention to the flange-pipe clearance when making the manifold.
Soooo back to the original question, has anyone had any locktight experience?

Thanks for the info though guys! Lance, it's good to know that mine is not some freak occurance or that it's just because I'm stupid.

RobertoX: Still not exactly sure what you're talking about. Sound like a hybrid betwwn a 'tabbed nut' which generally pokes into a hole next to the pertruding bolt and a splitpin type scenario.

[takai]

Ive seen splitpins used with some reasonable efficiency. The other trick i have seen is to get some lock wire and cut a little slot in the top and bottom of the bolt and then lockwire around the bolt, that way the nut cant completely vibrate off. Doesnt help much though if it gets 3-4 turns away. I have also seen people do the same thing but drilling a small hole all the way through the bolt, and then putting lockwire through and around.

[Starfire]

Try calling your nearest locktite dealer and chatting with them about your requriements. There are about 6,000,000 different locktite products...

[Cruiser97_80]

Hi Dave,

On the factory turbo installations that I have taken apart there has been a metal plate that goes between these nuts and the flange, on the plate there are some tabs that you bend up around the nuts once you have them torqued. The tabs are to stop the nuts coming off, did you have one of these installed? If not maybe you should find one for your turbo, if its a common sort of flange they shouldn't be too hard to find, or you could make your own pretty easily.

I think i know what u mean. I have tried to draw a pic to explain for you.
Please excuse my dodgy drawing skills.

[YLD-16L]

The above method is an excellent option or if this method is not suitable for your application head to your local bolt shop and get the thread locking nuts which are all metal (no nylon used like a nylock nut). They will never come undone but are a bitch to remove.

[clubagreenie]

They are called cone lock nuts. The thread hole is actually pressed into a semi triangular shape so there is nothing but metal. Definately single use only. If you wanted to split pin it and don't have muchj thread then get slotted nut rather than castellated nuts.

Slotted is just like a hex nut with the cut outs, castellated is like most steering nuts with a plain round section on top.

[YLD-16L]

They are called cone lock nuts.

That them clubagreenie. Thanks mate.

[Joshstix]

You can also get lovely copper nuts with a cut in the side that is then bent down making it lock into place once you torque it down. I don't know how many places you can get them from but I'm sure Rod could show you what I'm talking about at SAS on Sunday as I know they use some of this style of nut.

[Roundy]

i had the same prob on my GT4 with the Garret.

I used those cone lock nuts, and also used 'spring' washers.

They are washers with splits in them and space out a bit, so when u tighten it up they push back on the nut, therefore applying more pressure to the thread, hasn't come undone yet

[dave368]

Is there a lock-tight product that will help grip my nuts?

Try talking to Speciality Fasteners. They are able to source multiple use nuts called Glenlock nuts. Its difficult to describe but they have a captive c-clip about 0.5-1mm from the top of the nut embedded in the thread that locks the nut up until melting points of steel (rather warm ) .

They are pretty expensive at about $2-$2.50 each nut in 8mm thread size but they haven't come off and they are multiple use (within reason).

Cheers,
Dave