reality check on exhaust studs.

[theiceman]

I have a 78 SC and have validated i have thin flange exchangers. They are rusted out now but i did get a set of exchangers off a later car that have thick flanges. I am aware i will have to replace all the studs and machine off the lip off the replacement ones so they will fit my car.
here comes the confusing part.

The replacement studs listed by our host for a 78SC ( 78 79) is 51mm.
The exhaust studs listed for the later car ( 80 -89) are listed at 46mm.

But my flanges are definitely thin compared to the ones i am putting on .

Just want to make sure i am ordering the right part ..

[john walker's workshop]

take a short length of 2x4 and sharply wack your forehead. it will be less painful than trying to drill out and insert 12 exhaust studs. they rarely just unscrew. just find the proper exchangers.

[Dan J]

Originally Posted by john walker's workshop

take a short length of 2x4 and sharply wack your forehead. it will be less painful than trying to drill out and insert 12 exhaust studs. they rarely just unscrew. just find the proper exchangers.

True dat

[theiceman]

Actually i was painfully aware of this exercise.

My plan was to just cut off the old exchangers and give the heads with flange still bolted to it to the machine shop. I figued that may be easier for them to deal with.

But you are making me rethink my plan.

[JJ 911SC]

Here is the story of my 12 exhaust studs. It was fun Had to do 1 Time-Sert.

2 studs came out with the barrel nut
2 barrel nuts came out clean
2 barrell nuts snap right at the end of the nut

I cut out all the 6 nuts

Of the 10 Studs lefts (which the HE out of the way);

7 come out using a stud extractor and a air gun starting at 30 pounds, increasing to 40 and they came out at 50.

1 broke but we (me and Alex) got it out.

It left the two out. We put the extrator to one and it broke but left the flat part, so we grab that and I swear it start it to turn but snap flush, that is the one that I drilled out.

After taking a long break trying to figure out how to get the broken one which was close to the cooling fin, I decide to try a bolt out. I got it on using a 1/4" wrench... and put the air gun to it. Sure enough, after the 30 and 40 pound racheting, it come out at 50"

Help... Exaust Stud Drilling

[Hawkeye's-911T]

Pay heed to Mr. Walker. Ask me how I know.
Cheers
JB

[theiceman]

i am now looking at the possibility of getting my exchangers machined so the flange is thinner.

A lot will depend what happens when i try to take the old exchangers off.

[scarceller]

Originally Posted by john walker's workshop

take a short length of 2x4 and sharply wack your forehead. it will be less painful than trying to drill out and insert 12 exhaust studs. they rarely just unscrew. just find the proper exchangers.

John, I've found that removing these is best done by tacking up some weld with a Mig/Tig welder on top of the nuts before you even try taking them out. I'm not sure why it works but for some reason the heat induced by the arc seems to break them free. I've used this method on a lot of exhaust studs and it works every time. I no longer even bother trying to remove a corroded stud without applying some weld.

[theiceman]

Sal how exactly do you do this ? if you are applying some weld how do you manage to get tools on it after wards to remove it ? i think you are dead on with you hypotheses the rapidly heated stel sud am sure microscopically expands the surrounding alluminum giving the stud some breathing room.

[scarceller]

Originally Posted by theiceman

Sal how exactly do you do this ? if you are applying some weld how do you manage to get tools on it after wards to remove it ? i think you are dead on with you hypotheses the rapidly heated stel sud am sure microscopically expands the surrounding alluminum giving the stud some breathing room.

First, I've only done this with engine on an engine stand and out of car. The idea is to weld onto the stud (not the nut) and sort of build the stud up without fattening the stud more than the nut. This allows you to still put a long socket onto the nut.

Also if you can get the nuts off first and remove the exhaust so that you have just the studs left in the heads then it's easier to work on just removing the studs without the exchangers in the way. Here you put the nuts back onto the stud and then weld them to the stud and apply enough weld to get the stud hot. Then they usually come right off.

[sc_rufctr]

Originally Posted by scarceller

First, I've only done this with engine on an engine stand and out of car. The idea is to weld onto the stud (not the nut) and sort of build the stud up without fattening the stud more than the nut. This allows you to still put a long socket onto the nut.

Also if you can get the nuts off first and remove the exhaust so that you have just the studs left in the heads then it's easier to work on just removing the studs without the exchangers in the way. Here you put the nuts back onto the stud and then weld them to the stud and apply enough weld to get the stud hot. Then they usually come right off.

This... I've done this on a few different engines over the years. It heats the stud more directly than use MAP gas or similar.

A MIG welder is almost an essential item in any decent DIY garage. There's just so much you can do with one.

[theiceman]

this sounds interesting ,

does anyone have any comment on my original question on the part numbers of the studs ?

[wacko]

I recently ordered the 51mm studs for my ROW '78 911SC and they were too long. I was only replacing 3 so I just cut them shorter. I have no experience with the 46mm studs.

[lespaul]

Iceman,

I did the same thing you did. Nearly all my exhaust studs broke on removal. I sent them to the machine shop for removal. I then purchased the thick walled HE from another Pelican to replace my rusted thin walled ones and had the same question as you. I ended up buying the 51 mm studs and they worked perfectly.

As far as the part number, I called the guys at Pelican and they helped me get the right order number for the 51 mm studs.

Brad

[JJ 911SC]

When it come to fastener measurement, the length listed in catalog is a crap shoot.

My suggestion for when not dealing face to face, is to send a pictures of the stud you want with the measurement and have the staff find it.

Here is a pictogram of the bolts for the CV joints, which Lobro describe it as 47mm.

Nothing on it measured (or add up to) 47mm:

[boyt911sc]

Originally Posted by theiceman

this sounds interesting ,

does anyone have any comment on my original question on the part numbers of the studs ?

Someone made a blunder by interchanging the stud lengths in the catalog and no one has corrected this error. This has been there for a while. Take a quick measurement of your exhaust studs and you'll find that 51 mm is too long for your need. The '78-'79 heads in the garage measure about 20 - 21 mm exposed lengths while '81-'83 have about 30 - 31 mm exposed lengths. A difference of about 10 mm. HTH.

Tony

[JJ 911SC]

Originally Posted by boyt911sc

Someone made a blunder by interchanging the stud lengths in the catalog and no one has corrected this error. This has been there for a while. Take a quick measurement of your exhaust studs and you'll find that 51 mm is too long for your need. The '78-'79 heads in the garage measure about 20 - 21 mm exposed lengths while '81-'83 have about 30 - 31 mm exposed lengths. A difference of about 10 mm. HTH.

Tony

Correct, the unused studs are still in the package somewhere in my garage. I was quite sure that I had mentioned in a review but I could not find it.

This is not just happening here. At work some major supplier send us some 1st Level/QCA (Submarine Valve) studs that does not meet the Standard. Very expensive mistake on their part when they get rejected.

[pete3799]

I put thick flange SSI's on mine this spring. Found the studs (46MM IIRC) at the local parts store.
They had 10 in stock ordered 2 more and had them the next day.
Pelicans listing for the studs is baffling.