New Supertec studs

[lindy 911]

I just chased the case stud threads in my 3.0 SC. I used a #10 1.5 tap. When I screw in the new studs, or the old ones for that matter, they seem loose in the threads. The pitch of the threads is correct, it just seems that the hole diameter is slightly too big. Did I use the wrong tap?

Waynes book says to chase the threads on the stud with a #10 1.5 die but I can't find where he talks about chasing the holes in the case. It has to be the same thing, right? A #9 is too small. I'm concerned. Any ideas?

Lindy

[911 tweaks]

a die will cut a slight amt of thread material out of a pre existing tapped hole...I don't know where Wayne says this in his book...the common approach to claening out previously tapped holes is to use a "thread chaser" = which is not going to cut any material out, just clean the threads and gunk out...some guys use old head studs to clean this out and they cut cleaning slots 90 degrees to the threads on the used stud...many also do this for the other holes thay want to 'chase' clean out before re assembly...
You may have an issue here now... maybe you will have to use a loctite type of material... best to call Henry in the AM to discuss...
good luck here!!
Bob

[lindy 911]

Thanks for the info. Who is Harry?

Lindy

[lindy 911]

Sorry, who is Henry?

Lindy

[rluciano]

Henry is the owner of Supertec, the source of your studs, and also a good and helpful guy to talk to...

[BURN-BROS]

Porsche used a "tight" spec on all of the threads in the case. Running a normal tap thru the case makes the threads loose. Never use a cutting tap to chase threads.

You will have to run a permanent loctite in the threads to prevent the studs from loosening up.

[lindy 911]

Thanks Aaron, Do you think the permanent type of Loctite will work? I was thinking I was going to have to add case savers.

Lindy

[BURN-BROS]

Originally Posted by lindy 911

Thanks Aaron, Do you think the permanent type of Loctite will work? I was thinking I was going to have to add case savers.

Lindy

I have run into a few cases where the threads were loose.

Thread the stud untill it bottoms out, then back off 1/2 a turn. Ideally the stud should be snug in the case, requireing some effort to remove the stud. If the stud does not require any effort to remove it but does not wiggle(a very small amount is fine), Loctite will save your bacon. If however if the stud does wiggle, then you may need to repair the threads.

Please describe how loose the stud is before proceeding with case savers as that should only be the last resort.

[lindy 911]

I just installed two studs on the exhaust side of the spigot. One tight against the bottom of the hole and the other tight minus a half turn. The loosed stud moves .04 measured at the top of the stud against top of the tight stud. It is a sloppy fit, not the barely loose fit you described.

Lindy

[tadd]

Loctite makes a product that is red on steroids - but with a twist. Once it hardens you can remove the stud/bolt/fastener. It's supposed to be for stripped/damaged threads. It is also supposed to be a perminate repair. I'm sorry, but I forget what it is called.

[Henry Schmidt]

Aaron is correct on all counts.
The threads should never be cleaned with a tap, just a thread chaser or even chemicals with a bottle brush and air.
There are many products on the market that will snug a loose thread but the use of the products is always a judgment call.
Your the builder, use your best judgment. If you are lacking in the confidence to make the call take your case and studs to someone you trust.
Good luck.

[E Sully]

Have you considered using case savers? It should solve your problem and reinforce the case at the same time.

[lindy 911]

Thanks for your help Aaron and Henry. On page 127 of Wayne's book he describes cleaning the case and the need to clean out the threaded holes for the head studs. It states to use a M10x1.50 tap for this purpose which is what I did. I "chased" every stud hole before I tested a new studs fit. It is slightly loose in the hole now as I mentioned above.

I took the case to a race shop machinist who is confident that Permatex green sleeve lock will hold the studs. He said there is plenty of thread contact but suggested bottoming the stud in its hole and snug it up with doubled up nuts. He also said that future removal of the studs would be a ***** but not impossible. I also got a similar suggestion from Aaron over the phone with the only difference being he suggested the use of Locktite red in place of green.

I am going to go for it with the green and not worry about it. If a stud pulls, I already have the case savers coming from Pelican. I think it's important that this information be shared with other first timers though. Is the a method on this site to do that so others don't end up with the same problem?

Again, thanks for your help! I'm sure you all will be hearing from me soon with my next problem. The bottom end goes together this weekend.

Lindy