Stripped Exhaust Stud, Type 4 Head M9

[monkbonk]

My two rearmost step studs pulled their threads. When ordering the timesert kit, I was wondering if I could opt for the M8x1.25 repair kit? Or is there not enough material there/I'd be safer sticking with the m9x1.25 kit?

I've also done some reading after finding an old post here where someone suggested tapping the stripped hole with a 3/8 tap and using 3/8" hardware. I was looking at going with a 3/8-24 pitch.

EDiT: If I act fast, I can get a free flashlight with my timesert kit.
_________________
---------------------------
1978 Volkswagen Bus 2.0
1973 Volkswagen Beetle Standard 1600dp
1969 Amante GT Roller

[monkbonk]

Gah. I think I am going to go ahead and order the m9 timesert kit. I have two 3/8-24 taps on the way (they were cheap). I'll compare everything.

If using the 3/8 tap still allows me to go back and use the timesert kit still as a backup option, then that's the way I'll go. If it looks like there is only enough material to do one or the other, I'll opt for using the timesert.
_________________
---------------------------
1978 Volkswagen Bus 2.0
1973 Volkswagen Beetle Standard 1600dp
1969 Amante GT Roller

[my59]

I'd go with the metric....nothing like a PO that mixes it all up to drive you batchit
_________________
my59: Well son, my grandfather died before I got to drive it, so does that answer your question?
our79: sunroof bus w/camper interior and 2.0 FI
Other:'12 Jetta, '77 Benz 300D, and a 74 MG Midget.

[monkbonk]

I would be willing to do over the next owner as a means of alleviating my exhaust pops.

My 3/8 taps came in today. I went ahead and ordered the timesert kit. $100 is little expense went you put it into perspective.

EDiT: I measured the 3/8 taps. They are about .360". The drill that comes with the m9x1.25 kit, designated as drill "U" is 0.368".

I should be able to use my 3/8 taps and hold the m9 timesert kit as a backup. I'll wait until I get the timesert kit to be sure.

Also, I found a "Big Sert" timesert kit for M8. The drill size on it is 13/32 or .406". Looking at the engineering data (they call it), it could allegedly be used after a m9 timesert failure as well.

So now I have three walls of protection (if my though process and info is correct). HAHAHAHA. I conquer teh werld.
_________________
---------------------------
1978 Volkswagen Bus 2.0
1973 Volkswagen Beetle Standard 1600dp
1969 Amante GT Roller

[busdaddy]

Sounds like you have little to lose by trying, I don't think there will be enough meat left for the M9 if the 3/8" fails though.
A "plan C" may be cut down case savers for type 1 cylinder studs but I don't know if there's enough room to get something that big in there.
_________________
Rust NEVER sleeps and stock never goes out of style.

Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
Stop dead photo links! Post your photos to The Samba Gallery!

Слава Україні!

[raygreenwood]

Timeserts are excellent...but I find them far too expensive for no benefits more than this product....

http://www.ezlok.com/InsertsMetal/carbonSteel.html

I have used the EZ Lok inserts numerous times to replace type 4 exhaust studs without fail.

To use these, get the correct insert and drill bit and two bottoming taps.

Make a stop line on your drill bit with tape so you only drill to the existing maximum depth of the threaded bore. i have found on type 4 heads that you can actually safely go 2 whole thread widths deeper than the hole already is.

Thread in the bottoming tap as far as it will go. Then take your Dremel or a bench grinder and cut the second bottoming tap off about 1 thread ring above the taper so you can run threads all the way in.

But...thread to about 1.5 threads from the bottom of the bore ONLY.

In this way...the threaded insert can bottom on the threads and be locked down tight.

Test the insert fit for depth. The object is to make sure it bottoms in the threads....and also if necessary depending on insert length...grind the bottom of the insert so it threads in far enough that it is 1/2" thread below flush on the outside so there is no interference with the manifold.

You can use the original epoxy that comes applied to the insert...works very well....or clean it off with dremel tool and brush and acetone and apply loctite.

For studs....last time I could find them I used Holochrome grade 8 allen screw stock for the stud. Its nice because the quality and hardness are superb and they have a nice allen screw socket to facilitate threading them in. I have also used grade 10.9 threaded on both ends 8mm studs.

Lastly.... thread a clean stud into the insert and make sure bottoms. then back it out 1 full thread. then mark the thread on the outside with a sharpie pen just where it enters the insert. Remove the stud....and with a punch...distort the thread on the stud at the mark so it cannot screw into the insert ...ever...and bottom out.

If you don't do this...no matter what thread insert brand you use....one day you will find the outer nut slightly loose during an inspection...and you will tighten it up.....but unknown to you the nut will be frozen (most common)...and the stud will start turning in and bottom out...and in one half turn of the wrench it will shear the threads out of the head and jack the insert out of the head.

This is how most exhaust studs get stripped in the first place.

Lastly lastly.....the EZ-Lok inserts have a screwdriver slot in the outer end that allows them to be easily screwed in. When you are done and the loctite is dry....take a sharp punch and peen the surrounding aluminum into the ends of the screwdriver blade slot. This will not prevent removing them later....but it prevents them from rotating outward if the locktite fails.


This is far far far far superior to the crappy 9mm step studs directly in the head. If you strip the 8mm outer section of one of those....there is a high chance of damaging the 9mm threads in the head getting it out.

If you strip the outer 8mm stud on an EZ-lok....just heat the stud to weaken the locktite and screw it out and replace it.


Oh....one more thing. Buy the insert with the coarsest outer thread that will fit in the smallest oversized hole you can make.

Dont fall for the common argument that fine threads have more holding power. The correct argument for fine threads is that they have more engaged surface area...so they resist TWISTING out.

However what we are looking for here is the widest CROSS SECTION of thread. the V-shaped cross section of the thread is wider in coarse thread. soft aluminum you need the widest thread land cross section you can get to keep heat cycling and tension from cracking those threads and shearing them off.

Ray

[GusC2it]

Nice reply Ray!
_________________
75 type 2 http://gusc1.tripod.com/1975vwtype2
Old vices have now been upgraded to bad habits.
http://www.facebook.com/pages/VW-Wild-Weekend-2011-St-Pete-Fl/197064760336111

[Tcash]

"raygreenwood"wrote]
Timeserts are excellent...but I find them far too expensive for no benefits more than this product....

http://www.ezlok.com/Home/index.html


Link



Link




I have used the E-Z Lok inserts numerous times to replace type 4 exhaust studs without fail.

To use these, get the correct insert and drill bit and two bottoming taps.

Make a stop line on your drill bit with tape so you only drill to the existing maximum depth of the threaded bore. i have found on type 4 heads that you can actually safely go 2 whole thread widths deeper than the hole already is.

Thread in the bottoming tap as far as it will go. Then take your Dremel or a bench grinder and cut the second bottoming tap off about 1 thread ring above the taper so you can run threads all the way in.

But...thread to about 1.5 threads from the bottom of the bore ONLY.

In this way...the threaded insert can bottom on the threads and be locked down tight.

Test the insert fit for depth. The object is to make sure it bottoms in the threads....and also if necessary depending on insert length...grind the bottom of the insert so it threads in far enough that it is 1/2 thread below flush on the outside so there is no interference with the manifold.

You can use the original epoxy that comes applied to the insert...works very well....or clean it off with dremel tool and brush and acetone and apply loctite.

For studs....last time I could find them I used Holochrome grade 8 allen screw stock for the stud. Its nice because the quality and hardness are superb and they have a nice allen screw socket to facilitate threading them in. I have also used grade 10.9 threaded on both ends 8mm studs.

Lastly.... thread a clean stud into the insert and make sure bottoms. then back it out 1 full thread. then mark the thread on the outside with a sharpie pen just where it enters the insert. Remove the stud....and with a punch...distort the thread on the stud at the mark so it cannot screw into the insert ...ever...and bottom out.

If you don't do this...no matter what thread insert brand you use....one day you will find the outer nut slightly loose during an inspection...and you will tighten it up.....but unknown to you the nut will be frozen (most common)...and the stud will start turning in and bottom out...and in one half turn of the wrench it will shear the threads out of the head and jack the insert out of the head.

This is how most exhaust studs get stripped in the first place.

Lastly lastly.....the EZ-Lok inserts have a screwdriver slot in the outer end that allows them to be easily screwed in. When you are done and the loctite is dry....take a sharp punch and peen the surrounding aluminum into the ends of the screwdriver blade slot. This will not prevent removing them later....but it prevents them from rotating outward if the locktite fails.


This is far far far far superior to the crappy 9mm step studs directly in the head. If you strip the 8mm outer section of one of those....there is a high chance of damaging the 9mm threads in the head getting it out.

If you strip the outer 8mm stud on an EZ-lok....just heat the stud to weaken the locktite and screw it out and replace it.


Oh....one more thing. Buy the insert with the coarsest outer thread that will fit in the smallest oversized hole you can make.

Dont fall for the common argument that fine threads have more holding power. The correct argument for fine threads is that they have more engaged surface area...so they resist TWISTING out.

However what we are looking for here is the widest CROSS SECTION of thread. the V-shaped cross section of the thread is wider in coarse thread. soft aluminum you need the widest thread land cross section you can get to keep heat cycling and tension from cracking those threads and shearing them off.

Ray

Put in Tech Tips
Thank You
Tcash

[monkbonk]

My only reservation in using the ez-lok inserts was that there wasn't a full kit that I could find with the tap and drill bit already included.

I found the kit on their website, but when I googled the part number I only found the inserts.
_________________
---------------------------
1978 Volkswagen Bus 2.0
1973 Volkswagen Beetle Standard 1600dp
1969 Amante GT Roller

[busdaddy]

Check the specs on the ez-lok, they likely use common tap sizes and a set of number drills from Harbor freight will provide a correct sized hole, the aluminum won't wear those cheapo Chinese bits out that fast.
_________________
Rust NEVER sleeps and stock never goes out of style.

Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
Stop dead photo links! Post your photos to The Samba Gallery!

Слава Україні!

[raygreenwood]

I see the point but its really no big deal. The taps for these for use in aluminum are standard hardware store or big box store. As long as they are high speed steel its no issue. Drills are same.

Thank you for the tech insert Dr. Cash!

I used these for years before I ever got to use the insertion tool...which is nice but not necessary. Its just a screw with a screwdriver blade on each side. In tight threads it makes it a little easier. Ray

[monkbonk]

I got my timesert kit in today. While the EZ-Lok is probably the better option, I am already married to this avenue.

The drill measures at 0.35 to 0.36" which is the same as the 3/8 tap. The insert itself is wider than a type 1 10mm rocker arm stud hole. That's not too cool.

I'm going to practice on a junk type 1 head I have and see what happens. Going to try my 3/8, then use the timesert, then a 10mmx1.5.

I just hope I don't get too tapped out.

EDiT:
I can use the 3/8-24 tap and then follow with the timesert as a second option. The timesert's pilot drill takes off about half of the 3/8 thread and then the timesert's insert tap threads over that.

I tried a 10x1.25 tap after that. It tapped threads, but the stud was too loose in the hole.
_________________
---------------------------
1978 Volkswagen Bus 2.0
1973 Volkswagen Beetle Standard 1600dp
1969 Amante GT Roller

[jpcrane]

I've stripped the holes for the exhaust studs on my 77 type 4 engine, just the driver side rear but I thought I might as well replace them all now.

I looked on the EZ-Lok website but it isn't clear to me what I need. Too many options in the drop down menus etc.

Can anytime tell me exactly what insert I need?

Also, I was thinking that the inserts are big enough that I could use an exhaust stud that is 8mm on both ends rather than the step to 10mm. Has anyone had experience with doing that? Also what is a good source for new 8mm x 8mm studs?

I appreciate everyone comments thus far, when I stripped mine I really thought I was in deep doo doo.

Thanks!