Exhaust Studs/Holes, Stripped, Suggestions?

[Mikldom]

Helicoil back to the 10mm 1.25 pitch thread?

 

Tap it to 3/8, maybe a little bigger and then put a 3/8 helicoil in it?

 

I have had a hell of a time finding exhaust studs, so maybe just retapping the holes to a standard size, put common studs in there, and call it a day?

 

The side that the threads are messed up on are holding, currently, but can't torque them too much, but the hold enough pressure to keep from backfiring, or echoing off the pavement, but this won't last.

 

I plan on fixing this, this weekend, as well as installing the new tans mount I picked up and the steering gear boot I bought.

 

BTW, The tranny from Joe up in Pottstown, PA i picked up a couple of weeks ago, is in the wagon, and performing FLAWLESSLY,,, THANKS JOE!!

 

Let me know, I want to firm everything up!

 

/mike

mikldom@yahoo.com

[ShawnW]

Look at Timeserts. They have a website http://www.timesert.com/

 

They are far better than a Helicoil as they are a solid insert and lock harder.

 

I would not do them 3/8 as the problem with this,,,and I have seen it countless times on Engine cores that come in at work is once you go 3/8 its really hard to put a stock size anything back in its place later. The timeserts can be done stock back to 10x1.25 but also if you really screw up the hole and need to double insert it (put an insert inside another) you can by using a 12x1.25 and thread the one into the other. By going to SAE you are committing to that forever pretty much.

 

Congrats on the used tranny! Always nice to find a good used anything these days.

[idosubaru]

take in an old exhaust stud to an auto parts store (mom and shop places are better here, the national chains will have them but in packs of two and not as good of a selection). they will have the 10x1.25 size exhaust stud you need, you just need to take on in and size it up, i've done it a bunch of time but can tell by looking really. their computers and parts books won't show any matches, but they will have it, just go look. on some you'll just notice that the stud needs to be screwed into the engine block one way and not the other, it will be obvious once you see it. some studs have a small 1/4" section that is threadless - you'll want this side closest to the engine to leave enough room for the nut to grab all the threads...like i said, it's obvious when you get in there.

 

they are also readily available at junkyards, they have hundreds of them, find some non-rusty ones and go to town. probably put a thread in the parts wanted section here and someone will hook you up as well.

 

there's tons of information on these exact bolts on here, i'd spend some time searching and read to your hearts content.

[GeneralDisorder]

A 7/16x20 tap will thread right in without drilling and will still allow you to heli-coil or timesert it later. Although I've never had to. The 7/16x20 is larger and so provides better grip than the old 10mm studs did anyway. I've done a number of them this way and never had to go back. I just use regular bolts. The trick is to not allow the weight of the y-pipe to rest on the block threads. As long as you observe this rule carefully the threads should last just fine.

 

Make sure to use a bottoming tap to get the threads all the way to the bottom of the hole.

 

Or you could spend a lot more and get the same results..... at least that's my feeling on it. But I understand the desire to "do it right". I've just never had the money for that route with this particular problem.

 

GD

[TomRhere]

I agree with both Shawn and GD. Heli-coil or timesert would be best method of repair. However, one may not have stuff on hand or money in pocket to do the repair the "proper" way. So the use of a 7/16" bolt/stud is a quick and reversible repair. This repair comes up from time to time and gets argued over. Here's the real deal on thread sizes and drill bit size for them......

 

From a tap & drill chart for 75% thread in aluminum;

 

tap size.............drill dia. .............decimal equivilant

7/16-14................U...................... .3680

7/16-20..............25/64.................. .3906

10X1.25..............11/32.................. .3438 (standard exhaust stud)

 

According to the chart for Heli-coil insert for the standard exhaust stud one needs to drill the hole`using a bit diameter of .4193 minumum to .4714 maximum which is somewhere between a 13/32" and 15/32" in diameter. A bit larger than the one needed for a 7/16" tap. Then one must tap threads into hole for the insert to go in, removing even more material.

 

One does not need to drill hole for a 7/16" tap, it goes right in the stripped out thread hole in the head, leaving more than enough material to do proper repair at a later date.

[ivantruckman]

dosnt subaru have an extra set of holes in the cyl head . i just cut the flange and rotated it 90 degrees and used the other two holes. unless is been done already. dude hilsdale is just down the street.

[Gloyale]

+1 for tapping the hole directly with 7/16 threads. 7/16 studs are easy to find and cheap, and this leaves the helicoil option for later.

 

Rotating the flange works too, but I wouldn't do it unless I was welding new exhaust anyhow.

[4x4_Welder]

Two points-

Don't use bolts. Use studs with nuts and high temp locktite or locking washers. People tend to try and crank bolts in, but this will damage the head, making a crack from the hole into the push rod passage, possibly blowing a chunk loose into the engine.

The torque spec is something like 12ft/lbs. Any tighter, and the threads will strip.

 

A plugged cat will also cause the gaskets to blow. If you have blown gaskets often, or have to drop the exhaust on a regular basis, use some sort of insert to protect the threads in the heads.

[TeamCF]

I had one of mine strip out on me as well the other night while replacing the gaskets. (which were too big from the subaru dealer, my pipes just went thru the holes, so I had to use some old RX7 gaskets I had laying around, they fit.)

 

Seems the previous owner relpaced one of the studs with a 3/8. I went with it and had the heli coil kit on hand so I repaired it that way.

 

Also check your specs. Dosn't need to be as tight as you might think.

 

I'll just have to deal with it better at rebuild time.

[TomRhere]

dosnt subaru have an extra set of holes in the cyl head . i just cut the flange and rotated it 90 degrees and used the other two holes. unless is been done already. dude hilsdale is just down the street.

 

 

Yes there are 4 holes for the exhaust flange. EA-82 uses only 2 as far as I know. 1 carbed,1 SPFI engine here so that's what I know. MPFI or Turbo may vary. EA-81 engines use all 4 holes, 2 for the ASV adapter flange, the other 2 studs go thru the other 2 holes and mount the Y-pipe.

 

And DUDE, get thy backside down here then!!!!!!!!!!!!!!!!!!!!! Bring your Subaru too, don't want people to get the wrong idea here.......

[ivantruckman]

Rock on Hilsdale, ill pm ya when im in the detroit area, well hook up get a beer. (after driving of corse). rock on

[Mikldom]

got the one done.. bought a 7/16 20 pitch x 2.5 inch stud, a 7/16 20 pitch tap, and some cutting oil...

 

oil'd her up, cranked it in, took it all the way back out, reoiled, back in to clean the junk, sprayed brake parts cleaner in there and installed the stud..

 

worked like a charm.. Now I have another to do, and still need new 10 mm studs for the other side, as they are all rusted up.

 

thanks.

[daeron]

got the one done.. bought a 7/16 20 pitch x 2.5 inch stud, a 7/16 20 pitch tap, and some cutting oil...

 

oil'd her up, cranked it in, took it all the way back out, reoiled, back in to clean the junk, sprayed brake parts cleaner in there and installed the stud..

 

worked like a charm.. Now I have another to do, and still need new 10 mm studs for the other side, as they are all rusted up.

 

thanks.

Did you get the bottoming tap?? A normal tap is tapered at the end, and won't fully tap out the bottom ~1/4-1/2"(?) of the thread.

[Mikldom]

It is tapered.. should I get a new tap (bottoming tap).

 

My understanding is that the studs just hold, and the nuts is what provides the torque to bring the flange up.

 

it is working tho.

 

 

Did you get the bottoming tap?? A normal tap is tapered at the end, and won't fully tap out the bottom ~1/4-1/2"(?) of the thread.

[TomRhere]

It is tapered.. should I get a new tap (bottoming tap).

 

My understanding is that the studs just hold, and the nuts is what provides the torque to bring the flange up.

 

it is working tho.

 

It's not an absolute requirement to use a bottoming tap, but it's advisable to do so. Reason being is the hole isn't really all that deep, so use of bottoming tap will allow for a couple more threads to be cut in the hole. As long as one doesn't over-torque the fastener, it really won't be a problem if one uses a starter tap, (tapered point).

 

Myself, I use both. Starter tap to start the threads, bottom tap to finish cutting them. Starting a bottoming tap by itself in a blank hole is not always the easiest thing to do, especially lying on your back working overhead.

[daeron]

thanks for replying with some actual knowledge and experience to follow up on the point I brought up. I catch little details like that alot, and hesitate to mention them because I have zero firsthand experience to speak from.... but I try to point it out and open the door for someone who HAS "been there" to make comments I feel may be of assistance... sometimes I wonder if this is just a really well rationalized excuse for post-whoring and talking too much :-\ but you people seem to tolerate me OK, so I can't be doing too much evil.

[GeneralDisorder]

I have a nice set of taps, but no set of bottoming taps. I just buy a "cheap" tap for my bottoming tap and cut the end off. Works great and doesn't cost a lot like genuine bottoming taps.

 

GD

[idosubaru]

and cut the end off.

sweet, what do you cut a tap with?

[dhise]

sweet, what do you cut a tap with?

 

 

If you have a bench grinder, just grind the bottom off.

 

-Doug

[GeneralDisorder]

If you have a bench grinder, just grind the bottom off.

 

-Doug

 

That causes too much heat - you can detemper the tap if you aren't careful. But with enough water you could do it that way - takes too long for me.

 

I use a die grinder and keep it wet and cool.

 

GD

[Mikldom]

the "replacement" stud (7/16 20) is holding quite nicely, no problems there

 

No luck on replacement 10 1.25 studs..

 

went to the Dealer, they gots nothing.. went to Toyota dealer, they were a much better help, but what they had was 1/2 inch too short.

 

Went to a specialty fastener store, they don't have it long enough either

They did have "all thread" in 10mm 1.25 pitch.

 

23 bux!!! ouch!! but I did buy it, and cut it with my air cutter, and smooth the ends with the dremel.. put them in, and all is well.

 

New problem, on another post..

 

Thanks guys for helping out!!!

 

/mike

mikldom@yahoo.com

[Gloyale]

There is usually a section of any chain auto parts store that has the "HELP" line of products. You know in the red packets. They have a generic "foreign car" stud kit that comes with 2, 10x1.25 studs

[Mikldom]

Trust me, I looked in the "help" section.

 

At Autozone, Advance, and went to Napa, and some place called O'Reilly's.

 

I have looked in Tidewater, VA area, Elizabeth City, NC, and Greensboro, NC.. ?(I know that is a long way from each other, but I travel),, no luck..

 

what I did is working good, but my suggestion is to get the Genuine Subaru Exhaust gaskets as the crap I got that matched up hole wise, with the steel rings, blew out pretty quickly.. the Subie gaskets are much stiffer, better material, thicker, and they were had at the dealership for less than 7 bux each.

 

 

There is usually a section of any chain auto parts store that has the "HELP" line of products. You know in the red packets. They have a generic "foreign car" stud kit that comes with 2, 10x1.25 studs