Wo is me!

I'm always saying that there are no usable machine shops near me. Here's what I mean:

I'm rebuilding a customer's 850 engine with an RH4 head. The rear stud pulled before I even got to 10 ft lb. Went to a local machine shop and took them a Recoil kit (like Helicoil) and explained how critical it is that the three studs be in the same place as original and perfectly vertical. Took them one days which is excellent, but all three studs are all leaning towards the center by enough that they miss going in the holes by about 1/16" so there's no way to get the head on - not excellent .

That's the second area machine shop that ruined an expensive part for me. I was planning to be done testing this bike this weekend – won't happen.

I have another head ready for another customer but I have no cylinders so I could use that head, but it wouldn't shock me to have one of those studs pull out. My plan was to take the machine shop four heads when I picked that one up – sure glad I decided to wait until Monday to take them!

Jim Comstock could rescue me because his method uses a much bigger insert that he makes in-house, but he is so busy he probably can't get to it anytime soon.

Any bright ideas how to recover this head?

A bit of a bodge I have done in the past Greg - though not this application...

Find a bolt with a coarse thread that you can safely drill and tap up the centre to accept the 3/8 stud.
Then helicoil the head to accept that larger bolt.
Cut the larger bolt to the correct length and wind in to the helicoil, followed by the stud
Just make sure the larger bolt isn't overly large.
A bit of a pain in the arse but the result will be much stronger
Oh - and find a better machine shop!!

The application I used this method was the head-steady hole on my 650ss - hole was in a very sad state.
Cheers - I feel for you.

Bummer, Greg.

Greg, take it back to the shop, get hold of the owner / manager and TELL him to freakin’ well fix it !!

Fast Eddie said:

Greg, take it back to the shop, get hold of the owner / manager and TELL him to freakin’ well fix it !!

Click to expand...

Would love to but I know they do not have the capability. They never heard of British threads so they would never be able to find a thread insert larger and in BSF. An since they clearly don't know how to indicate in a mill, they would just get it wrong again. I am so glad I found out now. I planned to strip/inspect all heads I have and take all useable ones to them Monday. I'm now stuck on 2 current customer projects, then on the next one on the list, and three bikes waiting to be rebuilt.

This is why I try hard to do everything myself. I'm in a mental war - a mill and a lathe would put a need to almost all outside help I ever need. But, at 73 I'm not sure it's good idea to spend around $10k minimum to buy equipment I have no room for and then to pay the country for owning it every year.

I worked with the owner and he did the work! It's so disappointing. I was elated to find them and was very happy to pay $80 for the work - imagine the change in feeling when the head didn't come close to going on!

I'm starting to wonder if using Red Locktite and no inserts if that would prevent them from pulling. In this case of this head, all threads looked good, and the studs screwed in fine - I didn't expect it to let go when just "nipping them up" - it wasn't like I was applying final torque or anything close.

Here's the best one of the three:

That sucks Greg.

Don’t think loctite is your answer tho… it stops things coming loose, but not from being stripped…

Had similar story when repairing the mounting studs on a tank. Now I have to modify the mount so I can use the tank. And the tank was just painted. It is so annoying.
Stateside, I cannot help you but someone on this list can. You need to have the holes bushed and coarse threaded
and custom studs run up. Keep the fine side BSF and the next owner can always use stock fasteners. If you are in UK
there are several who do this I used Patrick Seager. Long wait great work.

Nigel is right - it has nothing to do with knowledge of pommy thread types.
It is basic machining 101 to be able to put a helicoil in perpendicular to gasket face.
Maybe they should open a pizza shop instead!
Have a go at them.

Dang... Almost not worth the trouble to force them to pay for a replacement.

You MIGHT be successful, probably not. MAYBE if you dictated tolerances beforehand, otherwise they'll just say "close enough, take a walk"

grandpaul said:

Dang... Almost not worth the trouble to force them to pay for a replacement.

You MIGHT be successful, probably not. MAYBE if you dictated tolerances beforehand, otherwise they'll just say "close enough, take a walk"

Click to expand...

If the part does not fit, how can they possibly argue it’s close enough ??

Fast Eddie said:

If the part does not fit, how can they possibly argue it’s close enough ??

Click to expand...

I'm assuming they didn't have the cylinders to test the fit, and PERHAPS were not given a tolerance "Not To Exceed".

If they HAD an allowable tolerance limit, there can be no argument that they've destroyed the part or made it financially non-viable.

AT THE LEAST, I wouldn't pay for that destruction, certainly...

grandpaul said:

I'm assuming they didn't have the cylinders to test the fit, and PERHAPS were not given a tolerance "Not To Exceed".

If they HAD an allowable tolerance limit, there can be no argument that they've destroyed the part or made it financially non-viable.

AT THE LEAST, I wouldn't pay for that destruction, certainly...

Click to expand...

I don’t agree, even without having the barrels to hand it’s quite obvious that the studs are designed to fit into mounting holes, and equally obvious that they‘ll struggle to do so if they’re all at different angles !

Now, as to whether Greg can be bothered to have the fight, that’s another matter. Sometimes it just ain’t worth the effort.

grandpaul said:

I'm assuming they didn't have the cylinders to test the fit, and PERHAPS were not given a tolerance "Not To Exceed".

If they HAD an allowable tolerance limit, there can be no argument that they've destroyed the part or made it financially non-viable.

AT THE LEAST, I wouldn't pay for that destruction, certainly...

Click to expand...

I made it very clear that if the holes were not in exactly the same position and were not perfectly vertical, the head would be junk - in other words, no tolerance. Also, that since buying a new one, when available, was about $3000 and decent used ones would cost at least $500 it was critical that he not take the work if he could not do that. We had a long talk about how he would set it up in the mill. His plan was good, except that he obviously did not run a dial indicator in both directions and get the head dialed in and he did each hole with a new setup. He trusted that the top of the head was parallel to the bottom and that his mill table was perfectly perpendicular to the bit.

I'm sure I could cause a scene and get my $80 back. I'm also sure I could go to court and get the damage covered. My time and quality of life is worth more than both of those. I have informed them that they failed. We'll see if he is a gentleman or not.

It's my own fault - I know there are no usable machine shops here and I know I need to do all my own work. I'll probably drop the money to fix it myself. I have at least 3 more to do this year and unless JC will take the work, I have no more ideas where to go.

Greg:
You might contact
BIG D Cycles Dallas TX.
I have no recent experience with them, but have heard they do head rebuilds and other machine work.

Slick

Fast Eddie said:

That sucks Greg.

Don’t think loctite is your answer tho… it stops things coming loose, but not from being stripped…

Click to expand...

My idea about Locktite would only be for decent looking threads to make then tighter to the studs but your point is well taken.

New idea. I inspected the other heads I want improved so they don't pull. I noticed that the holes are threaded much deeper than the studs use. RGM sells head studs that are 1/8" longer and have 9/16" of threads on the head end (about 1/8" more). That alone will raise the pull-out resistance quite a bit. Then something to tighten the threads that have been used to the studs, maybe JB Weld. I think I have a cracked head (junk) I can use to test the holding power. Jim Comstock uses JB Weld when he puts in his inserts for both the studs and exhaust threads.

Besides the head that caused me to start this thread, I have two more engines I'm building plus several more Commandos to rebuild. I don't want any more pulled studs! I can buy a mill and fix them myself but space is the problem and of course, spending thousands just to fix a few heads is bad business.

I just measured the new AN stud that pulled out and some old studs. The threads are 3/8" (~9.5mm). If the RGM stud's threads are 9/16" (~14.3mm) like they say, then they should have about 50% more holding power assuming they can screw all the way in. That may be all it takes to prevent them from pulling out if the existing threads are still good. I'll know soon, they are ordered.

Problem: Your shop-replaced studs are a little too canted to align to the head.

Admittedly a very big problem, but before I gave up, I believe I'd try a hammer and block of wood to tap them into position.
Jaydee

marshg246 said:

I'm always saying that there are no usable machine shops near me. Here's what I mean:

I'm rebuilding a customer's 850 engine with an RH4 head. The rear stud pulled before I even got to 10 ft lb. Went to a local machine shop and took them a Recoil kit (like Helicoil) and explained how critical it is that the three studs be in the same place as original and perfectly vertical. Took them one days which is excellent, but all three studs are all leaning towards the center by enough that they miss going in the holes by about 1/16" so there's no way to get the head on - not excellent .

That's the second area machine shop that ruined an expensive part for me. I was planning to be done testing this bike this weekend – won't happen.

I have another head ready for another customer but I have no cylinders so I could use that head, but it wouldn't shock me to have one of those studs pull out. My plan was to take the machine shop four heads when I picked that one up – sure glad I decided to wait until Monday to take them!

Jim Comstock could rescue me because his method uses a much bigger insert that he makes in-house, but he is so busy he probably can't get to it anytime soon.

Any bright ideas how to recover this head?

Click to expand...

"Unscrew" the insert , re tap the hole , i:e cut a little out of the correct side , install new heli coil , turn installation tool 90 degrees and tap with the side of some pliers to remove the tang, .thread will be a tad looser but should be ok . Unless they first installed them at 45 degrees

I used to be the guy that had to go around town and do broken studs and sump bungs etc , one year (drag racing season) I had to do a heilcoil on a top fuel main bearing cap , not too many too fuel cars in nz , Garth hogans car , the pressure and stress I had a team mechanic staring over me like a parent would if the child was in intensive care , worse still I needed a 2D length and had to stack two std length, , and snip off two threads , I did that by hand ,
All was good , thank God.

Update: Jim Comstock is going to fix it for me.

Update that I don't want to write but must: The stud that pulled was a new one from AN. The other stud that pulled this year was a new one from AN. I checked several heads. All are drilled just over 5/8" deep. All have threads that are at lease 9/16" deep and a RH10 head I checked would take a BSF bolt a full 5/8" in. The original studs (or as least old) are threaded .515" on the head end and the studs are 1.9" overall length. The new AN stud threads measure .449 on the head end. I checked with AN - they are making them to the factory drawings. The current studs have 13% less threads than the original I have.

RGM sells a version with an overall length of 2" and they state that they are threaded 9/16" (.563") on both ends. That's 25% more threads than AN. I have some coming to test. I'm not fond of them being stainless steel. Also, I'm looking into having studs made 2-1/16" long with 5/8" of threads on the head end.

I will do some testing to prove what I think, but to me the studs pulling was first a Norton self-inflicted wound, and now an AN self-inflicted wound. I hate saying that - it's well known that I am an AN fan, but this is not something I can stand.

I'll use the AN studs in the bronze inserts Jim will install but will no long sell them or get more.