Helicoiling the valve cover mounting holes

[Gale B.T.]

This will get lots of comments but from my experience with helicoils and their installation I have found most of the time when steel bolts remove the threads from aluminum heads/parts, the hole left with the threads stripped out is just the proper size for the tap. I just carefully start the tap for the helicoil , going very slowly so as to follow the exhisting hole.

I have had super success with this. Also I have used the drill bit in a t-handle to remove what's left of any threads, easier to control than a electric or battery drill.

let the fur fly,
gale

[_cy_]

Originally Posted by gn77b

so the threads on two of the mounting holes went. I bought a V-Coil (similar to Helicoil) kit and want to know if there's any tips I should know before taking the drill to it.
first, I can't get the parts to a machine shop, that's a given so I'll do it myself. no drill press either, just hand drill available.
what I'm worried about is enlarging the hole (M7 thread, 7.3 mm oversize drill). experience taught me that the bit will wander and sometimes will even get stuck causing a mess or even injury. I practiced on some scrap and results were that on the first one (soft aluminum) the oversize hole was off-center, and on the second one (hard aluminum) the bit got stuck and started rotating inside the chuck. the parts are not available separately so damaging one means a new head.

in a sensitive location, try a stepped stud before drilling out for helicoil.
you've got nothing to lose by doing this. if a stepped stud doesn't work. then go on to helicoil.

if metric thread, then find next size up in SAE thread that goes into head. then stud steps down to metric to mate to original nut.

if SAE is stripped, then go to slightly bigger metric thread. most times no thread cutting is needed. slightly larger threads self taps into damaged threads. don't bogger up threads any further if you intend on doing this.

this fix is permanent and equally strong as original threads.

[gn77b]

ok, so I'm learning a new thing each day. so the head is a different alloy.

the stripped threads I'm talking about are not in the head itself but in the camshaft journal caps, the bolts that hold the valve cover are attached to them. 100% perfect perpendicularity is not an issue, the bolts protrude maybe 10-15 mm and have rubber gaskets beneath them.

using oversize/stepped bolts has two disadvantages: I need to have all 8 made on a lathe (they have a special form) and second the new threads will still be at risk, somehow those seem to be the most easily damaged ones. there's not a single thread damaged on my engine except those, not even the M6 ones that hold the side covers and I've removed those a few times. I'm looking at the Helicoil/V-coil as a more permanent fix that will take away any fear when doing valve adjustment.

[Bounder]

Have you seen Timeserts? They are a bit better than the Helicoil type thread repair, one piece instead of formed wire.

[gn77b]

I know about Timeserts. the problem is that there's not enough meat around the hole (the thread is M7 and the diameter of the "tower" it's part of is 12 mm) and as I understand it it's required. also, I haven't been able to source them in Europe and the price is incredibly high compared to Helicoil/V-coil. almost 3x including P&P. I gather that Helicoil is ok for low torque applications (manual specifies 16Nm).

[Bounder]

Originally Posted by gn77b

I know about Timeserts. the problem is that there's not enough meat around the hole (the thread is M7 and the diameter of the "tower" it's part of is 12 mm) and as I understand it it's required. also, I haven't been able to source them in Europe and the price is incredibly high compared to Helicoil/V-coil. almost 3x including P&P. I gather that Helicoil is ok for low torque applications (manual specifies 16Nm).

They are a Wurth product so should be easily got here in Europe.

[gn77b]

Originally Posted by Bounder

They are a Wurth product so should be easily got here in Europe.

I did not know that.

though all ebay UK and Germany searches only return products located in the US. a search on the Wurth website returned some M10 and M12 inserts. I'll give them a call though.

[bomber60015]

GB -- forgive me, but you're putting a great deal of thought into this, and have done much research, but, if you'd gone out and gotten a drill motor whose chuck you can tighten properly, drilled the hole slowly, using progressively larger bits, and being very careful . . . .well, you'd be done by now.

Again, not trying to poke you in the eye, but for a fella that is having trouble drilling a hole in aluminum, you seem to have all the answers . . . . . . .

I do this too, and try to drop back to basics when I do . . . . it helps me.

[gn77b]

Originally Posted by bomber60015

GB -- forgive me, but you're putting a great deal of thought into this, and have done much research, but, if you'd gone out and gotten a drill motor whose chuck you can tighten properly, drilled the hole slowly, using progressively larger bits, and being very careful . . . .well, you'd be done by now.

you're making assumptions. I have ordered the V-coil kit and it's on its way to me so I can't do anything right now. normally it should reach me this week. I can't see how researching before doing irreversible damage can be a bad thing. the camshaft caps are not available separately from Suzuki and most breakers in their right mind would sell the head as a whole. I'm not really into rendering my bike temporarily unusable while searching and paying stupid money for another head.
I did drill various types of aluminum alloy before and it never was a problem until bad luck made me practice on that piece that turned to be 7075 and I started to wonder. I don't know if you ever drilled 7075 but it IS tough. I could not believe how a new and decent bit repeatedly got stuck while I was using very light pressure, almost none. imagine my surprise when I found that 7075 is known for causing drilling problems, especially when enlarging holes. I can't find the website right now, but that guy was doing a great job at describing what I experienced.

Originally Posted by bomber60015

Again, not trying to poke you in the eye, but for a fella that is having trouble drilling a hole in aluminum, you seem to have all the answers . . . . . . .

I know what you're getting at. sometimes the engineer with a degree can do a wonderful job at overcomplicating things while the tech just gets it done. I recently had a talk with a friend who's a lawyer. he told me that he managed to repair himself an expensive piece of hardware after two repair shops deemed it as good for spare parts only.

but... I may never have learned that some aluminum alloys can be a bitch to hand drill if it wasn't for this. meanwhile I managed to find a 3/8'' x 24 UNF chuck that uses a key, I could not believe how hard to find this combination is. I replaced my old and keyless chuck already.

all in all, it may look like "that nagging guy that can't drill a hole" to you, but I'm actually owning this bike and really feel that I need to do my research before risking to ruin a critical part.

oh, and thanks to one of the above posters I found that there's a Wurth distributor in my town. I called them and they were very helpful, although they recommended against "those springs or whatever some other firm makes" :) he even said that I can cheat and get away without buying their drills, taps and counterboring tools. bad thing is that they only sell inserts in 25 pieces packs and that actually makes it much more expensive.
huh, finding locally some part that I'd normally have to buy from overseas at a much lower price, how's that for an useful thread at ADVrider?

[bomber60015]

glad you took my remarks in the spirit in whihc they were intended . . . . . I certainly wish you luck in the repair (and the fact that the caps are removable, so you can drill them someplace other than on the engire is a good piece of news).

[Flashmo]

Here is some food for thought for you:

As you have noticed, aluminum can be nice to work with, and it can be a pain at the same time. Tapping thick pieces of aluminum and stainless (in a previous life) was always looked on with trepidation...to the point that our shop picked up a portable EDM machine to get broken taps out of material. Both aluminum and stainless have the potential to gall and seize a tap, and that ends with the tap breaking off right around the top of the hole. Many drilling lubes and pastes help, but they are not a cure-all.

The best all around tapping lubricant for taping holes over 3/8" deep we found (for our work) was anti-seize. Standard anti-seize for non sensitive equipment, food grade anti-seize for food production machinery, and the nuclear rated black stuff for the DOE/DOD/NASA equipment. The best all around...is the food grade, works great, but most people don't have access to it.

Remember that the anti-seize is a paste, and will hold all your cuttings, so it is important to back out the bit and wipe the chips off several times on a deep hole. Better to go slow...and mundane...than break off a tap.

[gn77b]

this will likely turn into that special kind of thread, where you feel that you got it just until one guy replies "STOP IMMEDIATELY IF IT'S NOT TOO LATE!"

I was taught the tapping technique by a neighbor that passed away meanwhile (I think that was the only time we spoke): ANY lubricant is better than none (I'm using 10W40 engine oil), turn tap in small increments, back up, turn again, etc. after ~1 turn take tap out, clean tap and hole. repeat until tap bottoms. and, of course, first turns are critical for perpendicularity. it's nerve-wrecking but hopefully one does not get to do it each day.

I did not get to practice it many times but the times I did it seemed almost fun.

do you think should I get an EDM just to be safe?

[Flashmo]

Originally Posted by gn77b

do you think should I get an EDM just to be safe?

At this point..................you better buy TWO!

[JimVonBaden]

Wow, this must be some interesting stuff. I have tapped dozens of valve cover bolt holes on BMW heads with never an issue. Installed helicoils just as easy, and used a battery powered drill to size it by hand, then hand tapped and installed the heli-coil.

Not sure what the difference is in the metal, but since the holes are stripped out, drilling the next size up was never an issue. The drill always self centered and went in plenty straight without wallowing.

Jim

[gn77b]

Originally Posted by JimVonBaden

I have tapped dozens of valve cover bolt holes on BMW heads with never an issue.

well, I haven't...