The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: BSA500 on 30.06. 2010 08:50

Title: Helicoils
Post by: BSA500 on 30.06. 2010 08:50
I have to helicoil the drive side crankcase bolt holes(x 3).I have the kit and am ready to go(kit from Unithread great prices and service).Problem is one of the threads to be done has been previously(sp) helicoiled and it seems to be backing out or at least not sitting as it should.Can I just drill it out with the drill bit supplied and carry on *sad2*
Title: Re: Helicoils
Post by: bsa-bill on 30.06. 2010 08:58
doubt you will have much luck trying to drill the insert out BSA 500, probably too hard and if you get offline you'll take out metal you will need.
If you can prize up the top thread and get hold of it with pliers it should twist out, then put a new insert in ( maybe run the tap through it first, but lightly).
No harm putting a bit of loctite in with the insert.
I've used helicoils with great sucsess others prefer different types
Title: Re: Helicoils
Post by: muskrat on 30.06. 2010 09:10
G'day BSA500,
                         Don't drill it. Try to get a thin sharp scribe under the end of it and prise it out of its groove and get a pair of long nose pliers onto it and screw it out. I assume the cases are still together, you might be able to use the helicoil tap without drilling. Pack the flutes of the tap (and drill if you have to use it) with grease. Only go a couple of threads at a time and back it out, clean off grease and swarf, repack and go again. Use loctite on the new helicoils. To break off the tang pack the slot of the tool with grease and give it a sharp tap, the tang will be trapped in the grease not inside your motor.
Cheers
Bill beat me to it. *smile*
Title: Re: Helicoils
Post by: BSA500 on 30.06. 2010 09:14
Must be the way to go for two of you to have the same reply.Yes the cases are together I intend to wash down the insides with a solvent with the sump plate off as well.
Andy
Title: Re: Helicoils
Post by: muskrat on 30.06. 2010 09:25
Great minds think alike.
Title: Re: Helicoils
Post by: BSA_54A10 on 30.06. 2010 10:13
Gee dose that mean I have a "great mind" ?

Dental pick to lift the edge,
Angled end tweezers to lift it off the hole
Pointed nose lock jaws to wind it out
Title: Re: Helicoils
Post by: muskrat on 30.06. 2010 10:27
Some people have little tools  *red* LOL
Title: Re: Helicoils
Post by: chaterlea25 on 30.06. 2010 12:00
Hi All,
I prefer the "time sert" inserts as these are solid and cannot move after being fitted
there is a danger with helecoils that later they might move inwards (after several removals of the case screws)
time serts can be fitted into the helecoil tapped hole if required
HTH
John O R
Title: Re: Helicoils
Post by: bsa-bill on 30.06. 2010 13:21
Hi John - I think I maybe have these in my Alloy head, they are copper coloured with a bit of a flange at the top, is that them and what are they like to fit??
Title: Re: Helicoils
Post by: chaterlea25 on 30.06. 2010 22:37
Hi Bill,
Thats the guys!! copper or black in colour,
easier to fit then a helecoil, theres a gizmo to make a recess for the tiny flange then screw them in with the expander "tap" this expands the inner ends to prevent them moving
and theres no tang to break off and lose in the crankcase *smile* *smile*
HTH
John O R
Title: Re: Helicoils
Post by: trevinoz on 30.06. 2010 23:36
There is a tool for removing Helicoils.
It is a triangular shape and wedges into the coil and allows it to be wound out.
I have had success with a file tang.
Trev.
Title: Re: Helicoils
Post by: bsa-bill on 01.07. 2010 11:03
good to know that Trev but so much more fun to struggle along with wrong stuff and broken finger nails, and then there's those little blue/black bits you get when the pliers slip off and nip your skin - joy
Title: Re: Helicoils
Post by: BSA_54A10 on 01.07. 2010 15:08
I have a little rule regarding thread inserts.
Helicoils go where the thread dose not have to be gas/oil tight . eg primary covers, blind holes etc.
Solid inserts ( Time cert being 1 brand ) go where the hole needs to be pressure / oil tight , eg spark plugs, sump etc.
Any fastener that goes into a hole with an insert is always coated with anti sieze paste or loctite depending upon how often it is to be removed.
Wire inserts are not necessarily pressure tight.
Title: Re: Helicoils
Post by: BSA500 on 02.07. 2010 08:40
Sucess.The metal around the insert was damaged and I had to file it down,looked like it had tried to pull out.After filing I could'nt get hold of the end so I wound in a tap until it locked and then wound it out and out came the insert.Cleaned up the threads and wound in a new one with locktight,I think the thread in the case is a little sloppy so I will test to find out if its still not good I have some tappex self threading inserts but you need a larger hole for those.
Andy
Title: Re: Helicoils
Post by: BSA500 on 09.07. 2010 09:02
Well that went down the crapper.The insert is way too loose to use seems the old helicoil had done some damage while trying to escape.Looks like I have to strip the motor to get a more involved repair.Bugger.
Andy
Title: Re: Helicoils
Post by: muskrat on 09.07. 2010 10:10
G'day Andy,
                    Bugger is right. Which hole is it ? There might still be a way.
Cheers
Title: Re: Helicoils
Post by: BSA500 on 09.07. 2010 10:34
Bottom hole on the driveside crankcase for the primary chaincase so it leaks like a b*****d it looks pretty well stuffed.
Andy
Title: Re: Helicoils
Post by: BSA_54A10 on 09.07. 2010 11:33
Solid insert come in a couple of "oversizes" to counter problems such as yours.
Might be worth wile to chase up you local thread repair man and pop over armed with some good beer.
My local will do 4 or 5 for the same labour charge
Title: Re: Helicoils
Post by: bsa-bill on 09.07. 2010 11:34
Bottom hole - Providing the insert you will use will allow it, I would repair it in situ, with the sump plate off and as much precautionary grease as you can manage and then flush it clean from through the hole and up through the sump, something like an aerosol with the fine tube/pipe on it, block the end of the pipe and make a little hole on the side of the pipe in the direction you want the contents to go ( contents being something that wont harm engine oil)
Title: Re: Helicoils
Post by: BSA500 on 09.07. 2010 11:43
Looks beyond my skills pretty chewed up prob better to go for a clean up,weld etc maybe offer some 'favours' to the local engineering bods *eek*
Title: Re: Helicoils
Post by: wilko on 10.07. 2010 01:42
I'm amazed how people are ready to pull out a motor so easily!! Personally i find it a pain for such a fix.Can't you just go up to another size thread with appropiate sized screw until the next serious rebuild? I avoided a pull down due to leaking twin crankcases by withdrawing the front stud and meticulously cleaning with solvent, blasting with air and filling the stud hole with silastic, reinserting stud and now no leak after 2 thousand miles!
Title: Re: Helicoils
Post by: wilko on 10.07. 2010 01:43
By the way this was on a Matchless twin!
Title: Re: Helicoils
Post by: muskrat on 10.07. 2010 10:04
Or you could drive a timber dowel into the hole and use a self tapping screw !!! LOL
Title: Re: Helicoils
Post by: bsa-bill on 10.07. 2010 10:19
a screw ???, have they stopped making 6 inch nails then.

Wilko's thoughts on using a bigger thread might have repercussions further down the line when you come to fix it.
Can't help wondering though if just plugging the hole and relying on the other studs to keep it on would work to keep oil in until you get around to a more secure fix
Title: Re: Helicoils
Post by: MG on 10.07. 2010 10:24
One of these could be helpful:  *smile* *smile* *smile*
Title: Re: Helicoils
Post by: BSA500 on 10.07. 2010 10:41
Ha amatuers I can strip this down in 40 minutes.10 minutes in and the head is already off.I will go for a full repair as opening up a larger hole would mean opening up the chaincase as well to take the larger screw.This way its done properly and no need to go in again.As I am fixing her after being damaged by the thieving gits and waiting on the paint job(and cash flow :!) it gives me something to do.Typical the weathers great *sad2*
Title: Re: Helicoils
Post by: BSA500 on 14.07. 2010 14:22
Had an idea asked a ace welder at work to fill the hole with weld.That's done,now I will bolt on the spacer and use that as a template to drill the hole and then run the helicoil drill in and retap for the helicoil as I feel thats stronger.Cost? nothing ace *smile*
Title: Re: Helicoils
Post by: bsa-bill on 14.07. 2010 14:59
only thing better than a good fix is a free good fix *smiley4*
Title: Re: Helicoils
Post by: BSA500 on 14.07. 2010 15:17
You're not wrong  *smile*.Useful tip time if you can lay your hands on Xylene(I work for a pharmaceutical company) it dissolves red hermatite(sp) with a little rubbing with a rag dipped in it.BEWARE this is highly flammable and the vapours can give a nasty headache/high/death if not well ventilated-perhaps not a good idea after all.At your own risk etc etc.
Title: Re: Helicoils
Post by: BSA_54A10 on 16.07. 2010 11:31
If you have trouble getting Xylene, tell the druggist that you need it clean the oil lense on your daughters microscope that she is using for her college  homework.
In Oz it is a scheduled substance (used in manufacture of drugs ) and you need a license to buy it but the above usually works for a  1oz bottle.
In some places buying it will automatically get your name on FDA watch lists so be a little careful, particularly if you might have the odd puff on funny fags.
Title: Re: Helicoils
Post by: BSA500 on 16.07. 2010 12:58
Yep where I work its used to make drugs(man).I see a opp to make some money I have 2.5 litres under my desk ;).Back to the point I hope to file/grind/smooth down the weld and retap/coil this weekend(family allowing).Then repaint engine plates and dynamo and barrels and start to rebuild.
Title: Re: Helicoils
Post by: trevinoz on 17.07. 2010 22:50
Don't paint your dynamo, this can lead to earthing problems.
The best way is to have it replated.
Trev.
Title: Re: Helicoils
Post by: bsa-bill on 18.07. 2010 08:39
Quote

Don't paint your dynamo, this can lead to earthing problems.

Hi Trev - my dyno is painted, no problems, do they in fact need to be earthed externally or at all ?
Title: Re: Helicoils
Post by: BSA500 on 18.07. 2010 21:47
Well I have had the dynamo painted and plated and I don't rmember any problems.It was last plated ages ago when rebuilt and thats now rusty so painting(smoothrite) is the cheapest option.On another note redrilled and helicoiled and ballsed up.Template slipped inpatient me = needs filling again doh *sad2*
Title: Re: Helicoils
Post by: bsa-bill on 18.07. 2010 22:05
Ah - these thing do happen from time to time.
What's the plan now, assuming you don't have a spare inner case to hand to use as a template I think I would probably make one up out of thickish stuff I could bolt up to the crank with the other two holes
Good luck with it anyway
Title: Re: Helicoils
Post by: BSA500 on 18.07. 2010 22:19
I have the spacer plate(steel), last time I just used two bolts and didnt do them up tight enough.This time four bolts and tight and select a bit just slightly smaller than the hole(last pilot was too small increasing the chance of error)