LCGB Forums

Had a look at my horncast yesterday on my 62 chrome ring S3 Li 150 and I think Its dead , It has a split in the bottom part of the casting by where the horn grill fits and most of the threads are shagged where some bodge merchant has just forced a bigger screw in, I was hoping that was a good part (should of known better at my age)

So I'm thinking new one (non genuine sadly)(could buy used but likely to end up with another knacker), can anyone recommend one from somewhere that will fit ok that won't break the bank

Helicoil the knackered threads and get the crack welded. All told will cost you less than twenty quid.

I've used a pattern one before and it was pretty good actually, but I think it's a bit of a lottery.

If it's still a good shape, it's sure to be salvagable.

dickie wrote:Helicoil the knackered threads and get the crack welded. All told will cost you less than twenty quid.

I've used a pattern one before and it was pretty good actually, but I think it's a bit of a lottery.

If it's still a good shape, it's sure to be salvagable.

I'm sure the crack could be welded as its not massive, must admit I'm not a big fan of helicoils, I had a cooper s caliper bleed nipple helicoiled 30 odd years ago and it failed first tighten, wonder if the knackered threads could be filled with weld then drilled and re-tapped.

That's what I figured about a pattern one, great if I could stretch (big stretch) to a NOS one if I could find one but can't justify spending that much

I wouldn't be too frightened of helicoils. Properly installed they are better than virgin alloy. I had a bad experience with a woman 30 years ago, but I'm still married to her to this day

Seriously, helicoils will easily hold the load of a horn cast, just ask someone who you know is competent at fitting them to do it. If you get them filled, drilled and tapped, it may not fit exactly as it did in the first place unless the new holes are drilled bob-on. Easier to keep original position and angle with helicoils.

No, I'm not a helicoil salesman.

I agree with Dickie (apart from the marriage part. I wasn't aware that "menopause" literally meant "men-on-pause" as it did in "our" case as she refused medication. Ho hum.....)

Helicoils are ALWAYS fitted to non ferrous alloy parts by the likes of Rolls-Royce etc in aerospace applications.

However, if the failed threads are for the fasteners that go up through the mudguard, you are better in any case to fit a (preferably stainless or brass) stud with a rubber-faced penny washer & stainless nyloc nut.

It would take a card carrying anorak to spot that & it is a better engineering solution.

dickie wrote:I wouldn't be too frightened of helicoils. Properly installed they are better than virgin alloy. I had a bad experience with a woman 30 years ago, but I'm still married to her to this day

Seriously, helicoils will easily hold the load of a horn cast, just ask someone who you know is competent at fitting them to do it. If you get them filled, drilled and tapped, it may not fit exactly as it did in the first place unless the new holes are drilled bob-on. Easier to keep original position and angle with helicoils.

No, I'm not a helicoil salesman.

I can imagine they are stronger than cast alloy, very soft and very weak and very easily abused, yeah see your point about been spot on with drilling and tapping the holes again, I'll have to post a piccy of it cause the shagged hole is shagged in more ways than one, the hole is all to cock so might be a tuff one to helicoil it in the correct position.

Warkton Tornado No.1 wrote:I agree with Dickie (apart from the marriage part. I wasn't aware that "menopause" literally meant "men-on-pause" as it did in "our" case as she refused medication. Ho hum.....)

Helicoils are ALWAYS fitted to non ferrous alloy parts by the likes of Rolls-Royce etc in aerospace applications.

However, if the failed threads are for the fasteners that go up through the mudguard, you are better in any case to fit a (preferably stainless or brass) stud with a rubber-faced penny washer & stainless nyloc nut.

It would take a card carrying anorak to spot that & it is a better engineering solution.

Thank god I don't fly much no but really. guess they must be good if RR use them, like the stud idea though with plenty of coppa slip to stop any of them seizing in the alloy, as they do............

Lord-Spanner wrote:

dickie wrote:I wouldn't be too frightened of helicoils. Properly installed they are better than virgin alloy. I had a bad experience with a woman 30 years ago, but I'm still married to her to this day

Seriously, helicoils will easily hold the load of a horn cast, just ask someone who you know is competent at fitting them to do it. If you get them filled, drilled and tapped, it may not fit exactly as it did in the first place unless the new holes are drilled bob-on. Easier to keep original position and angle with helicoils.

No, I'm not a helicoil salesman.

I can imagine they are stronger than cast alloy, very soft and very weak and very easily abused, yeah see your point about been spot on with drilling and tapping the holes again, I'll have to post a piccy of it cause the shagged hole is shagged in more ways than one, the hole is all to cock so might be a tuff one to helicoil it in the correct position.

Warkton Tornado No.1 wrote:I agree with Dickie (apart from the marriage part. I wasn't aware that "menopause" literally meant "men-on-pause" as it did in "our" case as she refused medication. Ho hum.....)

Helicoils are ALWAYS fitted to non ferrous alloy parts by the likes of Rolls-Royce etc in aerospace applications.

However, if the failed threads are for the fasteners that go up through the mudguard, you are better in any case to fit a (preferably stainless or brass) stud with a rubber-faced penny washer & stainless nyloc nut.

It would take a card carrying anorak to spot that & it is a better engineering solution.

Thank god I don't fly much no but really. guess they must be good if RR use them, like the stud idea though with plenty of coppa slip to stop any of them seizing in the alloy, as they do............

The principle of studs fitted to alloy eliminates wear & is the better alternative ditched by Innocenti in a cost cutting excercise when the GP cases were assembled. I also find that the mudguard fitting to the horncasting much more secure & easier to achieve than the fitting of screws. I Loctite (low strength) the studs in & they are still removable should the need arise. Penny washers also spread the load on the mudguard to obviate cracking, especially if the mudguard is fibreglass.

As for the other horncasting fixings, the alloy, flat bottomed 'dished look' washers do not dig into the paint & a raised head countersunk screw can be fashioned from a stainless (preferably A4) socket button head screw to achieve a good fit with no danger of the tool slipping, unlike a slotted screw head. Before I acquired a lathe, I would put said button head in a drill chuck & spin it up with a power file on the underside to create the countersink to match the washers.

Warkton Tornado No.1 wrote:

Lord-Spanner wrote:

dickie wrote:I wouldn't be too frightened of helicoils. Properly installed they are better than virgin alloy. I had a bad experience with a woman 30 years ago, but I'm still married to her to this day

Seriously, helicoils will easily hold the load of a horn cast, just ask someone who you know is competent at fitting them to do it. If you get them filled, drilled and tapped, it may not fit exactly as it did in the first place unless the new holes are drilled bob-on. Easier to keep original position and angle with helicoils.

No, I'm not a helicoil salesman.

I can imagine they are stronger than cast alloy, very soft and very weak and very easily abused, yeah see your point about been spot on with drilling and tapping the holes again, I'll have to post a piccy of it cause the shagged hole is shagged in more ways than one, the hole is all to cock so might be a tuff one to helicoil it in

Warkton Tornado No.1 wrote:I agree with Dickie (apart from the marriage part. I wasn't aware that "menopause" literally meant "men-on-pause" as it did in "our" case as she refused medication. Ho hum.....)

Helicoils are ALWAYS fitted to non ferrous alloy parts by the likes of Rolls-Royce etc in aerospace applications.

However, if the failed threads are for the fasteners that go up through the mudguard, you are better in any case to fit a (preferably stainless or brass) stud with a rubber-faced penny washer & stainless nyloc nut.

It would take a card carrying anorak to spot that & it is a better engineering solution.

Thank god I don't fly much no but really. guess they must be good if RR use them, like the stud idea though with plenty of coppa slip to stop any of them seizing in the alloy, as they do............

The principle of studs fitted to alloy eliminates wear & is the better alternative ditched by Innocenti in a cost cutting excercise when the GP cases were assembled. I also find that the mudguard fitting to the horncasting much more secure & easier to achieve than the fitting of screws. I Loctite (low strength) the studs in & they are still removable should the need arise. Penny washers also spread the load on the mudguard to obviate cracking, especially if the mudguard is fibreglass.

As for the other horncasting fixings, the alloy, flat bottomed 'dished look' washers do not dig into the paint & a raised head countersunk screw can be fashioned from a stainless (preferably A4) socket button head screw to achieve a good fit with no danger of the tool slipping, unlike a slotted screw head. Before I acquired a lathe, I would put said button head in a drill chuck & spin it up with a power file on the underside to create the countersink to match the washers.

Sounds like a good plan Stan, I’m thinking of getting a specialist in Lambretta’s to sort it as they should know what and the way it should be (hopefully)

Did have some pictures but there to big to post at the mow.....

BUGGER now its really knackered I broke a corner off it last night so now I do need a new one