LCGB Forums

Hi All,

I've had a few issues recently with bolts coming loose on the stator plate, and stripping the threads in the casing.

I'm thinking a stepped stud would be a good repair, as there would be less screwing in/out of aluminium.

Can I use a M8 to M6 stud? I can get these made at work and have the taps to do the job.

Jordan

M8 sounds a bit too chunky, as the thickness of the engine casing at that point is a bit narrow and gets narrower behind the gasket face.

I would have thought that an M7/M6 stepped stud would be better, and no harder to manufacture.

The holes do tend to get ‘baggy’ in that area but rarely do they need little more than a thorough clean out & fresh M6 studs securing with a good thread locker. Beware of hydraulic lock, though.

Tapping M6 to M8 in the casting will work but there is not a lot of meat remaining around the holes & the casting can very easily crack. You can buy double ended M8 to M6 conversion studs but I wouldn’t choose them.

If you have access to engineering supplies, the better solution in alloy is to tap & fit an M6 thread insert such as Helicoil.

Many engineering firms fit these from the outset of making an alloy part, not just as a fix.

I'm going to go for the M7/M6 stepped studs. I'm really doubting there is enough meat there for an M8. Everything is massive at work so it all get a bit limited when you go small!

I've ordered the M7 tap and will order studs now.

As Warkton says why not try a helicoil , you can pick up kits from unithread for not much cash and once you have the steel thread inserted it wont wear out if you keep inserting/taking out the studs ?

Once the studs are in, you don't have to remove/insert them, you just tighten a nut and washer up.

I'm not a big fan of helicoils either...

Post by NorthernJordan » Fri Oct 07, 2016 12:44 pm

Once the studs are in, you don't have to remove/insert them, you just tighten a nut and washer up.

I'm not a big fan of helicoils either...

Presumably you’ll just be replacing three studs & will continue using M6 socket screws/bolts to hold the stator in place. That is, unless there’s room behind the flywheel for nyloc nuts & washers...

Those particular holes are the three most subject to wear, but I’m sure you have it all figured out.

The helicoil is by far the better option, tap them out larger and after a while you'll have the same problem. Steel to steel wont wear like steel to alloy..

Helicoil is the way To go got me out out of the sh@t loads of times in the last 25 years not just lammies I know some people don't like but I think there ok and not badly priced plenty on ebay

I must admit that my thread stripped, so I drilled it deeper and re-tapped it. It is now secured with a very long bolt, but it works.

I only remembered this at the weekend when I was testing some stators I had built.

Post by Knowledge » Mon Oct 10, 2016 4:42 pm

I must admit that my thread stripped, so I drilled it deeper and re-tapped it. It is now secured with a very long bolt, but it works.

I only remembered this at the weekend when I was testing some stators I had built.

I think many of us have done something similar. I have used longer, M6 studs on occasion. I have even Helicoiled the end plate stud holes ‘down’ to M6 (same pitch as M7) so that I could use much higher grade socket fasteners as I was struggling to find decent M7 nuts @ some point years ago

However, with the benefit of technology/engineering becoming much more accessible within the realms of DIY, I reason that advice given by the majority of us is our best advice, often with the benefit of hindsight.

There are ‘get-you-home’ bodges & there are ‘best-engineering-solutions’

Unfortunately, the choice often comes down to cost.....

Well I've gone with stepped studs and nuts... We'll see how I get on!