Advice sought.

At weekend I replaced the front brake shields and cleaned up the brake discs, the lip on them and brake dust build up on pads. I had to remove the 18mm brake  carrier bolts to remove carrier after 12mm bolts for caliper. The bottom 18mm hex  M12 bolt 1.5 thread pitch came out ok, but looked like garage had overtightened it and flattened bolt threads. I bought new carrier bolts but later that evening, after picking at the old bolt it appeared the bolt threads were ok. The garage I usually take car to investigated a noise 1.5years ago. The mechanic told me he tighted up loose bolt causing carrier to become loose. I thought it was ARB bush worn.

Mechanic said he used thread lock. 

 

Q1 can use of thread lock pull out hub female threads when bolt untightened? I cannot see evidence of thread lock , or no coloured paste.

Q2 do I replace hub along with new wheel bearing? 

Or use a helicoil? Helicoil kit is £58 from Screw fix for M12 1.5 thread pitch. A new hub is £135. Wheel bearing extra.

 

What I don't want is the next time I service brake discs is the helicoil comes out. I contacted loctite / Henkel adhesives and they said use red loctite after tapping new threads with helicoil. Use blue helicoil with bolt and helicoil.

Red is strongest then green blue then purple loctite.

 

This experience with sloppy work, is pushing me to do more work myself. I had just replaced front struts, ball joints, track rod ends and ARB bushes, droplinks.

 

Work needed is to remove bottom of strut from old hub and also drive shaft hub but which is front drivers side and a 35mm 12 multipoint size , 36mm will fit however.

 

Shame I didn't discover this sooner before front strut work.

 

Q3 I m leaning towards new hub but might consider helicoil. Anyone recommend a wheel bearing press kit anyway in case I do a job in future requiring wheel bearing replacement? 

Thanks

 

 

Edited 25 September, 20187 yr by bmbmdmb
Typo

I think using a Helicoil kit on the carrier bolts given that they need to be fairly tight is probably asking for problems in the future, especially if a mechanic gets his hands on it again but 'technically' it should be fine and up to the job so its probably up to you.

 

I suspect the threads must have been corroded and it a bad way and the mechanic just bodged it together, you can't pull out a perfectly good set of threads with loctite

 

Also, just get a second hand hub, no need to buy new when there will be plenty of used ones about.

Edited 25 September, 20187 yr by SuperbTWM

Would the same thing, corroded threads be likely with a second hand hub? I m keeping car until engine goes or diesels outlawed.

 

Anyone suggest a wheel bearing press tool. Freetec or tectake? Any good

Can you check what else is available to rework that hub on the car? 

What I mean is, I think/thought that I've read that some company sell "sort of" tapered "top hat" threaded inserts for this sort of job and they are meant to be better at staying alive/in place than cross wire inserts which I think helicoils are.

Laser Tools or Machine Mart or some proper fixings company might have a solution for your problem.

 

Loctites, I always thought that in order of strength or at least resistant to bolt turning after compound had set was, from weakest to strongest:- Blue, Red, Green with some other colours like Golden for setting bearings in place.  Anytime I came across (RAF) experts using Green Loctite on small or medium bolts instead of Red - it was game over and the assemblies ended up as scrap or needing lots of spark erosion to get rid of that locked bolt part.

 

Edit:- after looking for these top hat tapered inserts I've found that they seem only to be available for the lower powered VW Group cars were the carrier and hub are one unit, so no one seems to be offering a solution to your problem.

 

So, against all proper best practise, I'd think that using helicoils is your way forward, and as these kits come with extra inserts, you just pull the current insert out if it causes trouble next time you work on the brakes.

 

Just remember to buy in a good quality 12.4mm drill to open the holes out to the correct size!

 

One other thing on the Loctite front, after using red Loctite on the helicoil, make sure that you remove all traces of that red stuff from the insert and clean it using maybe brake cleaner etc before fitting the bolt with the blue Loctite so that you don't end up locking the bolt in with red Loctite.

 

 

Edited 26 September, 20187 yr by rum4mo

3 hours ago, bmbmdmb said:

Anyone suggest a wheel bearing press tool. Freetec or tectake? Any good

You'd need to link to the specific ones you're referring to, but at first google, no those aren't suitable.  Needs something to get in behind the hub face for insertion, to avoid pressing on the inner of the bearing (which is what the wheel bolts to). "Gen2" tooling is what you need to be looking at,  have a look here to see the type of thing.  You'd be better off in many ways repairing the thread.

 

39 minutes ago, Wino said:

You'd be better off in many ways repairing the thread.

 

+1, a Helicoil repair is much stronger than the original thread in the hub carrier.

That's really great information. Thanks.

I'll try helicoil first and see how I go.

 

Here is the helicoil advice from loctite :

Just checked web for loctite colours 270 is green.

243 is blue

 

Q Should I go for red or green loctite? I'm inclined to go for green like Rum suggested?

 

If your threads are stripped then a helicoil is a better bet as threadlockers only bond through very small gaps. Loctite 270 threadlocker (high strength) is recommended to bond the helicoil into place permanently, then you can use a medium strength threadlocker (Loctite 243) to lock the bolt into the helicoil to prevent loosening through vibration. This will be lower strength than the 270 so should give way first during disassembly/maintenance

 

As with all adhesives, make sure the surfaces are clean first. Either brake cleaner if you have available or Loctite SF 7063, a non-resisdue solvent cleaner (comes in handy 400ml aerosol can with an applicator tube, great for cleaning out internal threads.

 

Kind regards,

Jeremy Thatcher

Technical Sales Engineer

Common problem on this type of hub according to the machine shop that replaced one of mine( I'd suspect the pads were replaced early by one of the fast fit places who did the 39 point service and having filled the screen bottle with water never noticed that the rear pipe had come off) . Bloke that did mine said that the replacement helicoil was superior to the original job.

Vwd 

Thanks for info.

Do you know whether loctite was used with your helicoil repair? Been quoted £10 for helicoil job in Doncaster at Engineering firm. This sounds like a quick drill stick in  helicoil and nip up carrier bolt . I think using loctite , it seems high strength 270 , and allowing time to cure before putting carrier bolt in helicoil might be more sensible. I would do this myself with proper helicoil kit. Looking to order soon. Thanks

If you're going to loctite the helicoil in place then you should also fit the carrier bolt to force the helicoil insert in tight, just lightly grease the carrier bolt first so it doesn't bond as well.

Your Loctite man says to use green Loctite to retain the Helicoil into the hub, so I would go with that, I was only pointing out the order of strength wrt colour.

 

If/when you want/need to remove/replace a Helicoil, if it has started to come out (normally because someone has not broken the inserting tang off), you just tap a small screwdriver down behind the start of the thread to distort it out of the casting's thread, then grab it with suitable pliers and pull it out, it will unwind nicely.

 Have a look here. Mines still holding fast. no issues.

Torque setting

Would a Time Sert be a better choice than a helicoil in such an application?

 

Instead of buying the kit and doing it yourself try your local bolt and nut supplier and ask them for an engineers who could do the job. I’ve used this approach before when my brother pulled the threads out on an aluminium engine. Making a mess of the job would be much more expensive and the engineers only cost £40

 

4 hours ago, CWARD said:

Would a Time Sert be a better choice than a helicoil in such an application?

What is difference between timesert and helicoil? Is timesert more solid? Helicoil more like a spring, looking at pictures. 

Looked similar and pricey £130 for kit.

Not sure who does this repair. If I bought the kit and the helicoil dislodged later I could diy again when fitting new discs for no extra cost 

Typically these beefier "solid" inserts (obviously) need you to drill a bigger diameter hole, which you might not have the option to do at this location.

 

The "solid" inserts tend to need to be chosen by length as well as other things, and typically used down blind holes and into softer material like alloys.

 

Edit:- maybe the "daddy" of fixes for that application is a top hat solid insert that is not just bigger in diameter than a cross wire insert type like Helicoil and it gets extra strength from the top hat, but unfortunately there does not seem to be much call for that so Helicoil it is.

Edited 27 September, 20187 yr by rum4mo

Just a thought, is there room to use a slightly longer bolt and put a nut on the back?

18 hours ago, sepulchrave said:

If you're going to loctite the helicoil in place then you should also fit the carrier bolt to force the helicoil insert in tight, just lightly grease the carrier bolt first so it doesn't bond as well.

Let me get this correct then, I drill with quality drill bit, 12.4mm, supplied with helicoil kit. Use the supplied tap for M12 1.5 thread pitch. Clean up metal shavings then apply green 270 medium to high strength loctite to outer side of helicoil. Instead of using supplied helicoil tool to insert helicoil I should insert M12 1.5 bolt into helicoil prior to fitting into hole? Add blue 243 medium strength loctite to M12 bolt threads, or not?

 

Thanks

1 hour ago, SuperbTWM said:

Just a thought, is there room to use a slightly longer bolt and put a nut on the back?

There is room, probably 1cm of bolt threads protruding. The bolt is about 35mm long of threads from below hex head. This seemed too good to be true. This seemed a bit of a bodge, mot failure?

Edited 27 September, 20187 yr by bmbmdmb

6 hours ago, valvedoctor46 said:

Have a look here. Mines still holding fast. no issues.

Torque setting

I think that is a good next step, a larger bolt,  if the helicoil fails. Thanks 

1 hour ago, rum4mo said:

The "solid" inserts tend to need to be chosen by length as well as other things, and typically used down blind holes and into softer material like alloys

The female threads are in the metal that looks like cast iron, not soft aluminium. So helicoil perhaps best like you suggested. The bolt hole is the bottom hole so actually more accessible than upper bolt hole. Thanks

Edited 27 September, 20187 yr by bmbmdmb

2 hours ago, bmbmdmb said:

What is difference between timesert and helicoil? Is timesert more solid? Helicoil more like a spring, looking at pictures. 

Looked similar and pricey £130 for kit.

Not sure who does this repair. If I bought the kit and the helicoil dislodged later I could diy again when fitting new discs for no extra cost 

 

Timesert are a solid fixing not a spring insert. The tooling to fit them is more expensive but it is a permanent fix superior to the original thread, you’ll not be replacing it again. 

The reason I suggested using an engineers is due to the cost. Helicoil or Timesert and you’re paying for the tools and additional inserts, which you’re unlikely to use again. If you’d stripped an m8 or m10 it might be worth buying a kit. 

 

1 hour ago, CWARD said:

Timesert are a solid fixing not a spring insert.

I ll ring this engineering place suggested by fellow car enthusiast in Doncaster and Google around. 

 

Would the Timesert need loctite? 

No loctite needed

4 hours ago, bmbmdmb said:

Let me get this correct then, I drill with quality drill bit, 12.4mm, supplied with helicoil kit. Use the supplied tap for M12 1.5 thread pitch. Clean up metal shavings then apply green 270 medium to high strength loctite to outer side of helicoil. Instead of using supplied helicoil tool to insert helicoil I should insert M12 1.5 bolt into helicoil prior to fitting into hole? Add blue 243 medium strength loctite to M12 bolt threads, or not?

 

Thanks

 

I think what he was meaning was to apply high strength (green) Loctite to the Helicoil external thread and using the fitting tool fit the Helicoil fully into the hole and probably snap off the tang, then fit the proper bolt into the new thread in the hub but make sure that it has a coating of grease on it to avoid it picking up any green Loctite and locking onto the Helicoil.  One thing though, I don't know the length of the Helicoil inserts relative to the material thickness of the hub area, after fitting the Helicoil full depth into the hub, there might be some length of Helicoil left out of the hub, cut this use flush with the hub surface, ideally the insert would be just short of the full thickness of the material when fitting into a through hole so that you don't distort/disturb the end of the Helicoil when fitting the bolt in.

 

Edit:- the plan with temporarily fitting the bolt greased is to force the Helicoil out as far as it will be in use before the Loctite has set, after that remove and clean grease off the inside of the fitted Helicoil and the calliper bracket bolt, after refitting the calliper bracket fit the new bolts with blue Loctite.

Edited 27 September, 20187 yr by rum4mo

1 hour ago, CWARD said:

No loctite needed

 

Maybe not for some people, but these Time Serts don't seem to have any built in locking element, so I'd expect anyone not wanting any trouble in the future, to use some strong retaining stuff.  In fact, at work, if we used TeeSerts, which are same as Time Serts but without the increased diameter at the top end, we always removed the hard nylon locking pellet and cleaned them up and applied a strong Loctite product for that job of locking them in.  On aluminium or mag alloy blocks, we used inserts that had 4 wedges to lock them in place - called KeenSerts.