Potential disaster - wheel knuckle threaded - suggestions?

[magnum44]

Hi All

Looking for suggestions/advice to get me out of a small predicament, but I think I know what the answer is going to be!

I'm in the process of renewing the discs and pads all round on my 2007 V8V and, after much swearing and cursing as they were both seized, eventually managed to remove the brake caliper bolts from the O/S/F wheel hub. However, upon refitting said caliper, I have noticed the top M12 80mm bolt is no longer tightening and on closer inspection have realised the thread inside the hub knuckle is "threaded" (presumably overtightened by a former owner)!!

Would it be fair to say the only solution is a replacement hub knuckle (part number 7G43-3K186-AB), or is there an alternative? If it is a new hub knuckle is this something that I can do myself? Whilst I'm fairly competent in the car DIY department, this is not a job I've ever tackled before.

Thanks in advance of any assistance.

[LTP]

My first reaction would be Helicoil, particularly if it's a through hole rather than a blind one that you can get access to drill and tap, because you could then possibly do it in situ. Then new bolts, obviously.

If you don't know about Helicoils then watch this. It's in aluminium, but the principles are the same
https://www.youtube.com/watch?v=9rtiFBC0wms

added video

Edited by LTP on Monday 7th February 15:21

[leerandle]

Sorry to here of your problem.

Sounds like the knuckle bolt hole has been 'cross' threaded or thread completely stripped if not even torquing up.

I suppose drilled oversize hole, tapped and new insert would be the only repair possible and avoid a brand new knuckle.

This is standard practise, but you would need to ensure the new hole size/thread depth and insert are safe/strong enough to take the bolt torque.

Good luck !!

[john ryan]

As stated, helicoil would be a standard repair and well up to the job.

[magnum44]

I've never come across Helicoil but am going to give it a go, having watched a couple of Youtube videos

Thanks for your quick tips guys, much appreciated.

[dudleybloke]

Another vote for Helicoils here. Very easy to install and is stronger than most standard tapped holes.

[rickyf1]

is it just me that that doesn't like the sound of using helicoils to hold the calipers on? what torque figures would you use for the caliper bolts when they're going in to different metals from original spec?

[8Tech]

This is the exact reason I used studs in the hub carriers with titanium nuts. Kit offered by DAE Racing.

https://www.ebay.co.uk/itm/224561205566

[JonnyCJ]

I'd replace the knuckle rather than helicoil. Should be plenty around at breakers yards etc on ebay. People like AM Performance, McGurks etc may have spare knuckles in the parts store. AM Performance were doing a 6 piston calliper upgrade to a V8V when I was up there once, which necessitated the replacement of the knuckles. They rarely go wrong, so they may even be pleased to get shut if they have them.

Edited to show one on eBay and pics when you get them vapour blasted and coated with XCP Rustblocker

https://www.ebay.co.uk/itm/334187484200?fits=Model... This is apparently new according to the seller


[url]


|https://thumbsnap.com/N8b79HGU[/url]

And whilst the callipers are off, get them cleaned up and the pistons replaced. They'll look like mine in this thread and you won't want them going back in looking like that !

https://www.pistonheads.com/gassing/topic.asp?h=0&...

Edited by JonnyCJ on Monday 7th February 18:00

Edited by JonnyCJ on Monday 7th February 18:00

[RB99]

rickyf1 said:

is it just me that that doesn't like the sound of using helicoils to hold the calipers on? what torque figures would you use for the caliper bolts when they're going in to different metals from original spec?

I wouldn't be happy repairing a stripped brake caliper thread with a helicoil. I'm sure they're fine for all manner of applications, but surely not holding the brake calipers on?

[LTP]

magnum44 said:

I've never come across Helicoil but am going to give it a go, having watched a couple of Youtube videos

Thanks for your quick tips guys, much appreciated.

No problem. One issue you may have is that it's sometimes easier to drill a hole in a blank piece of material than drilling out an existing hole, as with a pre-existing hole you're only cutting with the very outer edge of the drill bit and, at the start especially, it's easy for the drill to "wander" and cut oversized. Also, as you're only using the outer tips, they can chip easier than if you're cutting across the whole width of the drill bit.

Get brand a few new drill bits in the correct size, preferably something better than cooking HSS - something like cobalt or carbide. Use an oil to keep the drill lubricated and take your time. It'd be easy to be too gentle and then the drill bit rubs and blunts - you need to apply sufficient pressure to get the bit to cut.

Good luck and post how it went.

[LTP]

RB99 said:

I wouldn't be happy repairing a stripped brake caliper thread with a helicoil. I'm sure they're fine for all manner of applications, but surely not holding the brake calipers on?

Most Helicoil repairs are better than the original threaded base material, particularly if it's in an alloy. I'd have no compunction, but I guess it depends how deep your pockets are and how expensive a replacement hub.

If you're really interested read the report appended to this article. It concludes that in aluminium an insert depth of over 1 diameter will mean the bolt will fail before the threaded insert shears out of the material
https://www.crosstools.com.au/helicoil-type-insert...

[anonymous-user]

Nothing wrong with a helicoil repair, but for the cost of a new hub I'd fit one of those.

[paulrog1]

JonnyCJ said:

I'd replace the knuckle rather than helicoil. Should be plenty around at breakers yards etc on ebay. People like AM Performance, McGurks etc may have spare knuckles in the parts store. AM Performance were doing a 6 piston calliper upgrade to a V8V when I was up there once, which necessitated the replacement of the knuckles. They rarely go wrong, so they may even be pleased to get shut if they have them.

Edited to show one on eBay and pics when you get them vapour blasted and coated with XCP Rustblocker

https://www.ebay.co.uk/itm/334187484200?fits=Model... This is apparently new according to the seller


[url]


|https://thumbsnap.com/N8b79HGU[/url]

And whilst the callipers are off, get them cleaned up and the pistons replaced. They'll look like mine in this thread and you won't want them going back in looking like that !

https://www.pistonheads.com/gassing/topic.asp?h=0&...

Edited by JonnyCJ on Monday 7th February 18:00

Edited by JonnyCJ on Monday 7th February 18:00

Yeah I agree with JonnyCJ on this, you should be able to find a good secondhand knuckle, call Mcgurks or BR or etc.

Its easy to remove the knuckle yourself.

I just try to keep to factory spec whenever i can, except for the primary decat on my car, so if the part is damaged i would replace it.

Mine after vapour blasting

Edited by paulrog1 on Monday 7th February 18:54

[RB99]

LTP said:

Most Helicoil repairs are better than the original threaded base material, particularly if it's in an alloy. I'd have no compunction, but I guess it depends how deep your pockets are and how expensive a replacement hub.

If you're really interested read the report appended to this article. It concludes that in aluminium an insert depth of over 1 diameter will mean the bolt will fail before the threaded insert shears out of the material
https://www.crosstools.com.au/helicoil-type-insert...

In practice, I think it would be very easy to drill the hole to an incorrect size, and/or off axis, and then do something similar with the tap, when carried out insitu on the car. I would worry that the sum of these uncertainties compromise the thread in the hole and the security between the helicoil and the body. If it was carried out with the hub in a pillar drill ot lathe, I think I'd be less concerned.

[JonnyCJ]

paulrog1 said:

Yeah I agree with JonnyCJ on this, you should be able to find a good secondhand knuckle, call Mcgurks or BR or etc.

Its easy to remove the knuckle yourself.

I just try to keep to factory spec whenever i can, except for the primary decat on my car, so if the part is damaged i would replace it.

Mine after vapour blasting

Edited by paulrog1 on Monday 7th February 18:54

And whilst the suspension arms are off you can change the bushes for the newly released Powerflex ones !

V8V - the gift that keeps on giving for the home spannerer

[magnum44]

Thanks everybody for your great advice. Never ceases to amaze me how much knowledge there is on this forum.

I'm going to give the helicoil a go but, given the hub is in situ and not on a lathe/pillar drill, the first sign of "drill-wandering" (as mentioned above), then it'll be a replacement knuckle. Also, if the helicoil takes, but the bolt torque fails, then that'll be a new knuckle, for which I've already made some initial enquiries.

I'll keep you posted on the outcome!

Cheers all, have a good evening.

[Darkslider]

Not familiar with the car at all but is a longer bolt with a nut on the other side of the hub knuckle an option at all?