Up s**t creek with caliper carrier thread, paddle needed

[Tim Cognito]

After a bit of a stressful week involving an MOT failure and an electric window module deciding to die whilst the window was fully down, the mk1 Fabia VRS is not done with me yet.

Yesterday I set about the simple task of changing discs and pads, all going smoothly until I went to torque up the m12 bolts which mount the carrier to the steering knuckle. 124nm is the torque spec which I thought spelled trouble but I dutifully followed the manual.

As I was tightening it up I had that unmistakable moment we all dread - righty tighty became righty not so tighty. First reaction - denial, I must be mistaken, maybe....the thread just hit a more slippery bit. .

But no, it's not torquing up. MF.

Anyway, turns out there has been a previous helicoil repair done and the helicoil is winding out the back of the carrier as I tighten the bolt. I assume once it gets to a certain torque there is more friction between the bolt and the helicoil than the helicoil and the knuckle so it just winds out.

Oh and the same thing happened on the other side as well.

What is the best way forward? I really don't want to have to replace two knuckles because they are expensive and also it looks like a lot of work which has the potential to snowball into more problems which is beyond my level of ability.

I could get another helicoil and some mega solid billy big balls loctite but seems to me a helicoil with no "bottom" of the thread is always going to want to wind out like this?

I've just found this, looks like a better option than helicoil and not too expensive. Doesn't look like it will matter if the thread on the knuckle is a bit buggered also?

https://www.ebay.co.uk/itm/254255540314

Anyone had much success with a similar kit?


Bolt 14 on the diagram below

[Belle427]

the threads are in caliper carrier part 6 are they not so im not sure why you want to replace the hub assembly?
Or am i mstaken?
Carriers are readily available.

[Tim Cognito]

No, the diagram is a bit misleading, the threads are in the hub assembly.

Same problem

https://www.briskoda.net/forums/topic/499335-fabia...

[Belle427]

Ok just checking.

[shirt]

I can’t see that eBay kit taking the torque as it is not threaded on the outside.

A time sert is the only repair method I would use but the tooling is expensive. The only other option would be to remove the carrier and have them welded, drilled and tapped.

[GreenV8S]

I prefer Time-sert. They are stronger and hold a lot better than helicoils. However, now that it's been drilled and tapped for a helicoil, you may not have enough base metal left for any other inserts. The usually pilot based cutting tools also won't work.

You could try just winding in another helicoil with some permanent thread lock if you wanted to get the car back on the road quickly. The risk is that the.grooves you are inserting it into are worn or poorly formed - in which case the replacement may do no better.

Another option is just to drill and tap to a bigger size and fit bigger bolts, if you have enough metal left on both parts.

[520TORQUES]

Try winding the helicoil back in to position using a V shaped tool. You can either take it all the way out and replace the helicoil, or just wind it back to the desired position.

This video shows you what i mean. https://youtu.be/Zjgfhb69LXo?si=67WxiKQQ9Xu5rlOP

Then clean the helicoil thread and bolt thread thoroughly, the helicoil will wind out if there is any crap jamming the threads on the bolt. Ideally fit new bolts.

If what you are feeling is not the helicoil winding out, but is the thread in the housing pulling, then you have no choice but to use a different method such as replace the part or use a larger area insert.

A keensert is probably your best next option. https://www.clarendonsf.com/products/inserts/keens...

[Tim Cognito]

shirt said:

I can’t see that eBay kit taking the torque as it is not threaded on the outside.

Why would it not being threaded make a difference? It's a different solution which goes on the opposite side to the male thread, more like a sunken nut.





I think first I will try new bolts, new helicoil with red loctite. If that doesn't work I'll look into the other kits which may involve damaging the thread that has already been tapped for the helicoils.

[finlo]

Is a nut and bolt solution doable?

[GreenV8S]

I haven't used those, but I assume you'd drill an interference hole and then pull the inserts home with the caliper mounting bolts. Is that a copper washer? I wonder what that's for.

[shirt]

Tim Cognito said:

shirt said:

I can’t see that eBay kit taking the torque as it is not threaded on the outside.

Why would it not being threaded make a difference? It's a different solution which goes on the opposite side to the male thread, more like a sunken nut.





I think first I will try new bolts, new helicoil with red loctite. If that doesn't work I'll look into the other kits which may involve damaging the thread that has already been tapped for the helicoils.

Ah I thought it went in from the bolt side, haven’t seen these before, interesting.

Time sert normally can be fitted in place of a failed helicoil but will be £150+ for the kit. Given the carrier is easily removed I’d personally get it welded up and retapped. Redoing helicoil plus loctite seems a bit of a bodge solution to me.

[Belle427]

Personally where brakes are involved it's either drill and tap larger size or new hub for me.