Disc retaining bolt

[vmaximus]

Hi chaps, I have got to drill and re tap the disk retaining bolts on a Renault kadjar, they are 8 x 1.25 x 16mm, would it be ok to use a 7mm drill for the hole, or have I got to get a 6.8mm drill bit. Thanks in advance.

 

[hotponyshoes]

It's only 0.1mm of difference in the thread holding although that 0.1mm is at the base (strongest part) of the thread.

If you can drill the hole on a rigid machine I'd be happy with a 7mm.
If you are trying to do it on the vehicle with a hand drill I'd be worried about it wobbling around and ending up bigger than intended.
Maybe go 6.5mm first so it makes it easier to control the 7mm.
Or spin a 7mm bit backwards against something to reduce it down.

 

[dobbslc]

Have you got a welder?
I you have then weld a nut on it if it hasn't snapped off deep in the hub.

 

[Melvyn Best]

Why have you got to drill it out? If it’s because you can’t shift the screw try using a center punch to drift it anticlockwise. If it’s siezed the just drill the head off then weld a nut on the remains

 

[vmaximus]

Have you got a welder?
I you have then weld a nut on it if it hasn't snapped off deep in the hub.

Unfortunately it was rusted solid so I had to chop the bevel head off to replace the disc, I have already drilled a 5mm hole, just got to enlarge it and re tap when the weather is a little kinder. It's only for retaining the disc in place so I didn't think that it is that critical, perhaps Locktite or PTFE tape would take up the play.

 

[vmaximus]

Why have you got to drill it out? If it’s because you can’t shift the screw try using a center punch to drift it anticlockwise. If it’s siezed the just drill the head off then weld a nut on the remains

Because it's rusted solid and was not going to get the welder out with rain ******* down, easier to re drill and tap, I don't think anything has been taken off since new so everything you touch is hard work.

 

[BrokenBiker]

Personally I wouldn't bother retapping...they arent a requirement for safe use of the brakes, i would just drill the head off and leave the rest in there

 

[vmaximus]

It's only 0.1mm of difference in the thread holding although that 0.1mm is at the base (strongest part) of the thread.

If you can drill the hole on a rigid machine I'd be happy with a 7mm.
If you are trying to do it on the vehicle with a hand drill I'd be worried about it wobbling around and ending up bigger than intended.
Maybe go 6.5mm first so it makes it easier to control the 7mm.
Or spin a 7mm bit backwards against something to reduce it down.

6.5 seems a more logical, Thanks.

 

[The_Yellow_Ardvark]

If it is not impacting the fitting off the disc, i would leave it, not an issue.

 

[hotponyshoes]

If it's just the retainer bolt then I'd be happy with 7mm in a hand drill.
It's only to hold the disk in place while you fit the wheel.

Or, as said, just leave it off. A bit of Copper grease will help hold the disk in place.

 

[bricol]

Only time I've had an issue leaving them out is on cars using bolts - when you put the wheel on and turn to line up with the bolt holes, the disc sometimes rotates too.

 

[vmaximus]

If it's just the retainer bolt then I'd be happy with 7mm in a hand drill.
It's only to hold the disk in place while you fit the wheel.

Or, as said, just leave it off. A bit of Copper grease will help hold the disk in place.

That's what I thought, but i'd rather ask people more experienced that me. Thanks.

 

[iNf]

If you've drilled it 5mm, tap it 6mm.? It'll probably come out then

 

[vmaximus]

Only time I've had an issue leaving them out is on cars using bolts - when you put the wheel on and turn to line up with the bolt holes, the disc sometimes rotates too.

As it did yesterday, so I'd rather fit a disc bolt.

 

[8ob]

Why faff about, turn the disc 90 degrees bung a couple of wheel bolts in and use the disc as a jig to drill/tap a new hole.

Bob

 

[vmaximus]

Never thought of that. Thanks

 

[JOEPRO]

Always pre heat any brake retaining screw and and use an impact driver to undo them. Works every time.

My S600 came to me with pre - stripped disc screws. In cases like that - electric glue every time works great. Plartly because it pumps alot of heat in

 

[minimutly]

Because it's rusted solid and was not going to get the welder out with rain ******* down, easier to re drill and tap, I don't think anything has been taken off since new so everything you touch is hard work.

No bolts holding the discs on my Jag....

 

[JOEPRO]

No bolts holding the discs on my Jag....

Its a Jag - they probably forgot to fit them

PS - Sealey is carp but you drive a Jag?

 

[dobbslc]

Why faff about, turn the disc 90 degrees bung a couple of wheel bolts in and use the disc as a jig to drill/tap a new hole.

Bob

@8ob why didn't you tell me that when I was working on that Fiat 500