Going nuts about bolts

cajos1968

Well-known member
Joined
May 13, 2008
Messages
372
Location
Leiden, The Netherlands
I'm installing new brake rotors. So far without any problem, counter sinking and treading went smooth. Even compensating rotor run out went well. In all I'm very happy with the end result.

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BUT.
I am having problems with the right rear. After breaking a single stage tab last week. Luckily I could drive it round with a small punch. I thought that I miss aligned it and it hit the emergency brake.
This seems not to be the case. Yesterday I tried again and had a hard time getting a 3 stage tap to engage, I did 2 but it took me more then an hour, going back and forth. With the third hole I broke the 1st stage Tap. And it is in rock solid. It seems that this spindle is made from harder material then the other 3.

Q1) How do I get the broken TAB out?
Q2) Is it possible that the spindle is made from harder steel?
Q3) Any suggestions how I can get the remaining holes threaded without breaking more expansive tools (thus far 25 euro first tab and 10 euro for the other).
 
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That part of the spindle should be soft. If you can't get the tap to cut the steel it's too hard. It takes quiet some temperature to harden the material (and fast cooling). I'd be worried about the part of the spindle where heat is usually generated. :shocking:
Maybe the holes are a little too small ???
 
That part of the spindle should be soft. If you can't get the tap to cut the steel it's too hard. It takes quiet some temperature to harden the material (and fast cooling). I'd be worried about the part of the spindle where heat is usually generated. :shocking:
Maybe the holes are a little too small ???

Agree with that.


Q1) How do I get the broken TAB out?
You might just have to drive it thru with a flat punch and live with what is left for a hole. You can get into diamond bits etc, but not worth the money or the work for this application if it's that tight. Use no heat.

Q2) Is it possible that the spindle is made from harder steel?
Your answer is, how did it drill. You can get a good idea from that.

Q3) Any suggestions how I can get the remaining holes threaded without breaking more expansive tools (thus far 25 euro first tab and 10 euro for the other).

This application isn't that critical and you can get by with a lot less the 75% engagement. Try it on some scrap metal first to get a bigger acceptable hole size.
 
Q2) Is it possible that the spindle is made from harder steel?
Your answer is, how did it drill. You can get a good idea from that.

Q3) Any suggestions how I can get the remaining holes threaded without breaking more expansive tools (thus far 25 euro first tab and 10 euro for the other).

This application isn't that critical and you can get by with a lot less the 75% engagement. Try it on some scrap metal first to get a bigger acceptable hole size.


You're saying 8.5mm hole.... I'm assuming standard M10x1.5.... the hole should be nearly 8.5mm without drilling. For 3/8"x24 thread you do not want to enlarge the hole - 3/8" is just under 10mm....

With cutting oil it should be very easy to thread the hole.

Unless the hole is too small I'd say the material hardened.....

These HSS taps normally cut steel like butter......
 
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I got the MF out!! Couple of blows on it, to get it loose and then with a small puns hitting it round.

I enlarged the hole to 9mm, guess what broke the damn drill bit. No issue getting it out.

I have no clue what kind of rear spindle this is, it feels strange drilling it, it has hard and soft areas. In the end I got all holes tapped and the rotor run out measured. Both rear run outs where with in tolerance, and needed no compensation. Both fronts needed 3 "shims" (alu tape) to be with in tolerance.

Problem with slotted rotors is the slots, the clock shoots down.
Here is a video:
http://picasaweb.google.com/lh/phot...?authkey=Gv1sRgCPrklfn6tc7WbA&feat=directlink

This is a metric clock so || = 0.01mm you can barley make out that it stays within 0.1mm.

Rotors are done!! another item from the list. Now hook up, fill and bleed the brake system.
 
Clock it way on the inside where there are no grooves.

So, how do you feel now, after drilling and tapping all those holes? I have never bothered, put the wheels back on and go.
 
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