brake disc removal

[docc]

You strike this with a brass mallet or a machinist's hammer? Sounds like it's worth waiting til I can get one of these and also a fresh propane bottle.

 

Thanks for all the feedback!

[dlaing]

I always have used an impact driver. Rarely ever had a problem. When I did manage to round one out, A quick blast of heat, Mapp or Oxy/Act and then used a sharp chisel to turn the bolt.

This is the only impact that I have found that worked well. The one that you have to turn and hold just does not cut it. http://buy1.snapon.com/catalog/item.asp?P6...amp;dir=catalog

Do they make impact hex bits in metric?

Torx impact bits might be even better if you can find them.

[emry]

A big metal hammer. A machinists 18 or 24oz works really well. I have been using mine for 10+ years and the end is barely marred. The impact sockets I use are made by Wright, both metric and standard.

[docc]

Thanks, Emry. Hammers I got.

 

The local parts store (not AwtoeZoan, but the kind with dirty floors and counters) has a driver made by Lisle. I may give it a go since I can have it in the garage today. If it breaks I know where to order that Snap-On!

 

I'll try it with the new SK hex drive as they say it's a no-questions-replacement -guarantee.

[docc]

The dirty deed is done.

 

Propane for about one minute, rap the new hex drive twice then the Lisle impact drive three or four times with a 20 once (500g) machinist's hammer and turn the bad boys out with a breaker bar. I only munted one coming out and one going in having to resort then to the chisel and punch method.

 

The thread locker on the original bolts coming out was definately blue not red.

 

Should I repaint the little lines that would show them backing out as on the factory set-up? (What do you call those lines, anyway?)

[jrt]

I thought the paint was just a flag, applied after tightening. I never thought about it as an indicator. Hmmm.

 

Well done Docc. What are you going to use as replacements for the rotor bolts?

[Dan M]

I thought the paint was just a flag, applied after tightening. I never thought about it as an indicator. Hmmm.

 

Well done Docc. What are you going to use as replacements for the rotor bolts?

 

I think you have it right. Seems those lines are applied after inspection indicating critical bolts have been checked. I suppose one could watch them for indication of movement, but as this thread indicates, if properly tightened and loctighted, loosening is not something these bolts do. I've been in the habit of cleaning that ugly yellow paint off of my fasteners.

[stormsedge]

Docc, sometimes I put lines on bolts as an indicator of backoff.

 

PS check the new bolts you recieved to be sure they have the correct size head for your new discs...the first set I got on the last go round would not go into the indentions on the disc face and had to be swapped for the smaller button head bolts. k

[docc]

I used stainless bolts. They seem a little soft torquing them up to the 30NM. I munted one and had to re-use one of the originals.

 

I learned the line indicator from a pilot friend with a turbo Kawi 1000. I've used it on the shaft bolts having found one backed off a bit.

 

Most of the yellow paint is on the injection adjustments to deter tinkering. Or to help tinkerers find all the screws to turn.

 

The whitish lines on the rotors are different and, I suspect, one more attempt to show due diligence in keeping the rotors from coming loose.

 

My 'new' (slightly used) rotors are a bit grabby. I'm hoping the slightly used pads will bed in and the whole affair will smooth up.

[John A]

Metric stainless have a different marking system than the ferrus.There are property classes 50,70 and 80 with corresponding grades of A1, A2 and A4, roughly equivelent to SAE grades 2, 5 and 8.There are others but that's the gist of it.The heads will be marked with the manufacturer and the grade.I use A4 when I replace disc bolts and I always do for the factory bolts are one time use.If you get new ones from the dealer they come with a locking adhesive already applied.Blue 242 medium strength loctite is sufficient. The anti tamper paint that is found on fuel system adjustment areas is Torque Seal and comes in different colors.I like to put it on just to screw with peoples heads.

[Guest ratchethack]

I used stainless bolts. They seem a little soft torquing them up to the 30NM.

Docc, they ARE soft!

 

Stainless fasteners should NEVER be used on rotor carriers or calipers!

 

Wot you're looking for here is not tensile strength, but yield strength.

 

Metric class A2-70 is the typical Stainless Steel known as 302. It's rated at 65K PSI yield strength.

 

Metric class A4-80 Stainless Steel is rated at 87K PSI yield strength.

 

Metric class 10.9 grade is hardened steel, rated at 136 K PSI yield strength.

. . . . . . . . . .

 

NOTE: The significant measurement here is half for A2-70 wot it is for 10.9!

 

You should always go a minimum of 10.9 grade here. For greater shear strength yet:

 

Metric class 12.9 grade is rated at 160 K PSI yield strength.

 

12.9 grade is overkill, but there's no downside to higher shear strength than needed, and wot d'you figure a few buck$ worth o' insurance is worth here?

[docc]

The original fasteners are ferrous and have no markings. So what is their rating?

[Guest ratchethack]

The original fasteners are ferrous and have no markings. So what is their rating?

Dunno f'er absolute certain, Docc, -- especially on the rotor carriers -- because I replaced my caliper bolts many years back. But I've got four suspicious looking identical bolts in the fastener bin on my Guzzi operating tray of the exact size that're marked 8.8, and I'll bet these are the original caliper bolts I took out.

 

Grade 8.8 is rated at 93K PSI yield (shear) strength.

 

A4-80 Stainless would appear to fall short of stock issue by not much -- 6K PSI -- hardly enough to get overly excited about.

 

But then, wye not make it an upgrade rather than a small downgrade, long as y'er at it?

[John A]

I'm guessing 10.9 or better cuz I've never had the head twist off even as hard as they are to get out.

[docc]

Dunno f'er absolute certain, Docc, -- especially on the rotor carriers -- because I replaced my caliper bolts many years back. But I've got four suspicious looking identical bolts in the fastener bin on my Guzzi operating tray of the exact size that're marked 8.8, and I'll bet these are the original caliper bolts I took out.

 

Grade 8.8 is rated at 93K PSI yield (shear) strength.

 

A4-80 Stainless would appear to fall short of stock issue by not much -- 6K PSI -- hardly enough to get overly excited about.

 

But then, wye not make it an upgrade rather than a small downgrade, long as y'er at it?

 

I don't see any marks on the original button head bolts at all. Am I missing something?