Z1 brake disc grinding

[wilsonsjw11]

Anyone had any success with getting a Z1 brake disc surface ground where it does not squeal when applying the brake, if so who carried it out.
Regards
Steve.

[CAT3]

No experience of this on Z1's, but I would imagine by the time the disc is ready for surface grinding to get a good, flat surface finish the thickness of the disc would be below the minimum service limit.
To get a good flat surface also involves shimming the disc on the magnetic chuck before the chuck is "switched on". As it would be quite common for these discs to be ever so slightly warped, you loose even more thickness.
If you do not shim the disc first & just switch the chuck on, it will pull the disc flat prior to grinding & then when you release the chuck the disc will have a nice flat surface, but it would still be warped.
Also, as most surface grinding machines work by moving the chuck left to right repeatedly grinding the outside of the disc would be fine. However, to grind the inside face you'd have to removed the disc from the carrier.

[pertonpc]

Hi Steve
DaveZ1 on here did this on his rebuild.
He did ring grinding (whatever that is) and showed before and after images on his rebuild thread.
Which looked good.
Give him a pm
Cheers

[engz1b]

ring grinder is like a surface grinder, only it has a rotary table

[Plummen1]

I've always used a shop that grinds flywheels,never had a problem.

[warren3200gt]

Thurston engineering in Essex did a pair of 650 discs for me. Surface ground inside and outside face without taking the middle out. Cost about £50 per disc if I remember right. Before and after braking was chalk and cheese.

IMG_20200914_124946.jpg (243.61 KiB) Viewed 4632 times

[warren3200gt]

Are 7mm and 5mm discs made from different material? If not, why shouldn't 7mm discs be ground to the smaller 5mm wear limit ?

[CAT3]

Are 7mm and 5mm discs made from different material? If not, why shouldn't 7mm discs be ground to the smaller 5mm wear limit ?

Potentially you could, but there might be issues regarding the hardening of the disc.
I'm assuming the disc goes through some sort of heat treatment process to give the disc surface a certain degree of hardness. I don't know if that "hardness" is right through the disc or just to a certain depth & depending upon how much you grind it down you might take away that hardness.

What we need is a disc expert !

[engz1b]

to, grind off a couple of millimeters would cost a lot of money, cheaper to buy new, i have ground new discs years ago, for racing go karts , they were case hardened , but i have seen a few discs which have cracked so some may be hard all the way through

[jonhunt]

My front brakes squealed like a pig. Change of pads fixed it

[wilsonsjw11]

What make of pads prevented the squeal?
Regards
Steve

[z2.john]

What make of pads prevented the squeal?
Regards
Steve

Yeah, that squeal gets you some funny looks alright.
A member a few years back (can't remember who) said that the pads being sold by Z-Power cured it. I was a bit sceptical but tried them and they did indeed solve the problem. Was about 10 years ago so might not be applicable anymore but worth a check with Dave or Phil over there.

[jonhunt]

Got them from z power 2 years ago

[King of Kings]

Dunlopads don’t squeal, and increase braking power hugely.