Nightpager Brake upgrade supra 323mm disk walkthrough for z20 soarer

[ed]

i wouldnt delete it. its good info. even if its dead topic, its got relevant info worth reading.

id be interested, as i said before, on what structural changes actually took place in the metal due to the grinding. yes, me, id use a lathe, but im curious none the less.

but my main concern is still how much material there is remaining around the studs after 2.5-3mm is removed, and what that does to material stress around the stud holes

[WDE_BDY]

but my main concern is still how much material there is remaining around the studs after 2.5-3mm is removed, and what that does to material stress around the stud holes

That is an interesting area to look at. I had hubs machined down to the same diameter for a brake conversion and you don't end up with a lot of meat left around the studs, but then the factory hubs the brakes came from must be the same anyway in order to fit the disc. So Skyline, Altezza etc all run with the same amount of meat left on them, are those hubs of similar material and design or have other changes being made to increase strength in that area? Or is it not really an issue as the studs shouldn't actually be locating the disc/wheel, just clamping it to the hub?

Callum

[CrUZida]

If someone can edit the original post and replace the suggestion of using a bench or angle grinder with the recommendation of a lathe, and then delete every post after it, then it would be a good thread.

but my main concern is still how much material there is remaining around the studs after 2.5-3mm is removed, and what that does to material stress around the stud holes

The MA61/MX73 upgrade required 3mm from memory (150mm down to 144mm dia) to be shaved off. My engineer had zero issues with the left over meat.

[brett_celicacoupe]

Can you explain your thoughts behind this statement please Brett? (just the bit in bold)

generally, grinding is used to achieve a finish superior to machining [fundamentals of modern manufacturing 3rd ed].

after further reading of this text, i think it probably isnt wise to take the grinding route on this particular brake upgrade. while i still expect the job can be completed without any problems under the right circumstances, someone carrying out the conversion may not be aware of heating consequences.

[CrUZida]

Its also worth noting that in my experience, genuine discs seem to have small ID's than aftermarket ones.

ie If you grab an original Z32 disc, you'll need to shave the full 3mm off the hub, but if you use an aftermarket one (RDA/DBA), then you'll only need to shave 1mm or so.

[CrUZida]

generally, grinding is used to achieve a finish superior to machining [fundamentals of modern manufacturing 3rd ed].

Totally agree, but do you think most people would have right wheel on their grinder to achieve this finish?
Or do you think they'll just have the super rough one you use for 'grinding shit' ?

[brett_celicacoupe]

The MA61/MX73 upgrade required 3mm from memory (150mm down to 144mm dia) to be shaved off. My engineer had zero issues with the left over meat.

did he ask what temperature the surface reached during the material removal process?

edit: im not trying to stir things up but im just raising valid points from both sides

[CrUZida]

No he didn't, but he was told it was done on a lathe at a professional machining business (engineering workshp if you will).

Personal opinion here, but it would take a pretty careless and poor machinist to get the hub up to any serious temperature on a lathe.

[brett_celicacoupe]

If this type of modification was as critical as it being portrayed in this thread, i would expect your engineer would like to inspect it for himself. possibly carry out a dye penetration test.

i dont expect that the safety factor on the hubs is that close to 1 that removal of a small amount of material will reduce it below 1. realistically the safety factor is probably in the 20s

i would be far more concerned with the safety of this type of practice. [ http://www.toymods.org.au/forums/sho...d.php?t=37888]

Plenty of people redrill axles from 4x114.3 to 5x114.3 and vice versa with no problems.

again, im just trying to put things in perspective.

[eeeyan]

It doesnt get super hot on a lathe infact with Cast iron your not even meant to use coolant when lathe cutting just slow shallow dry cuts as if you wet it it basically turns into black toothpaste.

So i dont imagine it would get real hot at all in fact i would guess that the edge would almost cool with every rotation in the lathe.

[jeffro ra28]

generally, grinding is used to achieve a finish superior to machining [fundamentals of modern manufacturing 3rd ed].

Yes that is true, With a cylindrical or surface grinder. Not a bench grinder.

IMO this is a complete crock and a huge over reaction. Yes its dodgy but seriously is a shitty cast hub going to be factory balanced anyway? I know my hilux axles were massively out of round, which i corrected with a lathe because i had access to one. They certainly were not balanced and personally i could have done a better job getting them round with a set of verniers and a grinder.

Localised heat etc, seriously?
Sure, if he wants to grind the hub into the shape of a 50 cent piece in single steps.

[TheToyman75]

Fuck me, Talk about jumping on board and Riding the horse. Dodgy would be using a Jigsaw or a gas axe. Grinding them down is hardly a hanging offense.

Guilty bothered to take the time to write up the DIY guide and sure it may seem simple to those of us who have been around a while but to the newbies out there this sort of thread can be gold and its the kind of thread people should be encouraging.

By all means suggest that using a lathe would be a better option than Grinding it down but honestly that's about as far as any comments needed to go.

I am leaving the rest of the discussion up so people reading it can decide for themselves but people coming along and stirring the pot further will find themselves on a forum holiday.

[1gjet]

Hey guilty any more pictures of progress?

[PeteH]

are the hubs cast iron or cast steel?

From my experience hubs like these are typically forged from 4140, or similar, then fully annealled and machined.........lamellar pearlite is the microstructure.

You'd have to get pretty enthusiastic with a bench grinder, and the application of quenching water, to turn that into martensite.....possible, but not likely.

but my main concern is still how much material there is remaining around the studs after 2.5-3mm is removed, and what that does to material stress around the stud holes

That's the bit that would stop me from doing this to a car that was going to see street duty.

The hub is designed to survive a finite life, of which this one alread has +20 years under it's belt..........taking that into account, the removal of material from around a stud is not something I'd do to a vehicle I owned. But that's just my opinion.

Im dodgy
and i wouldnt do this.

That's pretty much what I thought too.......in between lols....

[GU11TY]

i wouldnt delete it. its good info. even if its dead topic, its got relevant info worth reading.

id be interested, as i said before, on what structural changes actually took place in the metal due to the grinding. yes, me, id use a lathe, but im curious none the less.

but my main concern is still how much material there is remaining around the studs after 2.5-3mm is removed, and what that does to material stress around the stud holes

yeh very valid point. ill measure how much room there is around the studs after im done for you

Fuck me, Talk about jumping on board and Riding the horse. Dodgy would be using a Jigsaw or a gas axe. Grinding them down is hardly a hanging offense.

Guilty bothered to take the time to write up the DIY guide and sure it may seem simple to those of us who have been around a while but to the newbies out there this sort of thread can be gold and its the kind of thread people should be encouraging.

By all means suggest that using a lathe would be a better option than Grinding it down but honestly that's about as far as any comments needed to go.

I am leaving the rest of the discussion up so people reading it can decide for themselves but people coming along and stirring the pot further will find themselves on a forum holiday.

thanks mate

Hey guilty any more pictures of progress?

sorry mate been flat out at work the last few days due to xmas so ill put pictures up when i do more