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rear disc brake conversion?


73skyline

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Hey 240K&Beyond:

What material are you making your plates out of? You say that you have a set in use at the moment - is this road only, or road / race? Reason I ask is that I have a few concerns regarding the sharp internal corners. I was working on a design with chamfered / radiused internal corners wherever possible to minimise stress raisers.

Don't take this as a criticism of your work. It was good of you to make your design available to us. I was just looking at whether the design can be simply improved on (hey, if it saves me having to engineer my own, then it's a bonus).

I have a freind who's a gun machinist (as in he's good, not that he machines guns, or operates machine guns. Well actually, he DOES manufacture parts for rifles - but...aww forget it :tapemouth ), and has his own equipment at home. He offered to make mine up for me pretty cheap (usual payment of beer / red wine plus materials). He might be interested in making up a few of these.

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Hi 440K,

As far as I know, the plates in use are roadworthy - they passed. You are right. Over the last couple of weeks, reviewing the CAD drawing I was given with Engineers quoting to make them, there is a discrepancy around the "hard" corners.

I chatted to the bloke who had them made and he has informed me that this is because the guy that made them for him used a machine that puts a 3mm radius on these edges, hence he did not put it on the drawing.

So yes, it is a good idea, and yes, they are made like that.

If you want to ask your "Gun", for sure !!! I am guessing that we will need around 10 pairs all up, first run, with all the interest shown. (I need two pairs myself.) If your fella can design a program to make them on an automated machine, this would probably be the easiest and cheapest way.

It needs to be made from 20/22mm plate mild steel with a minimum grade of 200, but 250 is prefered and used in the already construded units.

As soon as I hear back from the guy, I shall let everyone know. I was planning to make one set to "test" their construction, but if I use this guy who has already made them before, then I was planning to have them bulk built.

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Hi Bruce,

measured up the R31 pintara brakes, the bolt holes are 8mm wide, the distance from the outsides of the 2 mounting bolt holes are 105mm..

so that would make bolt centre to bolt centre 97mm (which doesn't seem to match up to your diagram :()

i am pretty sure they are a 260mm rotor, with 60mm height (according to the dba database)

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Hey Kent,

According to my plans for the conversion plate (As shown in the gallery) the R30 conversion plate adaptors holes are 114mm apart. (Centre to centre). Damn ! What about the dimensions of the actual disk rotor?

I have measured my R30 rear hatch rotors that suite my conversion plate diagram and they are as follows:

1) When placing the rotor flat on the desk with the wheel stud bolt holes up and the actual brake surface on the desk: the distance from the top surface down the side to the topside of the braking surface is 37mm.

2) The diameter of the top surface where the wheel stud bolt holes are is 170mm.

3) After flipping the rotor over so that it rests on the blot holes: The diameter distance ove the visable hole in the middle where the axle goes is 151mm

4) The distance from the edge of this "hole" to the outer edge of the rotor braking surface is 51mm.

5) Finally the actual width of the rotor (from one braking surface to another) is 10mm. The minimum spec is 9mm.

How does this compare to yours? If the offsets are the same and the length (51mm) of the rotor is the same: You may be able to adapt my design to suit your rotors.

Else, you may wish to consider a R30 modification instead of a R31.

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  • 3 weeks later...

I have just checked in with my mate that has already had a set of plates made. He has been trying to contact the original manufacturer of the plate. This guy has been on holidays and as such, my mate is going to try him again this week.

Hopefully I will have an answer by next week end.

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i was just curious, i read in the beginning of the thread that the 240z,280z has a different offset than the 240K when it comes to brakes....well if i were to buy the disc brake adaptors for a 240z/280z would i be able compensate for the different offset by adding or subtracting metal from the adaptor to make it work with my car? the adaptors you are making to fit r30/r31 brakes it may be hard for my to get rotors/calipers for i live in the states and we dont have DR30 skylines here. so i was thinking of buying a pair of Datsun 240z rear disc brake adaptors and modifying them to work with my 240K. would it be a waste of my time doing this or do you guys think it might work. i can weld, drill or lathe the adaptors if i have to but just wondering if it would be to much work and not worth doing. i was thiking of the disc brake adaptors to work with 240sx calipers.

heres the link of the adaptors i might try to modify to fit the 240K

http://www.modern-motorsports.com/catalog/product_info.php?products_id=8

thanks

mikey

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  • 3 weeks later...

Hi Fellas,

I have run into a snagg. The bloke that made the original plates does not want to make any more. Back to square one :-( Add to this I am moving to Sydney for 7 months on the weekend, I might be up the proverbal creek to organise another manufacturer in time.

I will see what can be done.

73skyline: These plates are for R30 not R31 rear calipers, the are different. You could modify the design to suite R31 as the offsets are very similar. However, as for Z brakes, the offset is extremely different, and I think you will find that you would need to make new axles to suite. This would over-complicate the process and would probably be expensive. I have heard of people performing R31 conversions, someone must have some details out there.

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  • 3 months later...

hey 240K

if your still having problems finding a fabricator let me know, i know im overseas but my fren has someone who customs fabs our stuff here. we had crank pulleys, brackets, etc...custom made. we basically give these people a part and they can re-create it out of aluminum or whatever material you want and wont cost an arm and leg. if you want send me pictures of the adaptor you have now and aprox. measurements and ill show it to them and see how much it would be to make. email me at mikeseez@cox.net the adaptor isnt as high demand here as where you live, i know of only 5 240ks in the US but im one for sure who wants a pair. thanks

mikey

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Thanks Mikey,

In my gallery is a copy of the adaptor blate. I will send you the original CAD drawings if you like. You could ask them how much for pairs of them. Likewise, a best guess on what it would cost to ship to Oz.

Pending results, we can organise a poll on who want them over here, but from memory, we are currently in the order of Ten pairs to Oz.

Cheers

Bruce

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  • 1 year later...

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