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Issues with disc brake conversion


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#51 WhaleOilBeefHooked

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Posted 22 February 2011 - 07:08 AM

Measuring a 5 stud PCD is different to measuring 4 or 6...... Measure from outside edge of 1st stud to centre of 3rd stud, Outside edge of 3rd to 5th & so on...... 4 & 6 stud is measured from centre 2 centre......

#52 _nicole_

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Posted 22 February 2011 - 07:15 AM

Measuring a 5 stud PCD is different to measuring 4 or 6...... Measure from outside edge of 1st stud to centre of 3rd stud, Outside edge of 3rd to 5th & so on...... 4 & 6 stud is measured from centre 2 centre......


Whats a PCD?

#53 _cruiza_

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Posted 22 February 2011 - 07:20 AM

Pitch Circle Diameter

#54 _nicole_

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Posted 22 February 2011 - 07:34 AM

Pitch Circle Diameter


Ok thanks for the info. Will give it a shot on a couple with very similar dimensions and see what i come up with.

#55 76lxhatch

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Posted 22 February 2011 - 12:10 PM

The pitch circle is the imaginary circle that runs through the centre of all studs. However most discs don't have any holes other than the ones for the studs, so it may be just a matter of finding one with the right number? Then even if the PCD is wrong you can drill new holes between them with plenty of meat.

#56 _uctorry_

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Posted 22 February 2011 - 01:20 PM

Hi guys
Have you thought about getting hats made up for the rear end and getting off the shelf disc fitted to these
May be more expensive up front not sure but in the long run you just replace the bolt on disc
just a thought

#57 _nicole_

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Posted 22 February 2011 - 04:05 PM

Hi guys
Have you thought about getting hats made up for the rear end and getting off the shelf disc fitted to these
May be more expensive up front not sure but in the long run you just replace the bolt on disc
just a thought


I dont really understand how this works, but will run it past the mister when he gets home and see what he thinks.

#58 dattoman

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Posted 22 February 2011 - 04:26 PM

Alot more exxy
Harder to find a suitable disc
Not recommened for handbrake style calipers as they tend to pull and can distrort the disc

#59 _nicole_

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Posted 23 February 2011 - 06:03 AM

Datto - how do i find out the PCD on another disc, I have found one which is pretty much a perfect fit, but the PCD isnt written in the book. Its a DBA884 off a volvo, to compare with a DBA616 off a skyline/pintara

Edited by nicole, 23 February 2011 - 06:03 AM.


#60 dattoman

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Posted 23 February 2011 - 09:44 AM

Early Volvo is Torana pattern
I think those later ones are different.... ask a tyre shop or net search the stud pattern

Then get a look at a disc to see if you can cut 25mm off it and still have room for the pad
Volvo runs a handbrake inside the disc like Commodore... the bell might be too big
The 2mm offset difference might be an issue too unless your going to space the caliper back somehow

#61 _nicole_

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Posted 23 February 2011 - 11:19 AM

Early Volvo is Torana pattern
I think those later ones are different.... ask a tyre shop or net search the stud pattern

Then get a look at a disc to see if you can cut 25mm off it and still have room for the pad
Volvo runs a handbrake inside the disc like Commodore... the bell might be too big
The 2mm offset difference might be an issue too unless your going to space the caliper back somehow



Thanks Datto, I called the brake place and they're going to get one in to have a look at. The 2mm will be ok, as there's a few washers we can take out to get an extra few mm. Wouldnt have a clue about the handbrake side of it, but hopefully it will be ok.

#62 AbsynthHatch

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Posted 23 February 2011 - 11:25 AM

Can you keep us all posted on the outcome please Nicole

As I'm sure there will be a few interested parties who are either doing or contemplating this mod.

Cheers Ab

#63 _nicole_

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Posted 23 February 2011 - 11:53 AM

Can you keep us all posted on the outcome please Nicole

As I'm sure there will be a few interested parties who are either doing or contemplating this mod.

Cheers Ab


Dont get your hopes up too much just yet! As Datto said, pretty slim chance of it being right, but its a lot cheaper and easier than the alternative if it works. If not, the only other alternative for us will be the blank rotors and there's not enough interest to warrant buying 25 sets of discs at above the equilibrium price.

#64 _LS1 Hatch_

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Posted 23 February 2011 - 12:35 PM

Mid 90's Ford Thunderbird was 5 on 4.25" bolt pattern as well, and most where 4 wheel discs as well. Might be an option if the specs worked out properly?
And not a bad price over here and could ship some over via container..

#65 _uctorry_

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Posted 23 February 2011 - 01:46 PM

Hi mate
what size are the discs and are they vented or solid
Cheers

#66 _LS1 Hatch_

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Posted 23 February 2011 - 02:03 PM

Just looked the specs up on rockauto...

Front first, than rear for thier original application...

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#67 _LS1 Hatch_

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Posted 23 February 2011 - 02:10 PM

Oh, and for comparison...these are what I used on my brake setup. (Just had to redrill them to Chev bolt pattern) sure alot heavier ! Ha ha....they are larger in diameter than the 14" hotwires I used to run on the car originally. :lol:

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#68 _nicole_

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Posted 23 February 2011 - 04:49 PM

Thanks for the info Jeff, however our engineer wont allow us to redrill, that's the whole issue. The DBA616 discs fit perfectly, except that we want to run sprintmasters which are a different stud pattern to the skyline/pintara's.

UCtorry - discs are the DBA616 specs, and Im really just chasing solid, but if vented is the same as slotted, then i'll take them if that's all i can get.

#69 dattoman

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Posted 23 February 2011 - 08:19 PM

Vented and slotted are totally different things

The Thunderturd disc is too thick and no good to you for the caliper your using

#70 Toranamat69

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Posted 23 February 2011 - 08:24 PM

Sounds like it may be easier and cheaper to get a new engineer.

#71 _LS1 Hatch_

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Posted 24 February 2011 - 01:27 AM

Thanks for the info Jeff, however our engineer wont allow us to redrill, that's the whole issue. The DBA616 discs fit perfectly, except that we want to run sprintmasters which are a different stud pattern to the skyline/pintara's.

UCtorry - discs are the DBA616 specs, and Im really just chasing solid, but if vented is the same as slotted, then i'll take them if that's all i can get.


I just mentioned the Tbird discs because they are Torana pattern is all...was not sure on the thickness issue though, good point.

The similar era Taurus was the same bolt pattern but assume discs would be similar.

I just found it out because I wanted a small donut spare wheel for my car ages ago and after a little checking around I found the Tbird space saver spare was a perfect fit on the Torana....course it's Chev pattern now with big brakes so different story..

#72 _nicole_

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Posted 24 February 2011 - 06:36 AM

datto - i have no idea when it comes to these things, I'll stick to my desk job and let you guys be the experts!!

toranamat - lol, i'll keep that in mind!

LS1 - Thanks for your efforts, hopefully the one which should be in today will be ok. If not, given its a 5 stud disc, if we turn it, then fingers crossed we can re-drill holes where we need them, and leave the old holes empty. We want to keep the torana stud pattern if at all possible, given the wheels just cost $2k to go on them!

#73 _nicole_

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Posted 26 February 2011 - 05:07 AM

The disc came in yesterday and it's the wrong offset - everything else was good, including the stud pattern which is really annoying.

#74 _nicole_

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Posted 20 May 2011 - 07:17 PM

Hi guys,

Just a quick update on this issue, have managed to source some RDA616 blank discs, which are approx 16 weeks away. The price is $135 for a pair standard, or add another $22.50 per pair for slotted.

If interested PM me and i'll update you further.

#75 _@milco@_

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Posted 26 March 2012 - 11:22 PM

how did you go with the blank rotors?

Hi guys,

Just a quick update on this issue, have managed to source some RDA616 blank discs, which are approx 16 weeks away. The price is $135 for a pair standard, or add another $22.50 per pair for slotted.

If interested PM me and i'll update you further.



how did you go with the blank rotors?




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