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Issues with disc brake conversion


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#1 _nicole_

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Posted 14 February 2011 - 12:23 PM

Hi guys,

After a bit of advice re a rear disc brake conversion on an LJ. We've put Nissan Skyline R31 disc brakes on them, but have to change the stud pattern, so filled in the holes and refitted new studs.

However, the engineer is not satisfied with this, and wants us to source either blank discs, OR discs which have the 5 studs but need to be machined to size.

Has anyone else done this conversion before, and if so, then how did they get round this issue?

Any ideas would be great!

Thanks.

#2 _judgelj_

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Posted 14 February 2011 - 12:29 PM

you could buy blank disks from DBA?

or even redrill r33 disks

#3 _nicole_

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Posted 14 February 2011 - 12:30 PM

Yeah i thought of that, but they will only sell them in lots of 50, so it will be quite an expensive option.

Do R33 discs have 5 studs?

#4 _BIGCAV_

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Posted 14 February 2011 - 12:34 PM

are you sure about the blanks? normally you have to wait till they do a new batch, they just dont drill a set from the batch

or try a different manufacturer

#5 _nicole_

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Posted 14 February 2011 - 12:36 PM

Pretty sure. I have sent an email to them to double check - I would have thought it would be as simple as you say!

Are there any other manufacturers you would suggest?

#6 derrin71

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Posted 14 February 2011 - 12:41 PM

I want a slotted set with HQ pattern. I've tried the two main manufacturer's DBA and RDA and neither if them are interested, Need to get a order for at least 50 and they will only sell blanks to brake shops.
The R33 thig sounds interesting though?

Edited by derrin71, 14 February 2011 - 12:42 PM.


#7 dattoman

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Posted 14 February 2011 - 12:49 PM

Ring Howard at Race Brakes in Melbourne and ask him if he can get you the blanks

1300 365 757

DBA616 is the number
Put a U at the end for undrilled
And SL/SL for slotted

And no R33 are very different discs so forget them unless your changing the whole rear brake setup

Bear in mind... most stuff comes out of China nowdays so they are already pre drilled
If DBA doesn't have any they need to do a production run to be able to pull some off the line as blanks
This could take months till they run out of stock and do a run
And no they won't drill your pattern for you
Not cost effective to reprogram the CNC just for a pair of obscure discs

#8 _nicole_

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Posted 14 February 2011 - 12:49 PM

So are the ones you want the same dimensions as the ones im after? If so, then if we find a few more people, we might be able to get 50 and just split them. I know another guy on here is doing hte same conversion and needs a set too. The whole R33 thing confuses me. by re-drilling them doesnt that give the same issue as the R31 ones?

Thanks for the info dattoman, will definitely look into this. I am in no hurry for the discs, its taken 2 years to get the new brakes on the car, so a bit longer wont hurt. Im happy to drill the holes myself, i wouldnt expect them to do that just on one set.

Many thanks again, and i'll see how i go with Howard!

Edited by nicole, 14 February 2011 - 12:51 PM.


#9 AbsynthHatch

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Posted 14 February 2011 - 01:37 PM

I to have made inquiries about blank R31 rotors and came up empty handed (got told the same story, minimum run of 50)

However I was also told by a brake specialist that redrilling a pre drilled set, to accomadate the torana stud pattern would not alter the structual integrity of the disc

They (I won't mention their name) said it was not uncommon for some commodore rotors to have another set of holes drilled for alternate stud pattern (I don't know if this true or not)

However I have stalled on buying them at this stage, on the hope that an alternative (blank) set of rotors could be sourced.

It was probably 6 months ago when I tried, and I'm again about to start searching as I need my car mobile and this is what is holding me back.

#10 dattoman

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Posted 14 February 2011 - 02:17 PM

RDA wants 100 .... should be a pallet load @ 176 discs
Paid for up front

Working on it still

#11 _nicole_

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Posted 14 February 2011 - 02:19 PM

Absynth - do you need 2 or 4? I need 2, and another guy i know needs 2, lol, so if we find another 22 people who need them then we might be right. In the interim i think the next option might be to machine a bigger set down, which already has the 5 holes drilled. I know our engineer is not happy with any type of welding or re-drilling and wont approve the modification.

Dattoman - thanks, as im not sure what i'll do with 174 of them!

Edited by nicole, 14 February 2011 - 02:21 PM.


#12 AbsynthHatch

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Posted 14 February 2011 - 02:28 PM

I need 2 but would buy 4 so I have a spare set

Then I won't have drama's in the future as I plan to keep this car for while

#13 ls2lxhatch

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Posted 14 February 2011 - 02:52 PM

After a bit of advice re a rear disc brake conversion on an LJ. We've put Nissan Skyline R31 disc brakes on them, but have to change the stud pattern, so filled in the holes and refitted new studs.

However, the engineer is not satisfied with this, and wants us to source either blank discs, OR discs which have the 5 studs but need to be machined to size.


Are you sure the engineer is only talking about the discs and not the axles?

Welding and drilling axles is not accepted by most engineers. If the engineer is unhappy with a disc being redrilled then I would expect they will also want new axles.

#14 dattoman

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Posted 14 February 2011 - 02:54 PM

Good luck finding a rotor with the right pattern and offset that you can machine the diameter down

Highly doubt that will happen

#15 _nicole_

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Posted 14 February 2011 - 03:18 PM

He hasnt said anything about the axles. As far as we thought, the brakes were going to be fine, until he saw the old holes filled in and new studs put in. He hasn't written anything in his report about the axles either so im definitely not going to prompt him on it!

I found this one http://www.dba.com.au/products/dba2463 which is close, but the centre hole is 1mm bigger. Im hoping that if i can demonstrate to the engineer that these are the solutions we've come up with, then he will just pick one.

I take it no luck with getting less than 176? I had no idea it was going to be so difficult!

Edited by nicole, 14 February 2011 - 03:20 PM.


#16 dattoman

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Posted 14 February 2011 - 06:27 PM

That disc is 72mm high
R31 rear is 60

So thats a no show

It needs to have a large enough centre bell to fit over your axle flange too..... and still have enough metal left for the pad to sit on once machined down

#17 DanWA

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Posted 14 February 2011 - 06:32 PM

i'm in this same boat and will just be re-drilling the R31 axles/rotors and hope an engineer is ok with it or wait until a bright spark on here can get a hold of some blanks

#18 ls2lxhatch

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Posted 14 February 2011 - 06:47 PM

Ask the engineer if you can buy another disc and drill the new holes without welding the old holes then have it tested to prove that it is still structurally sound. The engineers main problem may be that the old holes were welded.

Many factory axles have extra holes drilled in them yet still are strong enough for the job. The disc is sandwiched between the axle and rim and centred on the axle, the studs holes in the disc do not take any load. The disc itself does not experience the same loads as an axle.

#19 _nicole_

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Posted 14 February 2011 - 07:08 PM

Dan - we thought the same thing, and he wasnt. If we can get a few more people who need them then it might be worth getting them done.

LX - will do. Hope he says its ok!

Edited by nicole, 14 February 2011 - 07:08 PM.


#20 _@milco@_

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Posted 14 February 2011 - 07:35 PM

hey
i will buy two set of blank disk's, and i know of another two blokes that prob will buy a pair each as well.

and i have been toying with the idea of getting them cast welded up then lightly machining the face and back of the disk and then painting or plating the disk.... i reckon it will look pretty good...

#21 DanWA

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Posted 14 February 2011 - 07:40 PM

i will buy 2 pairs, so i have a 2nd pair for spares!

#22 _nicole_

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Posted 14 February 2011 - 07:59 PM

OK so we have so far:

Me - 4 discs
guy from Pt lonsdale - 2 discs
DanWA - 4 discs
Milco - 4 discs + 2 mates @ 2 discs each = 8 discs
Absynth - 4 discs
Derrin - not sure if you are after any or not??

So that's 20 definites so far. I've requested a price so will let you know how we go.

#23 derrin71

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Posted 14 February 2011 - 08:02 PM

Count me in for 2 pair of sloted.

#24 DanWA

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Posted 14 February 2011 - 08:36 PM

oh yeah should add, i wanted slotted to!

#25 _@milco@_

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Posted 14 February 2011 - 10:11 PM

OK so we have so far:

Me - 4 discs
guy from Pt lonsdale - 2 discs
DanWA - 4 discs
Milco - 4 discs ( possibly another pair.. waiting confirmation form a bloke.)
Absynth - 4 discs
Derrin - not sure if you are after any or not??

So that's 20 definites so far. I've requested a price so will let you know how we go.






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