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MG MGB GT V8 Factory Originals Technical - Measuring brake disks.

Measuring brake disks.

In order to be declared legal it looks like I will need to replace the front brakes in my 3.9 conversion.
I am given to understand that the RV8 had ventilated disks of 267mm diameter and I would like to have this as a minimum as it means I don't have to go and do expensive brake fade tests for the engineers report.
The local MG place have an upgrade kit for sale ($1250.00) and over the phone they say that their ventilated disk is 275mm, which would be great. However the guy I spoke to wasn't all that knowledgeable and I'm a little concerned that these might be SD1 disks (256mm) as the local Rover wrecker says that they (the MG place) have been buying a few of these of late. Also in his book Roger specifically warns against using these smaller SD1 disks.
Question is , how are these disks measured, is it from edge to edge, or from where the pad first contacts the disk. Given the money involved I need to know where to apply my ruler, can anyone help with this?

I am once again adrift on unfamiliar waters. Doing this conversion certainly has been an education, where would I be without the bbs?.

Peter Sherman

Peter,
Disks are normally measured edge to edge. Buying a kit is the convenient, but often expensive option. Many people, including me, choose the Peugeot 505 Turbo disks as these are ventilated and the same diameter as MGB (273mm). Being 5-stud disks they will need re-drilling. Try Disk Brakes Australia http://www.dba.com.au/home.htm You will still have the challenge of sourcing a suitable caliper. Princess or SD1 calipers are suitable, but I'm not an expert on options in Aus. I'll e-mail some additional disk & caliper info.
Pete
Pete Green

Peter,

The 4 pot conversion kits in UK are Wilwood and use 270mm by 24 mm vented discs. Wilwood have I believe both race brakes and road brakes now available for B, available from Rallye Design in the UK. Price in UK about £550.

Paul
Paul

Peter,
Are you aware of the Australian company DBA (Disc Brakes Australia)?
They make a huge range of original spec replacement and upgrades as well.
May be worth a call or email.
They are Sydney based and have a website (dba.com.au) staffed by car enthusiasts as well as tech bods.
Good luck, Cheers, Pete.
Peter Thomas

For the Aussie lads, A few years ago when i had my conversion done by MG Workshops ( in Melbourne ). They uprated my front brakes to 4pot ventilated calipers which were off a volvo and put them on Nissan 300zx rotors.At the time i was still running hubs and their was no problem and the braking power was amazing
Give them a try and ask if they still do that brake kit

Regards
Steve
Steve

Volvo is almost the same as Austin Princess caliper. However, the bolt holes are slightly different. You might have to use a bracket or something.
Don't the 300 zx rotors require redrilling of bolt holes and perhaps a bracket also?

Frank
Frank de Groot

Thanks Guys,
I also did a major search through the archives and have learned allot.
I also contacted MG workshops , and they still do brake upgrades ($1500). I emailed DBA and but have yet to speak to them.
wrt Volvo calipers there seems to be disagreement on whether they will fit. I went out to a wrecker the other day and after much industrious measuring, found that Frank is quite right, all the Volvo calipers I saw were about 5mm out. So unless there is one particular model Volvo that fits (and wouldn't that bit of information be worth knowing!) some sort of bracket must be used.
I would be very interested to get Steves input on this; In this instance he is the man with the experience; how did MG workshops solve this problem? Bracket or weld and redrill?. Also I get the impression that the Nissan disks bolt right on (is this true?) however I've read that the "tophat" of these is about 1cm shorter than the MG (or Peugeot) disks. That would mean using spacers to get clearance, is this true Steve?.

In the archives I came across reference to using alloy 911 disks and calipers. The hubs are almost identical to the MG ones (I read) , however there was mention made of a spacer, but no further detail. Has any one actually done this. I don't know how practical (expensive) it would be, but it certainly sounds impressive tho a bit esoteric maybe.
Peter

Peter,
I used the Porsche 944 hubs and rotors (same as some 911 ones) the hubs are the same as MGB. Same bearings.
As calipers I used the Wilwood Dynalite. Had to make a bracket to fit the calipers to the MGB front but was not difficult to do. Works great and brakes are as good as a Porsche!
The whole conversion for around $ 500 depending on how much you can find the Porsche parts in a junkyard.
Good luck
Werner
Werner Van Clapdurp

So did I read that right that Wilwood now makes a ventilated MGB rotor and caliper kit? That is great, they can be expensive, but are a WELL regarded company here in the states...

Larry
Larry Embrey

This thread was discussed between 17/03/2003 and 05/04/2003

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