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fitting sigma discs to bellett 
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Joined: Wed Sep 24, 2008 10:05 am
Posts: 543
Location: 12,450 miles away from the Big Warehouse in Melbourne
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jeffgair wrote:
The calipers I am going to use are from a Mazda mx5 (miata)which has 13" wheels so they are relatively compact.

First generation Miata brakes share several parts and overall design with the last generation Gemini brakes. The disks are not the same diameter, but the same vented front and solid rear. There may have been some shared origin of design or supplier. Vehicle weights and power were similar. In the Best Motoring test, they put the Miata against the FWD Gemini along with a pack of other similar 1.6 liter cars. The Miata was in the middle of the pack and the Gemini was pressed against its back bumper at the finish line.

That said, there are a lot of people upgrading the Miata brakes, and a lot of people who should know enough to be equally unhappy with the Isuzu brakes. They are not as bad as Elan brakes, but pretty rubbery and easy to push to fade on the track. The pins on the calipers do not move very smoothly over their life, and the inside pad and rotor are always wearing faster than the outside. And the rear calipers and emergency brake mechanism is a nightmare to get working right.

They aren't as bad as putting your foot out the door and dragging it on the ground, but more of a point to upgrade from, not upgrade to.

Thu May 03, 2012 10:29 pm

Joined: Fri Mar 20, 2009 8:23 am
Posts: 1816
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Jeff if you ues mx5 hubs you hubs will be 4x110 and the bellett rims will be 4x114 :?:

Sat May 05, 2012 11:02 am

Joined: Tue Jan 11, 2011 1:30 pm
Posts: 35
Car(s): isuzu bellett pr20 rhd
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gt orphanage and jt91,

Sorry - didn't make it very clear. Planning to use mx5 engine, MX5servo and Mx5 front brake calipers (as they are matched to each other), but use the sigma discs and bellett hubs with my original alloys that fit my Bellett now, not the mx5 alloys.

Still not sure - what stops us using the sigma disc conversion with 13"rims? Is it the caliper that fouls the rim? Would using a smaller size caliper (eg Mazda?) and / or machining disc to reduce its diameter solve the problem?

I love this techy chat stuff !



Sun May 06, 2012 8:52 am
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Joined: Tue May 10, 2011 2:23 am
Posts: 2603
Location: Melb.
Car(s): '72 Sport Bellett (imported 180912), had Belletts in past, 2 sed, 3 GT's. M/B A250 Sport, i30
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The Sigma disk conversion popular some years ago used 13" rims.

It did use modified stub axles which are NOT reccomended, but there is info on using another rear bearing to overcome that, although i understand the bearings are hard to get. Info on them though is in this thread.


'72 PR60 Sport

Sun May 06, 2012 9:20 am
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