http://page7.auctions.yahoo.co.jp/jp/auction/g92339305

The pictures shows a vented rotor said to be from a S130Z with a custom adapter between the rotor and the hub.
The four pot calipers show the name Sumitomo printed on the bodies. It says there is a small spacer between the caliper and spindle bolt surfaces, but no adapter bracket so this is just a washer type spacer.
The description also says they fit inside a Watanabe 13x5.5 wheel.

I do not see any identification of the origin of the Sumitomo four pot calipers. They are not from the US version of the S130/280Z, which uses one pot calipers with the big brackets and slide pins.

I found some reference to the Sumitomo MK63 caliper being a Nissan Sports Option.

Another reference says that parts and rebuild kits for the Mk63 calipers are "very, very rare". Eight sentences in and I have already killed the solution to lack of Sumitomo 2 1/2 inch caliper rebuild kits...

I will be the devils advocate here. They could not be used in Aus. even if you could get kits for them. Tghe rules here are quite clear. You have to use at least 3 of the original mounting holes. Apart from the welded in fill? only 2 mounting holes used. Where 4 were used on the original. Whether it was drum backing plate or caliper mounting bracket it does not matter. Brake and safety go hand in hand.

Peter

For GT? It should be just two bolts holding the original caliper, right? If it were a conversion for a car which came with drums, that sounds like a problem. But would I have to add two more bolts if it only came with two just so that I could upgrade calipers?

I may have found a better solution. I measured the distance between the bolt holes, it looks like 3.5 inches. There is a four pot Wilwood caliper with narrow mount that would call for a much larger disk, but the cast in mounting tabs are long, empty inside, and could easily be drilled to mount closer to a smaller diameter disk.
These are probably less expensive than rebuilding classic calipers. And, using decent quality 280Z disks would be a small fraction of the cost of AP disks.

GT has a bracket that is mounted to the stub with 4 bolts. It would bee deemed to be the primary source of mounting. Therefore under Australian modification rules the use of 3 bolts minimum apply. In the intereset of safety, I would discourage the use of a 2 bolt mounting particularly for any road use.
As per piccy
Peter

Time to chisel the 40 years of caked on dirt and grime off that piece. It looked cast as one piece. Looking at the auction, the Kaemeri kit with the MK63 caliper looses the dust shield also. One more reason that I think the aftermarket calipers with the 3 1/2 inch mounting bolt spacing is a better choice.

All the brackets that have been made up to fit various different calipers (Lancer and in my case Hyundai Excel !?) all use a copy of the GT 4 bolt bracket.

When I was looking at the Wilwood gear, I came up with a disc that would take the four piston calipers and fit over the Bellet hub, just needed to make the mounting for the disc to the back of the Bellett hub.

I would be interested in hearing what you have found that might be workable.

The other alternative was to get someone like Hoppers Stoppers to make a new Chrome Moly hub to take a hat or bell (depending on what you want to call it) or a rotor like Commodore or Falcon.

Cheers
Rob

This is what I am thinking:

Nissan/Datsun S130Z/280ZX front rotor: 248mm diameter, 22 mm thick, vented. Already used with the Kameari kit. Cheap, plentiful, source car has good reputation except among 240Z purists.
Wilwood Dynapro four pot narrow mount caliper. Redrill mounting holes closer to the body of the caliper and trim off the excess. Excluding the cost of machining to move the mounting holes, the calipers are probably less expensive than the parts and labor to rebuild either the original two pot Dunlop/Sumitomo, or the four pot Kameari Sumitomo MK63 calipers.
A hat between the hub and disk. Probably a thick washer between the caliper and the spindle to correct offset. Stainless hoses with the alternate end to fit the Wilwood caliper.

For the back, I am thinking 1985 Toyota Celica/Supra for the donor parts. I do not know what the reputation of this car is in Australia, but they were a solid middle field car over here without a lot of negative criticism. This choice is to find a vented rear disk with the small drum brake in the middle for the emergency brake. There are no aftermarket combination parking brake multi pot calipers. Using a single pot combination caliper sacrifices performance, reliability, and a cheap aftermarket parts source that is less expensive than rebuilding a used OEM caliper.
The rear disk is 266 mm in diameter, 18 mm thick (? minimum is 17mm), vented.
Adapt the original emergency brake mechanism to the Bellett hub.
Wilwood Powerlite four pot calipers.
An adapter hose from the end of the rear brake pipe to the caliper.

The 1985 Celica/Supra front disk is very close to the size of the 280ZX caliper, but more expensive, fewer companies offer it, and it doesn't carry the wow factor as saying the brakes are the same as a Z Car.

Thefluid capacity of the original Dunlop/Sumitomo two pot calipers is within 2.6% of the Wilwood Dynapro. The Wilwood Powerlite matches well with the Dynapro for a rear brake. I might want to change to the two piston late Bellett master cylinder, or a later Isuzu master cylinder, possibly with a vacuum booster.

This combination of calipers is what I am using on my daily driver and racing FF car, that is about the same weight as a Bellett. The rotors are a little smaller (9.7 inch front and 10.1 inch rear), but the rears are solid disk with no emergency brake. The braking power is amazing, especially considering the rotors are so small.
With the brakes set farther back from the wheel on the Bellett, the slightly larger rotors should fit behind 14 inch wheels. And this will bring the brake rotor combination up to the same size as the early Piazza Turbo or Mitsubishi Starion. Both of those are about 1 1/2 times the weight of the Bellett. I specifically excluded the Piazza rotors because they have a reputation for warping and have scarce aftermarket replacement sources (and the rear disk lug bolt holes are 4x100 mm).

This isn't meant to be the ultimate brake package for the Bellett, but as big as can be put behind the period correct performance wheel size without using $350 a piece rotors. And, without spending $500+ per side for the Brembo exotic car parking brake calipers. It should be easy to drive on the street, once the driver gets used to the enhanced stopping power, and will probably brake with the current field of exotic cars.

EDIT: Along with the Wilwood calipers being readily available, economical, and less expensive than labor and parts to rebuild the classic calipers, Wilwood has something like nine different grades of pads, and other companies like Hawk and Carbotech offer their own range of pad grades for these calipers as well.

Sounds pretty good.

I spec'd the 0.75" Willwood rotor as I didn't have any information on other discs that would fit at the time.
Not sure about drilling the caliper, isn't there enough room to make the caliper bracket with the holes further in?
I like the idea of being able to use the drum-in-hat discs to keep the handbrake operational and semi-stock.
Celica's and Supra's are fairly well thought of here as well.

In the master cylinder department I have a balance bar and was going to fabricate a mount to run two Bellett master cylinders.
I was thinking the large volume of the four piston calipers would be adequately serviced by a single Bellett master cylinder for each end.
Still a work in progress at the moment.

Cheers
Rob

That's the smallest Wilwood vented disk is 10 1/4. That extra 1/2 inch diameter is probably going to cause a lot of clearance problems. With the 9.9 inch Nissan rotor, 13 inch steel wheels might fit. And they are $75 USD, almost twice as much as the Nissans. The Nissan rotor bolt pattern is more similar to the Bellett, so the hat or adapter will be more compact and simpler. Using this extremely large caliper on a small rotor causes clearance issues between the inside edge of the caliper and the hub.

The problem is that the manufacturers follow what is popular, and do not offer even coverage across the range of sizes. So there are a dozen companies each offering dozens of 11 3/4 and 12 inch diameter rotors. It's all about fashion and people are either trying to fill the space behind 18 inch wheels or they are expected to buy 18 inch wheels when they put on bigger brakes. So 12 inch rotors are cheap and plentiful and calipers that fit big rotors are cheap because they sell in high volume to go with those 12 inch disks.
Try to do something smaller than 11 inch rotors, and it gets difficult to find the parts and those parts get exponentially more expensive.

The Dynapro caliper is available in a wide flange, a narrow flange, and a radial mount.
I like the radial mount, it slides onto two studs. You make the bracket to bolt to the spindle, and the offset can be fine tuned by adding or subtracting a washer between the bracket and the caliper. Want to change the rotor size? Make a bracket with a different offset. These are great for small rotors. But, they cost almost twice as much as the exact same caliper with the fixed flanges ($250 vs. $133 USD).
The Dynapro with the narrow mount flanges just happens to match the bolt spacing of the Bellett. But it is made to fit a 12 inch rotor. The tabs look really long. I'll have to get parts in hand and measure them to make sure.
But, since the nice people in Japan put a bracket between the spindle and the caliper, instead of casting the mounting tabs directly into the spindle, It might be easiest to just redesign that bracket to fit between the new caliper and the car...

I live in a suburban area, and don't have storage for all my cars at my home. So there is a little delay between formulating an idea and looking at the piece I am working on, unless I bring a piece of the car home with me.

So, I have bad news.

The first is that the front spindles I am working with have the caliper mounting tabs cast into the spindle. It is not a separate bolt on bracket. I am going to guess that some time around 1968, they changed the front spindles for the GTs and made them one piece. Or, this might be a change made when they changed to the Dunlop/Sumitomo calipers.

The second is that there doesn't look like there is enough space to go any larger than the stock 9.3 inch caliper, at least with my substitute Nissan/Datsun 510 steel wheels. I'm not up to buying another set of new wheels and tires at the moment, so I may end up force fitting a Wilwood caliper onto the original disk.
I found a cheap new 280ZX front rotor and a 1983 Supra in a local junk yard with the rear brake assemblies. I will probably do the drawings for the brakes, but might not build them right away.

this info may not be of much use to you JT, as you're on the other side of the pacific, but for Rob and the aussies (and JT if you can source the same as we have here)....

those are the same calipers as i have on my race car.
originally fitted to an 80's toyota hilux, and is the same one listed for the nissan "nismo" hot up stuff.
early hilux's use a 4 pot that goes over a solid rotor, and later one's, as well as landcruiser's, use one that goes over a vented rotor.
you'll need to fit discs to the rear as well if you use 4 pot fronts, as the car will be far too over-braked in the front (causing easy lock ups) if the drums are left at the rear. my race car uses discs at big-ish single pot holden commodore calipers at the rear, with a bias valve plumbed into the rear line so they can be set exactly as i need.
both front and rear use mitsubishi rotors. these all fit inside a 14" wheel, just, but are an easy fit with 15's.
a vacuum booster is a must with these brakes, as trying to apply enuf force thru such a big piston surface area is damn near impossible without one. and yes, i know it's impossible, due to my booster spilting a diaphram, and leaving me with a brake pedal that felt like it had a brick under it (as it wouldn't move....) while doing approx 120MPH and heading for an armco fence..... i saved it..... just.
my rotors cost me, brand new, with extra cooling slots, $120 each. the 4 pots, $95 each. the rear calipers, "freebe's" as they came with the brackets and other stuff from the donor car i adapted them from. the whole rear brake "kit" cost me $100, so that's $50 a side for everything (although i threw away the old rotors and fitted brand news ones).
i also fitted braided brake hoses, which at $235 for the bits and pieces (then i had to assemble them myself) was the most expensive single item, but this was for a line for each wheel, and a "to and "from" line for the bias valve, as it's fitted to the dash so i can reach it easily from the seat.

have a look here:
viewtopic.php?f=13&t=709
is my thread about my race car, and shows pics of the front and rear brakes.

JT.... with your GT being a late one, it will have the cast in caliper bosses. 'earlier' GT's have a bolt on bracket.
also, sedan's have a different upright to a GT, meaning that if something is designed for a sedan upright, it won't fit a GT one, and vice versa. the uprights can be interchanged tho, so a better brake conversion that's designed for sedan uprights can be fitted to a GT by changing the entire upright as part of the job.

imho, i wouldnt touch wilwood calipers with barge pole.
i have seen them spread apart from hard use (ie: race use), causing the pads to not sit square to the rotor, which means terrible pedal feel and reduced braking force. they can be fixed once they spread, but it's a pricey fix, and they'll keep on doing it in the future.

honestly guys, this has all been done before, with the hard work of designing and fab'ing the caliper brackets done too, so why try to re-invent it??

The listing I found for the Land Cruiser caliper shows the same caliper used from 1975 through 1989, so it is probably the one PR91 is suggesting, and it is a close match to the fluid capacity of the Dunlop/Sumitomo caliper. So it should give close to the same pedal feel. The pad is a lot bigger.
Rebuilt Land Cruiser calipers are selling for $31-75 USD each.

I am very hesitant to pull something like a brake caliper off a junk yard car and put it on something I am driving. I'm not sure if it is the abuse level, climate, or how long cars sit in a salvage yard exposed to rain and snow before the part is pulled, but these things usually end up costing more in the long run after rebuilding, than buying new or rebuilt items from the outset.
This is one of the big reasons I am generally opposed to the idea of "upgrading" with parts from a different make or model car, because the shopping trip is usually to the junk yard, and kids with a broken car to begin with, and no idea of how something is supposed to work, will bolt on a different broken parts that work marginally better, and believe they have created a Ferrari killer. (Not the case here, but the norm for many other groups and websites).

I like the idea of an aftermarket caliper. They make a range of piston sizes within each body size and a range of body sizes. Trying to match an OEM caliper from another car is a nightmare. Look at five different aspects and all may be perfect, except one, and then you are looking again at the next possibility that is totally different in all dimensions. Make something standardized (aftermarket) fit, and then find out it's not perfect, there is less of a problem, move up or down a size in piston diameter, pick a different body with the same mount, choose a different pad compound from the wide range available. And since the same caliper body is available for three or four different disk widths, changing disk thickness does not require reshopping and complete redesign for a different caliper.

Wilwood is not the best or most expensive caliper on the market. But everything I have heard is along the lines of "You can spend more, but you won't get more out of the more expensive alternative.". They are extremely popular with the American muscle car crowd, so they are designed a little beyond the requirements of the little cars I own.
Wilwoods are two piece aluminum. One piece would be stronger, and more expensive. But if someone managed to bend a two piece aluminum caliper enough that the pads didn't fit right, it should be leaking brake fluid.
And they are $130-250 per caliper. With that price range, replace once and then look for a more expensive alternative if the problem persists.

The used Kameari brake kit had a starting price of 77,000 Yen. The end price was 80,000 Yen. There were four bidders and three people willing to pay between 77,000 Yen and 80,000 Yen, who did not win, have money to spend, and are still shopping for brakes for their Belletts.
Kameari's website shows those calipers sell for 80,000 Yen new (or newly rebuilt, whichever the case may be). The Japanese Nostalgic Car board says there are no caliper rebuild parts except from Kameari.
Kameari do Nissan almost exclusively. I don't think the Bellett kit was a regular item they sell. Probably a special order or something that someone put together from one of their Nissan kits.
Looking at the Land Cruiser calipers and the Kameari calipers, they do not have the same appearance. I can't find a front view of the Land Cruiser caliper, but the back is different, and the hose attaches in a different position. The Kameari looks like it has equal sized pistons instead of the two different sizes of the Land Cruiser caliper, and the Kameari has a reinforcing beam cast across the face. The internals are probably not the same, which would actually be an advantage for the Land Cruiser caliper, because it could actually be serviced without spending a huge amount of money.


I'm new to this obscure corner of the already obscure Isuzu world, but not unable to operate a internet search engine. I've not found much of anything in the English speaking world as far as people selling performance or even replacement parts for Belletts. Who's selling brake kits or brake kit parts?

Thanks Brett.
Little bit silly that I forgot you have gone down this road and have heard from others over the years who have done this as well.
Sometimes we can get caught up in the nice bling (I still would love to have a full fab'd Wilwood, AP or Brembo setup on Bella), still it is also good to look at other areas as it can lead to some interesting finds.

Thanks for the info on the different stub axles, can add that to the bank of Bellett knowledge
JT the problem of getting better discs to fit is one of the reasons I went for the 14 inch wheels on Bella.

and having had a 87 Hilux 2wd I know how good the brakes and handling are (Lobethal and Chain of Ponds = great fun).
With all this interesting info, will have to spend a bit of time down the wreckers again methinks.

Brett, I do have a question regarding the heavy pedal.
What pedal ratio is the Landcruiser and Bellett? Did you need the booster because of the different pedal ratio, or just a function of the master cylinder to piston area?

Cheers
Rob

I wasn't trying to be ignorant about it, but short of someone selling the exact piece needed, or a set of documented step-by-step instructions, just about everything we do for a Bellett or any Isuzu car is or is close to starting from scratch.
I haven't figured out exactly what a Mitsubishi Sigma is. It seems to be either a Galant or a Diamante over here on the other side of the world. But the US versions of those cars don't appear to have vented rear disks. So even with that really good example, it's a 15,000 mile commute (according to Google Maps, I especially like the instructions to "Kayak the Pacific Ocean" mixed into the turn by turn driving instructions) to find one.
Also, the differences between the front spindle (early vs. late) and probably the front hub (which appears to be different in shape), throw even more of a wrench into the mix.

The way Isuzu managed to get at least three different versions of just about everything on the car, without significantly changing the specifications or performance, is frustrating. At least two different front spindles! I was looking forward to finding a bolt on bracket under the caked on crud. Something simple to measure, draw, move some holes around, and it's done.
With the mismatches between early and late, GT and non-GT, most of the stuff I have to build may not be of any use to those of you in Australia and I'm kind of inclined to build for what the car is, instead of changing over to the earlier pieces that I don't have access to either.

no probs rob.
was a result of master to caliper areas. the master would never move enough fluid for the amount of piston area it now has, so a booster was a must.
i looked at going with twin masters with a balance bar, but as my car has a gemini engine with sidedraught carbs, space is extremly limited in that area, even if there was room for 2 master's, then the clutch became the next prob. as your car uses a bellett engine, room around the master isn't the prob it is for me.
that's why i went bigger than needed with the rears so i could then use a bias valve to restrict them back to the balance i wanted. i have seen some cars (not bellett's, but others) done by using bigger front brakes without changing the rears, but this then needs a bias valve plumbed into the fronts to restrict them for a good balance................. and i think it's pretty obvious that restricting the front brakes for this is not a good option!

exactly JT.
is something i, personallly, have been accustomed to for over 20 years now, and some i know have been longer still. the best that can ever be hoped for with a bellett is to find something that is close, and adapt it. the only way to do something is to either blaze your own trail (lost count of how many times i've done that........), or ask other owners that u know who may have that knowledge (but i guess that's a big prob for yourself, simply due to your location and the total lack of other owners). that's where this media makes things for alot of people much, much easier than it ever has been in the past.
this is where the datsun and toyota guys don't realise how good they have it, coz if it's not something that bolts straight on from another dat/toy product, then it's something that 1, or heaven forbid, 2 phone calls will have a complete kit on their door within a week.
welcome to the joys of performance mods an belletts my friend!

I picked up a cheap S130Z rotor to measure and have a look at, and it's a really nice design. The cross shaped open area in the rotor and the open areas in the back of the GT hub are going to provide some space to recess the adapter around above and below the mounting surfaces, and provide a lot of meat for the bolt threads to hold onto.

Also, the Nissan rotor is small enough that it fits within the original dust shield nicely.

I took a look at the Dynapro calipers. Turns out that the narrow and standard flange mount calipers have a smaller body.
Bad news: The narrow flange mount, which is 3 1/2 inch from center to center on the bolts (the same as the Bellett GT), are 1.7 millimeter too long to fit the disk. The brake pads would hang over the edge of the disk, which is a bad thing. Slotting out holes on a brake caliper is not something I am going to get involved in.. So that one is a no-go.
More bad news: The radial mount body is bigger, and would require trimming the dust shield to fit. It is more expensive anyway.
Good news: It looks like the standard flange mount, which is has the mounting bolts spaced at 5.25 inches and shallower to the body of the caliper, will not require any trimming of the dust shield, and the bolt holes are far enough away from the mounting holes in the spindle to provide for a nice, beefy bracket to hold the caliper to the spindle.

I took a look at the brake master cylinder, and it is mounted almost against the fender skirt. I am not seeing how there is enough space for a booster with the original mounting position. The smallest hotrod boosters I could find are 7 inch in diameter, better than the 9 1/2 inch of the later Isuzu cars, but still too big.

I've been slowly working out the details in my mind on these two projects.

Ironically, the caliper mounting for the larger S130 rotors is going to be simpler. I wanted to use a larger body caliper that mounts easily, but the body won't clear the dust shield, and I do not want to put something together that requires cutting the car. So I opted for a smaller body that uses the same huge pad.
Good news, no bracket. Bad news, the caliper must be modified to move the mounting hole position, so the caliper is not an off-the-shelf item.
I need to have a set of rotor hats made to play with this one any more.

The smaller caliper to go onto the stock rotor is going to be more of a pain. It is going to require having the caliper in hand before designing the aluminum mounting bracket. The manufacturer's drawings lack a little accuracy. But because it requires a mounting bracket, and fits the stock reproduction rotor, it would be cheaper to go with the larger S130 rotor with the modified but bracketless caliper mentioned above.