Rei99

Hi everyone,
here again and ?im disperate....
I need to swap the rear drums because are not in good condition... And in Italy my Seven have no one that seemes to help it...
I see on the net, there are two kind of rear drums:

USA model:
- 1979/80 model year
- 1981/85 12A with rear drums.

My USA model is the first and it has those:
http://www.mazdatrix.com/pictures/brakes/j2-4.jpg
with air coolant file all around.

The BIG problem, is the European Black car that I need to check: it seems to have different drums and them are not like this upside in photo... I don't know if they were aftermarket or original Euro model, someone that have a pre-restyling Euro SA22C or know the model could help me?

I could buy the USA model or you know that USA model are different from Euro? And last, the 1981 drums, were the same or are different for 1979/80 m.y. car?
Thanks a lot!

innertwist

iTrader: (3)

I would imagine that the change in rear brakes was applied internationally. Yes, there are different drums on -80 and 81+, the part numbers are different. It's possible that the brakes were swapped on your car. Does it have an automatic adjuster? - it's 81-85 style. Manual adjusters? - then it's 79-80 style. Hope this helps.

SLIDN7

just do a rear end swap to disc brakes.

Rei99

I ask to Mazdatrix, they told me the same. The car isa a 79/80 manual
Them are unavaible everywhere, it's a great problem...

I would, but find an Rx-7 like mine in Italy is very difficult (just 20 in all time sold) and no one restyling, so there's no spare parts avaible.
Outside buy will be very expensieve due the high size of the rear axle...

You think I could swap manual with automatic? Brembo made those, so I could find (I hope) here.

trochoid

iTrader: (6)

Check Rockauto.com. They have better pictures than the one from MazdaTrix. They list 2 different brands of drums for the 79, 3 for the 80, 2 of which are the same as the 79 ones. For 81 they list 2 drums, both of which have different part #s from the 79/80 drums. The pictures they do show are slightly different in the same model year.

Part numbers and prices from Rock Auto are as follows:

79: Raybestos 9526, $54.79, AC Delco 18B272. $65.79

81: Raybestos 9364, $32.29, AC Delco 18B182, $39.79

Black Dragon's catalogue, (BlackDragonAuto.com), partially confirms the difference between the SA/FB brake drums. However they break down the difference by chassis # and build date. 7s built up to 3/79 with a chassis # up to 554324 take part # 64-920, $69.95. Chassis built from 4/79 through the end of the 1980 production, chassis # 554325 and on take part # 64-921, $69.95. Chassis's built from 81-85 take yet a different part #, 64-922, $69.95.

If you can't find the drums you need in country, both Rock Auto and Black Dragon ship internationally. Good luck.

Rei99

I phone to my mechanis: he found the original drums!
I don't know if it will be better or no (Mazdatrix says that them are terrible), but Mazda Italia found them in Austria, about 8days to arrrive.
Completely new rear brakes, swap of the last parts of the exaust, new support for it, mounting the new KYB front shocks and some others little thinks... 500€

I must done a check to the aspiration intake and the carb, because the Holley blown on low rpm when I step at max on the gas, and the Black '7 will be like new

Thanks to all you friend for information, video files when it will be ok

trochoid

iTrader: (6)

I have trouble interpreting your english, but you do much better than I ever did when I took Spanish and German. 500 Euros sounds like a lot for brakes but if all the other parts and labor is included, that may not be a bad price. Please do post vids when you're done. It's rare to see non-US 7s here on the forum, vids are even rarer.

Rei99

Sorry, I know, my English is terrible
This, with UK mazda rotary forum, is the best resource for rotary, and here in Italy there were just few person who knows well FD / Rx-8, and no one for the first gen like mines...

Here's you can see some video before the works:
http://sites.google.com/site/mazdarx...prova-al-banco

The other parts of the sites are just in Italian

innertwist

iTrader: (3)

You would not need the whole axle to swap to disc brakes, or the other style drums for that matter. For disc brakes you would need the backing plates, the calipers, caliper brackets, ebrake cables (just the portion that connects to the calipers), axle hardlines/proportioning block (the lines could be fabbed over there and the block is just functionally a tee), the soft lines, and of course the rotors and pads. Since it's an 81 with the older style brakes it may have the older threading as well, in which a new fitting would also need to flared on the existing front to rear hardline, or some other solution adapted.

Most of this can be bought new, and the only things that would really need to be shipped would be the backing plates, caliper brackets and ebrake cables (I think). This is assuming the hardlines are fabricated.

RX-7 Chris

iTrader: (19)

nice car. Where in Italy are you?

DivinDriver

iTrader: (15)

The original Mazda drums all have cooling fins around the outside.

The main difference between the early and later drums is the presence of a groove running around the inside face of the drum.

This groove (on the 80 and later drums) engages a thin second lip on the inside of the brake backing plate.

Look here:
https://www.rx7club.com/1st-generation-specific-1979-1985-18/parts-id-question-sa-drum-brakes-787270/

trochoid

iTrader: (6)

Sorry, but that's not true. The flange welded on the end of the axle housing that the backing plates bolt to is different between drum and disc brakes. Drum brakes have 4 bolts, discs have 3. One cannot simply bolt disc brakes on a drum brake axle housing. Also it's only the SAs, 79-80, that have the coarse thread flared brake line fittings. FBs, 81-85 have fine threaded flare fittings. Beginning with the FCs they changed over to banjo fittings on the calipers.

innertwist

iTrader: (3)

OK, I'm confused, I thought that was just for SEs. I've heard of it being done before. I just did a search and found at least one guy who has claimed to have converted to disc while using the same rear-end housing: https://www.rx7club.com/showpost.php...63&postcount=8
It's a little vague though, maybe the axles have to be swapped as well. I'm sure I've seen it elsewhere.

http://mrmazda.no-ip.com/interchange.html#AXLE - says all 79-83 axles are the same just with different backing plates, but it also goes on to mention the 3/4bolt mounting that you just mentioned. Oh well, would we agree at least that the he could switch to the newer style drums? Otherwise, where there's a will there's a way!

As for the threading, I mentioned that because it sounded like he was talking about an oddball 81 that has 80 style brakes. At least he started off talking about an 81. If they're the 80 style, then the threading would have to be accounted for.

trochoid

iTrader: (6)

85 FSM sec. 9, p. 7. The 2 middle diagrams on that page show the difference between the backing plates. (57U09X-003 and 57U09X-004) On the next page is a pic and a diagram of the drum housing and backing plate. The disc housing has 5 bolts, 3 for the backing plate, 2 for the caliper. Also check the diagrams in Sec. 11, p8 and p. 11.

As far as being able to switch to the newer style drums, that I don't know.

DivinDriver

iTrader: (15)

Ther's three different drum part numbers, apparently; in that previous thead of mine, we tracked down the diff between types "1" (solid rim, 78/79) and "2" (80 split rim.)

I've never discovered the difference between types 2 and 3, as I've only got the one car.

Rei99

There aren't 2 owner, one of the my 80 and one with 81 to check the car near?
By now, and for much time, I'm ok otherwise