So confusing 💀

 

I think the difference is, early drums are solid on the inner face of the outside rim. The later style, introduced in 4/79 have a groove cut into that inner face. This groove corresponds with a lip on the backing plate that rides in the groove. It forms a seal or barrier to help keep out water and debit from getting inside the drum / brakes.

A grooved drum will work with both backing plates w/o interference, whereas you can't put an early (non grooved) drum on a later car with the lipped backing plate.

 

I figured as much , It seems the seller hasn't shipped the drums and is not replying to me so this may end up a snipe chase. If they do arrive i will be ordering another set just to have a spare set but i'm not holding my breath any more .

 

Yeah I'm in the same boat. If they ship, awesome, but odds seem decent that it was a fake listing (or one without physical stock) - I had thought that might be the case originally which I why I mentioned that I couldn't vouch for the seller. My apologies to anyone else who might have jumped on it, but at least eBay/PayPal is good at making right on such things.

Personally I'm going to give them another week or maybe two, but after that I'll pull the plug. Would really like to see them ship out.

 

So i got a reply , they never had them to begin with and had to contact the place that did have them. They don't have any stock and will be refunding me . Welp.

 

Got the same message this morning as well. So much for that.

It does seem that the Mazda parts houses (and probably Mazda direct) have them around, albeit for $130-190 a piece. Better than the $300 they were at a couple years ago I suppose.

 

i just checked again, the early part 8871-26-251C is NLA in the US, alternate aftermarket numbers are:
1408-52237 Autopart international
YH140512 Carquest
123.45004 Centric
PDR0512 Bendix

the late part 8940-26-251A is available, although they don't actually have any
YH140647 Carquest
123.45008 Centric
1408-61277 API
9526 and 9526R Raybestos
PDR0647 Bendix

i think AcDelco 18B272 fits the early one, but i'm not sure and they aren't either!

good luck!

 

Summit sells the Bendix ones but they are on backorder. doesn't say they fit the 1979 or 80 7 though ( they fit the 79 GLC).
so I did some research, the pads, hardware kit, etc and the cylinder between the 79' GLC and the 79 Rx7 are the same.
The GLC drum cylinder looks almost identical minus the cooling fins.. I SWEAR if Mazda's only difference is the cooling fin Mazda can go shove a fat one up its taheeni hole.

And I solved it: The 79; GLC backing plate and the 79 RX7 REVISED backing plate SHARE A PART NUMBER. this means the drum of the GLC FITS, and ALL of the guts are the same, the bolt pattern is 4x110 as well.

So the question is, who wants to be the brave Would who puts them on his 79' Cause I'm currently ***** deep in Bar exam study.
If it works just credit my name people, credit my name, If you break your car, I take no responsibility

 

Summit list the parts but they have been to backorder for 4 or 5 years.

 

There seem to be a few GLC drums on ebay , and you can infact buy the first drum revision ( 2nd version with the groove) for 180$ from mazda . What version drums do you have ?

 

I think my 1979 with a build date of 3/78 has the grove. I will need to check.

 

You and I have the same drums . The Vin is what matters as the cut off was in mid 79 ( I have a car made about 1000 cars before the new drum design) .
The only thing that changes is that lip , If we have solid drums we can use lipped drums 100% , if our backing plate has the lip we can't use solid drums but solid drums are NLA.
I mean the drums have to work if all the guts inside are identical unless the shaft and drum don't mount the same but that's a stretch .