big vs small bearing question
 

how can you tell the difference? My car is an 83 built in august of 83. My old rear end had the driveshaft that you put the bolts through and a nut on the other side. I just swapped out my rear end for a gsl one, year unknown. It also has the pinion flange where there are bolts and nuts. I just changed a trans on an 82 gsl, and the drive shaft bolts to the pinion flange. If the bolts go through the driveshaft, through the pinion flange, and have a nut, is it a big bearing? If so, and my car did infact come with a big bearing rearend, are my front spindles big bearing ones too?

83 is a mutt year, the driveshaft flange is the same as the 84/85, but they typically are small bearing axle (both front and rear) at least the 3 83's i've owned/worked on have been that way.

There are rumors floating around here that some 83's had the big bearing rears, but there never seems to be much proof... An August production date is pretty late though for an 83, so it could be possible, although I doubt it.

how can i tell without pulling the axle apart? or isnt there a way? i more or less care about the front spindles. I have a big bearing set that i can put in if I eventually want to upgrade brakes to TII's but if I already have the big bearing ones id like to sell the set i have in the garage.

If you measure the outside diameter of the axle carrier where the bearings are, just inboard of the brake backing plate, you can judge from that.

Last numbers I was given were:
Large axle housing is 3.25"
Small axle housing is 2 13/16"

My car is manufacture date 8/83.

I have small bearings front and rear....

thanks guys! ill check... eventually! lol

its just rumor. people see the big axle flange and think they have the big bearing axle, but no its just an 83...

You must have one of the very last '83s. August is usually when they'd start production of the next model year.

My '84 is a 12/83 and it had the early-'84-only 3.933 final drive. And big axles.

Super easy way to tell, if you have a disk rear: Look at the backing plate bolt pattern, the three 12mm-head nuts. On a small-axle rear, only one nut is on the same side as the brake caliper. On a large-axle rear, two nuts are on the same side, parallel with the caliper bolts.

Good to know :). Awesome information!!!!

Yeah that is good to know Peejay!

j9fd3s: Thanks for backing me up on that. The 3 I've had are all relatively early to mid 83 production cars, so I wasn't sure if the later ones had been changed, but I didn't think they had...

And it SUCKS because I have a mint small-axle disk housing, a bunch of small-axle pumpkins (all open save for one welded), a bunch of small axle axles, but no small-axle backing plate/bearing retainers, and the big-axle ones (of which I have a bunch) won't work.

I'm thinking of taking one of the S1/S2 drum housings kicking around and attaching the ends from one of my pretzeled big-axle disk housings. Supposedly the small-axle housings are stronger. (Yes, I know that this is not a trivial task)

Hmm, interesting conversation, and although my thoughts on this don't pertain directly to the original post, I'll put them in here.

Sounds to me like this is a case of a hidden change very, very late in the 83 production run, likely in the process of changing over from 83 to 84 model years. When Mazda decided to switch over to larger bearings on the front hubs and rear axle, they probably ran out of the old small bearing units before the last 83 was built and just threw the large bearing units into that car, which were likely stockpiled (of sorts) already. Instead of manufacturing/buying more of the old small bearing parts, they just installed what they had to finish off the production year.

This was likely done in the last month or two of production of the 83, making for very few 83's that actually had the large axles, and its possible that the serial number cutoff was never captured, or if it was, it was never advertised. This can be considered a similar case (just in reverse, waiting for the new parts to arrive) to the early 79's that came with the prop rod on the right hand side on north american built 79's, even though the prop rod should have been on the left hand side. Another case on the 79 is coin holders that don't hold american coins.

Except it didn't happen.

What MAY have happened is that some states could title cars by the year of purchase, so if you bought an '84 in late '83, it may have been accidentally titled as an '83. And forever stuck with that error.

mazda isn't ford, they can count. they didn't build random numbers of cars and order random numbers of parts. what is more likely is that they had TOO MANY small axle housings, and they just sent these into the parts system.

remember there is no documented case of a big axle rear in an 83 car, just people seeing the big driveshaft flange and thinking they do. 83 is a weird year.

also the hood prop rod on the right side is documented in the parts fische, there are part numbers, and vin numbers (and dates) where it changed over. the axle thing is very clear in the parts catalogs

Ok, I retract what I said.