Aftermarket Motor Mounts - A Warning
 

With aftermarket motor mounts at about $9 a piece, and OEM listed at $40/$70 (stock / competition) I figured I'd throw on a set of aftermarket motor mounts to see how they work, and if they failed in a year just change them, since it's pretty easy and they're so much cheaper than Mazda ones. I did not expect, however, to receive them and have them not fit at all.

Below are pictures of the "Westar" brand mounts Rockauto sells for the 12A FB (EM-8055) compared to the originals I took out. Not only are they almost 1.75 inches thick (without the bottom cup), but the whole metal part is way oversized in both thickness and diameter. I couldn't even get them in place on the car - they are on their way back to Rockauto (which as another warning does not refund your shipping costs even when parts are wrong - first I've had this issue from them).

I'm not spending $150 on the competition mounts, so it looks like I'm shelling out $40 a piece for the 'regular' ones from Atkins...

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Damn it. I just bought these last night.

In their defense how thick are they supposed to be. I'd imagine there would be some significant squishing in 30 years of carrying an engine.

Oof. Did you get the exact 'Westar' (these were private label boxes but the parts were stickered Westar) or one of the other options? Maybe you'll get lucky and they'll fit. Mine won't be in the mail until tomorrow so you shouldn't end up with my returned ones, at least!

Yup, Westar. Oh well, you win some you loose some.

I might make it work or just use the old ones.

On a side note I don't like the "anchor" brand trans mount. When I was dealing with my vibration I swaped out the oe mount for an Anchor brand one. Now my shifter sticks up higher.

I might just go with OEM Mazda mounts soon but we'll see.

I bought the mazda competition trans mount since it's so much more work to replace; figured I'd save a buck on the front since they're a 15-minute job, but ran into this difficulty. I've got Mazda non-competition mounts ordered to put in, now. Best of luck with yours! Hopefully it was just a fluke that these were just an approximation of the right part.

I purchased the WESTAR EM8055 back in March 2017 and haven't installed them yet. I hope they fit.

I have one NOS Mazda one in my FS thread in the 1st gen section i will do $35 shipped if your in the US if anyone is interested...

Those look a little like FC mounts. FC mounts are bigger and taller than what we can use.

Timely thread, I was about to order motor mounts and the tranny mount from rockauto because they are so cheap. Or I'm cheap, anyway I wonder if it was a picker error or an actual error in the catalog?

Did you measure the diameter of the metal carrier by any chance? I'm curious to see if they fit anyway in my SA.

FC mounts don't even look like these, I thought they mounted from the middle of the engine and didn't use pancake mounts. <shrug>

I forgot to mention hockey pucks... For those who want new mounts on the cheap. I've done it before, and if these don't work I'll do it again.

Looking at the rockauto site at the various motor mount vendors for our cars and I only find one that has a different part number for RX7 vs 626. That vender is DEA/MRC. For an 80 RX7 the part number is 6407 and for the same year 626 its 6411 but the pictures both look the same. I suspect the other vendors are using the same part for all the applications while DEA/MRC is possibly more accurate.

Please let us know how the replacement part fits. Also can you describe in more detail how the first part didn't fit? It seems like it was not only taller but also too large in diameter to fit in the mounting position. Is that the case?

BTW I just picked 626 because I know its not a rotary and probably would have a different part number.

Measured my original OEM mounts as the sit in my SA. The metal shell is 4.25 " in diameter and it is ~1.5 " from bottom of rubber to top of shell in height. I would expect the height of new ones would be bit higher due to age and compression of the rubber.

James, any chance you could measure yours? I need to make an order and decide how cheap I can be :)

I just measured my brand new Westar EM-8055. The metal shell is 4.5 in diameter (outside to outside). It's 1.73 from the bottom of the rubber to top of shell.

No problem.

I haven't gotten my motor mounts in the mail yet, but I'll let you know. I ordered them for a 1984 Mazda RX7 1.1... so my original trim.

Eye balled the fitment and its not an issue on the passenger side but that extra .25 in on the drivers side will come close to the oil pan seam. Not sure if the extra height would seriously matter for the engine front to back angle.

Since we have some data on the Westar part, I think I'll order the DEA/MRC parts and see how they fare.

Its worth the price to play if it works out ok. :)

I was skeptical of fitment on the driver's side with the oil line and pan clearance, as well as being able to lift the front of the engine far enough to even get them in place without breaking anything else (I already loosened the trans mount to get the old ones out)

I hear ya. I'll have to remove the strut bar, coolant hoses, and possibly the oil lines to raise it up enough. The tranny will be off when I do it so that should make it easier. Unless I can cheat by tipping it side to side enough but I doubt it will workout.

The parts fiche lists two P/N's. 8545-39-040 for the LH and 1668-39-040D for the RH. I have both, new and unused. They both measure the same. The large OD is 4 1/8, and the height is just at 1 5/16. I think you are including the thickness of another part to get to 1.5 high.

Any idea what the difference is between the "left" and "right" OEM mounts? The price was the same so I ordered one of each, but I'm curious what the difference is if neither is larger than the other.

90% chance its a catalog error.

DEA catalog is here, its not very helpful, but Home Page - Dea Products Inc. - Engine And Transmission Mounts - Center Supports - Strut Plates

Got mine in the mail today. 1 &5/8" thick from the top of the hat to the bottom of the smaller disk. 4 & 1/2 diameter on the top hat.


If thickness is an issue I'll just smash it in the press for a day, and that'll make it thin enough.

MM54, some earlier cars had a special upper steel catch on one of the motor mounts to prevent the engine from torquing over too far. These were on the RX-4 and Cosmo, and maybe some others. These models had different part numbers for left and right.

They had a shorter length front mount bar than what the RX-7 got, so their engines had a tendency to move more. But what I found is the special motor mounts with the catch were all sagged badly and it was best to just throw in a set of new OEM mounts. Better yet, get the competition mounts if you are ok with a little bit more vibes, as they allow hardly any engine movement.

I've never used a torque brace. Are they any good?

I ordered the Mazda not-competition mounts from Atkins ($70 a piece for the competition ones isn't in the cards right now) - tracking says I'll have them Friday so I'll let you guys know if I see a difference between the left and right part number. It mentions the one (I forget which side) only fits manual cars, which makes me very curious how it's different - especially since the competition ones are the same part left/right. The ones on there now look the same side-to-side, so I'll report back when I get to looking into it, probably late this weekend.

I'll get my DEA/MRC mounts from RA today or saturday. I'll measure and let you all know what I get on those.

Tracking was wrong, got the mounts today. Here's some info:

Mazda Passenger's side (right) all 79-85: 8545-39-040 - height 1.33" ; diameter of outer 'cup' 4.12" ; has a single silver paint pen or sharpie mark on it
Mazda Driver's side (left) 79-85 (excludes auto GSL-SE): 1668-39-040D - height 1.32" ; diameter of outer 'cup' 4.12" ; no silver markings, otherwise identical to the above part

So they're within what I'd say is a very reasonable tolerance for this sort of part of each other. I wonder what the difference is? Different rubber compound to make up for tension/compression from engine torque? Why wouldn't the one work with automatic -SE's while the competition mounts (and all aftermarket) are interchangeable? I suppose it's possible that it used to be different, but at some point they changed the design realizing they can be the same, and just superseded the part number without considering it a different part or reviewing the fitment?