Question on motor mounts M30B34 (DC74)

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BRRV
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Question on motor mounts M30B34 (DC74)

Post by BRRV »

I'm in need of motor mounts for my 535i and I'm seeing wide pricing differences for the early versus the later wedge-style mount. The P/N that's listed for my car (build date 10/85) is 11-81-1-175-735. The later mount (1/87 on) 11-81-1-132-793 is close to forty bucks cheaper.

Has anyone used the later mount in a pre- 1/87 build car? Realoem lists either number under DC74, the build code for my model, but I'd like to know if anyone has actually used the later P/N before I buy them:

http://www.autohausaz.com/search/produc ... 1811132793

My car still has original mounts (with seven digit BMW part numbers and identification) and they are wedge-style, which seems in conflict with the round-mount shown in realoem for my serial number. I'm thinking I should be able to use the cheaper, later-style mount.

Anybody done this? I'd prefer to save the money and use it for the correct transmission mounts. Thanks, Rick
Mike W.
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Re: Question on motor mounts M30B34 (DC74)

Post by Mike W. »

I think the wedge was standard, it is definitely what was on my '85 535i. And if you look at Realoem, while the picture shows round, the P/N seems to be the wedge one. So I think you're good with the wedge.
10Asians
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Re: Question on motor mounts M30B34 (DC74)

Post by 10Asians »

I just installed a set of the green heavy duty motor mounts part# 11811132793. I bought them from RMEuropean. They are a local company so I gave them a shot, plus if it was the wrong mount, I could easily return them.

My production date is 11/86 but the ones I used were for 1/87 production and newer vehicles. They looked identical except for the color and they fit perfectly. They were $52.30/mount vs. $117.96/mount. It's on my daily driver too and I haven't noticed any harshness or anomalies. I hope that helps!
BRRV
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Re: Question on motor mounts M30B34 (DC74)

Post by BRRV »

It does help, thank you, to both of you. I'll order the later-style mount today. I probably should have done this a while ago but I was distracted all summer with the big project. I noticed the deteriorating right-side mount after I finished everything (it's collapsed a good half-inch and the rubber seems to have pulled away from the center wedge). I did re-install the engine hook on the upper case cover but I think I will use either the oil pan or the AC compressor bracket to lift the engine from underneath with a floor jack so that I can get the new mounts in. I don't have a cherry picker.
10Asians
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Re: Question on motor mounts M30B34 (DC74)

Post by 10Asians »

Hi Rick,

I just put my car on jack stands. I removed the 4 nuts from the engine mounts and the grounding cable on the right mount. I used an 8 inch long piece of 2" x 8" on my floor jack, and jacked the engine up underneath the oil pan. The engine mounts needed to be wiggled a bit and rotated but they came out pretty easily. The Bentley manual mentions that you should be careful not lifting the engine too much but I did not have any issues. It took me about 30 minutes but a skilled mechanic could get this done a lot quicker! :D
BRRV
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Re: Question on motor mounts M30B34 (DC74)

Post by BRRV »

Thanks for the tips. I'll update when I get this done - I have another trip back to The Mile High City next month, so its a priority.
Chimi-Changa
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Re: Question on motor mounts M30B34 (DC74)

Post by Chimi-Changa »

On my M30B34 project car, it was recommended to go with one M5 motor mount. Cant remember the exact reasoning, but looks like this setup:

Image
BRRV
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Re: Question on motor mounts M30B34 (DC74)

Post by BRRV »

Hmm, I wonder why. That M5 round mount cross-references to the 533i as well as the M5; both M30 and S38 iterations, including the E24 up to '89. I've ordered the mounts already, so, given the fact that they lasted so long, I'll just go with what I've ordered and put this tip aside for now. If anybody knows why this is recommended, I'm interested, but since I don't track the car, and tend to not abuse it if I can avoid it, I'm not sure I need anything beyond what I've ordered. That's a great picture of your engine, by the way.
Mike W.
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Re: Question on motor mounts M30B34 (DC74)

Post by Mike W. »

I think the round one is stronger and the wedge is softer and more comfortable. E3s and E12s used a similar round one although the P/N is different, but E28s were moving into the luxury world. Speculation, but it seems to fit.
BRRV
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Re: Question on motor mounts M30B34 (DC74)

Post by BRRV »

Mike. would you say that it's the right-side mount that would be used as shown in the picture? I can't remember if BMW lists the passenger side as the right side or if they do it from the front of the car.
Mike W.
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Re: Question on motor mounts M30B34 (DC74)

Post by Mike W. »

BRRV wrote:Hmm, I wonder why. That M5 round mount cross-references to the 533i as well as the M5; both M30 and S38 iterations, including the E24 up to '89.
No it doesn't, not by part number. The diagram shows the round one, but check the part number and it's the wedge one. It looks like the round one is only used on M cars.
BRRV wrote:Mike. would you say that it's the right-side mount that would be used as shown in the picture? I can't remember if BMW lists the passenger side as the right side or if they do it from the front of the car.
Yes, it's as if from the drivers seat, passenger side is right side.

Regardless, with a stock engine I think you're sweating it too much, stock, decent quality mounts, and I think you'll be fine.
BRRV
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Re: Question on motor mounts M30B34 (DC74)

Post by BRRV »

Yes I agree, it was more of a curiosity to be honest. I'll stick with what I've ordered. Thank you.
Chimi-Changa
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Re: Question on motor mounts M30B34 (DC74)

Post by Chimi-Changa »

BRRV wrote:Yes I agree, it was more of a curiosity to be honest. I'll stick with what I've ordered. Thank you.
Good thing, and glad I spoke to late. Just heard that is Euro spec for some reason in addition to M5. (that car is EU, Initially thought it might have something to do with running headers on the car)

Sorry, carry on...
jhh925
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Re: Question on motor mounts M30B34 (DC74)

Post by jhh925 »

Chimi-Changa wrote:On my M30B34 project car, it was recommended to go with one M5 motor mount. Cant remember the exact reasoning, but looks like this setup:

Image
Hmmm, so I'm puzzled by the orientation of the wedge mount you're showing on the left side. In my '87 535, when I bought the car, I had the wedge mounts on both right & left sides, and both were oriented so that the "wedge" part of the wedge ran parallel to the axis of the motor. In that orientation, I'd be seeing the rubber sides of the mounts (not the metal sides) in your photo. And when I put my new mounts in, I oriented them that same way, and there is a small metal tab on the bottom of the wedge mount that slips into a hole in the subframe to ensure that alignment.

Of course, that said, the number of "mis-installed" parts on my car when I bought it is pretty long, and the mount on left had partially disintegrated itself (the wedge had separated from the lower half), and maybe my mounts are rotated 90 degrees wrong.

Does anyone know for sure what the orientation of the mounts should be?
BRRV
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Re: Question on motor mounts M30B34 (DC74)

Post by BRRV »

Mine are apparently original (I've had the car for decades and have all of the repairs on file). The metal 'cup' that holds the mounting rubber is fitted directly to the frame; the rubber then meets the metal wedge at the top of the mount, which then bolts to the engine mount itself. The metal wedge of the mount on my car is above with the point of the wedge pointing down. I can see the 'triangle' of the wedge from the side of the car, as well as the (small) opening directly below the wedge on the mount.
jhh925
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Re: Question on motor mounts M30B34 (DC74)

Post by jhh925 »

Sorry if my question was unclear (and I'm not intending to take over this thread) ... right, in terms of "up / down" it's clear that the metal cup goes down & the wedge faces up. In fact, I think the stud on the top is an M8 and the stud on the bottom is an M10, so you couldn't install the mount upside down if you tried.

I'm wondering about the rotation. My mounts are rotated 90 degrees away from what Chimi-Changa is showing in that pic.

BRRV, do you know if you mounts are rotated like the one shown in that pic?
BRRV
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Re: Question on motor mounts M30B34 (DC74)

Post by BRRV »

I'll rephrase this so I'm clear: I think you're asking about the stamped 'points' in the metal cup (frame) that bisect an imaginary line drawn through the wedge at its center, wider section. On my car, that line, from one point to the other, is oriented parallel to the frame rails, pointing fore and aft.

I looked at that pic very closely, and that's exactly how my mount is installed.
demetk
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Re: Question on motor mounts M30B34 (DC74)

Post by demetk »

The mounts have a protruding metal tab that fits into a corresponding hole in the subframe. Because of that they only go one way, unless of course you grind down the metal tab.
ahendra
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Re: Question on motor mounts M30B34 (DC74)

Post by ahendra »

Hello All. Sorry for starting an old thread. As OP said motor mount part# 11-81-1-175-735 is for pre 1/87 and 11-81-1-132-793 for post 1/87. My E28 built is 6/87, 793 is NLA but 735 is available. It appears they are both wedge style even when realoem showing a round style for 735 and the mount support is the same for both models. Anyone seeing issue fitting a 735 to a post 1/87 car? Wonder why was the change over given production ended 12/87. Thanks All.
Dirtym30
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Re: Question on motor mounts M30B34 (DC74)

Post by Dirtym30 »

I ordered the round ones,

We will see how it goes.
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