Thread: New custom lower motor mount design, NO MORE DOGBONES!

For a several years now, I have revised, redesigned, and played with this idea of a lower motor mount that completely eliminates the upper dog bones. Part of the engine vibration issues we feel in the cabin are due to the motor being supported by the front unibody framing above the radiator that directly transmits vibrations to the passenger cabin. Ive wanted a stiff and non moving engine, without the rattles and issues that usually accompany it. I know that cars that do not have the upper arms tend to not transmit these vibrations. However, short of crazy cradle changes, sometimes even the transmission casing itself, there was no easy solution.

Behold, the solution:

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This is a 1/2 inch thick aluminum plate, cut and shaped to follow the contours of the transmission. The tube at the bottom holds one of the original dogbone arm bushings. The angle brackets are also 5056 T6 aluminum. A steel plate with nuts are tack welded on, and slid inside the passage of the aluminum cradle for support. On a steel cradle car, you can tap and bolt directly in.

NO engine movement, but also still completely rubber isolated. There were previous versions of this mount, but they relied on just a single bolt hole, no rubber mount or isolation to prevent false knock readings, and were too harsh.

I am considering making more, making kits that can be installed in a few hours. Hardest part is lining it all up and drilling the holes in the cradle.

thats a cool mount you made.

any thoughts of making steel based ones for the steel frames? those would be way easier to weld on.

Originally Posted by Scottydoggs

thats a cool mount you made.

any thoughts of making steel based ones for the steel frames? those would be way easier to weld on.

I can, if there are people interested. Really all that would need to change would be the lower brackets would be steel instead. The rest can stay the same. I considered making it all out of steel, but I was trying to keep weight down and not void out the savings of going to the aluminum cradle.

The engine doesnt move but a mm or so. just what flex all the mounts give. I did a urethane fill to brand new motor and trans mounts too at the same time. Those have little to no give in then as well. Softer than ZZP poly mounts, but much stiffer than standard.

Originally Posted by wstefan20

I'm totally in if you design something for steel frames! I'm going to be swapping a 3800 in my fiero, and I don't want to have to shell out for swapping the alternator relocation and loose the option of power steering just so that I can have an upper dogbone mount. This would be a lifesaver! The mount should work with the fiero subframe as well if welded on. Looking forward to seeing how this turns out!

I can, and I actually have a 3800 swapped fiero here.

This reminds me of the H body design. I've seen a few different versions of this idea and overall, I always liked it.

Originally Posted by BillBoost37

This reminds me of the H body design. I've seen a few different versions of this idea and overall, I always liked it.

Yea, IIRC "Janice" was her screen name, she had the original variation. About 8 years ago I purchased the templates and all remaining stock from (insert longtime member in community i cant remember who took over the project) and have been revising it since.

Problem I had with all the previous variations was there was no isolation, it was all metal to metal with the brackets and a bolt, sandwiched. This version has the ability to even upgrade to poly, since there are poly dogbone inserts available.

ClubGP Message Forum troubleshooting

the original thread of its first iteration. Some other cool stuff in there too!

We got some mounts from west coast fieros IIRC. it was built about 10 years ago. we integrated the full obd2, pcm, and original dash in factory locations and wiring points, so if you dont pop the rear hood, it all looks stock. even managed to keep the factory manual shifter and it just moves back and forth for the auto now. Whole thing drops out using all the factory bulkhead wiring connectors. it was fun to build. Hardest part was wiring it all, wire by wire, running each one how we wanted, and to each pin in the PCM at the factory location.

itll pull the tires off the ground on the street across an intersection. scary little plastic car.

Very cool.

Slick.