custom motor mounts

3573 Views 5 Replies 3 Participants Last post by RallyBob, Jan 27, 2003

bear

Discussion Starter · Jan 26, 2003

hey guys,

i have a quick question for the forum. i am swapping a 2.3L trubo ford into my 71 gt. everything is going amazingly well. i want an opinion on how/where i should place the front motor mounts.

in the opel the engine cross member comes from pretty far back on the chasis, and the mounts are about in the middle of the engine.

on the ford 2.3L the mounts are up at the very front, around the area of the opel front suspension member. it would be very easy to bolt off to the top of the frame rail where the suspension bolts come thru, so the mounts would be sitting on top of the 'frame', which sits on top of the suspension member

would this cause any problems? the weight would be bolted off closer to the front, but this doesn't change any weight dist. or handling from bolting if off further to the rear? does it? assuming the engine is in the same location. or could i treat the suspension crossmember also as the engine crossmember and weld my mounts directly to the spring 'cage'. since any weight from the engine would eventually find its way to the ground thru the suspension anyway, this should be ok?

any input would be great! rb?

jon

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RallyBob

· #2 · Jan 26, 2003

Opel Kadetts used the front suspension crossmember as the mounting for the engine, and the crossmember is essentially the same as the GT's. So no problem dealing with the weight of the engine there. I would fabricate another crossmember where the OEM engine crossmember mounts attached....just to tie the framerails together from side to side.

Bob

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bear

Discussion Starter · #3 · Jan 26, 2003

thank you rally bob!

i will proceed as planed....good idea about the lower brace

i also plan on making a rice burner type strut brace for the shock towers.

jon

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bear

Discussion Starter · #4 · Jan 26, 2003

Yeah, I have heard this in racing circles as well, a lot of bigtime drag racers do this. It theoretical eliminates the energy that it takes to stretch/ compress the bushings. It would also give you better throttle/launch response. But I would not do this in a daily driver. It would make the car very unpleasant to drive on the street. I am making poly bushings for my mounts. These will be better than the stock rubber mounts.

good luck, I would love to compare notes on these swaps, then we need to go race'm

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Nathan Acree

· #5 · Jan 26, 2003

I had some of the same concerns when I was making the motor mounts for my V6 conversion.

You can see the mounts here:
http://mywebpages.comcast.net/nacree/images/CNXT0001.JPG
http://mywebpages.comcast.net/nacree/images/CNXT0002.JPG
http://mywebpages.comcast.net/nacree/images/CNXT0003.JPG

Basically what I ended up with was the engine mount ear sandwiched between two rubber body mount donuts with the bolt hole in the ear slotted trasversely. Originally I was just going to use one rubber donut between the mount ear and the upright from the engine crossmember. I think this would have worked OK to absorb vibration at idle, but would not have allowed the engine to move enough when it torques under full throttle etc. sandwiching the mount ear between two donuts and slotting the bolt hole in the mount ear slighly will allow the engine to rock slightly on the mounts putting the bottom donut on the drivers side in compression and the top donut on the passengers side in compression thus absorbing the engine motion and isolating it from the uprights and the rest of the car.

I was going to use the 1.9 mounts, but I did not want to use parts that were not commonly available. The body mount donuts are easily obtainable at any parts place for about $4.

I have not been able to test the mounts yet, the project has been on hold for a while (real life getting in the way) but I hope to have the engine up and running soon.

I would appreciate any opinions on how well you guys think this mount set up will work.

Nathan Acree
Albuquerque New Mexico

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RallyBob

· #6 · Jan 27, 2003

19693SGTEOPEL said:
I have a question on this too? My engine bolts up the same exact spot as the oem 1900 spot. but should i bolt it up metal to metal like this racing shop said or should i use rubber/polly mounts i am verry skeptical of bolting the engine directly to the metal. a lot of noise and posibility of damage. I dont know why they told me to do it direct when i asked they said it would deliver more power onto the road? doubtable its that siginificant.

Solid mounts don't tranfer any more power to the road, but they really DO improve the response time. I.E, a blip of the throttle will help 'set' the chassis mid-turn with a lot less effort than with rubber mounts, as the torque is not being absorbed by the mounts but rather being directed to the drive wheels virtually instantaneously.

But, solid mounts will be virtually undriveable for the street. Horrendous vibrations. AND, out of the three mounts (both engine mounts and the tranny mount), at least ONE of them has to have compliancy, or something will break. Like the bellhousing, or the block, or the mounting bracket. Even on racing vehicles, I always ran one pliable mount. I used a solid tranny mount, and one solid engine mount, with one urethane mount. I made the 'compression' side out of urethane, to absorb the twisting motion but reduce the chances of mount breakage.

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