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Motor Mounts

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Old 12-07-2007, 03:25 PM
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Transmission: 700R4 and NV3500
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Motor Mounts

I left the title vague because I have a couple questions.
First off I had my motor mounts changed years ago when it was a 305 (H) motor. After I installed the 355 I built, I left those mounts in place. I remember the mechanic I had do it at the time ,since I didnt have time to do it myself, told me it was a PITA.
I noticed at some point that the engine doesnt sit lever when viewing it from directly in front. Thus when you drop the tranny crossmember at the tail and lower it down, one side there (frame rail to crossmember) meets first B4 the other. I would say 1" before the other side. The drives side is higher than the passenger.
Is there a seperate mount for the drivers and pass sides?
I had bought some auto-part store specials and dont remember weather they had Left and Rights seperately. It was a long time ago. They are rubber inside the rivited clamshells.
Has anyone changed these themselves on the car?
Any pointers?
It looks like the nuts on the back are free and will fall into the K-Member upon removal. And they look impossible to get a wrench onto. Ive tried a little but am getting the Tranny back in from a fresh rebuild. So my focus is mostly there.
Any info or help would be greatly appreciated THX
Old 12-07-2007, 04:57 PM
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One of the sore points of 3rd gens (the other being exhaust routing).

A royal pain to replace, unless you drop the a-arms from the crossmember. Piece of cake if you do that.

The chassis half doesn't have left or right, but the inserts do have upside down and right side up. The engine-side shell has a left and right, but I wasn't able to figure out what was different functionally between them (they look different, but the bolt holes all seem to be in the same place relative to each other).
Old 12-07-2007, 06:19 PM
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Re: Motor Mounts

The through bolt holes are actually slightly different, IIRC.
Old 12-07-2007, 06:23 PM
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Re: Motor Mounts

you can remove the motor mount to k-member bolts with the a-arms in, i did it. Its not fun, and a variety of crows-foot adapters and universal joints helps. I had all the nut fall out of the a-arm pockets, and only one stayed in, but it didnt fall in far enough that i couldn't get it back out. Getting them back in afterwards is also a real joy. Its a lot easier to do with the a-arms off.
Old 12-07-2007, 06:23 PM
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Engine: 355ci and 4.3l
Transmission: 700R4 and NV3500
Axle/Gears: 7.625/3.42 Auburn and 8.5/3.08 Gov-
Re: Motor Mounts

Yeah, somehow the last mech didnt have to drop the a-arms. But I was looking at that and it seems to be the way to go.
So there are 3 parts : The engine mount which is formed steel and 3-bolts, the clamshell which is formed steel rivited together and had 4 ears but 3 bolts and the inset which is rubber encapsulated steel.
Sound right?

So, it is just the insert which is directional or right / left OR is it the entire clamshell/insert assembly.
These came insert and clamshell rivited together when I bought them. Its been 7 years ago, but thats about all I remember. Having not done it myelf like I always do usually, I dont recall muche else.
THX
----------
A few months ago I found a bolt floating inside the K-Member. It looks to have been dropped in there during the mechanics install. But I checked and there is nuts on the back of all the bolts. So he replaced the lost one

Last edited by Mikz86TA; 12-07-2007 at 06:28 PM. Reason: Automerged Doublepost
Old 12-07-2007, 06:31 PM
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Originally Posted by Apeiron
The through bolt holes are actually slightly different, IIRC.
Must be very slight. I put a rod through them laying on the bench, the bolt holes to the engine seemed to be lined up. Certainly not a 1" difference.

You've got the pieces right. The little tabs on the inserts kind of make a shelf for the engine half.

I wasn't saying you have to take the a-arms out. I was agreeing they're a pain to get to, unless you take the a-arms out.

I've done it twice with the a-arms in (well, technically "I've" only done it 1+ times - my son did it mostly the 2nd time) - the first time for the V6 to V8 swap, and the 2nd time for poly inserts when the 350 went in.

Polys are so, SO worth it!
Old 12-07-2007, 07:23 PM
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Re: Motor Mounts

I second the polys, and autozone and discount carry them now.I replaced mine last year, get a skinny flexible friend for underneath. and a open end wrench with some duct tape on it to hold the nuts when putting them back on
Old 12-07-2007, 07:59 PM
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Re: Motor Mounts

i put the energy suspension motor mounts in w/out removing a-arms. they came with step by step instructions.
Old 12-08-2007, 12:10 AM
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Re: Motor Mounts

OK I'll probably catch all kinds of flack for this but when I replaced my motor mounts I tried everything without much luck until I decided to cut the crossmember about 3 inches long on each side so I could reach up inside. Took about 20 min per side including cuttin and welding back. Just a suggestion and I've had no problems from it.
Old 12-08-2007, 12:46 AM
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A while back somebody posted about their holesaw job.
Old 12-08-2007, 12:35 PM
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Engine: 355ci and 4.3l
Transmission: 700R4 and NV3500
Axle/Gears: 7.625/3.42 Auburn and 8.5/3.08 Gov-
Re: Motor Mounts

I thought about that, and its not a terrible idea, but I am not cutting mine up.
Old 12-08-2007, 01:42 PM
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Re: Motor Mounts

I've put poly inserts in by only removing one bolt (the "easy" one), drilling the rivet out, and prying the shell open enough to get the old rubber insert out and the poly one in.
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