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Poor motor mount life

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8.6K views 39 replies 6 participants last post by  butch_n  
#1 ·
Is there any way to get better life out of the motor mounts on these cars? Not sure about oem mounts as they aren't available anymore but i've been using mounts from rock auto and they last like a year or 2 and need to be replaced again (minus the dog bone mount).

Is there any way to get the mounts to last longer? I don't even drive the car hard and only about 5-7000 km a year
 
#2 ·
just the front mount?

The easiest thing you can do for that one is to get a new one, cover one side in duct tape and then slowly fill the cavities with PL Premium construction adhesive. Same thing for the trans mount.

for the rear motor mount, weld the bastard solid.

For the Dogbone, you can find poly bushings that fit in it, they'll last longer than the car.

Now if you have some old ones and want to burn the rubber out and make some that'll completely out-last the car then pick up some of this:

Hard: http://www.mcmaster.com/#8644k11/=yizq8x

or

Extra Hard: http://www.mcmaster.com/#8644k18/=yizpal

Burn all the rubber out making note of the core's correct position (Maybe build a jig to hold it there). Cap off one side with duct tape and fill 'em solid. I know it works for the front one, trans might be a challenge.

You can also build your own trans mount if you have a welder. Just need some flat stock, a tube to fit some poly inserts and that's it.

this is what my 3500 did to a stock trans mount:

Image


Here is a solid/poly one that I built for Moon's car, I also built a similar one for my car at the time:
Image
 
#4 ·
Same problem here. My 92 had Duralast mounts with around 3,000 miles on it when I bought it. All 3 and the dog bone were failing. I replaced them with the same mouints and now after maybe 6,000 miles they too are 'sagging'. The rubber in them is terrible.

I'm going to try fill a new set. They are Anchor brand from O'reilly's (no idea if they are any better or worse or the same as the Duralast brand from Autozone).
I've never done it, but I guess I just fill all open areas around the rubber with PL Adhesive? No need to leave any places around the rubber open, correct?

Please look at the pictures and let me know if there is anywhere I shouldn't put PL. You'll see where I lined the areas I think it is suppose to go.
 

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#6 ·
Agreed sir!
I would like to add only: That I have now noticed that my right headlight vibrates at idle. I only notice it at night at stoplights, but I DO notice it. But I used Polyurethane windshield adhesive from AutoZone on brand new DuraStrand (Ha!) mounts. I just filled the voids between the rubber and the steel shell. That motor's not going ANYWHERE!! LOL
 
#7 ·
I have a new front mount on my car now filled with what superdave suggested. I let it cure for like a week and the stuff is like rock hard lol. When I let the mount take the weight of the motor, the poly at one edge shifted and pulled out a little bit but it is so much stiffer than the stock mount. Going to keep an eye on it and see how long this lasts compared to a non filled one. Am probably going to get a new trans mount next summer and fill one of those since I only put a new trans mount on a couple months ago.

Edit: By the way butch_n, i've used anchor and dea mounts on rockauto and they both have the same short lifespan fyi the front mount i filled is currently a dea mount
 
#8 ·
Thanks for the help guys. The probably not really an issue electrical issue put the mount mod on hold :cry:
But it won't be for long. However, I do need to do some other things first. So maybe next weekend or week after I'll begin the mounts. I'll fill a little at time in the bigger voids. Then they may sit for a few weeks before I change them. They'll have plenty of time to cure :wink:
 
#9 ·
I picked up a front mount today, the other two were not in and I had them order those.

Reading the tude of PL I see it says; "To help curing on non-porous surfaces apply a slight mist of water to adhesive prior to joining."
So, since the front mount has smaller area to fill than the Trans mount, for instant, I'm wondering if it will okay to fill the entire cavity, only spraying a mist of water on it at every 1/4 while filling?

As long as it cures, I'd much rather fill it all at once. One reason being, I'm concerned that if say 1/3 is done, allowed to cure and then another 1/3 put on top of it, the bond between the cured and fresh (once it too cures) may not be ideal. I'm thinking this 'joints' so to call them will tend to split apart weaking the fill.

The voids need to be washed out real good first. They feel a little slick like some release agent is on them. It will likely hender good adhesion to the rubber.
 
#10 ·
Here is the front mount, filled and ready to sit for a while in the shed.
The tube says low temperature and humidity will increase cure time.
So, down here in this heat and high humidity,,, it will be cured in about 10min :lol:

I cleaned it real well with Purple Power and the wifes toothbrush. I did rinse it out well after I got done,,, and the toothbrush too.

I filled the bigger voids about 1/3, the smaller ones 1/2 and sprayed a mist of water over it. Filled the smaller ones up and the larger ones to 2/3 and again sprayed water over it. Finished filling and then use card stock to level them.

Took about 2/3 of a tube of PL.

The other two mounts should be here by Tuesday. I'll fill them sometime this week.

These mounts are going in my 88, as a trial. If all goes well, I'll do a set for the 92 soon.
 

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#11 ·
Just to warn you I filled my 3rd gen with the 8x stuff. I left it sit outside for 3 days in 90*+ weather and when I installed it in the car and drove it, I popped the hood after a short drive, there was construction adhesive everywhere. It never dried on the inside only the outside. I suggest real poly or doing small layers and baking it.
 
#13 ·
Thanks guys.

When the other two come, I'll do a little at a time. This one will have a couple weeks to sit before I plan to install it. So, hopefully it will harden throughout in that time. If not, I've got an old toaster oven in the shed, I'll put it in it for a while.

I noticed it also expands a good bit too. I trimmed off the excess with a utility knife blade. Had to trim it down 3 times, so far.

When I do a set for my 92, I will probably use real poly. Might even get some now and do the other two for the 88 with real poly, rather than getting more adhesive.

EDIT:
I just ordered a pound of the Hard Poly Dave posted a link to above.
 

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#14 ·
cavalier3400z said:
I left it sit outside for 3 days in 90*+ weather and when I installed it in the car and drove it, I popped the hood after a short drive, there was construction adhesive everywhere. It never dried on the inside only the outside. I suggest real poly or doing small layers and baking it.
Click to expand...
I didn't see a maximum temperature this stuff will withstand. You don't think it melted rather than wasn't completely cured, do you?

The real poly I ordered says its max temp is 180° F. I'm a little concerned with that, especially the front mounts. Maybe I should get an inexpensive Infrared Thermometer and check the temperature of and around the mounts.
 
#15 ·
Ive have my filled front mount on for almost a month now and while it doesn't get very hot here, I haven't noticed any problems with the mount. There was a super thin piece of rubber inside the mount in the middle basically dividing each side and i filled one side completely, let it cure, then filled the other side. Didn't have to tape it because of the tiny bit in the midde separating both sides.
 
#16 ·
rowe said:
There was a super thin piece of rubber inside the mount in the middle basically dividing each side and i filled one side completely, let it cure, then filled the other side. Didn't have to tape it because of the tiny bit in the midde separating both sides.
Click to expand...
I saw one of those on RockAuto. I wondered how thick it was. Thanks for letting me know how it is working well.

I'm looking forward to using the real poly. I'm just going to fill the voids of them, not remove all the rubber first. Sometime I might try that, but for now I'll keep it simple.
 
#17 ·
rowe said:
Ive have my filled front mount on for almost a month now and while it doesn't get very hot here, I haven't noticed any problems with the mount. There was a super thin piece of rubber inside the mount in the middle basically dividing each side and i filled one side completely, let it cure, then filled the other side. Didn't have to tape it because of the tiny bit in the midde separating both sides.
Click to expand...
I would have got rid of all the rubber. The rubber will be a failure point of the Poly.
 
#18 ·
cavalier3400z said:
rowe said:
Ive have my filled front mount on for almost a month now and while it doesn't get very hot here, I haven't noticed any problems with the mount. There was a super thin piece of rubber inside the mount in the middle basically dividing each side and i filled one side completely, let it cure, then filled the other side. Didn't have to tape it because of the tiny bit in the midde separating both sides.
Click to expand...
I would have got rid of all the rubber. The rubber will be a failure point of the Poly.
Click to expand...
Yeah I thought about that as well, if it doesn't last long I can always try that lol mounts are cheap. I'm sure it will be better than a mount that lasts 1 year though!
 
#19 ·
The poly came and I'm going to get the mounts filled later today.

Got another question though.

On the Trans mount. Before filling, should I put a load on the mount to compress the rubber in the mount some?
I'm wondering if without a load on it, that once the poly cures, the mount will be too high.

You can see in this pictures how the rubber and sleeve are positioned without any load. Shouldn't the sleeve be more centered up in the housing? Like when you put a new mount in, how it settles as soon as you lower the jack holding the engine up.
This is it's natural loaded position. And I'm thinking that maybe the mount should be loaded (using a large C-Clamp) before I fill it.
What do you think?
 

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#23 ·
After a good bit of searching for the ADH1020 and not finding it (I found 1002, but it is for something else). Anyway, I decided to go ahead and get these filled.

I used 100 grit sandpaper to rough it up a little. The rubber was very clean and free of any wax or oils.

My plan was all laid out and should be smooth as silk. Well, that ain't exactly how it went.
This stuff is a good bit thinner that I imagined. It is pretty close to the thickness of Latex wall paint. I was expecting something a good bit thicker.

My seals did not work very well :eek:

So, what should have been a piece of cake turned out to be me standing there scooping up resin and pouring it back in the holes. Thankfully the leaks were not real bad. It finally hardened enough to leave it alone.

Next time I'll set them in a pan of sand.

The dog bone could probably be done with waxing the ends closed. Or just fill it will the tube adhesive instead of real poly. I have no idea what is under the those caps I made for the dog bone end that is sealed. I had to wrap it in paper and tape it up to stop the leak. As soon as it appears to be setup enough to handle, I'll take the caps off and see what it looks like. I think maybe the open end in the picture will come out exactly like I was hoping the caps would do to the other end. But I feel sure the covered end is probably ran and messed up and I may need to add some of that PL adhesive to fix it.

Hope to have them in the car in two weeks.
 

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#24 ·
Well here is how they came out. One side of the Dog Bone has to be filled with PL, but the other side came out okay.

Trans Mount has a mess of cardboard I have to get out. But it came out very good.

Rear mount, same as trans, needs the cardboard cleaned out, but it turned out great all the same.
 

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#25 ·
Got the Rear and Trans mounts cleaned out.

Using waxed paper in the rear mount made the job so much easier. I used the end of a file to dig into the cardboard to drag it out. Worked very well and was able to clean out the deep corners too.

The Trans mount was simply pealing the cardboard off of it.

I also cleaned the dog bone and filled in the one end with PL. It had not hardened in the tube since doing the front mount with it, so I didn't have to buy more.

I'm looking forward to getting these on and seeing how they do. I'm wondering if vibration will be much higher now?
 

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#26 ·
That's AWESOME!
Nice work!!!
I just used PU windshield adhesive that I got from AutoZone. It was $20 for the tube tho! :eek:
The one tube was enough to fill all my mounts using a little masking tape. Never had any problems with it not curing and I filled everything at once. I let it set for almost a week tho... It came out of the tube with the consistency of silicone, maybe just a little stiffer.

Please let me know if you now notice a vibration in your right headlight.

Again, nice work!
 
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