AdamP

I am planning on rebuilding my motor mounts. Now from what I have seen polyurethane is good from -40F to +180F. I am worried that the mount will get above that temp and distort the properties of the polyurethane. Any one know how hot the mounts get, if they can take the temps in that position, or if there is a better material.

Also I need to know what hardness to get. I am guessing in the A60-A80 rang. What do you guy's think?

RX7Elmo

I bought polyurethane from www.mcmaster.com and i used 80A shore. That is the middle between the 60A and the 94A they have. This polyurethane is strong and they give you enough to do something like 2 pairs of mounts. I filled the mounts on my MR2SC and it's perfectly fine. The car has better throttle response and actually seems to handle better. I do get more engine vibration which i oddly like. urethane can take the heat, and motor mounts do not get that hot. It's an excellent mod that will give you that solid mount feel without the non-streetablitliy.

Danny

JeffShoots

PM JIMLAB. If anybody would know about polyurethane and how to get it. Jim's your man.

AdamP

mcmater is where I plan on getting it, but I was thinking that 80A would be to hard but maybe 60A is to soft. (where's baby bear when you need him) Anyone know around where the stock mount would fit on this scale. I really don't want to much vibration, but I don't want it really soft. My existing mount is toast so I guess anything is better.

Thanks for your help

AdamP

what do you guys think of Neoprene? it is good up to 200F.

AdamP

I was looking at the properties of latex and natural rubers at the mcmaster sight and asuming that they used natural rubber for the stock mounts the polyurithane should be fine. The highest natural rubber I could find there went up to 180F and was only 40A.

So I am thinking that Polyuethane at 60A will be a little stiffer then stock and will endure the heat just fine.

My other option is the Neoprene that I will handle 200F and is 75A. My hesitation is that I have never heard of Neoprene being used for this application so I am hesitent and not sure on how long that plastic will last.

RX7Elmo

i say go wiht the 60A then if you are really concerned with excess vibration. I would go 80A b/c it's the middle ground. It's stiff, doesn't vibrate much. I also recommend you let the mounts cure for AT LEAST 48 hours if not more. They harden up in about 4 hours to the touch, and are rock hard after 24 hours.


Danny

nrolfes1

i was considering doing the same thing but i didn't want my car to be out of commission all summer while i engineered the perfect motor mount, so i caved and got a new stocker. be interested to hear how your project goes though, i think it was about 60 bucks for the 6" long 2" diameter shaft of urethane.

AdamP

I have not taken the mount out of the car yet, I thought I was going to have to go with 3 inch, but if it is 2 inch will do that will cut down on cost. If it turns out good I will right a DIY for it.

What is this talk of cureing? I was just going to buy a roll from mcmaster and drill a hole through the center for a bolt. I don't plan on molding my own. Am I missing something here?

My big concern is the passanger side mount that is close to the turbo and downpipe. I am concerned that the polyurethane will not be able to take the heat. So I was think of Neoprene. But I need to get more info on it.

VTAOE

Does anyone happen to have a picture of a stock motor mount and then maybe a picture of their "solution" to the problem. In other words the motor mount that you ended up designing?

I like this thread guys. It sounds like some very useful information for down the road whenever I may have to do this. Let us all know what you come up with and what kind of results you got. It might be helpful too if you could take some pics along the way so that those of us that are new to the idea of designing the motor mounts could get some ideas. Thanks.

- Cody

AdamP

I plan on doing a full write-up. Here is a pic of RotorSports Racing's version. I think this one in the pic is missing the stud out of the top. I don't have a pic of a stock one, but once I pull mine I will take some with my digital camera. When I do the write up I will have lots of pics and a step by step. If anyone has a pic of a stock one please post it it would be a big help. Thanks

Single7

Does RotorSports Racing put a metal "cover/cap" over the polyurethane? Is it necessary? I know the steel band is suppose to keep the engine from popping out of its craddle should the mount give out, but was not sure if the "cap" was necessary?

Brian P

I think the cap is used to protect the mount from heat.

Single7

Hi Brian P,

Wouldn't the cap be on the other side of the polyurethane then since the heat is coming from the top (motor) and not the bottom (engine craddle)?

On a side note, how hard would it be to "shape" i.e. cut and saw the polyurethane into the proper can shape? Is it even possible?

Thanks.

AdamP

Ok I was looking at myt mount (still in the car) and It looks like I should use a 2inch diameter rod. Now I had just assumed from memory of handling the joint I was going to end up using 3 inch, But it looks to me that that would be way to big and 2 inch might be a tght fit. My mount is in the car so I was hoping some one had one out of there car so that they could tell me what the best diameter roll I should get. Thanks.

yodaddy

i went with neoprene, just baught it today. i baught a cupple of chunks of it from a rubbeer shop and am going to cut it myself. it sounds like the best idea for me because it handles a lot more heat, stands up to the elements like poly, and is cheaper.

AdamP

What diameter did you go with?

nrolfes1

Heres a picture of my completely thrashed motor mount. it fell apart into three pieces as soon as i took the metal band off of it.

yodaddy

i still need to see if it will fit but i'm gonna go with three inches. it should fit considering the the stock on is close to that. i just baught some 3x4 chunks from the guy and will drill and trim them when i get some time. still working on making a down pipe. man i hate being a perfectionist, everything takes so damn long.

jfirko

I am in need of some motor mounts as well. If this works it would save me some serious cash. My driver's mount is completely hosed and I think the passenger side one will be gone soon too if I don't replace them quickly. Definately keep me posted. How exactly does the mount work, I haven't had a close look? Does the engine bolt into one side of the mount and the frame to the other? Would the threads screw directly into the poly or what? Thanks.