First posted at racingstrong.com in 2001.
The motor mounts were replaced when I right after I bought the car. I had no choice really as the front mount ripped away from the chassis and almost killed me at high speed. I purchased new mounts from carparts.com and had the front mount rewelded.
When we replaced the engine in the spring of 2001 I noticed that the rear mount was showing some wear. So during the winter of 2001/2002, I am going to ‘refill’ the front and rear mounts with urethane.
UPDATE January 13, 2002
I have made the decision to update my mounts using 80 Shore A Urethane. I have gone through 2 sets of mounts in two years. My clutch is putting too much strain on the stock rubber. I have started removing the rubber. I ordered the Urethane for us$21.00 from McMaster-Carr.
Here are the latest images:
All of the original rubber was pulled from the old mounts. The steel bearing tubes were cleaned up. The center of the mount was cleaned up. I bought 2 bags of sand and a tub with a lid. The sand can be used for other stuff later. It is regular construction sand… nothing special.
The Mounts were then taped up with duct tape. I then took the center bearing and placed it in the exact center. I took a hammer and made some indention’s in the tape. And then cut a hole in the tape smaller than the bearing. I pushed the bearing through the hole and centered it in the mount. I then placed it in the sand. The sand will support the whole assembly to keep bubbles from forming within the urethane. This is very important to keep the mount as strong as possible.
I checked the mounts after 5 hours. They are sitting in my basement shop. The temp is 65° F. They are solid enough to pick up. I am going to leave them in the sand for 24 hours. The destructions stated 72 hours for total hardness.
Reactions will be posted when I get the car completed.
AJ Perez states:
I’ve recently done this mod and it made a big difference in the feel. Power is instant, shifts are crisper. If you use the urethane way (what I did) 80shore A is plenty hard for a streetcar… make no mistake, it does make it louder inside the cockpit… sometimes a bit drone’ish.
But anyway, just be SURE that you have sealed off the other side of the mount with tape. This stuff will get through even the tiniest hole until it hardens. If there is a hole, it WILL find it and it WILL make a huge mess.
Update May 2020
This is a great mod to keep the engine from rocking. It’s fairly cheap and easy. But… There is always a but.
You need to inspect them regularly. They don’t take exhaust heat well, and as you know, they sit next to the exhaust system. The urethane will deform and the engine weight will droop in the mount.
There are also a few companies still making urethane inserts such as the Kirk Mounts. I believe you can still get them from Kirk or other types through TwosRus.com
We used urethane mounts on the V6 MK2 MR2 race car. We kept breaking axle tips. When I mounted a camera onto the engine, I discovered that the engine was rocking about 2″ on its axis. This was bad. The urethane failed fairly quickly, and this was using inserts. We ended up taking the mount, removing the rubber, and welding 1/4″ plate to the mounts, thus making solid steel mounts. After about 25,000 miles of endurance racing we have not had a failure, and stopped breaking axle tips. You do need to inspect the chassis and the mounts on a regular basis for cracking. Troy Truglio had some cracks on his chassis form after doing the same mod. Mainly on the front firewall. Welding some new plate to the firewall where the mount bolts to fixed his issue.
NVH? Hell yes. But they are race cars.