LH header contacts body - motor mount mod

Grubby · #1 (**permalink**) 03-03-2013, 12:23 PM

This is my second ERA and both cars had marks on the LH header pipes showing they contacted the body under acceleration.

My car does have the ERA modified LH motor mount, so I know the LH mount is not stretching. I even tightened the bolt thru the LH mount so there was no free play.

I shimmed the RH mount up 1/8" and the problem is noticeably less. My guess is the RH mount is compressing under hard accel and this causes the LH side to raise as it engine rotates.

My engine is now positioned with the LH side slightly lower than the RH.

I think the obvious solution is a stiffer mount on the RH side, but no one seems to offer polyurethane or solid mounts for FEs.

I am thinking about making a RH motor mount. If I use polyurethane, what durometer rating would be harder to compress than the rubber? Roughly 25% harder should be about right. How harsh would the vibration be if I made a solid mount for the right and left the ERA modified rubber on the LH? This car is primarily street driven.

My plan is to start with an OE style mount; cut the rubber away and bolt in some Polyurethane or weld in a chunk of steel.

John

patrickt · #2 (**permalink**) 03-03-2013, 01:08 PM

You might consider these from Total Control Products. Total Control Products, LLC - Motor Mounts

JST4FUN · #3 (**permalink**) 03-03-2013, 01:19 PM

Here's another option:

Polyurethane Motor Mounts

Grubby · #4 (**permalink**) 03-03-2013, 02:11 PM

ERA uses FE mounts for something like a 64 Galaxie. 3 bolts into the block and a single stud sticking out that mounts into the frame.

It doesn't seem very practical to redo the mounts on the frame.

John

patrickt · #5 (**permalink**) 03-03-2013, 02:24 PM

I just looked at shots of my frame -- you might be right that they won't mount properly.

patrickt · #6 (**permalink**) 03-03-2013, 02:53 PM

Are you sure that the passenger side mount is squishing down so much that it lifts the driver pipes up through the fender hole? Why not just fab a mount from billet aluminum block? These cars shake so much to begin with how would you even notice a little more?

ERA Chas · #7 (**permalink**) 03-03-2013, 04:01 PM

John,
It's simple. Loosen LH mount stud. Slightly raise RH side of the oil pan. Remove RH mount.
Drill completely through the mount adjacent to the stud.
Install a 7/16" grade 8 bolt, washer and nut. Tghten to compress the the rubber block. Reinstall.
I did both my mounts after delaminating one side (replaced that one with new) at the drag strip.
Forget aluminum, urethane or voodoo chants.

Jim Holden · #8 (**permalink**) 03-05-2013, 08:15 AM

Is the opening on the side of the car in the correct location and "tall" enough. Even with the ERA motor mount (bolt through) there can still be some interference when the motor torques over. With the inevitable differences in tolerances for side pipes, motors, etc. a fraction of a difference at the mounting point on the head can make a big difference some 2 1/2' away where the side pipe exits the body. On more than one occasion, we've had to carefully "clearance" the top of the opening and then touch up the paint...

I would be concerned that with solid motor mounts, sooner or later little things (like welds, etc) may begin to crack. Its one thing for a race car that gets inspected virtually every time it goes out to have solid mounts. It's something to avoid on a street driven car where comfort, durability and reliability are of some modest concern... at least to me.

Jim

Grubby · #9 (**permalink**) 03-05-2013, 02:57 PM

Jim,

This car was built by ERA as a turn key minus with the engine and side pipes installed.

I have considered raising the hole and doing a touch up.

I have similar concerns with solid mounts. Polyurethane would likely dampen the movement enough to stop contact without the solid pitfalls.

I will stew on this one a bit longer before I decide.

It requires a full throttle launch to cause interference. It went all summer without contact and then I went on a December 1 cruise. Some guy looked like we was going to hit me from behind at a stop light and I did a full throttle launch to avoid the crash. Crash was avoided, but the header did touch the body - slightly.

John

ERA Chas · #10 (**permalink**) 03-05-2013, 04:30 PM

No need for the slide rule and thinking cap. What I told you in post #7 will fix it easily and permanently.
How do I know?

Grubby · #11 (**permalink**) 03-05-2013, 07:24 PM

Chas,

How much did you compress the mounts? Same on both sides?

Your fix is free. Free is good.

John.

ERA Chas · #12 (**permalink**) 03-06-2013, 05:49 AM

Quote:

Originally Posted by Grubby

Chas,

How much did you compress the mounts? Same on both sides?

Your fix is free. Free is good.

John.

Yes same on both. Just tighten until very snug and you can't any more. You are just keeping the rubber from de-laminating from the steel. You're firming-up the mount, not making it solid. The give is contained in the rubber.

flaflier · #13 (**permalink**) 03-06-2013, 01:46 PM

Chas, did you really just say "the give is contained in the rubber"?