Front Motor Mount Bushing?

[belize1334]

I just noticed that the ID of the metal bushing in the front motor mount is bigger than the OD of the bolt which passes through the bracket...
Is there a bushing or spacer that's meant to slide in there to take up the difference? 'Cause if so I must have lost mine at some point!

 

[gramkrakr89]

I think its supposed to be that way

 

[belize1334]

Why would they design metal-on-metal clearance into that bushing?

 

[broxma]

If I recall, the OD of the bolt matches the ID of the mount on the motor. You could always drill out the motor mount to have both the ID's(Motor mount and body mount) match, and use a larger bolt.
As for why they do this? Who knows. But it certainly explains the sagging rubber mount bolted to the body. Those things are always nearly flat when I see them.


/brox

 

[belize1334]

You're correct, the "fork" hole is appropriate for the bolt OD but the bushing inside the rubber mount is larger. It seems that Mitsu has perpetrated this tactic all the way through to the Evos. The general feeling is that it is built in tolerance for subtle variations in OEM parts. I think the trick is gonna be to get my poly mounts installed and then determine whether the bolt is centered in the over-bored bushing. If it is then I'll add a second bushing to tighten it up. If not then I'll determine the appropriate offset and drill the fork out to the right location/diameter.

I assume that it's not that big of an issue since, once bolted down, it should be the clamping force on the bushing and not the actual shear force on the bolt which holds everything in place. But, just the same, I'd like a tight fit...

 

[gramkrakr89]

^ I think the "clamping" idea is where they were going. The instructions for the prothane mount bushings that I installed in 689 specifically said to let the through-bolt rest on the bottom of the metal insert, and then tighten. Personally, I balanced this by lifting the motor ever-so-slighly so that the bolt was "suspended" slightly from the bottom of the tube insert.

I've had my prothane motor mounts installed for quite some time and have never had any problems with it coming loose once it is set. Perhaps some loctite on the through-bolt thread will provide the extra peace of mind you need?

EDIT: by the way... happy birthday! /ubbthreads/images/graemlins/grin.gif

 

[belize1334]

Thanks!

 

[DynastyLCD]

a good friend of mine used to fab front roll stop mounts to unbolt the factory and install in its place. fully solid aluminum piece. he drills out the engine mount bracket to fit, and puts an old ARP headstud in place to make up for the play you're experiencing.

i cant remember for the life of me, if the center hole is larger on the solid mount, or if that would work for a stock or prothane mount.