Need Advice on the Top Motor Mount

[steve_wood]

Somedays you just can't win....

I'm working at installing the manifold, horn and upper motor mount. I'm dry fitting all of them to make sure they fit. When I went to put the top motor mount in place, something didn't seem right. I can't recall 100%, but I'm pretty sure this motor mount was fitting properly when I removed it. The heads are stock and so is the bottom end. There were no shims on the lower engine mounts when I removed the bottom end. When I put it back in, i detected a small gap in the right rear mount. I corrected this with a .007 shim.

If you look closely at the picture, you can see that the mount is tilted to the left, like it's too tight to fit on the studs and match up flat against the top frame mount bracket. It's almost like the top end is too far over to the right.

There's a 1/4" gap between the top of the motor mount and the frame. The bottom of that vertical tab is right up against the lower part of the frame bracket. There's a 1/8" gap between the mount and the head inbetween the stud and the pan.

Again, I don't get it. This used to work! Am i missing something? Can I enlarge the holes for the studs until it fits? Any other suggestions?

steve

[Panacea]

The rear motor mounts should be tightened first, then shim the front if needed. That still won't pull it over 1/4"' you may need a shim on the top mount. Mike

[fourthgear]

There is a spacer (thick washer, check your manual or a parts manual )that goes under the front head part of the mount, between the mount and head. You will need shims between the mount and frame, how many and how thick is determined by the gap . Just make sure all other mounting surfaces are flush and tight before you do the top mount.

[steve_wood]

This is hard to explain. There is a lack of clearance between the mount and the frame tab. If there was a nice even space there it would be too easy to shim it and I'd already be done.

I can't even get the mount to fit flush on the heads because the vertical tab of the mount hits the frame tab and prevents me from pushing the mount inwards so it slides down over the studs and goes flush with the heads.

In short, I have a lack of clearance between the mount and the frame tab!

steve

[john HD]

steve,

is the top mount new nos or replated original?

john

[Panacea]

Have you placed the intake manifold in position to check head alighnment?

[steve_wood]

The motor mount is the one that came off the bike. I had it cad plated.

Since taking the picture, I've installed the intake manifold - it lined up perfectly - no surprise since when i torqued down the heads I had the manifold installed to guarantee that it would line up.

steve

[Panacea]

Steve, that's a head scratcher for sure, even if you had tightened the rear mounts first and eliminated the shim under the right rear, the problem would have been even worse. Is it possible you got somebody elses top mount back from the plater?

[steve_wood]

99.99% unlikely it's somebody else's mount. I had about 300 parts plated and everything else came back. Can't see how that one part could have got switched.

I'm wondering if maybe it was originally off kilter like that. I wouldn't put it past the bodge-master who previously owned the bike.

Will I ruin the utility of the mount if I elongate the holes a bit to provide enough slack to ensure it fits?

steve

[Panacea]

The only concern would be WHY... are there any dents in the frame near the front motormounts like she slid into a curb at some point, Mine was....I had the frame gone over mainly because of tranny alighnment issues and found the front mount was bent down from just such an impact, causing the front mounting bosses on the motor to break. She was full of surprises... Im not sure if modifying the bracket will cause any harm, other than possible exhaust clearances if you plan to use stock exhaust. Good luck. Mike

[john HD]

steve,

that is what i would do.

try shimming it up first and see if it fits better. i just did mine this winter and realized after looking at the parts book there should be about a 1/8 inch spacer on each mounting stud under the top mount.

then you add shims to the frame bolt IF needed.

will snap a pic of mine if needed.

lemme know...

john

[steve_wood]

Frame is in remarkable condition. Even has all the tabs - one of the reasons I bought this bike. No dents or bent elements.

I tried shimming up to 1/8" on the studs (i.e. in between the mount and the heads). That didn't solve the problem.

Guess I'll get out the rat-tail file and do some more finesse fitting. Seems like I do a lot of this....

I would appreciate pictures if any body has some....

steve

[john HD]

steve,

if you have shimmed it already my pics would just confirm that, i have found over the years all of these bikes are different.

a little work with a file would not be unusual in my experience.

john

[panz4ever]

"There's a 1/8" gap between the mount and the head inbetween the stud and the pan."...Couldn't you eliminate the gab by straightening out the bend?

[VT]

The top tab meets flush with the top mount of the V-Twin '55-57 frame. The fingers of the mount sit fairly flush with the top of the head as you'll see.

If any gap exists on mine it's at the rear head.

Front finger sits flat at the trailing edge of the front head. There's a tapered gap at the leading edge of the head.


Rear finger sits flat on the inside edge of the rear head, but there is a tapered gap at the outside edge of the head.
Top mount tab is still in 100% contact with the top frame tab.
So bend and tweak the fingers until they sit flat. No way you'll find a tapered shim.
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Here's the Colony top mount bolt and thick spacers. This are not the same parts illustrated in the '49-57 Spare Parts Catalog with the three 29/64 x 1-1/8 x 3/32 plain steel washer appearing as shim spacers. There is no lockwasher. The parts book calls out different thicknesses of washers, with parts numbers that don't match what's AM. Colony "re-wrote" the parts for the top mount assembly.
The 4660 7/16-20 x 1-1/4 bolt threads through one of the three thick plain steel washers (from the right side of the frame, not as shown) or not, I guess, or as you like it. Then, through the frame tab, then through the slot-hole of the top mount, and then the two remaining thick 6524 washers go on, then a 6520 plain steel washer, then the 7/16 flex-loc nut.
If you need spacers between the top frame mount and the top motor mount tab, measure the gap and use McMaster-Carr's slotted shim stock. The Spare Parts book shows those three thick washers as shim's, but I've never seen a frame with that much of a gap, that you'd need (or could) use them. 3/32" (per spacer) is some fat gap Fred.
50 ft. lbs. on the top mount nut.
35 ft. lbs. on the cylinder stud nuts.