Hi All,

I'm getting my mock-up engine/trans combo ready to get to the shop and noticed a mis-match in bolt hole sizes where the motor mount bolts to cross member.

<O</OThe cross member sleeves are 1/2" and the motor mount size is either 1/16" or 1/8" smaller. Is this how they are? Do I just drill the motor mount holes to accept the 1/2"?

<O</OI purchased a combo set that included the mounts, so I didn't expect to make modifications to it. I have a question ion to the eBay store where I got it, but have not yet
received and answer as to why there's a mis-match, so I wanted to ask you who have experience with crossbars/engine mounts.

<O</OCross member:


1/2" bolt (king pin lock bolt) in the cross member:


Same trying to fit motor mount:


So.....enlarge the motor mount holes or????

THANKS

 

Maybe I'm just dense, or something, but I would have expected a thru bolt going all the way through the crossmember and the mount. I'm not seeing how that little stub is supposed to retain anything.

A big problem I see here, and it's typical of these things, it that your insulator is not designed to have the weight of the engine sitting squarely on the bolt. If you were to look at the OEM application, the insulator (and the weight of the engine) sits flat on a pad on the frame, and the bolt merely retains the engine in place. If'n it were me, and I was committed to using that crossmember, I would redesign the mounting area to carry the load properly, and use a proper lock nut and long bolt attaching method, as the insulator was intended.

 

Hi Wayne - thanks for your response - the stub is not the bolt, it's only to show the size difference between the motor mount and crossmember.

I understand what you're saying about the way the pad sits on a "flat pad on the frame" on a stock application. I'm not committed to this setup if it's of poor design, I'll take a look at other crossbar mounting methods. I suppose I could have it modified by a fabricatior too.

If you or anyone else has specific suggestions as to where to find better engineered products, I would appreciate input (or has photos of fabricated solutions).

When questions about crossbars have come up in the past, I have seen suggestions such as no-limit and trasdapt (to name a couple) and it appeared they were all about the same.

Comments? THANKS!

 

Grade 8 bolt, closest to the I.D. of the crosmember, and you sould be just fine. Used this similiar setup in other righs without trouble. However, 52 Merc is right, these engine mounts were originally designed to sit on a pad that was part of the vehicles frame stands. These mounts were conmmon on 60s Mustangs, Fairlanes, Comets, Falcons, etc.. if you want to gander at how they are typically mounted in stock form.

 

My 50 had those same style mounting pads and a very similar tubular mounting system when I bought it. I was watching it pretty much daily because I had just installed a better transmission crossmember, and I parked it when the left side pad failed. But when I pulled the engine and looked closer, BOTH pads were split apart. I'm glad to hear that the factory applications of those mounting systems were flatter, because the angular pressure on that pad was obviously its downfall for me.

 

I used Fatman Fabrications mounts, but the concept is the same. The bushings welded to the crossmember have hole for 1/2" bolts. I drilled the engine mount (the part that bolts to the engine) to accept the 1/2" bolt. You could probably get away with grade 5 bolts, but as Dano78 suggests....grade 8 is a better choice.

The engine mounts that all of these kits use are factory mounts available at any Napa or O'Reilly store. Apparently, the factory engine mounts on cars equipped with a 302 or 351w had 3/8" bolts.

Dan

 

Interesting. Well, might have to step up to some aftermarket polyurethane units. Naturally a little more $$, but may work better for ya. Is it possible you had really cheap productions of these mounts? I've always had great luck with the line Napa carries.


@ old_dan: If I remember correctly, these bolts could have been 7/16" units, 3/8" does seem a bit puny. I have a '67 Ranchero & '72 Comet with smallblocks that utilize these mounts but would be hard to tell without pulling the bolts out.

 

Thanks all who are chiming in on this subject.

I have too much blood, sweat and $$ into this stuff to use the wrong stuff at the get go.

I'll talk to the fab shop to see if they can modify what I have to create the simulated factory resting point on this crossmember.


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It's too bad there's not a kit that "does it right" in the first place!!

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I don't think you have much to worry about....I've had the same mounts on a 302 in a 1966 Mustang for years....and thousands of miles without any problem. I think Dano is probably right....the bolts are probably 7/16 not 3/8.

That being the case, I don't think it is a big issue to drill out the pads to take a 1/2" bolt. That way the bolt won't have any wiggle room inside the longitudinal welded bushing. Here's a pic of mine in the fit-up phase. I did end up adding some gussets to the mounts for piece of mind....although Fatman was confident that they are strong enough without any added material.

 

Oh I'm sure the PO bought the cheapest possible things out there. I'll let this picture do the talking for what I've encountered with my truck. This is the homeade transmission mount that was holding a big C6

 

I have run into this before when using an engine saddle and have just run a die grinder around the inside of the motor mount hole and used a 1/2 inch bolt. Use a die grinder to keep the hole oval instead of rounding it out, you may need the adjustment later on. Good luck

 

Yeah, wow! Can't buy those at Summit Racing. You're lucky he took the time to actualy drill a couple mounting holes. Most of the time they just fit it and cobble-weld it in... Guess they never figure on pulling the tranny back out.

Probably the missing trans x-member for my '56!! Looks alot loke the engine mounts.