Trans Mount Spacers

[Doppleganger]

On the right side, its a common bolt and nut. On the left side, it has longer bolts with these spacers. Is this OE?

I see similar spacers on the steering box, so maybe there's a reason for them. Dunno.

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[yevgenievich]

Bolt and spacer should be on both sides

 

[PrairieDrifter]

The spacers are oem, the pic you supplied is the correct way to mount them, and they should be on both sides.

 

[Frankenchevy]

It has to do with torque yield or stretch. It helps the bolt stay torqued better than if the spacers were not present, iirc.

my CM is below the frame just like the picture, but my spacers are above the c-channel, fwiw. Lowest to highest is: bolt head, CM, frame, spacer, then nut...

 

[Doppleganger]

Makes sense but geezus. This is the opposite side. No idea where to find these things now. I swear this truck was built or fked with on $1/beer nite.

Thanks fellas.

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[Doppleganger]

Ok - been several months since I disassembled this thing and was going by pics of what to locate / do next. I do have all the spacers - ones on the left side were below the bottom of the frame; ones on the right side were above (inside) the bottom of the frame.

So, if there's a logical reason to that, I'll put them back the same way.

Thanks again.

FWIW.....the nuts on this trans mount are copper too. When I disassembled the straps for the fuel tanks, there were four 7/16" nuts.....and one of them was copper too. WTF?

 

[Doppleganger]

It has to do with torque yield or stretch. It helps the bolt stay torqued better than if the spacers were not present, iirc.

my CM is below the frame just like the picture, but my spacers are above the c-channel, fwiw. Lowest to highest is: bolt head, CM, frame, spacer, then nut...

So the bolt goes in from the bottom with the nut on top? btw...whats a CM? Washer?

THX

 

[Frankenchevy]

So the bolt goes in from the bottom with the nut on top? btw...whats a CM? Washer?

THX

CM-crossmember


Top to bottom

Flange nut
Spacer
Truck’s frame
Crossmember
Flange bolt

I guess the direction of the bolt doesn’t matter too much, but I have to use a tapered punch as a hole alignment tool when installing the CM. It’s easiest to slip it in from the bottom once you get it aligned.

 

[PrairieDrifter]

I feel like this topic has been debated forever. I've always seen it like this, from bottom to top

Nut/bolt
Spacer
Crossmember
Frame
Washer
Nut/bolt

Grain of salt.

 

[Doppleganger]

Is there a reason they used a copper nut? I ask only because BMW used copper nuts on their manifolds - worked like a lock nut only wasn't so hard to go on and would never seize/rust. I think after they were on-off a couple times, they were kind of done.

I have new stainless bolts for this mount - also picked up a stainless lock nut in case the copper ones are no good.

Thanks fellas - stupid questions, I know, but the devil's in the details.

 

[Frankenchevy]

I feel like this topic has been debated forever. I've always seen it like this, from bottom to top

Nut/bolt
Spacer
Crossmember
Frame
Washer
Nut/bolt

Grain of salt.

I think it depends on the CM. He looks like he has the 81up flat one.

 

[PrairieDrifter]

Is there a reason they used a copper nut? I ask only because BMW used copper nuts on their manifolds - worked like a lock nut only wasn't so hard to go on and would never seize/rust. I think after they were on-off a couple times, they were kind of done.

I have new stainless bolts for this mount - also picked up a stainless lock nut in case the copper ones are no good.

Thanks fellas - stupid questions, I know, but the devil's in the details.

The copper nut is not factory and probably not proper for the application, I opt to upgrade to grade eights just because of what components it's mounting.

 

[PrairieDrifter]

I think it depends on the CM. He looks like he has the 81up flat one.

Hmmm this may be true. I've just always seen it the way I explained and I haven't seen thousands of these trucks but multiple hundreds. But there's always been people messing with things and what not in these 40 year old trucks.

 

[Frankenchevy]

Hmmm this may be true. I've just always seen it the way I explained and I haven't seen thousands of these trucks but multiple hundreds. But there's always been people messing with things and what not in these 40 year old trucks.

Might also depend on your trans mount. My original combo was a 208/400 with the high pedestal adapter. It would hit the floor if the crossmember was above the frame.

All cucvs are this way...81-84 flat member under the frame.

 

[PrairieDrifter]

Might also depend on your trans mount. My original combo was a 208/400 with the high pedestal adapter. It would hit the floor if the crossmember was above the frame.

All cucvs are this way...81-84 flat member under the frame.

Don't know if I worded it wrong but I meant the crossmember is always on the bottom of the frame. I was trying to explain the order, like exactly how it looks in the OP's original pic.

This is true, I've personally never seen a truck with crossmember mounted on top of the bottom frame rail, so I can't speak on that, but I believe you. I just didn't think that would be an issue as it would be less than a 1/2 inch difference.