Gearbox crossmember mounts on GD

[shuggy]

Ok guys, everyone knows that if your replacing the 4spd with a 5 speed all you need to do is move the gearbox crossmember back to the second two holes right?

Wrong.

The second set of holes on my GD aren't threaded! What can I do? Cut the floor of the car, put some nuts in there and weld the floor back up?

[astronturbo77]

your car used to be auto then!

[shuggy]

I know for a fact that it wasn't. Its a57 sports pack and vin states manual. But that doesnt help how I'm going to fix it..

[davetrees]

Tap a thread into the holes ? Or aren't they deep enough ?

Alternatively, just drill the holes right through the floor, drop a long bolt in the top, and put the nuts on the bottom. The carpet will hide the bolt heads.

[astronturbo77]

well not trying to argue but all auto galants ive seen from personal experience of nearly owning 10 of them have no threads in the back holes unless they are auto, could be wrong..

you can get these 'nut' plate things that are put in a hole with a tool similar to a pop rivet gun, they have the thread in them. would be the easiest solution.

[75wagon]

Ok guys, everyone knows that if your replacing the 4spd with a 5 speed all you need to do is move the gearbox crossmember back to the second two holes right?

Wrong.

Well that's the way it was with my wagon, so I don't know why yours is different?

well not trying to argue but all auto galants ive seen from personal experience of nearly owning 10 of them have no threads in the back holes unless they are auto, could be wrong..

From my understanding, the 4 speeds use the front mount holes, and the autos/5 speeds use the rear set.
I could be wrong about the auto? I have an auto in the garage I could dig out and measure if I needed too?

Shuggy, don't just drill holes through the chassis rail/floor and use bolts. You'll end up crushing the chassis rail. If you do use bolts through the floor, you'll need to fit crush tubes to stop the chassis rail from being compressed.crushed.

Dave...

[astronturbo77]

yes they use the 4sp rear holes and the ones behind it. if they arent threaded then it was auto.

[81GL]

My GD started life as an auto... & its been a while, but I'm fairly certain that both mine have threads

Shuggy, before getting carried away, have you test fitted the box in there to make sure those holes do actually line up?

Nick.

[davetrees]

don't just drill holes through the chassis rail/floor and use bolts. You'll end up crushing the chassis rail. If you do use bolts through the floor, you'll need to fit crush tubes to stop the chassis rail from being compressed

You shouldn't need to do them up that tight !

[shuggy]

I like the rivet idea. Yes I measured from box face to mount. The box length is the same, just the mount is in a diff spot.

The other thing I thought about was those winged nuts that you push in and they clip inside, used for walls and houses n shit? Know what I mean?

[Smithy]

The threaded inserts are called nutserts shuggy

[davetrees]

Would nutserts/rivnuts hold a vertical downwards load like that ?

Another option might be :
- weld a nut to a 1" square piece of steel (or a decent size washer)
- enlarge hole in rail to diameter of nut
- weld plate/washer to rail

.... effectively creating a captive nut inside the rail, but stronger than a nutsert ?

[81GL]

effectively creating a captive nut inside the rail, but stronger than a nutsert ?

Not really, as all your weight is going to be held by the weld, that would be pretty likely to fail, being cars are made from tin cans & not even 3mm that you can get a decent weld onto.

Shuggy, before butchering anything on the chassis, just modify the standard crossmember to suit.
for example, this was in my gh, and I've got a similare one in the galant:


Can always do it properly later once a proper way has been found.

[davetrees]

Not really, as all your weight is going to be held by the weld, that would be pretty likely to fail, being cars are made from tin cans & not even 3mm that you can get a decent weld onto

I dunno who does your welding ...

[Tj.]

My hardtop started life as an auto and thus doesn't have captured nuts in the front set of holes. Now I've installed a 4sp for now so I need those front holes.
What I ended up doing was using a flat based nut, it kinda looks like it has a built-in washer. I got a length of reasonably heavy gauge wire bout the same as a coathanger (or Yknow, a coathanger) wrap the wire around the nut and twist it tight like wrapping a bonbon.
Thread it through the front end of the chassis rail and start with the nut at the back. Use a bit of loctite for good measure.
It'll take a few goes and a lot of swearing but it can be done.

Alternately, if you're good with a welded you can tack the nut onto the wire, my old man did this the first time we put the box in the coupe.

[paully77galant]

use a small hole saw to cut a hole into the side of the rail, drop in a flared nut, bolt up ya box, then weld the peice of steel that you cut out with the hole saw back in.