clutch master cylinder firewall holes

[bww3588]

I've searched and searched and I cannot find what I'm looking for.

I'm in the process of swapping my 89 700r4 equipped truck over to a 465. I'm wondering what size I should drill the holes out to put the clutch master cylinder thru. Common sense would tell me to measure the studs on the support rods from the pedals, which is simple enough. Same applies for the master body itself, but I'm not sure if I should put it thru a groomit or just thru bare metal.

Either way, what size have you used and had success with?

 

[nvrenuf]

The mounting studs are metric but a 1/4" hole works perfect. As for the body of the master cylinder, I think I punched a 1" hole but I can't remember for sure. Bare metal, no grommet.

Not sure if you know or not but the firewall is dimpled for the master cylinder and the floor has a dimpled "template" so you'll see exactly where to cut & drill.

 

[bww3588]

The mounting studs are metric but a 1/4" hole works perfect. As for the body of the master cylinder, I think I punched a 1" hole but I can't remember for sure. Bare metal, no grommet.

Not sure if you know or not but the firewall is dimpled for the master cylinder and the floor has a dimpled "template" so you'll see exactly where to cut & drill.

Ok, I'll start with a 1 inch. I just don't have any bits that big so I'll have to source one. That was the main reason for on question. I do already have small pilot holes drilled on the dimples.