Nv4500 swap question

[mrgoodwrench]

Working with a 1990 suburban. Im in the process of swapping in my clutch pedal assembly. Got the old one out. Working on drilling the holes in my fire wall for the clutch master cylinder. I found 3 dimples where others said they should be and the out side dimples match the spacing for my clutch masyer cylinder bolt holes so i have drilled those. I made a template of my clutch master cylinder and the center dimple looks a little off. Im wondering if thats just because the clutch master cylinder comes in at a bit of an angle. So question is can anyone confirm thease are the correct holes and does anyone have any idea what size hole to drill for the center hole the big one for the cylinder? I have measured and 1and 1/8 in would be a perfect fit around the cylinder but because of the angle im wondering if i should go larger. Here are some pics from inside and out side of the dimple and 2 holes i have already drilled. I marked the dimple and holes i drilled in yellow ignore the other existing hole.

 

[mrgoodwrench]

 

[obijuank5]

The center hole is offset a bit and yes I suggest 1-1/4" to facilitate install.

 

[ZooMad75]

Here are some pics of my swap that may help you.

https://flic.kr/p/2jnBkRm

 

[ZooMad75]

The center bore of the master cylinder is not exactly centered between the bolts.

https://flic.kr/p/2jnAdrY

https://flic.kr/p/2jnDJgx

 

[nvrenuf]

Here’s an internet pic I stole years ago.

That said, I have a 91 Blazer and can confirm that the dimples on the firewall are correct for the factory parts. You will find more dimples and an embossed shifter boot template on the trans tunnel.

 

[mrgoodwrench]

Thanks you guys are awesome

 

[mrgoodwrench]

My hole saw kit skips 1 and 1/4 weird i have 1 and 1/8 or 1 and 3/8. Should i use one of those or go get 1 and 1/4? Im thinking i could go 1 and 1/8 and grind more if needed or i could go 1 and 3/8 and have easy assembly i would not think that would hurt. What say you guys?

 

[mrgoodwrench]

Used the 1 and 3/8

 

[sweetk30]

And use the 85-91 master to feed the nv4500 slave . I did it on a external slave 4500 no problem .

 

[mrgoodwrench]

And use the 85-91 master to feed the nv4500 slave . I did it on a external slave 4500 no problem .

Yep got one for a 1990 like my truck would have come with that way its easier for me to remember if i ever need to replace it lol

 

[sweetk30]

Got 1 what ?

Slaves are different .

 

[mrgoodwrench]

Got 1 what ?

Slaves are different .

Got a clutch master cylinder. For my model year truck. Got an internal slave by LUK for post 1996 model nv4500.

 

[sweetk30]

Ahh got ya .

 

[YOUNGBLOOD13]

Use 1 1/8. The actual hole will be larger. Clean with die grinder or half-round file

 

[ZooMad75]

I think I went with 1 1/8" for mine. A little action with a half-round file brought it up to the right size to fit.

 

[HankScorpio]

I used my largest step drill bit and finished it off with a carbide burr. The bolt holes lined up fine when I did the swap, dimples were correct.

 

[mrgoodwrench]

Any advise for how to cut the shifter hole in the correct location?

 

[ZooMad75]

Any advise for how to cut the shifter hole in the correct location?

I don't have dimensions but the layout is here.

 

[mrgoodwrench]

I don't have dimensions but the layout is here.

Is that 1in painters tape?