I have a 92 rs with the stock 2.73 open rear, and I am thinking of upgrading to a 9bolt posi with 3.27 gears and disc brakes. What do I need to complete the conversion? I know i need to swap the proportioning valve, but do i need to swap the master cylinder? Also, as far as I know, the speedometer is electronic.. so can I swap speedo gears after the switch or do I need to electronically calibrate? If I can sawp the gears, anyone know the part no's?
Any other suggestions??
Thanks

 

What year is the 9-bolt from? If its 89 or 90, its a direct bolt in. If you've got an 85-88, then you'll need a new master cylinder and proportioning valve, from what I heard. The speedo gears for a 3.27 are the same as 3.23 and can be found in the FAQ on this site.

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I believe the rear is from an 86 or 87.. So I will have to swap the master cylinder as well. Does an 86 rear have 26 or 28 spline axles? I believe I have 28 splines now on my 92, and Im not crazy about going to 26 spline..
Thanks for the input.

 

The splines don't matter, you are going from one kind of rear to a complete other one. With a 305 TBI you'll never have an issue with axle splines regardless.

Is this a 5-speed or auto? It makes a big difference on the speedo gears.

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The car is an automatic.
So, exactly what else in addition to the proportioning valve and master cylinder will be necessary for the swap? Power booster? Also, how much of a difference will I notice by only going to a 3.27? Should I not even bother and go with at least a 3.42? I dont want to spend all the time and $$$ to end up disappointed in the end.

 

I can't help you, but i do have a similar question. I have an 89 2:73 drum rear and will be going to a 3:73 drum year (i don't know what year it is.. it does have 26 splines though) will i need to chane the master cylinder.. i don't think i do, but i want to make sure

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No you don't need to change M/C or the prop valve. The only time you need to change them is when you go from drums to disc or for some weird reason the other way around. But when going from drum to drum it isn't nessary. The gear ratio changing has no effect on the brakes. Also from 88 on the master cylinder is the same with disc or drums. So the disc brake M/C can be used on either disc or drums, just a prop valve change for that.