12 Rotors, better handling?

[Pat]

I've heard there's more than just braking that improves, handling does too? If that's the case I'll be real interested. I know the upper control arms are different so I'm guessing the geometry improves. Can anyone back this up?

 

[RealFastV6]

The Spindle is taller, the upper a-arm is longer I think (can't remember now), and the wheel base is widened by 1" total (.5" per side).

 

[Pat]

So adding a 1" will improve handling that much? I've gone through the whole front end and replaced everything already, but am interested in buying 12 brakes. Either the Bear kit or the custom spindles peices. Just looking at my options

 

[Ormand]

Handling

The 1" increase in front track is not what improves the handling. GM deliberately designed a lot of roll-understeer into the front suspension, to make the car "safer". The taller "B" body spindles, in conjunction with the shorter upper A arms, will change this to a more neutral design. This is explained,more or less, at the Hotchkiss web site, under the title "Negative Camber Curve". Basically, it keeps the outside front wheel from "tucking under" in a hard corner.

 

[salvageV6]

I would think the 16 and 17 inch tires that most people go to would be the major factor in the handling issue.

 

[UNGN]

Do search on 12 inch brake conversions. Search words like "12" "spindle" "UCA" "UBB". Lots of discussion on this. Remember that no 12" brake conversion will work with GN wheels. You can probably us 2nd gen F body 11" disks and taller F body spindles, for better braking and handling.

T-type wheels clear 12" brakes.

 

[Pat]

Thanks Ormand! That's the kind of answer I was looking for. I knew that the spindle ass. was different, but didn't know if this was better or not. A freind told me I would see a huge improvement in handling go with this style, but hadn't heard that anywhere.

 

[turbomark]

12 inch brake conversion

I have the 12 inch brake conversion on my '84 GN. I used the B-body spindles, IROC 1LE rotors, and the B-body calipers. For the swap to work you also have to install the Hotchkiss tubular upper A-arms. I have the alignment set at -.25 degree camber, 3 degrees caster, and .1 degree total toe-in. The car scrubs a lot less, but keep in mind its still a big soft sedan chassis. The stopping power is serious, but using the B-body calipers increases the pedal travel, which takes a little getting used to. For wheels, I'm using the 16 inch GTA rear wheels on the front, with GTA fronts on the back.