Rear Brakes: Crank out Calipers VS. Piston Calipers

[LUMINATOR]

On my 1990 chevy lumina it has the crank out style rear calipers (Witch suck! ) I was wondering if anyone had maybe switched there cars over to a piston style design? Not sure is my brake booster is going out or my rear calipers aren't adjusted properly but I've got a spongy brake pedal.  It says to set the rear brakes by pumping the parking brake put after doing that it seems to still be spongy.    

[jake91]

I know Psychomatt said the other day he had gen 2 rears on his GTP, and they are the piston style

[Psych0matt]

On my 1990 chevy lumina it has the crank out style rear calipers (Witch suck! ) I was wondering if anyone had maybe switched there cars over to a piston style design? Not sure is my brake booster is going out or my rear calipers aren't adjusted properly but I've got a spongy brake pedal.  It says to set the rear brakes by pumping the parking brake put after doing that it seems to still be spongy.    

 

Yeah, I have 2nd gen hardware in my rear , but everything back to the complete knuckles are swapped

[LUMINATOR]

Nice! Sounds like it wouldn't be your normal bolt on mod. Did you have to do a lot of modifications to make the 2nd gen hardware work  Psych0matt?

[Psych0matt]

Nice! Sounds like it wouldn't be your normal bolt on mod. Did you have to do a lot of modifications to make the 2nd gen hardware work Psych0matt?

i went all coilovers and adjustable lateral links, not sure if it's doable on stock

[LUMINATOR]

Oh ok! 

[Schurkey]

On my 1990 chevy lumina it has the crank out style rear calipers (Witch suck! ) I was wondering if anyone had maybe switched there cars over to a piston style design?

Both designs use pistons in the rear calipers.  Does the park brake work well?

 

When the boosters failed in my two first-gen luminas, the pedal was hard, not spongy.  Consider bleeding the brakes thoroughly.

[jman093]

I don't hate the calipers with integral parking brakes. To me it beats having an entire separate drum braking system just for the park brake. Lots of cars use the integral style calipers. True the w-body 88-93 ones have sticking problems which give them a bad rap on this forum, but most are fine. When I 2/3G aluminum rear knuckle swapped my old GTP I used 3G GP brake calipers that kept the integral parking brake.

 

http://www.w-body.com/topic/44745-bob-and-robs-gen-2-aluminum-rear-knuckle-and-brake-upgrade-how-to-with-pics/

[55trucker]

Interesting swap & writeup,

 

before I would attempt this swap I'd like to know if there is any change at all where the rear track width is concerned (measuring the distance from the hub flange to hub flange without the wheels on), and if the hub centreline of the gen2 knuckle places the wheel in the exact same location as the Gen1 knuckle for track width & ride height purposes? I did not see any comparison where the hub location is in respect to both knuckles. The gen2 cars make use of a wheel that has a deep offset (moves the wheel inboard) whereas the Gen1 cars make use of a shallower offset wheel (moves the wheel outboard).

 

Seeing as the car that was pictured has a modified rear suspension that is fully adjustable one can compensate for ride height & track width but one can't adjust those two on an unmodified suspension Gen1 strut.

 

will the original Gen1 lateral links be the proper length to bolt to the Gen2 knuckle?

 

any info on this?

[LUMINATOR]

Both designs use pistons in the rear calipers.  Does the park brake work well?

 

When the boosters failed in my two first-gen luminas, the pedal was hard, not spongy.  Consider bleeding the brakes thoroughly.

The park brake does not work the best. I set the the park brake, jacked it up I could spin the right rear tire but the left rear was locked up how its suppose it be when park brake is applied.  I probably need new cables, I mean I guess the car is 25 years old  . I'll try bleeding the brakes out and let you guys know what I end up with! 

[jman093]

Interesting swap & writeup,

 

before I would attempt this swap I'd like to know if there is any change at all where the rear track width is concerned (measuring the distance from the hub flange to hub flange without the wheels on), and if the hub centreline of the gen2 knuckle places the wheel in the exact same location as the Gen1 knuckle for track width & ride height purposes? I did not see any comparison where the hub location is in respect to both knuckles. The gen2 cars make use of a wheel that has a deep offset (moves the wheel inboard) whereas the Gen1 cars make use of a shallower offset wheel (moves the wheel outboard).

 

Seeing as the car that was pictured has a modified rear suspension that is fully adjustable one can compensate for ride height & track width but one can't adjust those two on an unmodified suspension Gen1 strut.

 

will the original Gen1 lateral links be the proper length to bolt to the Gen2 knuckle?

 

any info on this?

 

The track width doesn't change. Lateral links are the same length as first gens as well. Difference is in the subframe.

[Psych0matt]

I don't hate the calipers with integral parking brakes. To me it beats having an entire separate drum braking system just for the park brake. Lots of cars use the integral style calipers. True the w-body 88-93 ones have sticking problems which give them a bad rap on this forum, but most are fine. When I 2/3G aluminum rear knuckle swapped my old GTP I used 3G GP brake calipers that kept the integral parking brake.

 

http://www.w-body.com/topic/44745-bob-and-robs-gen-2-aluminum-rear-knuckle-and-brake-upgrade-how-to-with-pics/

so are 3G calipers a direct bolt on swap? And then you can use the integral parking brake (with the right cable set up)? This sounds easier than building a 2g park brake. Is there any other advantages? I can find these all day long

[55trucker]

The park brake does not work the best. I set the the park brake, jacked it up I could spin the right rear tire but the left rear was locked up how its suppose it be when park brake is applied.  I probably need new cables, I mean I guess the car is 25 years old  . I'll try bleeding the brakes out and let you guys know what I end up with! 

You'll need to determine whether the park cable for that side is at fault or the caliper park lever or the caliper sliders have seized.

The calipers will work, not the best, the rear calipers on these cars are the same design as the rears on a Fiero and those work *better*, the park brake HAS to kept in satisfactory working condition for the rears to adjust up properly and the rears need to be adjusted up to prevent pedal travel.

 

The 88-93 booster is a real question mark.......the 94 model year introduced a newer better design that carried over to 99, it is physically similar, the cam-lock mechanism looks the same, but I do not know for sure whether that later booster lock design will attach to the pre 94 car's mounting flange. If someone else knows for sure that it would and can let us know if it fits that's where I would start where a mod is concerned.

[55trucker]

The track width doesn't change. Lateral links are the same length as first gens as well. Difference is in the subframe.

I suppose as well that one could not use the Gen2 knuckles on a Gen1 car that still makes use of the leaf spring.

[jman093]

so are 3G calipers a direct bolt on swap? And then you can use the integral parking brake (with the right cable set up)? This sounds easier than building a 2g park brake. Is there any other advantages? I can find these all day long

 

I put the a 3G knuckle assembly on my 96 GTP. It swaps just the same as the 2G one BobRob describe. Yeah it will need the 3G cables, but I don't think they hooked directly up the 1G front cable. I think it needed fenagled somehow, I don't really remember on that. Way too many Grand Prixs ago for me. I do remember it had some dinky little pads, which I didn't like. Though it uses the 2G style parking brake, what would be cool is GXP rear brakes. I may revisit it all again on the black TGP sometime.

 

 

I suppose as well that one could not use the Gen2 knuckles on a Gen1 car that still makes use of the leaf spring.

 

No. The swap does require coilovers, which are heavier than the composite leaf spring setup. So there won't be any unsprung weight saving in the end with the aluminum knuckle. It just kind of offsets the added coilover weight. The only real advantage of the coilover setup is the ride height adjustment. If one does not care about lowering the car, it's just best to leave it all stock (or 88-93 cars wanting a better calipers can swap to 94-up ones).

[Psych0matt]

Well I have the BobRob swap, and if the only benefit to a 3G swap is a better ebrake setup I'm not gonna do another knuckle swap just for that. Now, is the gxp swap doable on 2g hardware, or is that another knuckle swap as well?

[jman093]

Well I have the BobRob swap, and if the only benefit to a 3G swap is a better ebrake setup I'm not gonna do another knuckle swap just for that. Now, is the gxp swap doable on 2g hardware, or is that another knuckle swap as well?

 

That I don't know, but looking up part numbers on gmpartsgiant there is only one part number on each side for an 06 Grand Prix knuckle. Makes me think it is the same GXP or otherwise. The same part numbers are listed when looking up a 2003 Grand Prix. So I assume all 2G/3G knuckles are the exact same. I imagine the backing plate and everything that attaches to the knuckle is all way different though.

[Psych0matt]

I might have to go to a yard and experiment. I wouldn't mind going 3G brakes if I can swap some parts, and not the whole knuckle

[l67ss]

You can use gxp brakes on gen 2 spindles....on a 1g thatd cause brake imbalance tho

[Psych0matt]

You can use gxp brakes on gen 2 spindles....on a 1g thatd cause brake imbalance tho

how so?

[l67ss]

Assuming you have 96+ front brakes they are 11.25". Gxp rears are 12" vented

[White93z34]

Biggest problems with the original rear brakes is the sliders and the tendancy for the rear pistons to fail to retract. I've yet to have rear calipers last. 

 

the 94+ brakes still have a actuator caliper and are the easiest and only "bolt on" swap available for us. I've had those calipers fail, I've had sliders seized, but not to near the extent that the original 88-93' crap is. 

[vipmiller803]

Assuming you have 96+ front brakes they are 11.25". Gxp rears are 12" vented

Good for donuts, deadly for the road...

[Psych0matt]

Ok, but for my use, would it be an unsafe or impractical swap/solution for having a functioning ebrake? The GTP is a cruiser with the occasional fun cornering time, so I'm not heavy into braking like on a track or anything (although I wanna autoX it sometime)

[l67ss]

Assuming you have 96+ fronts they are 11.25". Gxp rears are 12" vented