JA1 vs. JA2/JA8 Brake question.

[Sigurd Jarlson]

what determined what system went on our cars? My 87 Century had the light duty brakes, but my 88 Ciera has the medium duty. It's an FE3, but is that the only determining factor?

[86euro]

Well, I know with a Celebrity, the only thing that mandated the larger brakes was if it was ordered or not. I'm guessing the other brands were the same.

[CamoDeafie]

other determining factors, at what i know; whether or not alloys were chosen, wheter or not a 4 speed/v6 were optioned, i've yet to hear of a sporty trim car having JA1s, but at least in 1993, it no longer JA2, its JM4s with the ABS and 115mm bolt pattern from 89-1996 for the Cieras at least..I gather the same for Centurys...i;ve never seen a wagon with the JA1 option, but it wouldnt surprise me to find that 1983-1985 Chevy Celebrity wagons got tthe JA1s as standard, and upgraded to JA2 by dealer or factory if selected on options, ive yet to hear of a 4 speed/ V6 car having JA1s, but its possible. the JA1 is light duty, JA2 is medium duty, apparently theres also a "heavy duty" cooling system available for transmissions or engines, with tow hitches, again, presumably wagons. its a toss up really. if you;'ve 13" wheels, likely JA1s, if 14" wheels either. if 1994+, JM4 ABS....

[mechanizeddeath]

Wow Camo, again you astound with the knowledge! :D So mine is "JM4" then? I didn't know that, I just got what the NAPA computer said.

[CamoDeafie]

if theres a badge saying ABS, then yes its JM4. but computers only say JA2s or jA8 lol.

[a1veedubber]

I have never seen any rhyme or reason to what brakes a certain car has. 4cyl/3speed cars tend to have the JA1 and 6cyl/4speed cars tend to have JA2/JA8 but I have seen many exceptions to that rule!

IIRC the A-bodies are the only FWD GMs that had different bolt patterns available (5x100 & 5x115).

[CamoDeafie]

Matt.; correct! the N body dont quite count as they were split in 3 distinct generations that I know of (the 80s, then the 1991-1997, then 1997-current?) with the 1998+ having 5x115s and looking much more like the W body cars...

[86euro]

other determining factors, at what i know; whether or not alloys were chosen, wheter or not a 4 speed/v6 were optioned, i've yet to hear of a sporty trim car having JA1s, but at least in 1993, it no longer JA2, its JM4s with the ABS and 115mm bolt pattern from 89-1996 for the Cieras at least..I gather the same for Centurys...i;ve never seen a wagon with the JA1 option, but it wouldnt surprise me to find that 1983-1985 Chevy Celebrity wagons got tthe JA1s as standard, and upgraded to JA2 by dealer or factory if selected on options, ive yet to hear of a 4 speed/ V6 car having JA1s, but its possible. the JA1 is light duty, JA2 is medium duty, apparently theres also a "heavy duty" cooling system available for transmissions or engines, with tow hitches, again, presumably wagons. its a toss up really. if you;'ve 13" wheels, likely JA1s, if 14" wheels either. if 1994+, JM4 ABS....

Yeah I think your right about the wagons always getting JA2. Celebs had alloys for both bolt patterns in all the years, and I'm pretty sure I've seen a couple with 4spd auto and JA1 brakes.

BTW, JA1 brakes should have been illegal, lol. The most I ever got out of a set of front pads was MAYBE 20k, where JA2 is usually 40-50k.

[Jet]

My '93 Ciera with the 2.2L 4-cylinder and 3-speed auto has the JA2, thankfully.

[Sigurd Jarlson]

thanks. good info here.

[mechanizeddeath]

if theres a badge saying ABS, then yes its JM4. but computers only say JA2s or jA8 lol.

No badge visible on the body, but I've felt them kick in once and the pedal says the car is so equipped.

Weird too, because it seemed like GM was especially proud to advertise ABS back then, heck some of those Pontiacs had "ABS" on the center caps, not to mention the body badging.

[Buick_powa]

So if my Coupe is equiped with v6 4 spd, has a suplementary trans cooler, alloy wheels. Do i have the JA8?

[CamoDeafie]

probable; best way to check, spid label in trunk

[Slacker]

probable; best way to check, spid label in trunk

That's how I do it. I can never remember what I have when I'm changing my brakes. lol

[Sigurd Jarlson]

My label was long gone. I had to measure my rotors....