From drum to disk...
06-02-2003, 12:11 PM
#2
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Car: 1986 Firebird
Engine: 2.8 V6
Transmission: 700R4
From message https://www.thirdgen.org/techbb2/sho...hreadid=182261 ...
You could probably do a few searches on the suspension/chassis/brakes board; i know it's been asked plenty of times. Not sure if anyone's done it, other than swapping "drum" 28 spline axleshafts into a disc-brake axle that had 26 spline axleshafts.
Originally posted by TomP
As far as changing over to discs; did you want to bolt the discs to the drum axle? The drum axle has a different flange on the axle tubes. It's a rectangular shape, the disc axle has a square flange. It's been said that the rectangular flange could be cut down and redrilled into the pattern for rear discs. Also, on rear disc axles, the axleshaft hubs are a bit wider (extend out more widely after the lug nuts end). The discs won't fit over the drum axleshafts. Guys have had to get the axleshaft hubs turned down at machine shops to get the disc to fit over them. (This was usually done when they found the stronger 28 spline axleshafts off a rear drum car, and wanted to install the shafts on their disc brake axle.) One innovative guy put the car in the air on 4 jackstands, started the engine, and put the car in drive... he then ground off the necessary amount of metal from the axleshaft hubs using an angle grinder, as the car turned the hubs. Sounds a bit risky; don't know how fast those axleshafts were spinning!
As far as changing over to discs; did you want to bolt the discs to the drum axle? The drum axle has a different flange on the axle tubes. It's a rectangular shape, the disc axle has a square flange. It's been said that the rectangular flange could be cut down and redrilled into the pattern for rear discs. Also, on rear disc axles, the axleshaft hubs are a bit wider (extend out more widely after the lug nuts end). The discs won't fit over the drum axleshafts. Guys have had to get the axleshaft hubs turned down at machine shops to get the disc to fit over them. (This was usually done when they found the stronger 28 spline axleshafts off a rear drum car, and wanted to install the shafts on their disc brake axle.) One innovative guy put the car in the air on 4 jackstands, started the engine, and put the car in drive... he then ground off the necessary amount of metal from the axleshaft hubs using an angle grinder, as the car turned the hubs. Sounds a bit risky; don't know how fast those axleshafts were spinning!
06-02-2003, 12:16 PM
#3
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Car: 1986 Firebird
Engine: 2.8 V6
Transmission: 700R4
Duh; I could give more info...
As to the master cylinder, you wouldn't have to change it. J65 (82-88) rear discs used a different master cylinder with a larger bore (1 inch) instead of a 24mm bore. Apeiron dug up a TSB from GM in which customers were complaining the brakes were too hard to push. (Why would you get discs if you didn't want improved pedal feel?) Anyway, GM said the J50 (disk/drum, all years) m/c could be installed as a "fix". J50 m/c's were used on the 89-92 rear disc setups.
Prop valve should be changed. New from my dealer was $72, I hear they're cheaper thru Dale Lambert, andprobably cheaper thru http://www.gmpartsdirect.com . On 4-wheel-disc systems, the prop valve doesn't really proportion. All 4 wheels get an equal amount of braking pressure. The prop valve on rear disc f-bodies is really just there to (A) split the single front output of the m/c into two outputs for left and right, and, (B) to house the "low brake pressure" warning light.
82-88 rear discs were recalled due to a defect inside the actuator (caliper piston). If you do a search on the suspension/chassis/brakes forum, you'll find my messages, in which I give the part # for the recall kit. Thru GMpartsdirect, it was $40. Individual parts from a dealer run $90/actuator!! The GM recall kit (which the dealer won't give you the part # of, those sneaky bastards) contains both actuators, two rebuild kits (seals), and even has the caliper-to-piston anti-rattle clip. I paid $8/clip before i bought the recall kit, dammit...
As to the master cylinder, you wouldn't have to change it. J65 (82-88) rear discs used a different master cylinder with a larger bore (1 inch) instead of a 24mm bore. Apeiron dug up a TSB from GM in which customers were complaining the brakes were too hard to push. (Why would you get discs if you didn't want improved pedal feel?) Anyway, GM said the J50 (disk/drum, all years) m/c could be installed as a "fix". J50 m/c's were used on the 89-92 rear disc setups.
Prop valve should be changed. New from my dealer was $72, I hear they're cheaper thru Dale Lambert, andprobably cheaper thru http://www.gmpartsdirect.com . On 4-wheel-disc systems, the prop valve doesn't really proportion. All 4 wheels get an equal amount of braking pressure. The prop valve on rear disc f-bodies is really just there to (A) split the single front output of the m/c into two outputs for left and right, and, (B) to house the "low brake pressure" warning light.
82-88 rear discs were recalled due to a defect inside the actuator (caliper piston). If you do a search on the suspension/chassis/brakes forum, you'll find my messages, in which I give the part # for the recall kit. Thru GMpartsdirect, it was $40. Individual parts from a dealer run $90/actuator!! The GM recall kit (which the dealer won't give you the part # of, those sneaky bastards) contains both actuators, two rebuild kits (seals), and even has the caliper-to-piston anti-rattle clip. I paid $8/clip before i bought the recall kit, dammit...
06-02-2003, 12:28 PM
#4
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Yeah, I was hoping for a bolt-on solution...guess not huh. Don't wanna mod the car too much.
Well anyones, I guess I'll stick with the drums and get cross-drilled rotors up front.
The drums are solid performers though, never had any problems with'em warping or making weird noise.
Thanks.
-Akshay
89 RS T-5
Well anyones, I guess I'll stick with the drums and get cross-drilled rotors up front.
The drums are solid performers though, never had any problems with'em warping or making weird noise.
Thanks.
-Akshay
89 RS T-5
06-02-2003, 01:08 PM
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Car: 1986 Firebird
Engine: 2.8 V6
Transmission: 700R4
Might be better off; don't forget that discs weigh more... not only do you have the weight of the rotors, but you've also got the weight of the calipers and caliper brackets!
06-02-2003, 04:25 PM
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Car: '87 Chev
Engine: 60*V6
Transmission: DY T700
Baer sells a kit for drum rear axles to be converted to rear disc- complete bolt on. Sells for $785.00. Then you have to try and disassemble everything and pull the axles to get them on.
You are better off buying a disc axle and swapping it in.
You are better off buying a disc axle and swapping it in.
06-02-2003, 08:19 PM
#7
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OR:
Convert to LS1 (sorry to whoever I told you could convert to LT1 style...I hadn't checked it in a while.) style on your own.
http://members.fbody.com/86firebird/ls1/ls1brakes.htm
Convert to LS1 (sorry to whoever I told you could convert to LT1 style...I hadn't checked it in a while.) style on your own.
http://members.fbody.com/86firebird/ls1/ls1brakes.htm
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06-02-2003, 10:44 PM
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Car: 1986 Firebird
Engine: 2.8 V6
Transmission: 700R4
Woah, thanks for the link! NEW PBR calipers are $60?? Hell, maybe I'll ditch my cast iron 82-88 style and just buy new PBR's. I coulda sworn they were upwards of $200/new from GM... hot damn! Are those the same PBR's as on the 89-92's? I think i gotta do some digging at the suspension forum...
06-06-2003, 02:23 PM
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Car: 86 firebird
Engine: v6
Transmission: 7004r
drum to disk..
how do you know which you have on your car. I am sitting at home waitting for my mechanic to help me. (okay so it's my father)
but i went to pick them up at autozone and he asked drum or disk.
So i got a print out and bought my convertier kit for my AC
1986 Firebird v6 (does that matter for brakes?)
but i went to pick them up at autozone and he asked drum or disk.
So i got a print out and bought my convertier kit for my AC 1986 Firebird v6 (does that matter for brakes?)
06-06-2003, 02:44 PM
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Re: drum to disk..
Originally posted by cfirebird86
how do you know which you have on your car. I am sitting at home waitting for my mechanic to help me. (okay so it's my father)
but i went to pick them up at autozone and he asked drum or disk. So i got a print out and bought my convertier kit for my AC
1986 Firebird v6 (does that matter for brakes?)
how do you know which you have on your car. I am sitting at home waitting for my mechanic to help me. (okay so it's my father)
but i went to pick them up at autozone and he asked drum or disk.
So i got a print out and bought my convertier kit for my AC 1986 Firebird v6 (does that matter for brakes?)
The drums brakes are rusty looking and are barrel shaped. Whereas disks brakes have a shiny circular disk.
You can see the difference between the two without taking the tires off your car.
-Akshay
89 RS T-5
06-07-2003, 08:42 PM
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Car: 1986 Firebird
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Transmission: 700R4
CFirebird, the 82-92 Haynes manual gives a photograph-by-photograph (not hand-drawn pictures) sequence on how to replace the disc brake pads and drum brake shoes... if you pick one up (about $15 at Pep Boys), you'll see the differences...
06-07-2003, 10:19 PM
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Car: 86 firebird
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Picked up brakes
thank you guys.
Picked up my brakes at Advance. LLT Disc pads for 16.99, I will be putting them on tomorrow. IF doesn't rain.
Picked up my brakes at Advance. LLT Disc pads for 16.99, I will be putting them on tomorrow. IF doesn't rain.
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