88 Fiero GT rear caliper question (Page 1/1)
suzukitom SEP 23, 01:26 PM
Hello, I don't own a Fiero.. (Opels and Suzukis are more my thing) but I am helping a friend to revive her clean original 88 GT which has been sitting for the last 3 years.

A rusted off EGR and chewed wiring harness repairs are now done but the rear rotors and pads are quite rusty and require replacement.

When studying posts and pics of the 1988 rear brake caliper, I think I understand the basics of the unusual semi mechanical parking brake piston within piston design.. but am a bit unclear whether I should be able to compress the caliper piston with a large c-clamp after swinging the outboard half of the csliper out of the way.

As long as the e brake lever on the back of the caliper (which moves freely) is in fully off position will the internal screw attached to this e brake lever also be spun back enough so that I can fully compress the piston in order to install new pads?
Rick Vanderpool SEP 23, 03:20 PM
You can't push the piston in to install new pads. The 88 service manual references using a tool, J36621, to rotate the piston in in order to make enough room to insert the pads. There are several of these tools listed on Ebay. There is an alternative tool from Lisle for the same function. Look up "brake piston rotator tool" to see what is available.

Rick
suzukitom SEP 23, 04:03 PM
Thanks Rick.

I don't have that tool but I was able to use a similar wind back tool on the passenger rear piston to rotate the piston about 1 and a half turns clockwise. that rotation was smooth.. but the piston did not retract at all.

prior to working on the brakes I tested the e brake function and it held and released the rear wheels normally without drag. however when I removed the old pads the new pads require the piston to go in about 4 mm to fit.

a YouTube video demonstrated what looked like a large c clamp on an 88 Fiero to compress the piston. I thought the wind back rotation was needed only to position the piston notches with the nubs on the back of the brake pad?

Link YouTube https://m.youtube.com/watch?v=HR-J0DXHCoc
(Rear brake video around 12 to 16 minute marks)

Do you know whether the e brake lever in off position will has any internal mechanisms inside the piston that prevent the piston from moving inwards if I open the bleeder valve while pressing on the piston?

my main concern is breaking the piston and I have read warnings from folks that say to never press the piston while some say it's doable on the 88 without harm.

I guess I don't understand well enough how the e brake related parts inside the 88 Fiero caliper really work as it seems unique to the Fiero. The final year change doesn't really help in terms of understanding the function by looking at exploded parts diagrams.

[This message has been edited by suzukitom (edited 09-23-2022).]

theogre SEP 23, 05:19 PM
Turning tools including official GM tools often have problems, doesn't work or worse do more damage to system w/ issues.

88 is a bit different but most are same as 84-87 Fiero brakes...
See my Cave, Rear Brakes and rest of section.

88 can use "the clamp method" to retract the pistons w/ minor changes and without removing the big iron part.

remove the lever.
carefully pry the piston back using iron part for outer pad.
Or find big "water pump" pliers to squeeze piston in the body.
Use a block of wood etc between whatever you pry/squeeze and the piston.

It should retract with little effort.

If doesn't move then likely piston is bad. Getting replacement rear calipers is very hard now.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

[This message has been edited by theogre (edited 09-23-2022).]

suzukitom SEP 23, 05:33 PM
Thank you for your reply!

I realize now that I might also have been tried to compress the piston with a full master brake cylinder reservoir and closed bleeder! I will try again this weekend.

I was trying to figure out how to navigate to view your Cave information for a while. Thank you.

Yes, rebuilt parts are hard to find for these orphaned cars. Its a challenge for car enthusiasts trying to cope with a car hating world!

There is something about GM's tendency to stop selling certain cars just when they get interesting and better sorted.. (eg. Fiero, Corvair, Opel GT, Holden (aka SS, etc..)

[This message has been edited by suzukitom (edited 09-23-2022).]

theogre SEP 23, 06:35 PM
Brake Fluid isn't a problem and MC doesn't care about back flow. This is Not like ABS systems that will barf a lung if you compress a piston w/o opening a bleeder. Even than some ABS systems need special tools etc.

You need to drain some fluid out of MC so caliper back flow won't pop the top and make a Huge mass and eat paint.

If you have to open a bleeder, you have more problems like need new hoses to the calipers because Rust and anything w/ Oil/Grease can kill brake rubber parts.

Opal died same way as Vega. Both used same OHC Aluminum engine and burn oil to complete failure and often fast. By the time Cosworth Vega roll out, to most buyers Vega = Crap and Never Buy.
Is why "Iron Duke" was quickly push out for use in Monza and others into early 90's.

[This message has been edited by theogre (edited 09-23-2022).]

suzukitom OCT 13, 05:19 PM
I got a 6" c clamp and was able to compress the piston but only after removing the e brake lever nut and lever. A large 7/8" socket was fitted over the e brake hex/stud so that the stud could spin freely as the piston was compressed. I did not understand why the lever had to be removed first until I realized the lever arm's hex hole locked to the hex on the stud would prevent the stud inside the piston from spinning as the piston was compressed.

There must be a one way ratcheting mechanism inside the piston for the parking brake lever to still work effevtively as the pads wear and the piston moves outward over time.

I did open the bleeders with my 10 mm socket so that dirty fluid could be flushed out. I also used a dollar store turkey baster to withdraw old fluid and add new fluid from/to the master cylinder prior to bleeding at the calipers.

I will post picture later and some more notes for future reference.

[This message has been edited by suzukitom (edited 10-13-2022).]

suzukitom OCT 13, 05:51 PM
Thanks again, The Ogre ..

btw.. Opel and Vega engines are different.

My Opel 1.9 is an all cast iron, cam in head engine developed in Germany and was the basis for a lot of 4 or 6 cylinder variants.

The Vega 2.3 is an all aluminum engine that had a disappointing record for longevity
theogre OCT 13, 09:52 PM
Many Opels Did have same "Vega" Engine w/ same problems...
Very likely depends on exact model, trim level and year, even what county is to sell them.
Uncle had one of this and love the car but junk it because of the engine.

Is sim to "everyone" says 84 Fiero had same engine.... But 84 Fiero w/ Indy trim may have "later" version w/ roller cam setup making a bit more power just because of different cam grind. Other 84 only have them if recall/warranty replace the factory engine.

[This message has been edited by theogre (edited 10-13-2022).]