I am doing brakes for the first time my 1989 Formula 350 and I had already purchased parts. If I remember correctly WS6 cars did not come with drum brakes. Well I have a rear diff with drums and thought that it was a cheap replacement some one had used because of the 3.73 in it.

Did WS6 cars come with drums? It seems that the pads I got from the store (for a 4 wheel disc car) will not work either...leading me to believe the drum rear end IS factory after all. No wonder this thing stopped like a school bus.

I do remember my 1988 formula 350 had 4 wheel disc, BW 9 bolt, 3.27 gear, and different from calipers. This one however seems to be a cheap optioned WS6 or a fake...

 

I found a piece of paper under the dash pad, no build sheet yet, but it has:
L98 - 5.7 tpi
A31 - pwr windows
K34 - elec. cruise
U21 - cluster inst oil cool temp volts tach
C49 - Defog RR window elec
A90 - Lock control RR compt lid, rem cont elec release

Sounds like some one optioned the car well for the interior at least, but may have skimped on the WS6? Can you order a L98 formula 350 without WS6?

 

1. Formulas are ALL equipped with WS6. Same for GTA's.

2. Only some years the WS6 included rear disc brakes. 86-up its optional.

3. 99% sure in 89 if you had a 350, you had to get the rear discs as well.

 

Odd, the front calipers are even the model for cars with rear drum brakes. This isn't making much sense. It's a factory 1989 Formula 350, with Drum option front calipers, and drum 10 bolt rear.

I was also under the impression WS6 + L98 = automatic 4 wheel disc option, maybe that isn't the case?

 

Judging by this: https://www.thirdgen.org/forums/susp...6-consist.html
and this:
89:
12.7:1 quick ratio steering
Gas-pressurized shocks
Special springs and bushings
36mm front swaybar
24mm rear swaybar
16"x8" Cast aluminum wheels
P24550VR16 Eagle GT 'Gatorback'(subject to availability)
Notes:Rear discs not part of WS6, standard with the 350 TPI option. This included the Limited-slip rear differential as well. Purchase of TPI engine requires purchase of WS6.

The car SHOULD have come with 4 wheel disc due to it being a 350 TPI. Perhaps the disc brake shortage I hear about in the early 90-91 year may have started in 1989? Or am I reading wrong and they mean that it was an option but not required even with a 350?

 

The front calipers are the same all the way from 1982-1992 for both disc/drum and disc/disc. The only ones that use different front calipers are 1LE's.

 

Its 21 years old. You mentioned a 3.73 which is the wrong rear for the car anyway, its supposed to be a 9 bolt so that'd be a 3.70 if someone swapped the gear only. The brakes are not interchangeable from 9 to 10 bolt directly, so you got the brakes with the swapped rear.

 

I must have been really drunk when I counted those bolts. I'll post some pics tonight but there are most certainly two different caliper styles. I have the drum brake style, which makes me think the rear is stock. I appreciate all the help guys, something isn't right with this car, just not sure what.

My 1988 formula 350 has the disc brake style.

Drum car front pads:


Disc car front pads:

 

The top pads are delco moraine pads, used on all disc drums and disc discs except for 1LE. So even if you had J65 brakes (all the way through to 92) you for the delco moraines. The lower pads are PBR pads and only used on the 1LE.
We have an 87 Iroc L98 here w/ J65 brakes, an 88 LB9 w/ J65, an 88 L98 w/ J65, a 92 GTA w/ J65 and they all have the moraine front calipers. Only the 92 GTA has stock pbr rear calipers (89 up on the firebirds and 90 up on the camaros I think)

 

don't tell me that...if that is the case my 1988 formula 350 has 1le brakes. I surely hope it's not a 1le car, as I wrecked it a while back...

 

If you put those with the two metal holders on your 88 it had the double piston calipers.

 

I'll have to check when i get to go back and look at the car, but I am 95% certain they were dual pistol aluminum calipers, that being the reason I thought all WS6 cars had them...

 

Or someone upgraded them, PBR calipers are used on Corvettes and other cars too. The popular Baer Track systems use the same calipers and as such the same pads. You cal also still buy the calipers (hefty price), rotors and the brackets and modify the spindle just like I did for my Baer caliper install.

 

Did some hunting, and if i remember right my speedometer was off when I first got the car, so I used the calculator on here and came out with a rear end that had 3.73 gears. And the speedometer was calibrated for a rear end with 3.23/3.27 gears.

Yall may be right, I'll check tomorrow and see if the rear is a 9 or 10 bolt, since WS6 cars came with ONLY 9 bolt rears right? Luckily my old 1988 firebird has 4 wheel disc and a BW 9 bolt rear with 3.27 posi. I may yank all of that hardware and transfer it over. My 1989 also seems to nose dive on braking, is it possible it still has the disc brake proportioning valve and that is the reason for the poor braking performance?

 

Ok, went with new rotors, old rotors were 2+mm under min spec. Went with new pads and greased everything up with synthetic grease. Those castle nuts always make me paranoid, they are pretty much just finger tightened with a pin through them, but any tighter and it caused bearing bind.

It looks like my bad braking may be from a proportioning valve for the stock disc rear end, which was swapped out for a drum rear end. Looks like the rear end is getting the boot next.

 

Strange..

And no, WS6 cars came with 10 bolts as well.

my 88 formula ws6 has disc front and drum rears, 10 bolt 2.73.

 

Yeah I was just under the impression If the car is a L98 (350 TPI), WS6, it was required to have rear disc brakes. Unless it was a ~1991 model when they disc shortage came along.

I also noticed the rear end has 3.90 ring and pinion (speedo set for 3.73 and is reading 5 mph off). I am just going to have to pull the cover to see why some one would put this rear in a disc car.

 

Well I crawled under and counted the bolts 3 times...It's definitely a 10 bolt LOL

The diff also either has 3.90 or 4.10 ring an pinion. the cover is leaking a bit and has an aftermarket seal (cover lip is bent), so I am a bit curious to see what I find. I'll take pics and post them up later.

Gotta love the mysteries that previous owner's leave you with!

 

Well, I wouldn't put too much time into matching numbers and scratching your head. I have an 89 Formula 305 TPI That has the 5 speed, dual cats, rear discs, etc.. So one would imagine it would have the aluminum rear calipers that WEREN'T so prone to having an e-brake failure... nope, 88 rear with 88 crappy disc brakes, 3.23 gears and an Auburn posi unit. Could be better could be worse. probly blew the original rear.

Point is these cars have had the pedal to the floor more than once or twice by previous owners, and that makes for some repairs along the way. Junkyard motors, trannys and rear ends are just the beginning to the weird things some people probably come across.

EDIT: Forgot to mention my car is a WS6.

 

Agreed, we decided the rear is not original. It has a gov-lock in it, which was not an option in these cars after 82-84? We are thinking that it might be out of an S10 or something, it also has a 4.10 ring and pinion, so no matter the case, it's not original.

I also blew it up this weekend, seems the gov-lock could only handle 1 2.2 60' run on street tires. So I will be putting a 9 bolt borg warner with 3.27 and aluminum calipers back in it very shortly. The thing drives like an open carrier car now, only a one wheel peel.

Ran a 13.9 in the 1/4 mile, track prep was pretty horendous, 2.2 60' , spun hard on launch and most of the 1/8th mile, had to let out just before the 1/8th due to wheel spin going into 3rd. That caused me to short shift into OD, then I had to mash it and kick down into 3rd again. Not a great run, but it was my first time ever to the drag strip.

vid link: http://www.youtube.com/watch?v=-DFKiYmGzQs
After breaking the diff: http://www.youtube.com/watch?v=SyKl1BTHxnc