1986 GT Rear Brake Shoes and Drums

[86Stripper]

I have an 1986 GT Automatic and I'm looking for information on the rear brake shoes and drums. Seems like a simple issue but got somewhat complicated as these things sometimes do.

The car is a fairly low mileage (60K) original with the original 8.8" rear end and original finned drums. The drums are Ford logo D9ZC-1126-AA date stamped 86C7B which is right on the production date of the car. The brake shoes were replaced in the past with Raybestos units with inked on number BPI-4090-FE. It looks like the wheel cylinders were replaced when the shoes were replaced. One of the wheel cylinders leaked which prompted me to dive into the rear brakes. Cleaned everything and bought a new hardware kit but ran into problems getting the supposedly correct rear shoes.

Issue is:

Raybestos and other suppliers such as Delco list separate brake shoes for 1979-86 versus 1987-93. Motorcraft seems to list the same shoes for 1979-1993 but their information is hard to follow. I always thought that the shoes were the same from 1979 to 1993. I have a complete 1991 5.0L automatic 8.8" rear end I bought for a spare which has nice Raybestos brake shoes on it with good looking drums. Inked on the shoes is the same Raybestos number of BPI-4090-FE. This number seems to correlate with Raybestos part number 569PG for 1987-1993. 1979-1986 are listed as part number 474PG. My question is: are the shoes actually different and if so what is different. Backing plates? Shoe size? Shoe material? What else?

Also, Raybestos lists different drums for automatic cars for 1989-1991. Pictures seem to show that they are not finned like the standard trans and 1979-86 cars. Part number for standard trans is the same as for 1979-86. My spare 1991 automatic rear has what looks like replacement drums that are finned. Anyone know anything about rear drum differences?

[Haystack]

Stock rear drums should be 9" no matter which year it is. When they were out of stock on my 86 cougar part number, I've given them 87- 93 cars to look it up as before. Now the part numbers all appear to be the same. I had to "special order" brake shoes for my 9" brakes. Had to come from Colorado, closest place with them in stock.

[erratic50]

I've heard others say this 9" no matter what before. My early production run 86 came with pathetically smaller rear drums. Only one anyone has ever heard of or seen it seems, but when I swapped in the 1989 GT rear diff back in the 90's the rear brakes on it were identical to the 89 LX sport convertible we had and very clearly larger than what was factory. Shoes were different, etc.

Fun - poorly documented - variations in these cars. The last time I had to run down brakes for my original rear ended before I scattered it I had to have NAPA special order them. The parts guy went off numbers on the shoe and a few measurements. I have absolutely no idea what other car used those damn Mickey Mouse brakes.

Probably my mom's 86 Tempo..... Never had any love loss for that car even though it was the first 5 speed I had ever driven. Silly to think how well those sideways mounted fwd 2.3L 5-speed cars actually ran and how dead as a door nail the N/A 2.3 was in the Mustang.

[86Stripper]

Thanks for replies. I appreciate it.

Interesting info erratic50. The 1986 cars being sort of a hybrid intro to the later 1987-1993 cars have some unfortunate quirks when trying to get parts. A number of parts are one year only.

The drums are definitely 9" finned and certainly are date coded correct for the car. So, I'm assuming they are original. I'll post a picture when I can get one. The brake shoes installed were what appear to be Raybestos 569PG for the later 1987-93 cars. I have no idea what brake shoes the car came with. What sent me down this path is that the brake shoes installed just don't seem to fit completely right. I've done a lot of brake jobs and the subtleties can sometimes bite you. Just trying to be extra cautious as I intend to take the car to the drag strip for the local Friday night street legals and I'm going to be stopping regularly from 90 MPH (hopefully) and possibly more later.

Luckily the local Lordco auto parts store was able to order a set of the supposedly correct for 1979 to 1986 Raybestos 474PG brake shoes from their local warehouse where the inventory computer says they are in stock. Supposed to come today but I haven't heard anything yet so may be Monday now. They have the Raybestos 569PG for the 1987-93 cars in stock which are the same as the two sets I have. Will be interesting to see what the differences are if they actually come.

There is a quite good local NAPA store here with a large local NAPA warehouse close by so if I strike out at Lordco I'll try them.

One thing I can say is that the car stopped really well with the installed brakes. No issues at all. The only problem was the leaky wheel cylinder which got me going on all of this.

Will post the results.

[Haystack]

One of my cars has 10" drums which doesn't even show in most parts store computers. I usually get 10" ranger brakes and they looked identicle.

[86Stripper]

I have run across listings for 10" brakes and hardware parts. For example the Raybestos spring hardware kit for 10" is H7248 and the 9" is H7246. The 10" are listed as heavy duty in some listings and might have been an option on early cars. Which one or your cars has the 10" brakes?

[erratic50]

Yea - no way my original brakes were 9". I can't tell you what they were because that rear diff is long gone.

[gr79]

Gotta love it when auto parts started using pc databases.
Prior to that used books and microfiche. Slower but more accurate and detailed.

Over the years, a lot of database info is miss-entered or missed entirely.
Product line coverage has changed too. More generic universal fit product lines for older apps.

#474 and #569 interchange. Both 9", same width.
I mix and match shoes between my 79 Cobra and 93 Ranger as needed.
474 is for years up to about 86, newer number 569 listed for early and late.
I believe the diff is in the hardware holes/slots.

Found Rock Auto is good source for accurate as possible info and parts.
NPD good too. Lists 10" app for 81-82 Mustang.
Seen 9" as having both 1.75 and 1.81 shoe widths.

Auto chain stores not always consistent with each other. E-bay iffy. Must do homework.

Different companies may have different interchange numbers.

Numbers also code the type of product build.
Shoes with bonded or riveted shoe pads.
Different types of pad friction material. Semi- Metallic or organic.
Anti rust metal shoe coating or not.
Reman or new metal shoes.
Shape of friction material.
Kits or 'A la carte'.

[86Stripper]

Haystack

Just for your info the Raybestos online catalogue lists 9" and 10" brakes for the 1986 and 1987 Cougars.

Shoes are 9" 474PG same as 1979-86 Mustang and 10" 151PG. 10" are also listed for 1979-84 Mustang. ???
Wheel cylinders for 10" are different than 9" and are WC37697 and WC37698. Different for each side whereas the Mustang 9" take the same wheel cylinder for each side.
Drums for 10" are 2679 and the picture shows them as not being finned. My experience with Raybestos pictures over time is that they are pretty accurate. Not always but most of the time.

I've found the Raybestos online catalogue pretty good over time and they also have a downloadable PDF for various parts that lists the applications by part number. Handy when looking for other apps that might fit.

[86Stripper]

gr79

Yes, the old days before the extensive use of pc databases were different. Catalogues and paper data. Some of it was also not the best. I was there. I worked in the trade in the late 1960s early 1970s long before the PC. The problem then was getting a catalogue. At one time our local auto parts chain, Lordco, had a complete department that just dealt with catalogues. I've developed a library of that old information and am lucky that my wife is an enthusiast and looks for all the old catalogue stuff when going to flea markets, thrift stores and garage sales. She has found some cool stuff. Unfortunately us here in Canada do not have a lot of the big chains that you have in the USA so purchasing and distribution is a little different. More smaller independent chains here except for NAPA.

I agree that you have to do your homework which is why I'm posting here to see what I can find out from others and post my results so it can help others.

[86Stripper]

Here is what I've found out so far and a few pictures.

Pic 1542 is of the original brakes drums on the 1986 GT. Shows the cast part number and the date code. Nice clean drums. One is dated 86C7B, the other 86C7C. Last letter is likely the shift. Looks like the drums have been turned once. I'll check them for actual size with the brake drum micrometer at the shop this week.



Pic 1546 is of the Raybestos 474PG shoes (red) I picked up yesterday compared to the shoe on the 1991 rear end I have. The shoes currently on the 1986 GT are the same as the ones on the 1991 rear end except they are painted red like the 474PG. All of the shoes are the same size and shape, are relined and have the same Raybestos inked code of BPI-4090-FE. BPI is Brake Parts Inc. which is Raybestos. The only difference I can see is the form of the metal shoe where it contacts the backing plate in three places on the red 474PG. The metal shoe on the 474PG has just a twist in the metal where it contacts the backing plate while the other two, which I believe are the 569PG type, have an actual pad. The pad design is far superior to the twisted metal design. The twisted metal design is really hard on the backing plate pads and chews them up. Chevrolet used this twisted metal design for years and I've replaced a number of backing plates over the years because of severe wear. I believe that the 474PG design is an early design that Ford updated to the new pad design. Possibly sometime in 1986 when they introduced the aero 1987-93 car and the 11" front rotors.



Pic 1551 shows the Ford number D7EC-2220-AA stamped in three of the metal cores. This is a 1977 code. The other core has Aimco Canada stamped in it with no number.



Pic 1553 shows the full 1/2 set of the Raybestos 474PG.



Pic 1555 shoes the full 1/2 set of the shoes on the 1991 rear end the same as those on the 1986 GT. The inked number by the BPI-4090-FE looks to be a date code 051413C, possibly May 14, 2013 shift C. The shoes are a little rusty but comparing pad depth to the new 474PG they have very little wear.



I stopped at the local NAPA on my way home from picking up the 474PGs and checked with them. They also list different shoes for 1979-86 and 1987-93. Part numbers are: 1979-86 UP474R and 1987-93 UP569R. Likely sourced from Raybestos. I didn't look at them but I might stop by again and see if I can. Some of the sales reps are pretty good. Unfortunately they didn't have the UP474R in stock so I might have to go to the warehouse store to check if I want too.

I am going to go back to Lordco this week and see if they can order another set of 474PG so I can check to see if the metal cores are the same. If they are I'll get the 569PG as they look exactly the same and have the updated pivot wear pads that go against the backing plates. Unfortunately the 569PG Lordco had in stock were not painted or coated. Much better for rust if they are coated in some way.

Interestingly the 474PG is also listed for 1975-80 Pinto. Certainly not the best brakes for a high output Mustang

[Haystack]

Haystack

Just for your info the Raybestos online catalogue lists 9" and 10" brakes for the 1986 and 1987 Cougars.

Shoes are 9" 474PG same as 1979-86 Mustang and 10" 151PG. 10" are also listed for 1979-84 Mustang. ???
Wheel cylinders for 10" are different than 9" and are WC37697 and WC37698. Different for each side whereas the Mustang 9" take the same wheel cylinder for each side.
Drums for 10" are 2679 and the picture shows them as not being finned. My experience with Raybestos pictures over time is that they are pretty accurate. Not always but most of the time.

I've found the Raybestos online catalogue pretty good over time and they also have a downloadable PDF for various parts that lists the applications by part number. Handy when looking for other apps that might fit.

The xr7's turbo coupes and hd/towing package cougar birds had 10" rear drums. Interestingly I've had two out of four 87 v-6 cars with 10" drums and only 2 out of probably 8 5.0 cars had them. All 86-88 years.

The regular and base model cars all had 9" drums. The 10" drums do have different wheel cylinders, but I've also had different styled 9" wheel cylinders. One car I had they were obviously different bores.