I have an 85 which i am restoring, I debated back and forth between keeping the 7.5" axle or swapping out to an 8.8". In the end, due to budget and simplicity I decided to keep the 7.5 for now. My question is, when shopping for new backing plates, are the 7.5 and the 8.8 the same part? I already verified that my new axles and drums fit 79-93 so I'm 75% sure that back plates are the same but want to make sure. Thanks!
7.5" vs 8.8" drum brake compatibility
- Thread starter philcore3
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I know that the brakes from a 7.5 from an 84 V6 car will swap onto an 8.8. I did this when I swapped the 84's drivetrain with that of a Mark VII. 
All of the drum brake components are the same between 7.5" and 8.8", on the Mustang...backing plate, drum, shoes, wheel cylinders, etc.
10" rear drum brakes were OE on V8 LTD/Marquis, and maybe Fairmont/Zephyr wagon? (I don't remember exactly other than LTD/Marquis.) They were not ever on Capri/Mustang so that LRS kit is an 'upgrade' and would require parts in that kit (larger diameter backing plates, large diameter drums, large shoes, etc.).
10" rear drum brakes were OE on V8 LTD/Marquis, and maybe Fairmont/Zephyr wagon? (I don't remember exactly other than LTD/Marquis.) They were not ever on Capri/Mustang so that LRS kit is an 'upgrade' and would require parts in that kit (larger diameter backing plates, large diameter drums, large shoes, etc.).
85GTStangGuy
Advanced Member
They all did. Same as all the 8.8s... 9" drums also. That's what FoxChasis is saying.... that the 10 inchers were only on V8 LTD's and Marquis' (and maybe F/Z's).... never on Stangs or Capris.
So if you have 9" 7.5 backing plates and you are running 10" drums, will the smaller backing plates work??
85GTStangGuy
Advanced Member
I don't actually know myself, but I'd assume not. I would think the wheel cylinders, brake shoes and the shoe contact points would all be further out radially, necessitating the larger diameter backing plates.
I think Rangers got the 10" drums as well.
But my understanding was the same about the 7.5" and 8.8 drums. They are the same 9" units. Even the axle shafts are the same. You could take a 7,5" with drum brakes and swap them onto an 8.8 housing and use everything.
EDIT: However, i typically think of 86+ when I say this. The early 4-eye cars got some weird parts. There were aluminum drums, 9" front brakes, and even a 6.75" sterling axle. There was even a weird German 5-spd trans that nobody knows about.
Aluminum drums were on early (before 1983) turbo cars. If they happened to make it onto turbo cars before 1983, so be it. Same years for 9" front disc and 6.75" rear axle .. but they were for non-V8 and non-turbo cars.
The 5-speed, which was NOT a T-5, was made by Tremec in Mexico, and dated back to late 1980 model year and went through the end of 1983 model year. (So there were TWO 5-speeds in model year 1983 but almost no one knows about the Tremec 140VS 5-speed). The German transmission was a 4-speed and was used through 1986.
Fox Capri/Mustang manual transmissions:
Ford of Germany (FoG) nnET 4-speed (trans tag "78ET" or "83ET" and "FOG", door tag "7")
Borg Warner 4-speed (trans tag "RAD", door tag "6")
Tremec SROD 4-speed overdrive (trans tag "RUG", door tag "5" 1979 and "4" 1980-83)
Tremec 140VS 5-speed overdrive (trans tag "RAP", door tag "5")
Borg Warner T-5 5-speed overdrive (trans tag "13-52", door tag "2") --- Borg Warner sold manual transmission division to Tremec in 1998
The 5-speed, which was NOT a T-5, was made by Tremec in Mexico, and dated back to late 1980 model year and went through the end of 1983 model year. (So there were TWO 5-speeds in model year 1983 but almost no one knows about the Tremec 140VS 5-speed). The German transmission was a 4-speed and was used through 1986.
Fox Capri/Mustang manual transmissions:
Ford of Germany (FoG) nnET 4-speed (trans tag "78ET" or "83ET" and "FOG", door tag "7")
Borg Warner 4-speed (trans tag "RAD", door tag "6")
Tremec SROD 4-speed overdrive (trans tag "RUG", door tag "5" 1979 and "4" 1980-83)
Tremec 140VS 5-speed overdrive (trans tag "RAP", door tag "5")
Borg Warner T-5 5-speed overdrive (trans tag "13-52", door tag "2") --- Borg Warner sold manual transmission division to Tremec in 1998
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Ah. I confused those. The German "ET" 4-spd from the pinto.
The other 5-spd had a non-standard shift pattern if i remember correctly. I think i've seen it only once.
The other 5-spd had a non-standard shift pattern if i remember correctly. I think i've seen it only once.
