well, I know the GTUs uses TII components........after my TII swap I kept the stock brake booster and master cylinder and it's leaking a little bit.......enough to send a signal to the idiot lights....when I order the part should I ask for the NA master cylinder or the turbo one? are they different? can I still keep the brake booster or do I need to replace it too?

 

keep brake booster, only differance is if you got abs and awws. if not ALL MC are the same if it is for 5 lug. maybe 4 too not sure, but there is only 2 different one's ABS and NON ABS as far as I know, watch out for people on ebay advertizing a T2 Mc for an arm and a leg/ its the same a s 5 lug NA

 

ok.......so order either NA ot TII as long as it has ABS?

 

I 100% gurantee this info as I have spent stoopid time and money on this.

When in comes to the S5 cars there are two different braking systems under the hood. ABS & non-ABS.

You either have an ABS master and booster or a Non-ABS master & booster. Those are the only two types on the S5s and they are not compatable. As far as I know all turbo's (S5s) came with ABS all non turbos had conventional brake systems.

Likely all GTUs had the non ABS system. Thus you need non turbo components.

 

but the GTUs uses Turbo braking system......that's why I am confused.......I didn't swap anything from the TII braking system into the GTUs because it HAD turbo brakes to begin with.....I assume it is the same ABS unit as the TII but I need some verification before I buy the master cylinder.

 

So basically if your car had ABS from the factory you need to ask for Turbo components but I am almost sure you need the N/A parts as you car was N/A from the factory and thus did not have ABS.

 

Another way to tell is if your master cyl in steel then its the Non-ABS master, if it is aluminum then it's the turbo one (ABS).

 

dude it's simple turbo or non means nothing!!!!! only abs or non abs S4&S5 are the same look them up on ebay or mazdatrixs for your own look @ them there is ONLY 2 1 for abs 1 for non abs hope this helped you

 

There's no such thing as a "Turbo braking system". All FC's with 5-lug hubs used the same braking system.

 

The Master cylinder and booster appear to be different units for a turbo and NA. These specifications are for an 89. Check the FSM.

 

i do beleive its just based on 4 lug and 5 lug applications. my S has the cast iron/steel master as its clearly covered in surface rust.

do the different master cylinders have larger piston diameters or what? if they are the same,then they would sweep the same area and create the same pressure. right?

 

This is incorrect.

When talking about 5 lug cars. ABS cars had different hard lines, master cyl, and booster (including vacuum check valve hard line and soft line) than non-ABS cars.

Further 89-90 GTU cars came with 5 lug hubs but had different calipers all around and different rear rotors than cars equiped with 4-pot front calipers and vented rear rotors (TII, GXL, most 91coupes, 91turbo, GTUs, verts)

The GTUs was equiped with the 4-piston front calipers and vented rear rotors like the Turbo but do not have ABS thus if the source you are buying the master cyl or booster from distinguish between turbo and non-turbo when buying these items, one would need to buy the non-turbo components.

 

The ABS cars have a larger bore aluminum master cyl. This is to overcome the additional static pressure losses associated with the ABS pump being in the system. Thus maintaining proper brake pressure generated. BUT dont go and get one if you have an N/A because you will also need to change the booster and the hard lines between the proportioning valve and the master cyl. ABS brake boosters are almost impossible to find reman or new (save a 700$ trip to the dealer) thus you have to find a good used one....mine failed and i just changed the whole systtem over to the non ABS stuff including new hardlines, master cyl, and booster for less than the cost of a new ABS booster.

 

I got the ABS unit and it was fine......then on my way home my radiator gave out...........lol started overheating and I shut it down before it got to the first line..........;( car is down for the count.....driving the NA now but it might ALSO need a brake master cylinder....lol...........thanks you guys.