hey
quick question, ( yea I searched )
I have a 1990 gtu 5 lug with single piston calipers,
Now I know the rear is the solid rotors, but what is the difference on the front?
All that I could tell diff from my 87 gxl to my 90 gtu, was the caliper and the brake line,
I plan on converting them to the 4 pot calipers, and hopefully vented rear also ,
What all would I need?
The only topics I could find were about converting from 4 lug,
Would I just need the calipers and rotors?
My current calipers are sticking and I need new rotors So I plan on just converting as long as I don't have to like swap out anything crazy,
so... waht all is needed
thanx in advance
matt-

 

I always thought that 5 lug would onyl work with 4 piston/vented rears. I didnt knwo it was interchangable at all.

 

grrrr


OK for the fronts, all you would need to change is the 4pot calipers and the brake lines. For the rears you need to pull the vented rotor and the caliper also. The caliper that comes with vented rear discs are bigger than the calipers on the solid discs.




Just for future reference:
The above info is respects to the thread starter's car, 4 luggers, please continue your search

 

if your cheap you dont have to switch lines, they do fit. i did the 4 piston swap in my 90 gtu about 8 months ago with no problems. but since the car is 16+years old, new lines are a good idea

 

edit

 

Does that mean the rear brake pads are different (Vented and non-vented??

 

The rear brake pads themselves are the same.
The reason the calipers are different is becuase the vented rear disc is thicker than the solid rear disc.

 

sweet so all I need is the calipers for the front, and disk's and calipers for the back.
good news!

 

Plus 4-piston pads for the front.

 

ohh yeah make sure you use the 4 piston brakes caliper bolts!! i noticed the bolts are different lengh, if u use hte single piston bolt on a 4 piston caliper it doesnt thread in very far....

 

Does anyone know wether the rear brakes on the 88 Turbo II are?

the goodridge lines have them listed as:

Solid Rear Disc or Sport Suspension.

I don't wanna buy the wrong ones, anyone have an idea?

 

i would think that they are sport suspension, but i could be wrong, plus were in va beach do you live?

 

Buckner Blvd. rite next to TCC? U from the 757?

 

turbo2's came with vented rear discs

 

Appreciate the info. Thanks

 

Most people overlook a very important part of the conversion. The cars with 4 piston calipers have bigger brake boosters than the single piston cars. Yes you can still stop with the smaller booster but it's not as easy. Swap the booster, master cylinder, and proportioning valve. That's different too.

 

All 4 pistons FC's had sport suspension. The classification in the books at auto parts stores is sport or non and sport refers to 4piston vented system.

He needs more then just the calipers and pads. The vented rears will not fit he needs the hub assembly as well. I do not know about mounting the 4piston to the 1piston front hub bolt pattern it may work but then you will have two 4 lug wheels and two 5 lug wheels. So basically you need the hubs and rotors and calipers and booster and distribution and master cylinder.

 

This information is new to me so I checked the parts catalog. (No offense RG.) The MC and booster do have different part numbers in the catalog, but the proportioning valve numbers are the same for turbo and non-turbo.

My question is this: Is it worth doing the conversion without changing the MC and booster? I have all the parts, except for those 2 items, sitting on my bench awaiting motivation and if the conversion will not provide a noticable improvement in stoping/staying power I may hold off until I can get those parts. TIA

 

Another related question: It's my understanding that some S5 versions other than the TII came with the 4-pot system. So if that is correct, one would have to conclude, based on the parts catalog breakdown, that those versions used the non-turbo MC and booster. Can someone confirm that for me? TIA

 

It's easier to just pull off the master cylinder, booster, and proportioning valve all as one assembly which is why I mention the proportioning valve. It makes things very simple this way.

 

yeah, the 89-90 gxl, as well as the 89-90 gtuS came with the 4pot. dont know about the 89-90 gtu though

 

Thanks for that. I can verify that a '90 GTU does not come with the 4-pot brake system, because that's what I am converting right now. Of course, the GTUs and the GTU are entirely different models.

 

The GTU is the base model that year. It is the only one with single piston calipers. The GXL and turbo have 4 piston calipers.

 

Yeah, looking at the exploded views in the parts catalog it's apparent that the piping between the valve and the MC are completely different than the non-turbo. That would certainly seem to make the job easier. Of course, one would need to get the piping from the MC to the valve as well. Gettin' too complicated for me so I will just go with the calipers, pads and rotors required for the conversion.

Talked to my nephew today who instructs at local high-speed track schools. He did the conversion on his NA 2nd gen w/o changing the MC and booster, and he feels that there was a definite improvement in braking and that this conversion was more than adequate for high-speed driving events.

 

i would agree with him, i dont delivery food in the rex anymore, so i am not on the brakes as much but i did the front caliper switch back in july and have had not trouble at all. also fsm is confusing when it comes to all the mc and booster, the lines to the proportioner are the same, the turbos came with bigger boosters, but unless you are making a track car the difference will not be to much as compared to the switch to 4 pots.