I'm thinking about swapping out my front 91 si brakes with DA brakes but wasn't sure if it was worth the upgrade.. Is the master cylinder and booster larger as well?

 

10.3" rotors. Good upgrade. You will need to swap out the whole knuckle and get an alignment.

The MC and Booster is a 15/16" on the DA's.

Your Si civic is either 7/8" or 13/16"... both smaller than the DA.

The 1990/1991 civic sedan EX has a 15/16" MC just like the DA.


Use the EX MC to save a lot of hardship. You need to cut and reflare a rigid brake line and replace the booster to use the DA setup. For the EX setup you only replace the MC and that's it! No reflaring and no booster change!

And - if you use the EX MC you can use one of these later on!
https://honda-tech.com/zerothread?id=884449

 

would it be bad to upgrade the rotors but NOT upgrade the mc or booster?

 

You can't just upgrade the rotors.

you will need to upgrade the calipers too... which in turn requires different steering knuckles to make it all fit.

You can use either the DA knuckles or the 90/91 Civic sedan EX knuckles or you can do a little tie rod modding and the SiR knuckles fit as well.
They take the same rotors and the same calipers.

The caliper is larger and has a larger fluid capacity.
Upgrading the MC ensures that you have the right fluid flow when you press down the pedal. Too small of a MC and you have to press down the brake pedal closer to the floor more than normal (dangerous). Too large of a MC and you will have problems braking as well since you won't hardly have to press on the pedal to achieve wheel lock up (dangerous). I had the "too big" of a MC for a while and it wasn't nice for street driving. I almost got into 2 accidents from people pulling out in front of me. Instintively I slammed on the brakes, instant lock up - the brakes were either ON or OFF - not much gray area in between to deal with situations where you really need to slow down fast, but not lock up.

So, when swapping parts over from other cars you should try to match the fluid system as well to maintain stock pedal feel.

If you are going with a similar setup as the DA then get a similar MC to the DA.

 

I am also doing the DA rear disk conversion swap as well as the larger fronts..... so with that in mind.. am I definitely going to need the mc upgrade? or can i get by?

 

bump. anyone?

 

So basically you will have the same setup as a DA. Just use the same size MC as the DA (15/16" Civic EX is teh same size) and you're good to go.

You should also change out the proportioning valve since you are doing rear dasc.

 

Tie rods from my DX (I had to replace them last year) are Identical to Sir Tie rods.

How do I know? I bought a SiR half cut and have all the parts that fit on my car now.

And have 90-93 GSR rear trailing arms and brakes, with the SiR porportioning valve adn master Cylinder and radiator (fans needed connector mods to plug in.)

 

did you use the SiR rack too?

I had to mod mine because toe wasn't adjstable enough to correct with the SiR knuckles and USDM tie rods and rack.

 

You don't have to cut the stock line, you can just bend it...I did it 2 weekends ago...unfortunately we did something to the tranny at the same time which has prevented me from doing more than driving 20'.

Austin

 

If you use a DA MC and booster you most defintly have to cut and reflare it with the integra fitting. They are completely different sizes.

I think you are talking about the 1" ITR MC. I have a 97~00 ITR MC/booster on my Civic. With that one you only bend it. Is that what you are talking about?

Or maybe you go the 1" GSR from a DA? I heard those are 1" as well... never saw one though.

 

If your 91 is a civic and not a crx, then it's important to add the proper 4040 proportioning valve from a DA or Crx Si. On my 91 Crx, I run 91 DA GS brakes all the way around. I use the stock Si booster and MC, and the 4040 valve. With stock blank rotors and new rebuilt calipers with Hawk HPS pads, I'd say it was a great upgrade.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 4drEF &raquo;</TD></TR><TR><TD CLASS="quote">If you use a DA MC and booster you most defintly have to cut and reflare it with the integra fitting. They are completely different sizes.

I think you are talking about the 1" ITR MC. I have a 97~00 ITR MC/booster on my Civic. With that one you only bend it. Is that what you are talking about?

Or maybe you go the 1" GSR from a DA? I heard those are 1" as well... never saw one though.</TD></TR></TABLE>

Sorry...to clarify I added the itr MC/Booster, and a 4040 prop valve(I think it was 4040), also did the '90-91 EX knuckles, 11.1" rotors, itr calipers, speed bleeders all the way around...this is in a '90 CRX Si.

I bent the line to fit the itr MC.

Austin