Need r33 GTS-T Brake Advice

[IXMandalorianXI]

Hello all,

I have a 1996 Skyline r33 GTS-T.

This question is a two-parter.

Firstly, and more simply, my r33 has GT-R Brembo Brakes. I am buying new pads and rotors. Can I correctly assume that any GTR-Brake/Rotor that was originally compatible with the r33 is going to be the same shape/size, regardless of the model? By that I mean, without knowing exactly what GT-R model these Brembo brakes came from, I can safely buy r33 GT-R sized brake pads and rotors and should be fairly safe in them fitting correctly?

My second question is a bit more complex. I do not know if the previous owner put in Glycol-based brake fluid (DOT 4) or Silicone-based brake fluid (DOT 5). I did a test, by extracting some fluid from the reservoir and adding water. The brake fluid and water DID NOT mix, implying it is Silicone-based, but also the brake-fluid isn't purple, which is really throwing me for a loop.

 

So, to be absolutely safe, I've decided instead just carry out a full fluid flush and replace with Glycol-based, especially since I am putting new pads and rotors on anyways. However, I am uncertain as to what the best method would be. I have read that I should use denatured alcohol (methylated spirits) to push the original brake fluid out, then use cheap DOT 3 to flush the system, then put in my proper high quality DOT 4 or DOT 5.1 brake fluid of choice. Is this correct? I've never done this before and want to make sure this is a proper method. I've also read that I should use compressed air to fully flush out the denatured alcohol, but I'm sure I understand how that works? Would I just hook up an air compressor pump to the brake fluid reservoir and open all the bleeder valves?

I appreciate any/all advice, links and sources, and information you can provide.

Thank you

[Duncan]

Yes, the Brembo brakes across R32 Vspec, R33 and R34 GTR are all identical sizes and pad shapes, I think the colour might have changed in R34 but they are the same otherwise. They all run a 324x32mm disc (which we'd refer to as DBA 4928/5928) and a DB1178 pad

Same story in the rear, they are the same across R32 vspec, R33 and R34 with a DBA 4929 disc and DB1521 pads.

If you can't cross reference those numbers in the UK, the dimensions and pad samples are on the DBA website.

Re the fluid, I've never come across DOT5 in the wild, it is highly unlikely to be the case. When I get a new (used!) car I just flush the fluid out with 2 bottles of general DOT3 or 4 (whatever is cheap) and then put in whatever I was after for that car (generally Motul RBF600 if it is performance or race use)

[Murray_Calavera]

Using 2 different coloured brake fluids makes it very easy to do a complete flush as well. 

Say the proper fluid you want to run is yellow. 

Start with a cheap yellow DOT 3/4, then flush with a cheap blue DOT 3/4 and then finally use the brake fluid you want to actually run, keep flushing until the blue is gone. 

[GTSBoy]

6 hours ago, IXMandalorianXI said:

my r33 has GT-R Brembo Brakes

A word of caution. Unless you were explicitly told that they are GT-R Brembos, they could also be from a Z chassis car (or slightly less easily, from some other car altogether). My caution might not be necessary, because the pads could be the same anyway, but just on the off chance that the calipers is different and has a different pad, double check the pad dimensions before committing to anything.

[IXMandalorianXI]

4 hours ago, Duncan said:

Yes, the Brembo brakes across R32 Vspec, R33 and R34 GTR are all identical sizes and pad shapes, I think the colour might have changed in R34 but they are the same otherwise. They all run a 324x32mm disc (which we'd refer to as DBA 4928/5928) and a DB1178 pad

Same story in the rear, they are the same across R32 vspec, R33 and R34 with a DBA 4929 disc and DB1521 pads.

If you can't cross reference those numbers in the UK, the dimensions and pad samples are on the DBA website.

Thank you! That puts me much more at ease and I feel a bit more confident making my purchase.

 

4 hours ago, Duncan said:

Re the fluid, I've never come across DOT5 in the wild, it is highly unlikely to be the case. When I get a new (used!) car I just flush the fluid out with 2 bottles of general DOT3 or 4 (whatever is cheap) and then put in whatever I was after for that car (generally Motul RBF600 if it is performance or race use)

I'm really unsure. On the one hand, this stuff isn't purple (see picture), the factory cap says to use DOT 3, and upon messaging the previous owner, he "thinks" but does not for sure remember putting DOT 4 in. On the other hand, the extracted brake fluid does not mix with water (see picture), and at the suggestion of another forum post, I rubbed some of the extracted fluid between my thumb and finger, the extracted stuff felt slick (which I was told indicates silicone), DOT 4 by comparison does not (has a grainy feel to it). I have also read that DOT 5 can change color to yellowish over time.

I keep wanting to second guess myself, because as you have said, it's rare to find silicone-based brake fluid out in the wild, but the more I think on it, the more I think DOT 5 is what I have.

 

1 hour ago, Murray_Calavera said:

Using 2 different coloured brake fluids makes it very easy to do a complete flush as well. 

Say the proper fluid you want to run is yellow. 

Start with a cheap yellow DOT 3/4, then flush with a cheap blue DOT 3/4 and then finally use the brake fluid you want to actually run, keep flushing until the blue is gone. 

I agree, and that makes sense, my concern, is what happens if I have silicone in my system and want to replace it with glycol. I read that an alcohol flush does the trick, but others have said that you have to replace every hose, the master cylinder, etc, etc, every part, because if any remnant of silicone remains, it can destroy your braking system.

 

47 minutes ago, GTSBoy said:

A word of caution. Unless you were explicitly told that they are GT-R Brembos, they could also be from a Z chassis car (or slightly less easily, from some other car altogether). My caution might not be necessary, because the pads could be the same anyway, but just on the off chance that the calipers is different and has a different pad, double check the pad dimensions before committing to anything.

I am fairly confident they are GT-R Brembos, as they were listed as such when I purchased the car, but regardless I agree it's a good idea to do some measurements before I commit.

Edited April 3, 2023 by IXMandalorianXI

[Duncan]

The main difference in the 350z and GTR brembos is the offset of the disc and caliper to the hub, so check those measurements from the DBA site.

[Murray_Calavera]

I have no idea what they charge, but if it's cost effective, maybe send some brake fluid off for testing?

https://www.savantlab.com/applications/brake-fluid-testing/

If it's reasonably priced, might be worth the peace of mind. 

[joshuaho96]

If he put DOT5 in those brakes you can flush it by using methylated spirits/denatured alcohol. Fill the master cylinder reservoir, use a cap that holds pressure to pump 15 psi through the system, open up a bleeder and push all the fluid through until you're 100% sure you have nothing but alcohol coming through the lines. Repeat for all bleeders in the system. Then run the ABS pump using a scan tool to make sure there's no brake fluid stuck in the ABS actuators either. Then repeat using DOT3/4/5.1 until you get say 200 mL of clean brake fluid out of each bleeder. The process is going to take forever but should be ok. I recommend using a pressure bleeder because like I said it takes forever and you the owner is probably the only person with the patience to deal with this ordeal.

I would be concerned about seal compatibility in the system but what's done is done. Flush it and see if anything fails.

[IXMandalorianXI]

2 hours ago, joshuaho96 said:

If he put DOT5 in those brakes you can flush it by using methylated spirits/denatured alcohol. Fill the master cylinder reservoir, use a cap that holds pressure to pump 15 psi through the system, open up a bleeder and push all the fluid through until you're 100% sure you have nothing but alcohol coming through the lines. Repeat for all bleeders in the system. Then run the ABS pump using a scan tool to make sure there's no brake fluid stuck in the ABS actuators either. Then repeat using DOT3/4/5.1 until you get say 200 mL of clean brake fluid out of each bleeder. The process is going to take forever but should be ok. I recommend using a pressure bleeder because like I said it takes forever and you the owner is probably the only person with the patience to deal with this ordeal.

I would be concerned about seal compatibility in the system but what's done is done. Flush it and see if anything fails.

Many thanks for the detailed instructions!

As far as I know, the r33 doesn't have ABS, so that should simplify things a bit.

What do you use to pump pressure into the system? Just a pump with an adapter cap for the reservoir?

[IXMandalorianXI]

UPDATE: Did some googling and turns out these pressure kits with (mostly) universal caps are easy enough to find online.

This looks like a simple enough process, just need patience and to take my time to do it right. In the long run, I'd rather have DOT 4 in here than DOT 5, I think.

[Duncan]

yeah the only trick is to get the cap that suits your master cylinder. I use the SP Tools one. https://sydneytools.com.au/product/sp-tools-sp70809-25l-brake-clutch-pressure-bleeding-kit

The other option is vacuum bleeder but you still need to attach it to each nipple rather than once at the master cylinder.

Either way, if you use a pressure bleeder you need to be careful not to empty the master cylinder and suck air in because it is a bitch to clean back out

[IXMandalorianXI]

New rotors and pads have arrived! Just bought a bleeding pressure system, some denatured alcohol, some cheap DOT 4 to flush and some high quality DOT 4 for the final fill. Got a 4-day weekend this weekend and access to a lift.

This thread took me from being extremely nervous and willing to pay someone to do this for me to feeling confident in doing this correctly myself.

Thank you everyone for the advice and information!