Clutch fluid change

After 21 years of ownership, I am planning on changing the dirty clutch fluid myself in the near future. Although it seems rather straight forward, I have a few queries. (Although driven aggressively at times, I have no plans to track the car.)
1. Is removing the rear driver's side tire to gain access really helpful?
2.Is there an advantage to using a hand vacuum pump?
3. If using a vacuum pump, is it still necessary to pump the clutch prior to completing the bleed if neither the master or slave cylinders have been changed?
4. Which clutch fluid is recommended or should I stick with the Honda Dot 4 brand?

Thanks for any input.

There are dozens of threads on bleeding the clutch, changing the master, and changing the slave. Use the search. All you need is a wrench (10mm?, can't remember) and a helper. Reach in over airbox and you can get wrench over bleeder. Any DOT3 or 4 brake fluid is fine. Read the cap on the reservoir.

http://www.nsxprime.com/forum/showthread.php/20258-Clutch-pedal-fell-to-floor-then-fine/page2

A word of caution when it comes to bleeding a 21 year old master cylinder. There is a good chance that the walls of the clutch master cylinder have worn slightly over the years as a result of operation of the clutch. This results in a slight lip in the cylinder walls at the end of the normal stroke of the piston. If you pump the master cylinder as part of the bleeding process, you will likely push the piston past this lip which may end up damaging the seals on the piston with the result that the master cylinder develops a leak and you will need to replace it. If you use a pressure bleed tool such as the EZ Bleed (or others), it eliminates the need to pump the master cylinder and reduces the risk that the master cylinder will develop a leak after the fluid change. The pressure bleed tool also allows for single person bleeding of the lines since you don't need to have someone pumping on the clutch pedal.

As an observation, given that your master cylinder is at least 21 years old, if your vehicle mileage involves a lot of clutch operation (stop / start driving etc.), you might want to plan for a master cylinder replacement anyway.

In the interest of full disclosure, I have never replaced the brake and clutch fluids on my NSX myself (it was done by the shop). However, I have done brake system fluid changes on other vehicles and suffered the post fluid change master cylinder leak blues after using the pump the foot pedal style of bleeding (The two vehicles that this occurred on were high mileage / age vehicles).

Old Guy said:

A word of caution when it comes to bleeding a 21 year old master cylinder. There is a good chance that the walls of the clutch master cylinder have worn slightly over the years as a result of operation of the clutch. This results in a slight lip in the cylinder walls at the end of the normal stroke of the piston. If you pump the master cylinder as part of the bleeding process, you will likely push the piston past this lip which may end up damaging the seals on the piston with the result that the master cylinder develops a leak and you will need to replace it. As an observation, given that your master cylinder is at least 21 years old, if your vehicle mileage involves a lot of clutch operation (stop / start driving etc.), you might want to plan for a master cylinder replacement anyway.

Click to expand...

Remember this is not the brake master. The clutch master stroke is always a full stroke, as opposed to the brake master, never had an issue with the clutch in this regard, since it always goes to the floor in everyday use(dirt ridge does not get past during the bleed). But....fact is, the master is probably leaking onto the floor anyway and should be carefully looked at.

Regards,
LarryB

Thanks for the feedback but let me clarify the situation. I do not have a 21 year old master or slave as both were replaced when a new comptech performance clutch was installed about 3 years ago. The fluid level is at the appropriate level in the resevoir. However when the last oil change was done at the dealer, it was mentioned that the clutch fluid was pretty dirty.
What I was trying to communicate was that I personally have had zero experience doing a fluid change. My query was really whether a "vacuum pump & brake bleeder kit" purchased at Princess Auto would be useful in doing a clutch fluid change. I had reviewed a number of previous posts about this subject but they didn't seem to answer my specific queries.

I've used Mity-Vac's hand-operated and air operated vacuum pumps to bleed brakes and clutch lines. The air-operated ones work well, and saves a lot of strain on the hands. It makes it pretty easy for one person to replace the fluid. Worth it, as long as you have a good air compressor. And watch the fluid level in the clutch reservoir, it disappears quickly.

Using a hand-operated vacuum pump is extremely tedious and, while it works, isn't really recommended.

Hey Larry & Old Guy , this guy took you two right down the Bunny Trail , I figured the same as both of you , after 21 yrs everthing is shot , you gotta love this ! Ralph's Rule # 2 good decisions are based on good data !

I've changed the clutch fluid using a speedbleeder valve? No need to buy extra stuff. Actually I've thrown all the other DIY equippement away recently as nothing works better than those little valves.

The only downside of them is if you have a new component and air in the system.

I would suggest you do this from UNDER The car. There has been a report here of mal-alignment with the fork/slave union when done from above (assuming you are replacing the slave, which you should -- since you had dirty looking oil)
The person who was working with this problem solved it by working from underneath the car.

Are you going to replace the hose to the damper unit aswell? 46970-SL0-A02 (verify for your year)
?you may not even have a damper unit anymore if someone did work on it in the past with a different clutch, I don't know
Take pictures if you can, document it and show us your progress. Thanks

goldNSX said:

I've changed the clutch fluid using a speedbleeder valve? No need to buy extra stuff. Actually I've thrown all the other DIY equippement away recently as nothing works better than those little valves.

The only downside of them is if you have a new component and air in the system.

Click to expand...

Air in the system? How so?
I have Speedbleeders on my brakes and clutch and they
have all worked just fine, making it a one-person job to
bleed--which is, after all, a procedure for getting the air out.

BTW, the Speedbleeder for the NSX clutch slave is SB8125L.

Tom239 said:

Air in the system? How so?

Click to expand...

If you replace a part (master or slave) you naturally induce a 'high enough' amount of air into the system. If you press the pedal and built up pressure the valve does not open as the air is compressed so easily. So you won't get it out. I had this both on the brakes and the clutch system with the speedbleeders and had to use a conventional method to get wrid of most of the air until the speedbleeders value opened again. Replacing parts is the only drawback if you use them.

Olyar15 said:

I've used Mity-Vac's hand-operated and air operated vacuum pumps to bleed brakes and clutch lines. The air-operated ones work well, and saves a lot of strain on the hands. It makes it pretty easy for one person to replace the fluid. Worth it, as long as you have a good air compressor. And watch the fluid level in the clutch reservoir, it disappears quickly.

Using a hand-operated vacuum pump is extremely tedious and, while it works, isn't really recommended.

Click to expand...

Not recommended by WHO, and tedious ,whats changing a tire excruciating !, speedbleeders work good but before you install a master cyl (clutch or brake ) you should bench bleed it, this is why Gold Nsx stated the speedbleeders didnt work with a new install.How do you think production built cars are built ,somebody jumps in the car and pumps the pedal ? .The master cyl. is pressure feed and a vacuum is applied to the bleeder , fluid is recovered . Mity-vacs work good ,you just cant over pump them and draw too much of a vacuum

To make it go faster you can suck out all the dirty fluid and refill the res. with new stuff, this way the rest will flush through quickly.

I replaced my master and slave today, fairly easy but my issue was bleeding the system. Took me longer to do than replacing the components. Pumped and pumped and bleed and bled more, the pedal would not pressurize. I ended up using a turkey flavor injector hooked up a line from the injector to the bleeder screw and injected (4oz?)brake fluid. Then bled the usual way of pump and releasing the bleeder screw. This actually worked for me!
After getting pressure I found out I had a small leak in the clutch hose... Replace that too! No need to remove wheel, I jacked up the rear driver side, worked underneath the car.
good luck!

Would there be any issue if the brake master cylinder is brand new regarding pressing down the brake pedal all the way during the bleeding process? Should I assume it is ok since the cylinder wall of the master cylinder is new without any scoring? Thx.

Larry Bastanza said:

Remember this is not the brake master. The clutch master stroke is always a full stroke, as opposed to the brake master, never had an issue with the clutch in this regard, since it always goes to the floor in everyday use(dirt ridge does not get past during the bleed). But....fact is, the master is probably leaking onto the floor anyway and should be carefully looked at.

Regards,
LarryB

Click to expand...

nis350 said:

Would there be any issue if the brake master cylinder is brand new regarding pressing down the brake pedal all the way during the bleeding process? Should I assume it is ok since the cylinder wall of the master cylinder is new without any scoring? Thx.

Click to expand...

No there would be no issue if the brake master is new.

Regards,
LarryB

I just bled my brakes and flushed the clutch using the pneumatic vacuum bleeder I bought at Harbor Freight. It was so effective and easy on the brakes, I figured I might as well bleed the clutch too since the fluid looked a bit grimy (it's not even a year old, so wasn't that bad). What a joy. Yes, it needed some grease on the threads where the bleeder screw enters the housing to stop air leaking in, but that was pretty straightforward. If you DIY and have a substantial compressor, it's the way to go. One of the best $30 I have spent.

jwmelvin said:

I just bled my brakes and flushed the clutch using the pneumatic vacuum bleeder I bought at Harbor Freight. It was so effective and easy on the brakes, I figured I might as well bleed the clutch too since the fluid looked a bit grimy (it's not even a year old, so wasn't that bad). What a joy. Yes, it needed some grease on the threads where the bleeder screw enters the housing to stop air leaking in, but that was pretty straightforward. If you DIY and have a substantial compressor, it's the way to go. One of the best $30 I have spent.

Click to expand...

+1 I use the same tool to service both my cars. Makes fluid changes fast and easy. And, you ensure no air whatsoever in the lines, which is critical for tracked cars like mine. Good tip on the grease- I use a little Vaseline and just wipe off when I'm done. It will work without the grease, but takes longer as you will draw air through the threads.