1995 3000GT VR-4: Clutch And Brake Booster Hose Combination

• Why Do I Want To Do This?

  • If you have aftermarket devices installed in your car, some of these devices may require a connection to engine manifold pressure. Often, these devices are connected to the existing vacuum lines, such as the vacuum line for the fuel pressure regulator. An excessive number of devices or excessively long vacuum hoses connected to a vacuum port can render its readings delayed or inaccurate. The last thing you want in a car that you're running on the edge of disaster is for the fuel pressure regulator to see delayed or inaccurate readings and cause incorrect fuel delivery to your engine. This modification frees up a 3/8"ID vacuum port on the intake plenum, to which you can connect pretty much anything you have that needs a vacuum reading.
  • For installation of some aftermarket devices, it's convenient or necessary to free up the space on the firewall where the hard pipe for the brake booster hose is. This modification completely eliminates this pipe.




• How Long Will It Take Me To Do This?

  • Plan on an hour to complete this modification.




• Anything I Should Do Prior To Attempting This Procedure?

  • If you have an aftermarket front strut tower brace, you may want to remove it to make things more accessible.




• What Mitsubishi Parts Will I Need?

  • (1) MB892600 ($4.54) Clutch Booster Vacuum Line




• What Other Parts Will I Need?

  • 3/8" ID Brass Tee Fitting




• Where Can I Get the Stuff To Do This?

  	Part	Company/Contact	Part Number
  	Clutch Booster Vacuum Line	Mike Deal at Rockville Mitsubishi	MB892600
  	3/8" ID Brass Tee Fitting	McMaster-Carr





• What Tools May/Will I Need?

  • Pliers
  • Cutting Tool (utility knife, scissors, tubing cutter, etc.)




• Erik's Review

  • I've had this hose setup on my car for over a year now, and I've seen no negative consequences from it. I have all of my aftermarket devices connected to the former brake booster vacuum port, so I can be assured that my fuel pressure regulator and turbocharger bypass valve are receiving correct manifold pressure.

The Procedure

	Create New Combination Hose
	This picture shows my first version of this modification. This method works, but I found that a pre-bent hose, like the original OEM hose, would allow a tighter radius on the bend and result in a shorter hose. Whatever hose you choose to use, this is still the general idea. You'll need to cut the OEM hose near the middle such that the check (one-way) valve is on the intake side of the brass tee that you install. As for the new hose that you connect to the tee fitting, you'll need to make sure it's long enough to connect to the vacuum nipple on the brake booster.
	Connect Hose With Tee To Brake and Clutch Boosters
	The end of the hose with the check valve connects to the nipple on the side of the plenum. The other two ends go to the nipples on the brake and clutch boosters. Make sure to route the hose where it isn't going to catch or rub excessively on anything.
	Remove OEM Brake Booster Hard Pipe
	After you remove the brake booster line and hard pipe, you can connect your acccessories' vacuum lines to the open port that the brake booster line formerly occupied. I ran an 8mm vacuum line to another brass tee fitting with 6mm outputs. From there, I split the 6mm lines as necessary to connect my boost controller, turbo timer, boost gauge, and MAP sensor.