Project - Large Bore Master Cylinder

[Catmonkey]

When I looked at your pics, I remembered my line is constructed the same way.

 

[RJM's GT500]

When I looked at your pics, I remembered my line is constructed the same way.

Catmonkey, excellent to hear. I think the -4AN connection is much better for use on these cylinders as they're both easier to install without fiddling with the little clips and using the threaded fitting allows you to crack the line open to easily bleed air out of the line at the master cylinders output. Using the simple bleeding method of having someone pump +hold the pedal while opening the fitting for a second to let air escape, closing it and having them release the pedal had my new master cylinder fully bled in only 5 pumps to a rock solid feeling pedal. Took about 2 minutes in total to bleed it that way, while I can remember doing the OEM pedal pump method for over a half hour + about 100 pumps to before I had even a semi-firm pedal when I installed my RXT clutch.
Cracking the line and essentially bench bleeding the master cylinder in place with this quick method is something that could never be done with the OEM ford quick connect fitting.

 

[RJM's GT500]

Looks really good!

Have you had a chance to do any WOT 1-2 shifts?

Was a nice sunny day today and fairly warm (for January in Canada lol) so I got to spend more time testing out the high RPM shifting on some back roads. The verdict is... It shifts like Butter! Shifting it at 6200 the shifter just slides right into 2nd like I was sitting parked. No resistance, no grinds, super smooth and slides right in!
Additionally my issues with 1st and reverse being stiff to get into when cold are completely gone, again shifter glides right into any gear. As well I could easily slide it into 1st from a 20mph roll, not that I would ever want to be dropping into first at that speed but now I can should I choose too. Before it was stiff going into first just sitting still and completely locked out at anything more then walking speed with the oem master cylinder. So far the results are quite impressive and eliminated all my shifting issues. The pedal is fairly firm with a short uptake and engages about 2" off the floor with only a 4" total pedal stoke. I did many starts and stops, taking off gently which all felt great. Still easy to modulate the RXT with smooth chatter free engagement and while I wouldn't want to sit in traffic all day it feels perfect for a weekend car or track orientated vehicle where it'll bang off hard fast shifts all day long. I'll be testing out the intermediate 13/16" size upgraded master cylinder next which will be a little lighter for daily driving. That will be going into the car within the next couple weeks along with installing the new pedal unit bracing that I'm working on to eliminate the plastic pedal assembly from flexing around when operating the clutch. So all in all an awesome day of testing

 

[RedVenom48]

When do you think youll have large bore units ready to purchase? Very interested

Sent from my SAMSUNG-SM-G930A using the svtperformance.com mobile app

 

[RJM's GT500]

lexustech48, While I can`t discuss sales without having vendor status and I`m likely treading on thin ice at this point in the thread but I believe the first commercial units could be available within about 2 months.

 

[RJM's GT500]

Sorry this thread has been quiet lately, I've been busy pushing things forward with this project and continuing my testing. Been enjoying the 13/16" Bore unit in my 08' GT500 immensely and can click off 1-2 shifts at 6500 under boost even with the squishy oem shifter reinstalled in the car so the increased fluid flow definitely does the trick. Also completely gone is the stiffness going into first or reverse when cold that I was getting before and can still engage 1st or R even with the clutch not right to the floor so it's had the intended effect. Daily driving and low rpm shifts it's smooth as butter with only a half depress of the clutch pedal and zero notch from the shifter, just slides right in. So quite happy with the results thus far in testing.

Here's a few update photos of what I've been working on. The top mounting blocks for these cylinders have been sent out to be done on a local shop's CNC as well as the new adjustable 1-pc Billet Aluminum Rod Ends I had made for the project. The rod ends also get a press fit high load bronze bearing custom machined to match the stud on the factory pedal arm with zero slop/lash. Photo of the finished cylinder is the 13/16" Bore unit currently installed in my car along with a few photos of it bolted up to the factory pedal assembly. Now that I've had my factory pedal out a few times I can disconnect everything, pull the whole pedal unit out, replace the cylinder, reinstall the pedal unit and bleed the system in about 30 mins flat so it's a pretty straight forward install.

 

[turd burglar]

Any updates on this?

 

[merkyworks]

Here is his website
http://www.rjmperformance.com/05-14-mustang-gtgt500.html