Large spring was too long.
Larry K
Verified Purchase
0-Ring Rebuild Kit For Mc-4
 
October 3, 2025
 
Gohlinghorst 
Verified Purchase
Matco McmcrbD7 Universal Rebuild Kit
 
September 27, 2025
 
Mark K
Verified Purchase
0-Ring Rebuild Kit For Mc-4
 
September 3, 2025
 
Item arrived as ordered nicely packaged and quickly 
Douglas M
Verified Purchase
Matco McmcrbD7 Universal Rebuild Kit
 
April 6, 2025
 
It wasnt in stock because it is for a Vans Aircraft. Aircraft Spruce was able to come through with the order. Four flights later the cylinder is bypassing again.
Doug H
Verified Purchase
0-Ring Rebuild Kit For Mc-4
 
February 20, 2025
 
Excellent and priced right.
James M
Verified Purchase
0-Ring Rebuild Kit For Mc-4
 
January 31, 2025
 
Very nice kit to rebuild the MC-4 master cylinders. However, it may be a good idea to dismantle the existing cylinder and inspect it prior to ordering this kit. In my case, I found that the shaft was worn and needed replacement as well, this is a separate item available from Matco. The cylinder body may also be affected. I ended up buying a shaft separately and all is OK now. There is a good article from Kitplanes on rebuild of Matco master cylinders and the technical documentation from Matco is also useful.
Michel T
Verified Purchase
0-Ring Rebuild Kit For Mc-4
 
January 20, 2025
 
Fixed a leaking master cylinder. Easy to install.
Brian M
Verified Purchase
0-Ring Rebuild Kit For Mc-4
 
December 18, 2024
 
Inexpensive and includes every part except the shaft and the metal block the shaft runs through. But it does include the O-rings for that. Only complaint--as with many such things--is that they dont include any instructions. Dave Prizio has a good how-to easily findable on the web though
Richard B
Verified Purchase
0-Ring Rebuild Kit For Mc-4
 
May 21, 2024
 
Worked great, as usual!
George 
Verified Purchase
0-Ring Rebuild Kit For Mc-4
 
March 26, 2024
 
Great, speedy service 
Cliff W
Verified Purchase
0-Ring Rebuild Kit For Mc-4
 
August 30, 2023
 
Great kit, had all the parts needed for a great rebuild! Thanks! Steve 
Steve C
Verified Purchase
Matco McrbD5 Rebuild Kit
 
February 17, 2023
 
Exactly what I needed to rebuild a small leak. 
Scot T
Verified Purchase
0-Ring Rebuild Kit For Mc-4
 
November 22, 2022
 
Shipped quickly and worked like a champ!  What more could you ask for?
Chad H
Verified Purchase
Matco McrbD5 Rebuild Kit
 
September 30, 2022
 
Excellent product. Thank you for your continuing product support with parts.
Rev. O
Verified Purchase
Matco McrbD5 Rebuild Kit
 
July 15, 2022
 
OK
Donald B
Verified Purchase
0-Ring Rebuild Kit For Mc-4
 
July 9, 2022
 
Gary C
Verified Purchase
0-Ring Rebuild Kit For Mc-4
 
March 23, 2022
 
Super quick ! 1st class service.
Asw P
Verified Purchase
0-Ring Rebuild Kit For Mc-4
 
February 24, 2022
 
John M
Verified Purchase
Matco McrbD5 Rebuild Kit
 
November 5, 2021
 
Exactly what I needed. Rebuilt my cylinders and they are working perfectly! 
Neil H
Verified Purchase
Mc-4A Rebuild Kit McmcrbD4A
 
September 15, 2021
 
In stock at a reasonable price. Shipping was prompt, although the USPS was a little slower than it should have been for a  First Class from Chicago IL  to Wooster OH. No fault of Aircraft Spruce.
Norman L
August 20, 2020
 
The kit is very complete and easy to use with the right shop tools. Aircraft Spruce shipped quickly and the kits allowed me to rebuild two master cylinders for twenty five dollars. I would purchase from them again in the future if I need another rebuild.
Gerald K
August 1, 2020
 
Good kit, has everything included 
Fombell A
April 19, 2020
 
Exactly what was needed. 
Stewart C
December 10, 2019
 
      The exploding diagrams are on the Matco website.
Tom J
July 16, 2019
 
      As noted above diagram would be nice. My O-ring on the calipers went bad changed it and should have ordered one of these at the same time as O-ring in cylinder went bad also.  Needless to say I now have a spare rebuild kit in my wheels and brakes tub at the hangar.
Tim F
May 26, 2019
 
Palms T
Verified Purchase
Mc-4A Rebuild Kit McmcrbD4A
 
June 18, 2025
 
      Great kit but would be nice if it came with exploded diagram to assure correct assembly 
Rohn A
October 5, 2018
 
The kits are good value and include everything that you need except some instructions and an assembly diagram.
When dismantling the master cylinder take careful note of the position of everything. 
Jeremy H
September 2, 2018
 
The kit was complete but an o-ring that was too small drove us crazy trying to find an air leak.
Stuart D
Verified Purchase
0-Ring Rebuild Kit For Mc-4
 
June 3, 2023
 
I don’t know if I have an older style set, but the MC-5 kit did not work on my MC-5 brakes. It looks like the piston design was changed and the small o-ring on top of the piston is now a sealing washer that doesn’t fit over the shaft. 
Matthew L
May 17, 2025