Price: $54.75

Replacement Master Cylinder for Atwood Trailer Brake Actuators - Drum

Item # 85841

lowest price pledge

Our Price: $54.75

This item qualifies for Free Shipping


zoom in icon
zoom out icon
pop out icon replay 360 icon
horizontal rotate icon

Product Images

atwood accessories and parts brake actuator master cylinder
atwood accessories and parts brake actuator replacement master cylinder for trailer actuators - drum
atwood accessories and parts master cylinder 85841
atwood accessories and parts brake actuator
atwood accessories and parts master cylinder 85841
atwood accessories and parts master cylinder

Customer Photos

atwood accessories and parts brake actuator master cylinder 85841
atwood accessories and parts brake actuator master cylinder replacement for trailer actuators - drum
atwood accessories and parts master cylinder 85841
atwood accessories and parts master cylinder
atwood accessories and parts brake actuator
atwood accessories and parts master cylinder 85841


  • Brake Actuator
  • Master Cylinder Parts
  • Master Cylinder
  • Atwood
Replacement master cylinder fits Atwood hydraulic trailer brake actuators for drum brakes. Includes master cylinder and hardware. Boot not included. Call 800-298-8924 to order Atwood accessories and parts part number 85841 or order online at Free expert support on all Atwood products. Guaranteed Lowest Price and Fastest Shipping for Replacement Master Cylinder for Atwood Trailer Brake Actuators - Drum. Accessories and Parts reviews from real customers.

Atwood Accessories and Parts - 85841

Replacement master cylinder fits Atwood hydraulic trailer brake actuators for drum brakes. Includes master cylinder and hardware. Boot not included.


  • Replaces master cylinder for Atwood hydraulic brake actuator for drum brakes
  • Includes master cylinder and hardware
    • Does not include boot

671453 Atwood Replacement Master Cylinder

Replaces 85841 and 85736

85841 Installation InstructionsInstallation Details 85841 Installation instructions

Related Products

Customers compare 85841 to these similar products

Customers Who Purchased This Accessories and Parts Also Bought...

Replacement parts available for this product

Video of Replacement Master Cylinder for Atwood Trailer Brake Actuators - Drum

Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.

Video Transcript for Atwood Accessories and Parts 85841 Review

Today we're going to review part number 85841. This is the Atwood replacement master cylinder for the Atwood trailer drum brake actuators. Now, this part number includes everything shown here on the table - the master cylinder itself, the gasket, and the four screws for mounting it to the actuator. This is a replacement master cylinder. It'll fit the Atwood hydraulic trailer brake actuators for drum brakes. It does not include the rubber boot or the push rod. We do sell on our website another part number if you need this master cylinder with the push rod assembly.

It's part number 85837. That's the Atwood replacement master cylinder and push rod assembly for the Atwood trailer drum brakes. It includes this cylinder and all this hardware plus the push rod assembly and the rubber boot. That we do sell separately. That should do it for the review on part number 85841. This is the Atwood replacement master cylinder for the Atwood trailer drum brake actuators.


Customer Reviews

Replacement Master Cylinder for Atwood Trailer Brake Actuators - Drum - 85841

Average Customer Rating:  4.8 out of 5 stars   (72 Customer Reviews)

Replacement master cylinder fits Atwood hydraulic trailer brake actuators for drum brakes. Includes master cylinder and hardware. Boot not included.

- 85841

by: Jeff C.08/21/2012

I R&R'd not only the master cylinder but both wheel brakes (I actually just replaced the entire backing plate on both sides, it is much quicker, and I needed the full meal deal on one side anyway after some problems on the road). The whole project went quickly and works great. There are no install instructions included with the master cylinder, but if you watch the online video etrailer offers, and pay attention while removing the old master cylinder, it is really pretty easy. Key items are: make sure the old gasket comes off completely and has left a clean surface (a wire brush is needed otherwise); make sure the new gasket is properly aligned atop the new master cylinder (it is adhesive but doesn't stick very well), and above all, keep the new reservoir clean during install. I needed to save and re-use a 90 degree fitting between the master cylinder and the brake line, but your install may be different. If you use it, clean it! 52547


Does the ball end of the cable go in the slot on the front of the master cylinder? The video does not show this, looks like it should in the schematic.

-- comment by: Bill S - 05/01/2013


Check out the picture on part 85852. The cable attaches to the push rod assembly. In the event the trailer comes free of the tow vehicle, the cable will engage the push rod and the trailer brakes will activate.

-- Patrick B - 5/2/2013


I also had to reuse the 90 degree brake fitting. The new master cylinders do not come with it and there are no instructions showing it either. I order brand new brake lines and had to learn the hard way!

-- comment by: Ryan L - 09/10/2013


- 85841

by: Reno R07/05/2014

Product came in a few days. Fit perfectly. Worked great. One tip for everyone. I had some rust in my old Master Cylinder and thought I could soak it in parts cleaner but the small passages must have been too clogged. I had purchased all the new parts except for the shock which was in good shape. I should have purchased all the parts AND the Master Cylinder. After watching the great video on how to install all the parts from etrailer on Youtube it was a cinch. You save a lot of dough DIY so just buy all the parts and sleep easy. 139346


I still love the product the performance and your company. Highly recommend to all. Thanks for the follow up. I am very impressed.Thank You

Reno R - 07/09/2015


- 85841

by: Mike07/19/2015

Brakes work great again. My old master cylinder was clogged and corroded inside. exact same cylinder as my old one. The number that is stamped on the side of the cylinder is 85736. Very easy D.I.Y change out. 212970


This was easy in install after I watched the video. Like New

Mk - 07/19/2016


- 85841

by: Randy G06/18/2012

We have a 20 year-old boat trailer and the master cylinder was rusted out. After reviewing the installation video from etrailer, I was confident I could easily replace the master cylinder and bleed the brakes in just a couple of hours. The parts arrived right on time and after just an hour, I had brakes again! The only problem was removing the backing from the gasket adheasive. The backing stuck in one spot which caused the gasket to rip. Other than that, it was a very simple project. 44680

- 85841

by: DB Cooper08/22/2011

My only criticism is the the brake line fitting in this requires a fitting before the brake line can be attached (referenced as "an angle piece" in etrailer's installation video). it is not provided in any of the atwood kits. other than that its an easy installation. 22483


For Atwood 85841 Master Cyl, there is a small 90 deg brake line adapter. Video calls it an angle piece. Does eTrailer sale that?

-- comment by: Jess P - 06/03/2013


We do have one 1/8 NPT brass 90, but I am not sure if that is the right part. Different hydraulic couplers use a variety of different small parts and not all of them are available to us. We have to keep a stash in our shops for when we do repairs. If the 1/8NPT fitting I have linked will not fit the threads properly, good hardware stores or auto parts stores should be able to help you.

-- Patrick B - 6/4/2013

- 85841

by: Wendy W07/07/2011

All the parts ordered were exactly correct and job went well, other than I sure could have used a 3rd hand on the installation of master cylinder to keep everything aligned before the gasket fell off so I could get the bolts installed. Consequently I did not get any pix to submit, but everything is perfect with new boot and cap also. thanks to you all... WW 18801

- 85841

by: TJL11/10/2013

Worked like a champ. If the overall surge brake assembly is bolted on to the trailer frame rather than welded, it is easy to dismount the whole assembly then remove the old cylinder and install the new one. Ordering and shipping were reasonable. Installation video presents clear pictures and simple directions--well done! 106906

- 85841

by: DMAC11/23/2012

Order shipped almost immediately arrived at my door in 2 and 1/2 days I installed the master cylinder and other brake parts in about 3 hours. The video was good for info I may or may not have known or done. Quick service and exact product match on a 20 year old trailer. Locks also work great 59956

- 85841

by: Scott H.08/14/2015

Exact fit for 23 year old Atwood surge brake. Might want to bench-prime this master cylinder - mine would not prime on the trailer but worked just fine after I bench-primed it. Be sure to hang onto your 90 degree elbow fitting from the old master cylinder - new ones don't include that fitting. 219169

- 85841

by: James C.08/18/2012

I would recommend Etrailer to anyone. I ordered several parts late at night and got an email notice early the next morning that said not only did my order ship already, but my shipping was upgraded for free! Also, The instructional videos on the site were extremely helpful. Thank you Etrailer. 52202

- 85841

by: Jim P09/20/2017

I ordered from etrailers and it was a great experience. I ordered several items and one was the wrong part that was my fault. They helped me and got the right item shipped out the same day. Very good customer service. They will get all my trailer needs for sure. Thank you Samantha G. 434599

- 85841

by: Steve G05/31/2017

All parts for boat trailer brake repair (master cylinder, wheel cylinders, and brake pushrod) were exact replacements and fit perfectly, solving my braking issues. Paid for expedited shipping and parts were delivered in two days as promised. I'm very pleased with etrailer! 387980

- 85841

by: Aaron07/07/2015

I was concerned that the part numbers were different than the original master cylinder on the trailer. I spoke to Juanita at etrailer and she was able to quickly confirm that this was the correct replacement part. She was right. It fit and works perfectly. 209968

- 85841

by: KG07/06/2011

This master cylinder was a perfect replacement for my old popup camper that was full of rust and chunks. I really appreciate the video that walked me through the steps of replacing the part with an actual person working on the actual parts I ordered. 18525

- 85841

by: Richard M07/18/2013

I received the brake parts for my trailer right on time. The installation was simple and straightforward and the videos really helped. The surge brakes on my boat trailer work better than ever. You have a totally satisfied customer. Thanks. 90206

- 85841

by: Dan03/16/2011

The cross referenced master cylinder appears to be an exact replacement of the original and for a very fair price. Shipping and follow up were finest kind. I would recommend e-trailer to all of you who are rehabilitating old equipment. 9470

- 85841

by: Rebecca Nevel07/07/2011

This is the second time we have done business with you, and I have to tell you everything has been perfect! We received everything on time and all was correct as ordered. When we need anything else we will be in touch. Thank You 18836

- 85841

by: Gary C.06/09/2013

Looked all over the web for this master cylinder and e-trailer had it and all of the other parts that I needed to rebuild my brake system on my bass boat trailer. E-Trailer has everything you need and they have great service. 83899

- 85841

by: eric04/15/2012

i have never replaced a master cylinder or anything else for that matter on a trailer but this website with the video and quality easy to find products made the repairs very easy and saved me on labor cost. 37297

- 85841

by: Fred L06/22/2012

I ordered two separate parts to refurbish my boat trailer. The parts arrived very quickly and were exactly what I needed for the job. I found Etrailer to be an excellent source and will use them again. 45215

- 85841

by: Dave05/14/2017

Perfect replacement for the Atwood 171 on my trailer. Be aware that the outlet is just a threaded hole, so you'll need some sort of female flare fitting to attach the end of the brake line. 380153

- 85841

by: John B07/22/2011

My order came allot sooner than I had expected and the order was correct. I installed the product and I have no complaints. I look forward to doing business with eTrailer again! 19941

- 85841

by: Steve C08/23/2011

Received parts whilst on holiday in the USA. Fantastic service and delivered exactly when promised to my hotel. Will fit on my 30 year old trailer when I return to UK. 22553

- 85841

by: Craig F12/16/2012

I received the items ordered very quickly. It all went together just like they showed in the video. The video was excellent and made the job easy. Thanks Much!!! 61589

- 85841

by: Steve02/04/2013

Super fast shipping and exactly what I ordered. Only wish that the parts breakdown of my whole surge assy was linked in the web site because I need more parts. 64968

- 85841

by: Marty06/14/2013

This was easy in install after I watched the video. Very positive way to promote an item. Bleeding wasn't a problem, and everthing fit perfect. 84587

- 85841

by: Randy R.05/19/2011

Product shipped fast. Customer service updates me via email through the process. Love the how to videos. Etrailer earned my business. 14795

- 85841

by: mikey07/22/2011

great product, easy to do transaction, shipping was faster then expexted. I will diffently use and recommend e trailor again. 19838

- 85841

by: Mark10/01/2014

Fast shipping and the exact item we needed!! Thank you for great customer service!! Very satisfied customer!! 154032

- 85841

by: Jay09/24/2013

Customer service is outstanding, product is great, and delivery was fast! Highly recommend! 101230

- 85841

by: Todd04/18/2016

product was a perfect match, also works great! i now have trailer brakes after all these years. 245884

- 85841

by: Eric08/01/2017

Recived brake cylinder and it was as the site described. Shipping was fast and price was right. 413702

- 85841

by: kelly07/01/2016

I only wish the rubber boot to the foot shaft was included. Pleased with the overall service 267258

- 85841

by: Ron S10/12/2012

As advertized. Fast delivery. When I need trailer parts I now know where to get them. 57043

- 85841

by: jack05/04/2017

excellent service product was exactly what we wanted. great company to deal with 375915

- 85841

by: Richard W. New Carlisle Ohio01/12/2017

Excellent experiences. Patient and extremely helpful customer phone service . 331979

- 85841

by: Jay09/01/2016

Very Fast shipping to Canada and great parts to fix my old myco boat trailer. 290102

- 85841

by: Bryan a12/13/2016

Works perfect easy to bleed took alot off the vehicle stopping the trailer 324538

- 85841

by: STU NEW JERSEY10/22/2012


- 85841

by: Jiey d07/20/2017

Got my product in a few days. Packaged great anf the correct item. Thanks 408581

- 85841

by: Michael W.07/11/2011

Parts got here fast. Videos were great. Had no problems. Thanks 19168

- 85841

by: john s08/11/2017

everything fit and worked great - the videos were very helpful 419258

- 85841

by: Dan F02/23/2017

Master cylinder arrived sooner than expected and fit perfect 344900

- 85841

by: Tim M.04/18/2011

Exact part I needed.They shipped it right away. Fair prices. 11953

- 85841

by: mfh11/04/2011

just the right part . good price fast service thank you 26567

- 85841

by: JD03/23/2015

Easy to order quick delivery and product as advertised 180487

- 85841

by: Mike L05/29/2013

Exactly what I needed. Worked great. Fast Shipping! 82323

- 85841

by: Don06/01/2015

Great item. Have not installed yet.Will install soon 199400

- 85841

by: Jim M06/23/2014

An exact replacement for my 15 year old surge brake. 137128

- 85841

by: Chip S.11/19/2016

Fit just like it should. Extremely helpful video!! 318094

Show More Reviews

Ask the Experts about this Atwood Accessories and Parts
Do you have a question about this Accessories and Part?

  • Difference in Atwood # 85736 and # 85841 Master Cylinder for Atwood Brake Actuator
  • The Atwood Master Cylinder # 85841 you referenced is a replacement for the part # 85736 that is no longer available. The cost of the product is located at the link I have provided, not including any applicable sales tax and shipping and handling. I have included a link to an installation video for this product.
    view full answer...

  • Master Cylinder for Atwood is a Replacement for Hydraulic Surge Brake Actuators
  • This Master Cylinder for Atwood Brake Actuators, part # 85841, is a replacement master cylinder for surge brake actuators, which are used with hydraulic brakes. This master cylinder is for use with drum brakes only.
    view full answer...

  • Will The Atwood Master Cylinder, # 85841, Replace The # 85736 Atwood Master Cylinder
  • I called the manufacturer (Atwood) and they said that they did not have an Atwood coupler with the part number of 61101 (they thought it might be the date code on the coupler) but if it has the # 85736 master cylinder on it you can use the Atwood Master Cylinder, # 85841. The Atwood Master Cylinder, # 85841, is the exact replacement for the # 85736 master cylinder. The # 85841 master cylinder does come with the mounting gasket, but does not come with a replacement master cylinder cap...
    view full answer...

  • Repairing or Replacing Hydraulic Drum Brake Components on 14 Year Old Boat Trailer
  • Although it would be a bit more expensive, I would recommend replacing the entire brake assembly on each side, not just the wheel cylinders. This will provide all new parts, and you will know that it will be quite some time before the brake shoes, adjusters or springs will need replacement. The Demco # 40715 and 40716 you referenced would be an acceptable replacement. In my experience, there is not perceptible difference in quality between Demco and Dexter brake assemblies. This being...
    view full answer...

  • Troubleshooting Surge Brakes that are Locked Up
  • The shock of your actuator is designed to dampen the movement of the actuator so that the brakes apply smoothly without jerking. The shock itself does not push the tongue of the coupler out to release the brakes. If your brakes are locked up that is because the tongue of the actuator is stuck in the pushed in position with the brakes being applied. Most likely this is not the shocks fault, although the correct shock for your Atwood coupler is part # 85830. You have an actuator similar...
    view full answer...

  • Hydraulic Drum Trailer Brakes are Locking Up on Boat Trailer with Atwood Brake Actuator
  • I agree with your diagnosis. It does sound like the worn parts of the actuator are causing some kind of issue with the master cylinder. It may be sticking and unable to pull back and it could be getting air in the lines or other problems. Also, check the break-away cable and assembly to see if it is partially engaged. There should not be much play in the system so I do recommend going with new parts to get the system back to good working order. When looking for replacement parts make...
    view full answer...

  • Will Atwood Master Cylinder 85841 Replace an Older Atwood Master Cylinder 85736
  • I spoke with my Atwood contact this afternoon. Master cylinder # 85841 has been used on most, if not all Atwood actuators since 1980. If in fact your actuator is pre-1980 there are not any parts available for those older actuators, and it would probably be best to replace the actuator. I have added a link below to all our actuator couplers, both bolt-on and weld-on.
    view full answer...

  • Comparing Atwood # 84132 and Titan # T4339700 Trailer Brake Actuating Couplers
  • The Atwood actuator # 84132 comes with a manual reverse lockout and it has a 2-year limited warranty. On the other hand the Titan actuator, # T4339700, does not have a reverse lock out and it has a 1-year warranty. It will also fit on 1-7/8 inch, 2 inch, and 50mm balls whereas the Atwood only fits 2 inch balls. The Atwood coupler has an electrodeposited enamel finish and is rated over the 96 hour salt spray test requirements for corrosion resistance. The Titan actuator is steel with...
    view full answer...

  • Key Differences Between Disc Brake and Drum Brake Trailer Coupler and Brake Actuators
  • Drum brake actuators and disc brake actuators use different master cylinders. A disc brake actuator producer a higher psi than a drum brake actuator so the fittings will be a little different as well. The drum brake master cylinder will have a check valve in it that reduces the amount of psi the system puts out. The disc brake models do not have this valve because more pressure is needed to actuate disc brakes The problem could be air in the lines and/or pistons in the calipers that...
    view full answer...

  • Replacement Atwood Master Cylinder for Atwood 85739
  • I spoke to my contact at Atwood and she informed me that the replacement master cylinder kit for the Atwood hydraulic brake actuator for disc brakes 85739 is # 85840. I have linked the above mentioned product to this page for your viewing and purchasing convenience.
    view full answer...

  • Master Cylinder Boot Replacement for an Atwood Trailer Brake Actuator
  • We do have a replacement boot for Atwood actuators. It is the Replacement Boot Kit, # 84258. The boot is also available in the Replacement Push Rod Kit, # 85852. I have included a link to a video showing a master cylinder installation for you.
    view full answer...

  • Replacement Brake Actuator Master Cylinder for 2006 Ranger Boat Trailer
  • We offer Titan Master Cylinder for Titan Drum Brake Actuators, part # T2374400, which fits their popular Model 10 and Model 20 actuators. We also offer a replacement for Atwood Drum Brake Actuators, part # 85841. Disc brake master cylinders (which operate at a higher 1500-psi pressure) are also available. You should be able to find a manufacturer name and part number on your coupler and with that it should be a straight-forward process to find the correct replacement master cylinder....
    view full answer...

  • Atwood Master Cylinder # 85840 Recommendation
  • The replacement master cylinder that you would need for your 1993 trailer is the Replacement Master Cylinder, part # 85840. This will be a direct replacement for the # 85778 that you have on your trailer.
    view full answer...

  • Replacement Shock and Master Cylinder for a Model 60 Actuator
  • If you are looking for a Model 60 actuator brake master cylinder you would want the part # T4820000 as this is a model 60 master cylinder that is confirmed for disc brakes. For a model 60 shock absorber you would want the part # T2336200.
    view full answer...

  • Is it Better to Replace or Repair a Welded-on Trailer Surge Coupler
  • In most cases where the coupler is welded to the trailer frame, most owners find that it is easier to replace worn parts, rather than try to remove and replace the coupler. If you are not opposed to removing the old one and re-welding a new coupler in its place, I would go that route. The reason is because couplers can be tricky to work on and replacing some parts might reveal that you need other parts. With a new coupler, you get all new parts and will not have to worry about something...
    view full answer...

  • New Atwood Master Cylinder Will Not Push Fluid Through to Bleed Trailer Brakes
  • First, make sure that the red plug at the end of the master cylinder is removed (you would have to remove it anyway to connect the brake line). According to Atwood the reservoir of the Atwood master cylinder pressurizes to send brake fluid out to the brake lines. If you have the master cylinder sitting on your work bench then it probably can't pressurize. You will need to completely assemble the actuator and then test the master cylinder using the brake bleeding steps below. Atwood has...
    view full answer...

  • Replacement Parts for the Atwood Brake Actuator and Replacement Assembly
  • We do carry replacement parts for our Atwood Brake Actuators. Part # 85841 that you referenced is a replacement master cylinder for the Atwood Actuator, part # 82541. I have included a link to the available Atwood actuator replacement parts, many of which fit the Atwood actuator # 82541. I have also included a video of a technician replacing the master cylinder and the push rod assembly, part # 85852, on the Atwood brake actuator. In the event that you have to completely replace your...
    view full answer...

  • Replacement Master Cylinder for Atwood Actuating Coupler for Drum Brakes
  • For your Atwood Brake Actuator w/ Manual Lockout - Drum Brakes - Black - 2" Ball - Bolt On - 6,000 lbs # AT82543, the master cylinder you need is the Replacement Master Cylinder for Atwood Trailer Brake Actuators - Drum # 85841. This is a confirmed fit and I've attached a video to further assist.
    view full answer...

  • Replacement Parts for Atwood Trailer Brake Actuator
  • The Replacement Master Cylinder # 85841 referenced in your question is designed to fit Atwood hydraulic brake actuators for drum brakes. The model with the push rod assembly that you referenced is no longer available from the manufacturer, however the assembly itself can be obtained separately with part # 85852. This assembly includes the breakaway cable, cable retainer, S-hook, master cylinder gasket, master cylinder boot, hardware, push rod, and spring cushion. For the boot by itself,...
    view full answer...

  • Need Replacement Master Cylinder for Atwood Master Cylinder 85736 for Disc Brakes
  • The part that you referenced, Atwood # 85841, is a replacement master cylinder for the Atwood drum brake actuator. This is a correct replacement for the part number you referenced, 85736, for drum brakes.
    view full answer...

  • Does a Trailer Surge Coupler Return to Normal Position on Its Own after Braking
  • When manually bleeding the brakes, you will need to push the coupler in and out by hand as it will not necessarily return on its own. If it seems that your trailer brakes are not working as well as they should, the brakes may need to be adjusted due to wear. There could also be air in the lines and bleeding the brakes should remove any air. I have included a link to a video that demonstrates the brake bleeding process.
    view full answer...

  • Way to Identify Surge Brake Brand On Trailer
  • If you can't find a brand name stamped anywhere on the coupler the easiest way that I can think of would be to check out the link I attached that will take you to a page that has all of the surge couplers we have. You should be able to compare them all to what you have on your trailer and find one that looks the same.
    view full answer...

  • Replacement Parts for Atwood Trailer Coupler on E-Z Loader Boat Trailer
  • We do carry rebuild kits and replacement parts for many brands of trailer couplers, including Atwood, Fulton, Demco and many others, and you can see the Atwood parts by clicking on the link provided. We also happen to carry the complete Atwood drum brake coupler # AT82543. For a master cylinder you can use part # 85841 and for a rubber boot use part # 84258. The specs for the Atwood coupler AT82543 can be seen by clicking on that item number. This coupler is rated for a maximum 900-lbs...
    view full answer...

  • Need Replacement Push Rod Assembly that is 7-1/2 Inches in Length with a Heavy Duty Return Spring
  • I went to our warehouse to pull a couple push rods to measure the length of each one. The two that I recommend is replacement push rod assembly # T2346300 and fits Titan Model 60 brake actuators. The overall length is 7-1/2 inches. Secondly, the replacement push rod and break-away cable assembly # T4502700 will work with Titan Aero 7500 brake actuators. The overall length is 7-1/2 inches. See video I included. If you have the replacement master cylinder for Atwood # 85841 then you...
    view full answer...

  • Reoccuring Corrosion and Fluid Contamination in Master Cylinder
  • A hydraulic brake system is designed as a closed system. If a master cylinder is kept full of fluid, corrosion is not a problem. My guess is that somehow water is getting into the system through a leaky fitting or cap. If it is your cap that is leaking, if you can provide me with the manufacturer and model number of your master cylinder I would be happy to look for a replacement for you.
    view full answer...

  • Troubleshooting No Hydraulic Fluid Reaching the Trailer Brakes After Installing New Master Cylinder
  • The small red/orange plug in the Master Cylinder for Atwood Brake Actuators, # 85841, cannot be easily removed and the part is not available separately. There could be several other problems that are causing the issue you are experiencing. There could be a lack of fluid in the system, a kink in line somewhere, or air in the system. With a full reservoir, I recommend bleeding the brakes to release any trapped air in the system. I have included a link to a video showing how to bleed trailer...
    view full answer...

  • Replacement Master Cylinder for Atwood Drum Brake Surge Coupler in 1972 Ideal Car Trailer
  • The Titan Replacement Master Cylinder you referenced, part # T1027100, is intended specifically for use as a replacement for their Model 6 Drum Brake Actuator. We do offer replacement master cylinders for Atwood couplers for drum brake systems. Part # 85841 is for drum brake applications like the part you referenced. This master cylinder delivers the specific hydraulic pressure needed by drum brakes. The photo attached shows key dimensions of drum brake master cylinder part # 85841.
    view full answer...

  • Recommended Replacement Drum Brake Master Cylinder for Surge Actuator on 1972 Cardinal Trailer
  • In my research on your 1972 Cardinal travel trailer I was not able to find original specs on the brand of drum brake actuator originally installed. From the photos I found the coupler shown does not appear to be an Atwood product. I was able to view many folks' photos of this really cool vintage camper and yes, I'm a little bit jealous. The part number 298390 you provided (thank you) did not return any useful search results related to trailer couplers so your best bet is to try to find...
    view full answer...

  • Testing A Hydraulic Coupler and Bleeding a Hydraulic Brake System
  • If you look at page # 4 of the instructions I linked, you can see the typical procedure and a diagram showing how to test a surge coupler. The procedure involves using a 4 foot long 2 x 4 as a lever and the safety chains as a fulcrum. We have a video that shows how to bleed a brake system, click on the link provided. You will need a helper, a length of rubber tubing that will fit onto the bleeder valve and a clear plastic or glass bottle. I prefer a glass bottle because it is easier...
    view full answer...

  • Will Titan Electric Reverse Lockout Solenoid Work with an Atwood Trailer Actuating Coupler
  • The Atwood brake actuators appear to use a different type of electric lockout that works differently than Titan solenoid # T4748800. The Titan solenoid blocks the flow of fluid when energized whereas the Atwood ones bypass the fluid back into the master cylinder. Because of this difference you would not be able to use the Titan solenoid on an Atwood actuator. If the master cylinder is the type like # 85841 though then it is possible the Titan solenoid will work. But they have not been...
    view full answer...

Do you have a question about this Accessories and Part?

  • Why

    At we guarantee:

  • Highest quality accessories and parts for the best price.

    Our Lowest Price Pledge ensures you will never overpay for the parts you need.
  • Real product know-how.

    We make sure that the products we sell are what we say they are, and that they work the way they are supposed to work. Get real advice from a real person who has the knowledge and expertise needed to solve your problem.
  • Most detailed, accurate accessories and part information available.

    Because we take providing accurate product information seriously, we take our own detailed product photos, demo videos and installation videos, as well as verify measurements, instructions, and vehicle fit information.
  • Installations, made easy.

    We love helping people and have the most highly-trained customer service, hands-on experience, step by step videos and installation instructions.
  • Fast shipping.

    Your order is automatically routed to get out of our warehouse and to your door as quickly as possible. Receive free shipping on orders over $99.
  • Personalized service for life.

    We provide one-on-one, personalized service from the ordering process through the life of your product.
  • Trusted since 1946.

    We've been serving customers since our parts store first opened in 1946 and continue to be recognized by our customers, our vendors and third parties for exceptional service.
  • Returns Policy

    Satisfaction Guarantee
    Need to return an item? No problem. Please read our Returns Policy for more information.

Info for this part was:

Expert Research:
Jackie C
Expert Research:
Michael L
Expert Research:
Robert G
Expert Research:
Patrick B
Expert Research:
Michael H
Expert Research:
Jameson C
Expert Research:
John H
Expert Research:
Brandon M
Expert Research:
Adam R
Expert Research:
Rachael H
Expert Research:
Jeffrey L
Photos by:
Sam P
Updated by:
Lisa S
Updated by:
Sarah W

At we provide the best information available about the products we sell. We take the quality of our information seriously so that you can get the right part the first time. Let us know if anything is missing or if you have any questions.

About Us
photos and videos

Original Photos & Videos

Produced to make sure you know what you are getting and you get exactly what you need.


Installations Completed

To make sure products work and fit the way they are supposed to.

etrailer call center

Phone Calls & Emails Answered

1,125,924 phone calls and 1,350,587 emails to help find the right solution.

etrailer training

Average Hours of Product Training

We get to know our products firsthand so experts can better help you.

etrailer service

Years of Quality Customer Service

Assisting our neighbors and customers, face to face at the counter.

etrailer experts

Pages of Expert Information

Created to make sure you have all the answers to your questions, from real experts.