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Part 3 Honda CRV differential rebuild

Comparing Notes for the Nose Caps Old Vs New!

So in Part 2 we discussed the disassembly of the CRV nose cap, removal of of the clutch pack assembly, and prepared for the brake down of and we went over some of the So as we take these differentials apart we notice a lot of the similarities between the 2! One disassembling the nose cap of the 2006 to 2011 Honda CRV reveals that the nose bearing is much larger diameter than the older Honda CRV. However the inner diameter of the bearing races exactly the same diameter. At 1st glance the older 1997-2005 Honda CRV differential nose bearing uses NACHI-5206 Bearing which carries a 62 mm outer diameter With a 30 mm inner diameter and a 5 mm bearing race with a total thickness of 23.7 mm.

The 2006 to 2011 Honda CRV differential however utilizes a 64.2 mm Bearing outer diameter with a 30 mm inner diameter bearing and a 9.6 mm bearing race with a 14.6 mm total bearing thickness making the 2006 and up Honda CRV differential superior to that of the element and predecessor Honda CRV rear differential.

So for most people thinking about these builds they would imagine that a lot of these components are cross compatible because that is just the nature of Honda. And dealing some of the research for you documenting the build of these rear differentials we notice a lot of the similarities and upgrades in design that highlight some of the key features of additional performance put him to some of the newer Honda all will drive differential components.

RT-AWD Dual Pump Assemblies!

Moving from the RT-AWD nose cap assemblies its time to look inside and see what makes the system transfer power! This part is what most of our customers have been waiting to see. So lets Dive in! The initial look of both dual pump assemblies show vast differences in size and diameter! This technology didn’t change much from the old style RT-AWD differentials to the new other than the system was made shorter and wider for the newer differentials with the RAMP Assembly!

I can imagine that this is to allow a more consistent increase in pressure supplied by the dual pumps and a more gradual and stable transition into applying TQ to the rear differential through the clutches. More surface area with the added benefit of the RAMP assembly allows more power to be transferred quicker with let work from the hydraulics in the dual pump assembly. Well the only way we will know for sure is to take it apart and do some investigation! So lets dig into the Dual Pump Assembly!

Disassembly is pretty strait forward. There are 3 – 8mm 6pt bolts on the back of the Dual Pump Assembly that will need to be removed to begin this process. Turn the Dual Pump upside down so that the piston assembly is facing down and remove the 3 bolts from the bottom of the Pump Assembly.

Note: The Dual Pump Assembly has several Springs and 9.4 mm and 12.6 mm ball bearings internal that change and or block the flow of hydraulic fluid transfer throughout the pumps. When removing the hardware the assembly is under spring pressure. Maintain downward pressure on the assembly during removal of the hardware so that the pumps do not separate!

While maintaining downward pressure on the pump assembly remove the 3 – 8mm bolts and place them in a safe area. Slowly lift the bottom portion of the 3 part pump assembly carefully. For my customers doing the dual pump quick spool kit installation this is the information you need to see! The spring visible to the lower right is the pressure relief spring for the dual pump assembly.

Inside the Dual Pump we find the oil pump drive gear for the secondary pump, the 9.4 mm and 12.6 mm ball bearings that control flow through the dual pump assembly. Take these and place them in a small zip lock bag with the springs for each corresponding bearing. Remove the Oil Pump Drive Gear from the assembly and inspect it for cracks or damage from normal use. You want to look for scoring, cracks, debris, dents etc all that will reveal that the differential has been starved for oil like your engine oil pump. if these parts are damaged replace the dual pump assembly immediately.

Next separate the Primary Dual Pump from the Dual Pump Piston assembly. Remove the bearings and springs from the assembly and place them in labeled zip-lock bags with their corresponding springs. Inspect the Pump Drive gear and the Pump Drive Gear Cavity for damage as you did above.

In the image above I am inspecting the 1997-2005 CRV/ 2003-2011 Element RT-AWD Differential Dual Pump Assemblies (Bottom) compared to the 2006-2011 CRV Dual Pump Assembly (Top).

Honda didn’t really change the internal design and components of these pumps much over the years between generations of the V but they did change the size of the pumps themselves. What I discover during my tear down of these 2 differentials is that the old style RT-AWD Differential is under-driven by the T-Case and the newer style with the RAMP Assembly is over-driven by the Transfer Case. I Part 2 we discussed the difference in size of the dual pumps from the external but not how they function. So for those of you who do not know what makes this work here is the flow diagram for the CRV Non Ramp differential.

Non Ramp CRV Differential RT-AWD Dual Pump Assembly

The dual pump assembly is made up of 4 major parts. The primary and Secondary oil pumps, Clutch Piston Assembly and the Rear Oil Pump Cover. How this system works is relatively simple but follows the principals of Bernoulli’s theory of Fluid Dynamics where he states that an increase in the speed of a fluid occurs simultaneously with a decrease in pressure or a decrease in the fluid‘s potential energy. This compounded by Issac Newtons
Second Law of Motion stating If a small volume of fluid is flowing horizontally from a region of high pressure to a region of low pressure, then there is more pressure behind than in front. This gives a net force on the volume, accelerating it along the streamline. The RT-AWD Differential uses a Hydro-Mechanical Tq Control System that allows a series of flow controls to (spring and bearings) that regulate the flow of hydraulic fluid supplied to the Clutch Piston Assembly. The Dual Pump Quick Spool Kit increases the pressure and flow of hydraulic oil supplied to the Clutch Piston Assembly thus increasing the pressure and volume of oil supplied from the Primary and Secondary Oil Pumps to the piston assembly. The shims decrease the amount of distance between the clutch Piston assembly and clutch engagement.

RT-AWD Dual Pump Assembly Flow Characteristics

The main thing people forget to do in the installation process of the Dual Pump Quick Spool Kit installation is to take the 2 – Oil Orifices and clean them up! Remove all debris and dirt from the passages and reinstall them into their rubber O-Rings to reinstall into the Dual Pump Assembly.

Once this is done its time to install the modified Springs into the Dual Pump Assembly. In our kit we supply 2 spring replacements for the dual pump Assembly that increase hydraulic pressure and hold your V and decrease pressure bleed-off while in AWD operation.

Honda RT-AWD Dual Pump Pressure Relief Spring (Top Left) and 2wd/4wd Selector Switch Spring (Bottom Left), Dual Pump Quick Spool Kit Upgraded Pressure Relief Spring (Top Right) and Upgraded 2wd/4wd Selector Switch Spring (Bottom Right)

These pieces for the 2006-2011 CRV are a direct swap! Remove the old springs and replace them with the upgraded ones. However for the 1997-2005 CRV and 2003-2011 Element owners out there you will need to trim your spring slightly to allow proper fitment. Take your factory Pressure relief Spring and trim to the desired length of the factory Pressure Relief Spring. For those of you just doing the quick spool install this is the end of the road for you. Reassembly the dual pump assembly after your parts have been inspected and cleaned. For the rest of you we will continue our rebuild later this week with the pinion removal and bearing replacement. Tq Values for the Dual Pump Assembly Bolts are 5lb ft of TQ.

Thanks everyone for participating and following along! Like/ Share/ Comment!

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Part 2 CRV Differential Disassembly!

Continuing from our last post where we disassembled the rear differential from the carrier and talked about what we will be installing into our customers differential. Today we will be removing the nose cap from the differential carrier, the clutch assembly, and the dual pump assembly for the Dual Pump Quick Spool Mod and Racing Diffs Clutch Upgrade Install! So without further adieu Lets Get it!

To begin this process we will need to get some tools like last time to prepare for our disassembly! I’d recommend a “Strait Blade Screw Driver” always at the ready! But here are the tools that will be required to accomplish this task!

Required Tools

  • 3/8ths” Drive Ratchet.
  • 3/8ths” Drive 3″ extension.
  • 3/8ths” 8mm 6pt Socket.
  • 1/2″ Drive Ratchet or Breaker Bar.
  • 1/2″ Drive 24mm or 34mm Socket.
  • 1/4″ Drive Ratchet.
  • 1/4″ Drive 6mm Socket.
  • 1/4″ Drive 3″ Extension.
  • Driveshaft Flange Support Bar.
  • 6″ Long #3 Strait Blade Screw Driver.
  • A Hammer.
  • Small Center Punch.
  • 6″ Pry-bar.
  • Small Razor for Gasket removal.
  • Drip Pan.
  • Gloves.
  • 45 Degree Scribe.

Differential Nose Cap Removal

First I needed to get some illustrations from the CRV Master Service Manual. I acquired them from Honda thanks to a couple of good friends! This should help support this episode for you all to follow along. The procedure is pretty strait forward. Using a center punch you will need to take your hammer and remove the dimple on the pinion nut that locks the differential pinion nut. This dimple keeps the pinion nut from backing off and from loosening under normal driving conditions.

Hammer and Center Punch Pinion Dimple Removal Procedure
Pinion Nut Dimple Relief
Turn the Pinion Nut Counter Clockwise to remove.

While supporting the weight of the differential install the driveshaft flange support bar and hardware onto the U joint flange of the differential. Install the driveshaft flange support bar onto the differential and grab your 1/2″ drive breaker bar and (24mm or 34mm) socket. Place the socket into the differential and break the TQ of the 24mm pinion nut and remove it.

Note: 1997 to 2005 Honda CRV and 2003-2011 Element use 24mm pinion nut. 2006-2011 CRV & Accord Crosstour use 34mm pinion nut.
Remove the Driveshaft Flange and lock nut from the Differential Nose Cap Assembly. (TCD)

Next we will remove the 8x8mm bolts from the differential nose cap cover. Pay particular attention to not strip the bolts when removing them. Using your 3/8ths” drive ratchet, 3/8ths” drive 3″ extension, and 3/8ths” Drive 8mm 6pt socket remove all 8 bolts from the differential nose cap cover and place them in a safe area.

Separate the Torque Control Differential “TCD” Nose Cap from the Differential Carrier Assembly.

Once this step is complete use your 6″ strait blade screw driver and pry-bar to separate the nose cap cover from the differential by prying at the separation tabs on the nose cap and carrier assembly. Remove the nose cap cover over your drain pan to alleviate spills and messes. Separate the nose cap cover from the differential carrier assembly and place in a safe location. This should expose the differential TCD and Dual Pump Assembly.

Remove the differential clutch assembly and clutch cage by lifting them from the pinion shaft and placing them to the side. Warning! The TCD Clutch RAMP Assembly for the 2006 – 2011 RT-AWD differential have 8 small ball bearings that ride under the clutch assembly. Use caution when removing. Any damage to these ball bearings will render the TCD clutch RAMP assembly non-operational.

Dual Pump Assembly Removal!

I think it’s important to give some characteristics of both differential dual pump assemblies we support! At first glance the dual pump assemblies from the 1997-2005 CRV are noticeably different in size.

The 2006-2011 CRV differential with RAMP is exactly 76.2mm tall and is 118mm in diameter.

The 1997-2005 CRV differential is 101.6mm tall and 115.6mm diameter.

Carrier Assembly Preparation!

Since we are not replacing the pinion in this differential we will start with removing the strainer from the differential carrier assembly.

Using your strait blade screw driver use the side of the case to gain leverage to pry the strainer from the carrier assembly. *CAUTION! Please be careful not to damage the screen of the strainer during removal.

Lift the strainer from the carrier and place it to the side. Repeat this step for the magnet to the left if the strainer below the pinion.

In the next part of this build documentary we will perform the inspection of the internal differential components We will then compare the older CRV differential carrier assembly to the new and remove the pinion from the differential for bearing inspection. Stay tuned and we will be back soon! Thanks for following!

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Bisimoto RT-AWD Differential Tear-down and Preparation for our Racing Diffs Moly-Ceramic Clutch Upgrade!

Bisi discusses the disassembly and future plans for the RT-AWD CRV/ Element/ Cross-Tour Rear Differentials in partnership with Automotive Koncepts & Designs Inc, Bisimoto, Quaife and Racing Diffs!

Through our partnership we have created several aftermarket performance parts supporting the AWD platform for Honda. In this Bisimoto YouTube video Bisi discusses plans moving forward with development with additional support from “Quaife” and the future projected plans for testing our Dual Pump Quick Spool Kit with our new Racing Diffs Molybdenum Ceramic Coated Clutch Upgrade kit for the RT-AWD CRV, Element and Accord Cross-Tour.

More to come from Bisimoto Engineering and this amazing partnership with full length Tear Down and Assembly videos complete with technical specifications coming soon. Like what you see and want to learn more about what we are doing! Follow the team and learn about the future of our developments by following us with the links below!