Media Blasting Complete! Time for Some color! Norman and Shilo soon to be complete and 1 more for a special guest eagerly awaiting completion of their newly rebuilt RT-AWD differentials with our new performance upgrades! Service includes inspection, deep cleaning, new pinion bearings, fill/ drain port hardware, shims, washers, differential bearings, seals, dual pump rebuild, cleaning and clutch inspection then reassembly with close tolerances for your performance goals! This is our standard servicing but many upgrades are available as well to meet and exceed your performance goals.
A Glance into the Honda RT 1st and 2nd Gen. All wheel drive rear differentials!
So in this brief documentary I want to give you all the opportunity to see 1st hand the Honda first and 2nd Gen. RT-AWD rear differentials from the Honda CRV and Honda Element! Using Norman and Shilo’s differentials we have a rare opportunity to show and contrast the differences in design of these 2 differential designs as I await the carrier cases return from powder coating! Lets Dive In!
I chose these 2 as a comparison because there is a lot of misconception being thrown around about corrected gear ratios and about the actual functions of these differentials.
So utilizing these 2 generations of rear differentials I will give you the option of learning as we explore during our build process for these differentials while waiting for the differential housing has to come back from powder coating. So some brief comparisons.
From the naked eye both differentials appeared to be exactly the same even down to the diameter bearing diameter and thickness but newer slight changes in bearings design between generations. The trunnion gears are exactly the same amount of teeth, diameter, and metal thickness with the same over all design but again I wanted to engage you all in this discussion. The differences come in when you get to the Ring Gear and Pinion!
The 97-05 Honda CRV/Element differential carries 38 teeth on the ring gear and 15 on the pinion. So I guess it’s time to get into some math! Getting into it the ring gear ratio divided by the pinion ratio will give you the total gear ratio for the differential. This is the equation for the 97-05 CRV/ 03-11 Element rear (15 /38 = 2.533:1). Driven by a transfer case that sends 2.542:1 ratio to the rear differential this means that the older CRV/ Element differentials are over driven by the transfer case forcing the differential to build hydraulic pressure faster for clutching gagement in the rear differential.
However the newer style RT-AWD differentials for the 06 and up CRV and Cross-tour use an opposite method of engagement! Operating with a 16 tooth pinion and a 41 tooth ring gear they come in at a 2.562:1 ratio (16 /41 = 2.562:1). For the newer generation to increase performance and response Honda further opted to use further underdriving with a mechanical RAMP assembly consisting of 2 roller bearings, pressure plate, RAMP cam assembly and a new dual clutch assembly giving the 2006 and up CRV/ Crosstour rear differential much more response and immediate TQ power on demand capability while in operation. This one way CAM assembly aids in transferring 20% mechanical energy to the rear wheels instantly. In the imagine below is the 2006 and above CRV Torque Controlled Differential (TCD) nose assembly. It shows the base components and orientation of the ramp assembly its components! Think of it as a progressive style one way cam inside of a limited slip differential. As the ramp assembly spins it pushes on a series of ball bearings fitted in groves that roll inside of the cam forcing separation of the cam and pressure plate assembly forcing pressure to be applied to the dual clutch assembly.
The ramp assembly applies 20% torque immediately to the differential through the clutches to the rear wheels allowing instant torque application, faster engagement and response from the rear differential. The one thing that has been missing from the entire equation is a clutch kit that was capable of transferring more power with less heat and less wear. Innovations like our dual pump quick spool kit use shims under each snap ring to apply additional pressure to the clutches and ramp assembly forcing preload.
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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.
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.
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.
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.
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!
Well its that time! Got a customers rear differential in today for a Servicing! This differential will receive a rear GEAR-X / GTS Motorsports Torsen LSD, Racing Diffs Dual Pump Clutch Pack upgrade Kit and an Automotive Koncepts & Designs Inc Dual Pump Quick Spool Kit with new Bearings, Gaskets, O-Rings, Drain/ Fill Port Plugs, and Oil Seals after a nice cleaning and inspection for damage!
Preparing this one for a good build documentary and gathering the remaining pics needed for the DPQS Kit installation guide for those who want to do this at home on their own. Getting things moving at the new shop and preparing for a lot of new builds as well as some more parts to leave!
A couple more parts waiting to be received before we can kick this party off right! Ill show you step by step how this system works and additionally go over the differences between the 2 differential styles of RT-AWD Differentials in a short video. Stay Tuned and Prepare for some knowledge!
Ready to order the next batch of Gear X Torsen LSD’s! Available for the B/F/H/K FWD transmissions and B/K AWD transmissions these LSD’s feature a new Gear X design allowing them to be plug and play drop in replacements for the OEM open differential.
Many LSD’s have been shipped already and many more on the way! Contact us today to order yours!