This was made after purchasing 0.56 ratio 6th gear set from JH Motorsports.
Cost:
- Hugely dependent on which tools you already own.
- I purchased 2 special tools from the Snap-On Volkswagen Special Tools and Equipment Program.
Time:
- Dependent on how successful your scavenger hunt for tools was.
- Assuming every tool you need has been gathered in one room, about an afternoon start to finish.
Tools:
- Torx Socket Set (preferably 1/2" drive)
- Circlip pliers
- Detent Extractor - T40054
- Slide Hammer
- 12-Point Socket - T40097
- Spline Clamp - T10306 (or old clutch)
- Bench Vice
- 12-Point Key - T10307 (or big fuckin' monkey wrench)
- 20-Ton Shop Press with Arbor Plates
- Miscellaneous Hand Tools, mainly slotted screwdrivers
Consumables:
- 4 Quarts GL-4 Synthetic Gear Oil
- Ultra Black Permatex
- Blue Loctite
Overview:
- This DYI assumes you've already followed an appropriate engine removal guide and that you possess a certain degree of mechanical aptitude. While taking your transmission apart is slightly terrifying, it only can be reassembled one way and you can test functionality before reinstalling.
Steps:
The steps outlined in this guide mimics steps from the official Bently factory manual.
The order of dismantlement is:
1.) Drain Oil
2.) Selector Shaft
3.) Torsen
4.) Housing
5.) Output Shaft
6.) Input Shaft
7.) Reassemble
- 1.) Drain Oil
- Get the transmission in the air horizontally and drain the gear oil. The outlet is directly on its underside. DO NOT stand the transmission on its bell until the oil is drained, as it will leak from the gearbox breather cap.
- Return the transmission to the ground and remove the clutch release mechanism inside the bell.
- Remove 2 torx bolts and pull out the release bearing guide.
- Remove the input shaft circlip.
- 2.) Selector Shaft
- Place the transmission horizontally on the ground. Expose the selector shaft by removing its cover; this cover also holds the reverse switch and is held on by 3 torx bolts.
- Using the detent tool (T40054) and your slide hammer, remove the detents for the selector shaft.
(I rented a slide hammer, but the threads on the hammer didn't match the special tool. I grabbed a nut and welded to an appropriate metric bolt.) - Remove the dowel pin then slide out the selector shaft.
- 3.) Torsen
- At this stage, there should be no oil in the transmission and you can safely stand it upright on its bell housing.
- Grab your torx socket and remove the bolts for the Torsen housing.
- Lift off housing, lift out Torsen and set aside. Keep track of the spring and 2 washers on the back of the differential.
- Remove the circlip found underneath the Torsen then proceed to pluck out the underlying bearing and associated washers until you reveal the 12-point nut.
- Engage selector rods 1 and 4 simultaneously through the selector shaft opening. This will lock the transmission and keep the output shaft from spinning while loosening the nut.
- Using your special socket, T40097, remove the nut.
(I didn't own a 3/4" ratchet, so I grabbed a piece of 3/4" stock and an adjustable wrench.)
- 4.) Housing
- Remove all remaining detents.
- Remove the torx bolts on the side of the gear housing. There are 3 of these bolts and they support the reverse shaft and the internal bearing plate.
- Remove the one million torx bolts securing the gear housing to the transmission.
- Lift off the gear housing and set aside. Use a rubber mallet if it refuses to detach.
- Remove the magnet, check it out, ooh and aah at the pattern marvel a magnetic field produces!
- Grab the bearing plate and pull up, removing the entire reverse/1st/2nd gear system and corresponding selector shafts.
(Your experience may differ, as the Bently advises using a gear puller for 2nd's selector gear.) - Remove the oil plate.
- Grab the hollow input shaft and output shaft. Pull them out simultaneously, complete with their selector rods. They all come out at once!
- 5.) Output Shaft
- Using your press and arbor plates, press off 5th gear.
- Using a pair of slotted screwdrivers, pry off 6th gear.
- Oil your new 0.56 6th output gear (smallest gear), slide on, and lightly engage the gear's shaft splines.
- Reinstall 5th gear (ensure proper direction, check fitment with input shaft) and press back on until snug.
- 6.) Input Shaft
- Secure the input shaft in a vise with the special tool spline clamp.
(I used an old clutch and a vise. Make sure to support the opposite end with something.) - Remove circlip.
- Using the special key tool, remove the 12-point nut. This nut is LEFT HANDED and must be turned CLOCKWISE to loosen!
(If you are cheap, you can use a monkey wrench for this step.) - Attach a hose clamp towards the top of the input shaft. This will prevent your shaft crashing to the floor in the following step.
- Using your press, secure the arbor plates under 5th gear with the input spline facing upwards. You will press off every gear above at the same time.
(This is scary and requires lots of force. The BANG when it releases means you can stop peeing yourself and everything is OKAY.) - Check for synchronizer wear.
(If your selector gears dissembled themselves during the pressing, make sure not to lose the 3 ball bearing housings that neatly fit inside the selector gears. These are the smallest parts in the transmission.) - Begin reassembling, generally returning to the press after each selector gear. Double-check your gear orientation with your completed output shaft if you get lost!
- Oil and install your new 0.56 6th input gear (largest gear) similarly to the new output gear.
- Apply Loctite to the left-handed nut threads and tighten.
- Secure the input shaft in a vise with the special tool spline clamp.
- 7.) Reassemble
- Install hollow output shaft and input shaft, complete with their selector rods, at the same time.
- Install bearing plate.
- Install 2nd and 1st gears, complete with selector rods. Affix short reverse shaft back into its position.
- Use the black Permatex to create a gasket film on the mating of the bell housing and gear housing.
- Reinstall gear housing, using a screwdriver to poke around underneath until the selector rods fall into their upper holes.
- Place a dab of blue Loctite on each bolt as your reassemble.
- Place Loctite on the output shaft's 12-point nut, engage selector shafts 1 and 4, then tighten.
- Reinstall Torsen differential with bearing, washers, and spring.
- Install Torsen housing, bolt down using Loctite.
- Lay transmission horizontal, reinstall front circlip and clutch release components.
- Reinstall selector shaft and dowel pin.
- Use a rubber mallet to reinstall all detents; hammer until flush.
- Test! Make sure each gear correctly engages. After seeing the design of the selector gears and synchronizers, you should have a good feeling when hearing the different gears engage.
- WAIT 24 hours for your Loctite and Permatex to fully cure.
- Fill with your favorite synthetic gear oil.
- Done!
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Originally Posted by B6JoeS4
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