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5th gear swap modification- lower gearing on a VW 5 speed transmission
5th gear swap modification on a VW
This article shows how to replace the 5th gear or swap it for a taller 5th gear on your VW transmission. A TDI is shown.
difficulty: 2/5 for mk4 and mk5 VW
difficulty: 4/5 for mk3 passat due to firewall clearance and the need for special tools
The procedure is very similar for all mk3, mk4, and early mk5 VW or Audi with the 5 speed manual, 1996-2006 New Beetle, Golf, Jetta, and Passat. They use different transmissions with different gearing but the procedure is similar. This procedure is not applicable to automatic transmissions because they don't use the same gears or gear ratios as a manual transmission. This modification won't work on the 2009+ TDI since their manual transmission is 6 speed.
Also refer to writeup #2: http://www.myturbodiesel.com/wiki/5th-gear-swap-modification-mk-iv-golf-tdi-alh-02j-egr-5-speed/
The taller gear will lower engine rpm when in 5th gear. This reduces engine noise and slightly increases fuel economy. After doing the 5th gear swap, I was surprised at all the new noises I heard due to a quieter cabin! That's how much more relaxed the engine sounds at normal highway driving speeds. Your road surface and tires are another major factor on how quiet the car is. The difference in gearing from your current setup will also determine results. See 1000q: wheel/gearing/tire calculator to see the exact numbers.
Engine load will increase at the same speed due to the change in mechanical advantage and engine rpm. At average highway speeds, reducing rpm puts the engine into a slightly more efficient area of operation vs. before. You could expect as much as a 4% increase in fuel economy but most people see 2% or none at all. This is because you could spend more time in 4th gear depending on your driving habits and few people drive all highway. You will also notice less available acceleration in 5th gear. It shouldn't require downshifting unless you want to pass on a steep hill and are lugging the engine.
Ultimately, I would not recommend doing this swap if you drive mostly in a city or only 10 minutes to work because you won't spend much time in 5th gear and will not realize the benefit. In fact, if you find yourself in 4th gear more often due to the gearing, your fuel economy could actually get slightly worse. If you plan on selling the car soon I wouldn't recommend it. Otherwise, most people are happy with a 5th gear swap. After driving your car with the new 5th gear, you will realize that this is how VW should have geared their diesel cars, especially the mk3.
Doing the 5th gear mod is almost like losing 5th gear but gaining a 6th double overdrive gear. It's comparable to a double overdrive rather than a traditional 6th gear because most 6 gear manual transmission gear ratios put 6th gear near where a regular 5th gear is. In other words, most 6 gear transmissions are just more closely spaced and more suitable for low torque engines. A double overdrive puts a taller gear above the first overdrive 5th gear.
This is also a chance to change the manual transmission gear oil, something that should be done every 60-100,000 miles anyways. After removing your old 5th gear, you can sell it to a gasoline VW owner to reduce the final cost of the project. Their cars use the 020, 02J, or 02A transmission but with shorter gearing and final drive. Your old 5th gear will drop their 5th gear rpm by about 400 rpm! So although the initial cost of the gear kit, gear oil, and shipping is about $350, you can sell your old gears for $100-150!
Note: If you have a mk3 Passat up to 97, there isn't very much room to work because the unibody near the frame rails blocks the end of the transmission. You need to find a low-clearance gear puller because it's a machined fit and pulling on it with your hand or trying to pry it out won't do anything but cause damage. The mk3 Jetta and all mk4 and newer cars have a removable plastic fender liner over the end of the transmission case and plenty of room.
Note: If you have a mk4 pumpe duse (2004-2006), the transmission is slightly different and the cruise control may not work if you change the 5th gear. Mechanically the new gear will work great but the cruise control gets discombobulated and may sometimes cut out or stop working entirely. It might work fine but most people report that it doesn't. This is only a problem on mk4 with the pumpe duse engine.
Note: mk3 and mk4 gears should be interchangeable. However, there's been 1 case where putting mk4 5th gear into a mk3 caused a rattle. See this forum post for details.
Gear ratio details
Here is a listing of stock gear ratios. Because you will change the 5th gear only, your car's gearing will not change in gears 1 through 4. That would only happen if you changed the final drive or increased the tire/wheel size. There are a few choices for 5th gear ratios. Most people will be happiest with .681 because it lowers rpm enough to be worth the expense and time and doesn't create an excessive gap between 4th and 5th gears. The loss of torque with a taller .658 5th gear is too great for some people so if you're not sure of which ratio to choose, I suggest getting .681.
To see the exact engine RPM that a gearing change will produce, refer to 1000q: Tire, wheel, offset, and gearing calculator.
The stock 5th gear ratio in the 02A is .755.
The final drive is 3.157
It uses VW g50 fully synthetic gear oil 75w/90.
Click here for how to change your manual transmission gear oil: mk3
MK4 non pumpe duse (1999.5-2003, new beetle slightly different)
The stock 5th gear ratio in the 02J is .756.
The final drive is 3.389.
It uses VW g50 fully synthetic gear oil 75w/90.
See here for how to change your manual transmission gear oil: mk4
Mk4 pumpe duse (2004-2005, 2006, new beetle slightly different)
The stock 5th gear ratio in the 02J is .744.
The final drive is 3.389.
It uses g 052 726 a2 gear oil.
The stock 5th gear ratio in the OA4 (GQQ) transmission is .769
The final drive is 3.389
There's a trick to changing the mk5 Jetta 5 speed transmission gear oil, see 1000q: mk5 trans oil for details.
New 5th gear ratios: you can purchase either .658, .681, or .717. Note that .658 requires modification to the spring plate, which is outside the scope of this article. It also drops rpm by 13% which is too much for most people. If you have any doubt, don't get .658.
.681 drops rpm by 11% which is large enough to be worth the effort. .717 is a good choice to combine with large tires and for mostly stock power cars. However, make sure the rpm drop is worth it to you.
US dealers will not even order these parts for you since it's not in their standard ordering system. I had a friend in Germany price the parts in Euros and after shipping, it would have cost more than just buying from a US seller, so I recommend a local seller. Below is an example of gearing changes in an mk4 TDI at different speeds and rpms. To see the exact engine RPM that a gearing change will produce, see the gearing calculator in the FAQ and linked above.
.658 (for the 93-2003 Transporter (eurovan) synchro)
02Z 311 158A (large gear)
02Z 311 361A (small gear)
02D 311 158 (large gear)
02D 311 361 (small gear)
02A 311 158 R (large gear)
02A 311 361 M (small gear)
The end cover gasket : 02A 301 215 A
Below is a picture of the .681 gears next to the stock gears. The pictures are about life size.
Note - the small gear should look similar to your old one but it's smaller. There have been reports of incorrect gears where the number of teeth are incorrect with an additional groove in the gear. Below left are the correct gears, new vs. old. Below right is an example of an incorrect gear - note the additional circular groove in the flat side of the gear.
5th gear kit - you need 2 gears total - small and large
transmission end case seal (may be included in the kit)
gear oil - 2 liters
super low-profile gear puller (for mk3 passat) OR gear puller
metric tool set
17mm allen wrench
8mm 12 point "triple square" (VW/Audi) bit
14mm 12 point "triple square" (VW/Audi) bit (for mk5 2005.5-2006 Jetta and late mk4)
T60 torx bit (for all mk3 and almost all mk4)
T40 and T45 (or similar tools for removing the plastic fender cover and engine under cover)
Propane blow torch
gear oil catch pan
Gearing swap procedure
First, make sure that you have all the required tools and inspect the parts. Remove the driver's side front wheel, jack up the car, rest the car on jackstands, and chock the rear wheels as necessary. Make sure the car is in gear and the parking brake is applied. Comply with all safety precautions specified in the factory service manual. Make sure the car is safe and secure before getting underneath the car! See the FAQ for jack stand pictures.
Remove the black plastic splash shield under the engine and the driver's side plastic cover (pass side shown below for illustration). It's held in place with speed nuts and 1 torx screw. (1996-7 passat have the unibody structure here. If you have a mk3 passat, you must determine now if your gear puller will fit in the limited clearance. If not, stop now and attempt the job again when you have the proper tools).
Drain the gear oil with the 17mm allen wrench. As always, make sure you can open the fill hole first! Refer to the earlier links for more details and tips.
Remove the power steering line if it's in the way and remove the transmission end cover (10mm x 5 bolts, circled in red below). Some gear oil will seep out so I suggest removing the bolts at the top first. When you remove the bolts at the bottom, have some paper towels and the catch pan ready.
Here is a picture of what the mk4 looks like. The power steering line is in the way. The plastic side panel has been removed.
Below left is a picture of a mk3 Passat viewed from below. You don't have a power steering line in the way but there's very little clearance because of the frame. Your gear puller must be low profile and fit between the red marks. You could cut the non-structural part of the car, bend it back temporarily, and weld it back but I would rather use a low profile puller.
Below right is a picture of a mk3 jetta, like the mk4 cars, there should be plenty of room and no power steering line in the way.
You should now see the 5th gear (outlined in green underneath the selector gear), the selector gear (outlined in red), the selector lever (outlined in blue), and the small gear you need to remove. Warning: check the clearance of your gear puller! This is the last step where you can still stop the job. If you proceed, you may pass the point of no return: removing any one of the major components could require you to remove the rest of the components to put it all back, or at least make it much easier!
Remove the 8mm triple square bolts circled in purple. Then remove the gear selector pins and gear selector lever. Here is a picture of the parts removed from the car. Note that the top pin was removed, the bottom pin is in place with it's 8mm triple square bolt.
Next, remove the T60 bolts that hold everything in (circled in purple below). Your bolts may be slightly different sizes. There is a belleville washer underneath the bolt. Note its direction and shape - it's not flat! You can use a permanent marker to mark the faces. To counterhold against the gear, have someone step on the brakes and put the car in gear while you remove the bolts. It might move a little if it's tight. If you put the car on wood blocks and have the wheels securely chocked, the weight of the car will be on the wheels so having the car in gear w/brakes on should be enough to counterhold them. Having the car on jack stands with the front wheels in the air means only the brakes are counterholding.
Note how flush the belleville washer and gears are against the shafts.
Note - most late mk4 cars used a M14 triple square bolt instead of a T60 bolt. All mk5 cars use a M14 triple square. This is shown below (the small gear was damaged). A triple square is a common VW/Audi 12 point bit and not a torx so don't try to use a torx on it!
The selector gear has 2 circlip springs one in front, one in back. These do not hold the gear in place. I suggest removing the top circlip so you can fit a gear puller arm into the slots.
You must use a gear puller to remove the selector gear (circled in red in the pics above) which is pressed in. If you can't fit the gear puller arms in place, you may have to file them down to fit. Here are some tips to get the gear off: it's pressed on so don't try to pry it off! Try using PB blaster and squirt it around the center section. Also try removing the washer but leaving the bolt partially threaded in with a gap for something to leave the gear puller bolt to push against. You can also use heat from a blowtorch to heat the selector ring.
You need a low profile gear puller if you have an mk3 Passat. I didn't have one and it was late, so I made one myself. I used a small gear puller center section and 2 small gear puller arms. Note that 1 arm tip is wide, 1 arm tip is narrow (You can't really see this in the picture, but this is to fit into the selector ring slots. The slots alternate 1 wide, 1 narrow). Then I took old allen wrenches, used a blowtorch to soften them, and bent them into s-shapes to hold the gear puller arms. Don't bother using soft metal because it won't hold the force of pulling the gears. Note that the arms are directly opposite each other.
Here is the gear selector with the circlip wire spring installed. Note how the locks fit into the narrow slots. The wide slots are empty.
Once the selector gear is removed, the 5th gear just comes off. You MUST remove the large gear and the selector gear BEFORE you remove the small gear. The small gear will not come off before the large gear comes off.
Clean everything. Now clean it again!
The needle bearing just slides off by hand. In the above picture you should be able to see how the gear spins freely until it's locked by the selector gear.
Here is a comparison of the old and new gears. The old large gear still has the needle bearing on the inside edge (top left gear).
Here is a picture of the selector ring. Note the grooved tooth (center of pic) where the locking teeth sits.
Here is the selector gear. The bronze synchronizer sits between the 5th gear and the selector gear with the teeth pointing away from the trans. The locking teeth are held by the circlips, one above the ring and one below the selector ring.
For reassembly, clean everything again. Remember to put the small gear on first, then the large gear w/needle bearing. Then the selector gear. Press them in with a clean block of wood and a hammer or a clean dead blow mallet. Optional but suggested: heating the gears will make them expand and make them easier to press on. Putting them in an oven for 20 minutes at about 300-350oF should warm them up nicely. A torch won't do too much. You can use pliers and a heat resistant glove like the Ove Glove to handle the hot gears.
The washers are not flat washers! You may be able to see wear grooves on the inside or outside edge of the washer. They are belleville lock washer springs and are shaped like a cone to apply pressure against the gear and T60 bolt. If the washer isn't snug it's on backwards. In the below picture, the washer on the large gear is on backwards - you can see the wear ring on the outer edge - it should be on the inner edge. Torque the bolt to spec and that should press the gears back on if they weren't 100% on.
Reinstall the selector lever and pins. Clean the gasket and cover surfaces and reinstall the cover. Refill with gear oil.
T60 bolts: 59 ft lbs (80 Nm)
8mm triple square selector lever bolts: 18 ft lbs (25 Nm)
Transmission cover bolts: 9 ft lbs
Go for a test drive and check for any leaks. If everything is okay, go sell your 5th gear to a VW gasser! All of the VW mk3 and mk4 cars that are 5 speed can use this gear. (No 6 speed or automatics)
Macgyver Junor likes this.