BMW 1 Series Coupe Forum / 1 Series Convertible Forum (1M / tii / 135i / 128i / Coupe / Cabrio / Hatchback) (BMW E82 E88 128i 130i 135i) - View Single Post - DIY: manual transmission and diff fluid change

wolfe · 07-17-2010, 10:11 AM

Disclaimer: use any of this at your own risk. I'm not responsible for any damage, warranty denial issues, etc. caused by following this guide. The fluids used were my personal preference, and may not be officially approved or recommended for use in the car.

PLEASE DO YOUR OWN RESEARCH AND SELECT YOUR OWN CHOICE OF FLUIDS

My car is a 128i; the 135i procedure is probably similar but with some differences to capacities, bolt sizes, and torque specs. Likewise, other model year 128i cars may even have small differences, I don't know.

I did this service plus an engine oil and filter change on my car at 1200 miles. Apparently BMW used to do a 'break in' service on all cars, which went away with free maintenance and lifetime fluids. The amount of particles in the fluid that came out convinced me that this was worth the effort:

Factory fill transmission fluid after 1200 miles.

Factory fill differential fluid after 1200 miles.

Not relevant to this DIY, but interesting:
Factory fitted engine oil filter, after 1200 miles
Much of the white specks on the ridges and sides are camera flash reflection, though you can clearly see the amount of metal in the valleys of the filter.

Close-up of single oil filter pleat, after 1200 miles
Good to see the filter is doing its job but I still wouldn't feel good about letting that go 15k miles.

Tools & supplies needed:

~Gallon transmission fluid (I used redline d4 ATF) A gallon is a bit more than you need but is less messy than swapping pumps to multiple bottles.
~2 quarts diff fluid (I used redline 75w90)
Jack, jackstands or lift etc.
Sockets, extensions, wrenches.
14mm hex bit for socket wrench
low profile 8mm hex bit, or 8mm hex drain plug bit
breaker bar
fluid pumps compatible with fluid bottles
flexible tubing, just over 1/4" inside diameter
drain pan
torque wrench
new diff filler plug (optional) BMW P/N: 33117525064

This works best when the car has recently been driven so the fluids are warmer, thinner, and will drain more easily. I let it cool down a little so the chances of getting burned are lower.

First, the car needs to be raised up and level. My jacking procedure is a bit convoluted, because it's left over from my old BMW which had no real central jacking points.

Chocked the rear wheels, car's out of gear, and handbrake is on.

My jackstands won't clear the car when it's on the ground, so I have to use a floor jack to get it on blocks of wood.

Plywood 'pucks' which fit the jack and the car's jacking blocks without damaging either.

Make sure the jack/jackstand is securely located in the jacking point

Now the car should be off the ground and supported by all four jacking points. Having it level is important for complete draining of the old fluid and filling an accurate quantity of the new fluid.

REAR DIFFERENTIAL - 128i. 135i may be similar, I don't know for sure.

The diff only has a fill plug, no drain plug which makes this part a royal pain. It takes a 14mm hex bit, and if you're doing things by the book you should use a new plug when you refit it. The part number is 33117525064 and it's about 3 bucks. Have a drain pan in place because a little fluid will spill.

Rear diff drain plug. Luckily on this car access to it is good.

I couldn't move it with a regular 1/2" drive socket so I went for the breaker bar which made short work of it.

A bit of fluid will trickle out once you remove the plug, it was green/gray and looked dirty

Next, you'll need something capable of sucking out the old fluid. I've only done this once on a car with no drain plug, but I think something that can pull a constant vacuum would be much better than any kind of hand pump. I used this brake fluid extractor I got from Griot's Garage. I don't recommend this tool, it was useless for bleeding brakes, and not great for this. You pump it up to create a vacuum, then open the valve on the tubing to suck out the fluid. Some kind of air compressor driven vacuum pump would be ideal. A hand pump may do it but it would be hard to hold everything in place and still use the pump.

Fluid extractor

This diameter tubing turned out to be perfect. Here is a regular pencil for reference. I got this tubing on a rubber bulb hand pump at autozone. You want something that is wide enough to suck up the thick diff fluid, but narrow enough to fit through the fill hole and be moved around inside the diff.

You want to try and suck out as much of the fluid as possible, which is a challenge. I kept moving the position of the hose inside the diff until it was no longer sucking out any fluid. I re-pressurized the pump and redid this step about 5 times to try and get all of it. There may be better ways to do this, but I didn't want to risk dropping anything into the diff.

To refill the diff, I had ordered a fluid pump to fit quart size bottles from Amazon. This was incredibly hard to find, and as it turned out it was next to useless. It wouldn't pump 'uphill' very well and didn't fit the threads on the fluid bottle. I got two (quart) bottles of redline 75w90 fluid, as the BMW fluid is nearly impossible to get in small quantities and the redline stuff is reportedly very good. Partly due to the poor quality pump and some spillage, one quart would not have been enough even though I believe the capacity is just under a quart. I'm not certain on this though.

Note: Redline makes two versions of their 75w90 fluid: 75w90 and 75w90ns. I asked Redline about this and they recommended 75w90 for this application, as it would run a little cooler.

diff refill items

Put the pump hose into the diff fill hole and fill it until fluid starts coming out of the hole. Remove the hose and fit the drain plug, torque to 60NM / 44.2 lb-ft.

MANUAL TRANSMISSION - Again this is for the 128i. 135i would be similar but tools and torque specs are probably different.

Note: The A/C drain line is right next to this, so there will probably be water dripping from it. Watch your eyes.

Remove the central section of the splash shield. It's held on by about 7 or 8 self tapping screws, which have 8mm bolt heads.

There is also an angled catch, so after you've removed all the bolts you have to turn the splash shield as you remove it. The hole will then line up with the catch and the whole thing comes off easily.

Looking up at the transmission from underneath the car, you can now see the fill and drain plugs. On my car they took 8mm hex bits. I ordered new plugs for these too but they were different, so I reused the original ones. The plugs that came with the car were less tall, and didn't have sealing or crush washers so I assume it's safe to reuse them.

Transmission drain and fill plug locations

It's always good practice to remove the filler plug first. That way you don't drain all the fluid out and then find you can't remove the fill plug. Space is restricted on the fill plug, as you have limited room between the side of the transmission and the transmission tunnel. There was not enough room for an 8mm hex bit, and a 3/8" to 1/2 adapter plus the breaker bar. Once again these are on very tight from the factory. The fluid will come out VERY fast once the drain plug is removed, so have a drain pan ready and watch for splashing.

Limited space to get access to fill plug

I used an 8mm drain plug bit, which came from harbor freight in a set. It's much lower profile than a normal one, and fit in the space just fine.

For the transmission, I chose redline D4 ATF. In my last BMW with many more miles and some syncro wear, ATF gave the best shifter feel by far. However it may not be the best choice in a new BMW transmission. I will see how it goes in this car, and go back to the BMW fluid if need be. So far I like it though. I ordered a gallon, and I estimate I used just under 3 quarts. I got a gallon pump from autozone, and this one worked perfectly.

Update: It's now been ten years since I first posted this DIY. My 128i now has 80k miles and for the last couple of years I've been using Pentosin MTF2 in the transmission. I think I prefer it to the redline D4, it's not quite as smooth as the D4 on a 'good day' but feels more consistent regardless of temperature (though I don't see temps below freezing very often).

It's a tight fit, but if the car is jacked up high enough you can just about stand the atf container and pump up underneath. ATF smells horrible, so you want to avoid spilling it if possible.

With the drain pan in place, put the pump filler hose into the transmission filler hole. If I've bought plenty of new fluid, I usually give it two or three pumps with the drain plug still removed to try and flush out any remaining sediment.

Next, clean and refit the drain plug, torque to 35NM / 25.8 lb-ft

Pump fluid in through the fill hole, until it starts to come out of the fill hole. Re-fit the fill plug, and torque this one to 35NM / 25.8 lb-ft as well.

Put the splash shield back on, and lower the car to the ground. Take it for a short drive, then check for any leaks. If it's all good this shouldn't need doing again for 30k miles or so.

07-17-2010, 10:11 AM	#1
wolfe Captain 134 Rep 613 Posts Drives: e82 / e70 / r56 / r60 Join Date: Apr 2010 Location: USA iTrader: (1)	DIY: manual transmission and diff fluid change Disclaimer: use any of this at your own risk. I'm not responsible for any damage, warranty denial issues, etc. caused by following this guide. The fluids used were my personal preference, and may not be officially approved or recommended for use in the car. PLEASE DO YOUR OWN RESEARCH AND SELECT YOUR OWN CHOICE OF FLUIDS My car is a 128i; the 135i procedure is probably similar but with some differences to capacities, bolt sizes, and torque specs. Likewise, other model year 128i cars may even have small differences, I don't know. I did this service plus an engine oil and filter change on my car at 1200 miles. Apparently BMW used to do a 'break in' service on all cars, which went away with free maintenance and lifetime fluids. The amount of particles in the fluid that came out convinced me that this was worth the effort: Factory fill transmission fluid after 1200 miles. View post on imgur.com Factory fill differential fluid after 1200 miles. View post on imgur.com Not relevant to this DIY, but interesting: Factory fitted engine oil filter, after 1200 miles Much of the white specks on the ridges and sides are camera flash reflection, though you can clearly see the amount of metal in the valleys of the filter. View post on imgur.com Close-up of single oil filter pleat, after 1200 miles Good to see the filter is doing its job but I still wouldn't feel good about letting that go 15k miles. View post on imgur.com Tools & supplies needed: ~Gallon transmission fluid (I used redline d4 ATF) A gallon is a bit more than you need but is less messy than swapping pumps to multiple bottles. ~2 quarts diff fluid (I used redline 75w90) Jack, jackstands or lift etc. Sockets, extensions, wrenches. 14mm hex bit for socket wrench low profile 8mm hex bit, or 8mm hex drain plug bit breaker bar fluid pumps compatible with fluid bottles flexible tubing, just over 1/4" inside diameter drain pan torque wrench new diff filler plug (optional) BMW P/N: 33117525064 This works best when the car has recently been driven so the fluids are warmer, thinner, and will drain more easily. I let it cool down a little so the chances of getting burned are lower. First, the car needs to be raised up and level. My jacking procedure is a bit convoluted, because it's left over from my old BMW which had no real central jacking points. Chocked the rear wheels, car's out of gear, and handbrake is on. View post on imgur.com My jackstands won't clear the car when it's on the ground, so I have to use a floor jack to get it on blocks of wood. View post on imgur.com Plywood 'pucks' which fit the jack and the car's jacking blocks without damaging either. View post on imgur.com Make sure the jack/jackstand is securely located in the jacking point View post on imgur.com Now the car should be off the ground and supported by all four jacking points. Having it level is important for complete draining of the old fluid and filling an accurate quantity of the new fluid. REAR DIFFERENTIAL - 128i. 135i may be similar, I don't know for sure. The diff only has a fill plug, no drain plug which makes this part a royal pain. It takes a 14mm hex bit, and if you're doing things by the book you should use a new plug when you refit it. The part number is 33117525064 and it's about 3 bucks. Have a drain pan in place because a little fluid will spill. Rear diff drain plug. Luckily on this car access to it is good. View post on imgur.com I couldn't move it with a regular 1/2" drive socket so I went for the breaker bar which made short work of it. View post on imgur.com A bit of fluid will trickle out once you remove the plug, it was green/gray and looked dirty View post on imgur.com Next, you'll need something capable of sucking out the old fluid. I've only done this once on a car with no drain plug, but I think something that can pull a constant vacuum would be much better than any kind of hand pump. I used this brake fluid extractor I got from Griot's Garage. I don't recommend this tool, it was useless for bleeding brakes, and not great for this. You pump it up to create a vacuum, then open the valve on the tubing to suck out the fluid. Some kind of air compressor driven vacuum pump would be ideal. A hand pump may do it but it would be hard to hold everything in place and still use the pump. Fluid extractor View post on imgur.com This diameter tubing turned out to be perfect. Here is a regular pencil for reference. I got this tubing on a rubber bulb hand pump at autozone. You want something that is wide enough to suck up the thick diff fluid, but narrow enough to fit through the fill hole and be moved around inside the diff. View post on imgur.com You want to try and suck out as much of the fluid as possible, which is a challenge. I kept moving the position of the hose inside the diff until it was no longer sucking out any fluid. I re-pressurized the pump and redid this step about 5 times to try and get all of it. There may be better ways to do this, but I didn't want to risk dropping anything into the diff. To refill the diff, I had ordered a fluid pump to fit quart size bottles from Amazon. This was incredibly hard to find, and as it turned out it was next to useless. It wouldn't pump 'uphill' very well and didn't fit the threads on the fluid bottle. I got two (quart) bottles of redline 75w90 fluid, as the BMW fluid is nearly impossible to get in small quantities and the redline stuff is reportedly very good. Partly due to the poor quality pump and some spillage, one quart would not have been enough even though I believe the capacity is just under a quart. I'm not certain on this though. Note: Redline makes two versions of their 75w90 fluid: 75w90 and 75w90ns. I asked Redline about this and they recommended 75w90 for this application, as it would run a little cooler. diff refill items View post on imgur.com Put the pump hose into the diff fill hole and fill it until fluid starts coming out of the hole. Remove the hose and fit the drain plug, torque to 60NM / 44.2 lb-ft. View post on imgur.com MANUAL TRANSMISSION - Again this is for the 128i. 135i would be similar but tools and torque specs are probably different. Note: The A/C drain line is right next to this, so there will probably be water dripping from it. Watch your eyes. Remove the central section of the splash shield. It's held on by about 7 or 8 self tapping screws, which have 8mm bolt heads. View post on imgur.com There is also an angled catch, so after you've removed all the bolts you have to turn the splash shield as you remove it. The hole will then line up with the catch and the whole thing comes off easily. View post on imgur.com Looking up at the transmission from underneath the car, you can now see the fill and drain plugs. On my car they took 8mm hex bits. I ordered new plugs for these too but they were different, so I reused the original ones. The plugs that came with the car were less tall, and didn't have sealing or crush washers so I assume it's safe to reuse them. Transmission drain and fill plug locations View post on imgur.com It's always good practice to remove the filler plug first. That way you don't drain all the fluid out and then find you can't remove the fill plug. Space is restricted on the fill plug, as you have limited room between the side of the transmission and the transmission tunnel. There was not enough room for an 8mm hex bit, and a 3/8" to 1/2 adapter plus the breaker bar. Once again these are on very tight from the factory. The fluid will come out VERY fast once the drain plug is removed, so have a drain pan ready and watch for splashing. Limited space to get access to fill plug View post on imgur.com I used an 8mm drain plug bit, which came from harbor freight in a set. It's much lower profile than a normal one, and fit in the space just fine. View post on imgur.com For the transmission, I chose redline D4 ATF. In my last BMW with many more miles and some syncro wear, ATF gave the best shifter feel by far. However it may not be the best choice in a new BMW transmission. I will see how it goes in this car, and go back to the BMW fluid if need be. So far I like it though. I ordered a gallon, and I estimate I used just under 3 quarts. I got a gallon pump from autozone, and this one worked perfectly. Update: It's now been ten years since I first posted this DIY. My 128i now has 80k miles and for the last couple of years I've been using Pentosin MTF2 in the transmission. I think I prefer it to the redline D4, it's not quite as smooth as the D4 on a 'good day' but feels more consistent regardless of temperature (though I don't see temps below freezing very often). View post on imgur.com It's a tight fit, but if the car is jacked up high enough you can just about stand the atf container and pump up underneath. ATF smells horrible, so you want to avoid spilling it if possible. View post on imgur.com With the drain pan in place, put the pump filler hose into the transmission filler hole. If I've bought plenty of new fluid, I usually give it two or three pumps with the drain plug still removed to try and flush out any remaining sediment. View post on imgur.com Next, clean and refit the drain plug, torque to 35NM / 25.8 lb-ft Pump fluid in through the fill hole, until it starts to come out of the fill hole. Re-fit the fill plug, and torque this one to 35NM / 25.8 lb-ft as well. Put the splash shield back on, and lower the car to the ground. Take it for a short drive, then check for any leaks. If it's all good this shouldn't need doing again for 30k miles or so. Last edited by wolfe; 03-16-2020 at 07:26 PM..
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