BMW 3.0CS - 5 Speed Conversion

CS REGISTER  - Five Speed Conversion for CS - Carl O. Nelson

Many times in the past I have been asked about the difficulty of installing a later model 5-speed transmission into the
older CS automobiles. At our shop we perform this conversion every other week. The limiting factor is the availability
of suitable five speed transmissions. If your old automatic transmission has died or is about to, now is the time to
consider its replacement by a manual version. The great news is that the CS has been drilled to accept almost any
transmission used by BMW. The determining factor (other than the size of your wallet) is the presence of a
mechanical speedometer drive. It is possible to modify an 82 and later trans to work with an older type speedo, but it
is not worth the effort. Any of the large 6 cylinder five speeds, before 1982, will fit and drive the speedo. The speedo
drive is the same for either four or five speed, but the auto drive unit will not fit. Be certain to get the drive as it costs
a fair bit. I recommend the overdrive 5 speed out of the 528i; a close ratio (1:1 fifth) has the same external
dimensions. This was a common trans in euro cars, but it is not as durable as the overdrive, also the reduction in
noise and wear is not gained. I have found the sport box (close ratio) to be a poor choice as most big block 6 cylinder
cars have lots of torque and don't really need a close ratio box. In addition we have had really bad luck with the c/r 5
box (the lay bearings fail and the gear set is usually in bad shape ** really noisy**).

The conversion is not cheap. There are many pieces involved, but everything is straight forward, and the ability to
shift into fifth at speed is awesome, not to mention the reduction in the wear on the engine and the reduced noise
level in the passenger compartment is worth every dime. In my own cars I have over logged more than 150,000 miles
on these conversions. They are reliable and tested. The transmission is one of the most durable ever used by BMW.
We have probably installed or sold as a package 100 of these units. READ don't be shy. It works. I will describe the
process and at the end list the components.

The five-speed conversion for a CS is not difficult, but there are a great number of steps. The layperson might not
immediately understand some of these steps, but they have a reason.

1. Remove the exhaust system (you need lots of room) up to the exhaust manifolds.

2. Remove the drive shaft. A custom unit must be fabricated, shorten a 4 speed by 3.75 inches or lengthen an
automatic .75 inches, replace u-joints as necessary, replace center carrier bearing and renew hardy disc. This is
custom work and very few shops can do it.

3. Remove transmission and shifter assembly (be sure to disconnect the reverse light switch). An automatic is a pain
here, remove the bolts trans to engine and flywheel to torque converter. This is a heavy unit use a jack to support
and drop. The four speed is quite easy to remove. Separate the trans from the bel housing (four 19mm nuts), free
the clutch throw-out fork retainer spring and extract the trans. Remove the bel housing and clutch slave cylinder.
***Unbolt the engine electric ground. Be certain to reconnect this ground. It is the most important connection on the
car, we often add a second ground across a motor mount.***

4. Remove flywheel and replace the rear crankshaft seal. It will never be easier to reach. Install a new pilot bearing, if
you don't it will fail later .Use the new sealed bearing type and get rid of the old felt and tin plate pieces.

Now that you have your beautiful machine in a million pieces, most of which you never thought you would see out of
the vehicle, take a good rest. Let your nerves recover. It will be a BMW again. If you think you might be in over your
head, you might want to have a consultant around. The assembly should go fairly smoothly, but I would allow plenty of
time as you will probably need a key part that will have to be ordered.

5. Reinstall manual transmission type flywheel and clutch (we use Alpina B7 type it's cheap).

6. Install late style bel housing, throw out bearing, throw out fork and pivot (Plus retainers).

7. Bolt up the five speed (uses the same hardware as the four speed). We renew the rear trans seals at this time.

8. Install five speed shift assembly, trans cross member (this just straddles the large openings on the bolt track) and
drive shaft. To support the rear of the five-speed shift platform use an airflow meter mount (all holes are present). We
use a blend of Redline MTL and 80/90 mineral oil (50:50 part for easy shifting and part for noise reduction).

9. Install five-speed drive shaft

10.   Replace exhaust system. The exhaust hanger from a 2800 auto trans fits best to support the exhaust at the rear
of the transmission.

If this sounds simple it is. The real trick to the installation is in knowing the various pieces that need to be combined to
fit the five speed simply and easily into the CS.

The following is a list of the parts required to install a five speed overdrive trans into a CS. In simple words we are
trying to install the 528i five-speed transmission into the CS. The dimensions of the 528i tunnel are the same as the
Coupe. If a trans assembly from a 6 or 7 series is used the shifter components will need to be exchanged for a 528i.
All of the bolts, mounts, etc. are the same. It's a bolt in. The problems occur because of a change in 1974 to the bel
housing and throw out bearing components. The bel housing is different, and must be used with the five speed (trust
me on this one). The clutch slave cylinder is of the new style for this bel housing, ditto hydraulic hose, throw out
bearing, fork, and pivot. The five speed trans cross member is needed to clear the trans, and the shorter five speed
shifter pieces are needed for the shift knob to pop up through the opening in the tunnel (again the 528i). Add the
corrected length five speed drive shaft and we are shifting. The 528i has a mounting bracket in the tunnel to support
the rear of the shift platform. By using an airflow meter mount, it is possible to pick up the rear of the shift platform
and hang it from the tunnel using the rear auto shifter mount point. The speedometer cable for the automatic is the
correct length for the five-speed conversion.

A few special notes for those going from automatic to manual. You will need a flywheel and new securing bolts (long
28mm type) [same as Bavaria]. Pressure plate retaining bolts 8mmX20mm. The bolts that secure the auto to the
engine are different from those that attach the manual bel housing. You must get this hardware early. The bolts are
unusual lengths, as always special order. The manual radiator is different (there is no cooling tank on the right), as is
the right hand bracket, you can retain your auto radiator if you like. The shifter surround will have to be modified. If
you turn the platform over the opening for the manual is partially cut. Peel the vinyl back, complete the opening, build
up the leading edge of the platform, under the vinyl, to flush, pull the vinyl back into position and glue. Install zippered
shift boot with tacks or staples. It will be necessary to remove the starter interrupt relay. Follow the black wire down
from the back of the ignition switch. It will go into a relay. Unplug the black wire and plug it into the clear connector
under the fuse box with a similar black wire. This will be occupied with a black and white wire from the same relay.
Remove the relay and extra wires.

You should also remove all of the wires for the shift indicator and the lamp assembly. A jumper will have to be made
up for the reverse lamps. Two wires from the switch on the transmission to the connector in the passenger
compartment at the firewall below and to the left of the steering column. This connector has three wires gray/red,
blue/white and violet/black. Use the last two. You will need to change out the pedals. This is a simple bolt in. Use a
pair of pedals from a Bavaria. They go right in. Be certain to install the return springs. ** 1974 and later clutch pedal
has a top bracket that will not fit into the early pedal box. The early pedals will fit all pedal boxes. Do not try to use
528i pedals, the bushing split does not line up (trust me again).** You will need to install a clutch master and the
special bolt to attach it to the clutch pedal (also 2 nylon bushes). The holes are in the body (the shift indicator wires
feed through this opening).*** The really bad news is that the clutch master cylinder is now extinct. We are trying to
get another production run.*** A used unit may have to be reconditioned. Next install the hose to the slave. The brake
fluid reservoir will have to be changed out for the manual type with clutch feed hose. Install with feed hose. Bleed

Late bell housing
Purchase used unit
Throw out bearing
Throw out fork
Fork pivot

Fork retainer spring

Clutch kit, with pilot and rear main seal

Late clutch slave cylinder and 8mm nuts (2)
Extension hose for slave
5-speed transmission Purchase used unit

5 cross member
Trans mount
Auto speedo cable

5 shift platform
Shift platform mounts (2)

5 shill rod
E21 3 series lower shift lever
Shift lever bushings
Retainer clips
Shift joint
Foam pad
Shill shaft seal

Trans output seal

Hardy disc
Center support bearing
AFM mount and 6mm hardware

4 to 5 speed is easy, especially since you have the tranny lying there.
Question: Does it have a bellhousing? You'll need that. Good known candidates

- 1980-1981 528i, 633csi, 733i
- 1985 535i

You'll also want to replace the following:

- throwout bearing
- pilot bearing
- crank rear main seal (which you know about already)
- clutch

Other new parts you'll need:

- E12 5-speed trans support (big metal thing under trans)
- E12 trans rubber mounts (2 of them I think)
- E12 5-speed clutch slave
- E12 5-speed clutch slave hydraulic line
- E12 guibo

You'll need to get your driveshaft shortened. While they do that, they'll want
to rebuild it, which is fine. Should run about $300. I had mine done at some
place in Berkeley. I'll have to look it up, or you can call Bill Arnold at
415.459.2697. Basically, you shorten the front half, I think, 3.75 inches or 99
millimeters, I forget which. Someone on the list can tell you.

It all goes together the way you think it would. Some wacky parts:

1. shift tower - some mix and match here. It mostly all goes together. Now is
the time to do a short shift kit, in whichever manner you choose. You should
also use a bolt at the rear of the platform to attach it to the driveshaft
tunnel, for strength. I can show you mine.

2. clutch line - use the E3 and the E12 lines together to reach the clutch

3. speedo cable needs to be re-routed. It will reach, but just barely.

I'm probably forgetting something, but that's about it.



Getrag 265 Prep
Gear ratios        

      1st        3.82 : 1        

      2nd        2.20 : 1

      3rd        1.40 : 1

      4th        1.00 : 1

      5th        0.81 : 1

      reverse        3.71 : 1

      speedometer drive        2.5 : 1 (teeth 10/4)

Shaft end-play        

      input shaft        0 to 0.09 (0 to 0.0035)        mm (inches)

      output shaft        0 to 0.09 (0 to 0.0035)        mm (inches)

      countershaft        0.1 to 0.2 (0.004 to 0.008)        mm (inches)

Lubricant capacity        1.7 (1.6)        quarts (litres)


      gearbox to clutch housing        52 to 58 (72 to 78)        lbf-ft (N-m)

      drain and fill        29 to 43 (40 to 60)        lbf-ft (N-m)

      front cover        13 to 18 (18 to 25)        lbf-ft (N-m)

      output flange        72 (100)        lbf-ft (N-m)

      cross-member to body        16 to 17 (22 to 24)        lbf-ft (N-m)Seals

Input Shaft

Remove (7) 8mm screws; three are longer. Keep track of the shims used to preload the bearings. The input shaft
seal is 35mm ID, 52mm OD, 7mm thick and should be marked with a rotation direction so that it is installed in the
correct direction.

Output Flange

The output flange is secured to the output shaft with a large nut. Because the tip of the output shaft extends beyong
the flange, a 30mm deep socket is required to remove the nut. I've found that almost any quality 12pt socket will fit
inside the flange after the lock ring is removed. The flange is not pressed onto the output shaft, but it can be a little
hard to remove because of the sealant on the splines.

The output flange seal is 40mm ID, 55mm OD, 8mm thick and should also be marked with a rotation direction so that
it is installed in the correct direction. When installing, remember to put sealant (Loctite 270) on the splines and thread
locker on the flange nut since this is a potential leak path. Use a new lock ring (P/N) -- the old one will not work.

Selector Shaft

This seal can be pried out with a small screwdriver. Be very careful not to scratch the selector rod or the seal
housing. The new seal is easily seated using a deep socket (I used a 5/8").

Clutch Housing

Replace the pivot pin inside the bell housing. This pin is made of plastic and wears down easily. There are
after-market pins available made of aluminum. The clutch release arm pivots on this pin and is held onto the pin with
a wire clip.

The clutch housing is mounted to the engine block with 8 bolts. The 4-speed and auto trans use different bolt lengths
so you will need to get the correct bolts for the 5-speed clutch housing:

  (2) M10x1.5x95
  (2) M10x1.5x35 [near starter]
  (1) M8x1.25x90
  (2) M8x1.25x35 [near head]
  (1) M8x1.25x40 [through-bolt with nut]

You will also need (2) M6x1.0x16 bolts for the cover plate that goes at the bottom of the clutch housing on the engine
side. The 4 large studs in the clutch housing are M12x1.75 and the gearbox mounts to the clutch housing with (4)
M12 nuts and washers.


E12_shifter.jpg shifters.jpg 2002_shifter.jpg
shift rod (also refered to as a "schill rod") is 147mm long, and the ends have 10mm dia by 22mm long shafts.

Shift Platform

The knuckle at the end of the selector shaft is fastened with a pin. Slide the sleeve back to remove the pin. The new
knuckle should come with a piece of foam that fits inside to keep it from rattling.

The shift platform is attached to the transmission using two aluminum blocks with rubber bushings in them. Get new
ones (P/N) or machine solid blocks to replace the flexible ones. You'll have to change the mounting system entirely if
you use solid mounts because with the rear of the platform attached to the tunnel, the realtive movement will loosen
the platform. The blocks are attached to the transmission with (2) M8x1.25x40 bolts, and then the shift platform is
mounted to the blocks as shown in the picture with (2) M8x1.25x30 bolts.

Speedometer Drive

The spedometer drive gear is pressed onto the end of the output shaft. If it is present, then all you need to do is
install the speedometer drive pinion from the 4-speed. If the drive gear has been replaced with a spacer, then you will
have to remove the spacer and install the drive gear from the 4-speed. The gear can be installed through the
opening in the case, but it is much easier with the rear case removed.


Replace the old socket-head style drain and fill plugs with the newer hex-head plugs. These are much easier to
remove and install, and they have a magnetic pickup to trap any particles in the oil.

The reverse switch illuminates the reverse lights when the gearbox is in reverse. On a used gearbox, it is likely to be
banged up in some way since it is the softest thing on the outside. It's really inexpensive and very difficult to replace
once the transmission is installed in the car. Don't forget to put a 12mm crush washer under the new one.

Check this vent on top of the gearbox. If it's clogged, the motion of the gears can build up pressure inside the
gearbox and force oil past the seals.

If, after cleaning the outside of the transmission, you dont like the look of the corroded fasteners holding the
transmission cases together, you can repalce them with new ones:

  (8) M8x1.25x55 hex-head bolts (7 with nuts)
  (4) M8x1.25x50 hex-head bolts
  (10) M8x1.25x35 socket-head cap screws

Remove Old Transmission
empty1.jpg empty2.jpg
Clutch, Pilot Bearing, and Crankshaft Rear Main Seal
bearings.jpg crank_seal.jpg

With the transmission out, this is the best time to replace these parts. Of course, if you had an automatic transmission
then you need to install them anyway. I'm going to assume that you've removed everything (or never had the parts in
the first place).

Pilot bearing removal is another story.

Buy the Sachs clutch kit; it comes with a clutch disc, pressure plate, throw-out (clutch release) bearing, and
sometimes the pilot bearing and alignment tool. It does not come with the (6) M8x1.25x16 socket head cap screws to
attach the pressure plate to your newly resurfaced flywheel.

Rear Transmission Mount
I could not get my 4-speed crossmember to work at all so I used a 528i crossmember on the "right" ear. Here's a
trans_mount1.jpg trans_mount2.jpg

With this mount, when it is perpendiculer to the long axis of the car, you will find that the holes line up exactly where
the t-nuts come out of the tracks. I cocked the crossmember until it was in front of the hole on the right and behind
the hole on the left. I was still having problems with the cocked crossmember touching the trans and telegraphing
gear noise into the cabin, so I ended up drilling additional holes in the cross member to fix the alignment.
(2) M10x1.5 nuts
get new t-bolts (P/N) and M8 lock-nuts

Of course, you could go with a custom mount. This is on Jim Clark's car -- I think it's the metric mechanic mount:
Shifter Mount
Drive Shaft

For a CS 5-speed conversion, you need to shorten the drive shaft by 95 mm (3.75"). Alternativley you can use a CS
automatic transmission driveshaft. The auto driveshaft is only about 3/4" shorter in overall length than the correct
5-speed length, but the problem is that the rear section is not the same length as a 4-speed shaft so you have to
stretch the center bearing. Here's a picture of the 4-speed D/S and auto D/S with the ass ends aligned:

I couldn't believe this so I measured the bearing mount on the parts car. Turns out the auto trans cars have the
center bearing mounts welded about an inch closer the front of the car. The upper D/S is from my 73 3.0CS 4-speed,
and the lower one is from a 71 2800CS auto. As you can see, the rear section is longer on the auto D/S. You can
make up the overall 3/4" length by sliding out the splines (in fact, you have to do that). But, since the center bearing
is attached to the front portion, this makes the problem worse. I fixed it by reversing the direction of the center
bearing. Even with this, The rubber membrane on the bearing is really stretched out and I don't expect it to last very

Also, the guibo flange bolt holes on the D/S are different sizes. The 4-speed has 12mm holes on the D/S flange and
on the trans output flange. The auto has 10mm holes. So, you have to use 12mm bolts on the trans side and 10mm
bolts on the D/S side when you mount the auto D/S to the 5-speed.
Exhaust Mount

The center exhaust mount has to modified a bit. There are many ways of doing it, and the one shown in the pictures
is probably the easiest because it can be made with the fewest fabricated parts. I believe you need the 2800CS
auto-trans exhaust mount to make this work. These pictures were taken by TJ Noto on his installation:

TJ_exhaust_hanger.jpg TJ_exhaust_hanger2.jpg
© 2002, Devinder Grewal. All rights reserved.