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The "Ultimate" 5-speed Transmission Conversion
One of the most popular 'updates' for all BMW models with 4-speeds,
as well as any model with an automatic, is the conversion to an overdrive
5-speed or a close-ratio 5-speed transmission. The BMW overdrive 5-speed
will slow the engine speed down about 20%, giving you better engine
life and fuel mileage. It also gives the driver a more relaxed feeling
when driving at highway speeds because of the reduced engine noise of
a slower turning engine. A 5-speed conversion has the effect of updating
and modernizing a BMW. Since such a transmission was not an option until
1980, most of the parts in each model's respective conversion kit are
fabricated or otherwise modified by us to fit the application. This
means that not only are the kits comprehensive (including related hardware),
but we have taken special care to "work the bugs out” to
insure a hassle-free, "bolt-in" operation.
We have 5 speed conversion kits available for all BMW models with
4 speed transmissions. The following is a description of the parts necessary
to convert a 2002 with a 4-speed to a 5-speed overdrive transmission.
The 5-Speed Transmission Conversion Kit for
2002
The 5-speed overdrive "Ultimate Transmission"
is the only gearbox warrantied for 5 years, with no mileage restrictions.
It includes tapered roller bearings on the layshaft as well as "solid
brass" synchronizers for trouble free performance. NOTE: The price
of the transmission is outright, i.e., with no core exchange. See CREDITS
for core exchange options.
A special four bolt flange
is necessary for the 5-speed to properly mate with your four-bolt driveshaft
flange.
A Reverse Gear Synchronizer
is optional on all '83 and later models. Although not a necessity, it
is still a very convenient accessory for avoiding the "grinding"
that sometimes occurs when shifting into reverse gear. Although no gear
tooth damage can occur, your 5-speed could get ever more difficult to
shift into reverse if grinding is severe and frequent enough.
The Shift Linkage Assembly
has been re-engineered to a shorter, simpler and more efficient design.
(This was necessary due to the additional length of the 5-speed transmission.)
Most importantly, by using the late style shifter, extension rod and
coupling we can incorporate our Short Shift Kit which results in a more
distinct and tighter shift pattern.
Changing the Clutch Slave Cylinder
is necessary because BMW 5-speeds use a late model clutch slave cylinder
with a 2-bolt mounting system. You will have to change the remaining
hardware and parts of the hydraulics to accommodate the 5 speed. This
allows you to use your same pressure plate and disc. The advantage to
this modification is that these later style parts are more easily serviced,
readily available (some are used in the newest BMW's) and are still
compatible with the remaining hydraulic system.
A Shortened Driveshaft
is necessary because of the increased length of the 5-speed transmission.
Most of our conversion kits include a good used driveshaft that has
been (1) carefully inspected for sound universal joints and undamaged
front flanges, (2) shortened and balanced and (3) fitted with a new
center support bearing, front coupling and front alignment bushing.
You do have the option of ordering a factory new driveshaft (versus
"used") that we will gladly shorten and balance.
A Transmission Crossmember
must be fabricated to provide some sort of rear support for the transmission.
Of all the procedures needed to perform the 4 to 5 speed conversion,
none is a greater headache than this fabrication. Inevitably this involves
traumatizing the underbody either by drilling holes, cutting, welding
or some other kind of reshaping. However, Metric Mechanic has devised
an innovative type of mount bracket that BMW themselves would envy.
With this crossmember you not only get to make use of the stock mounting
points, but in addition this cylindrical style mount is structurally
superior to any BMW mounts.
There are Options to offset some of the cost of this conversion:
- 5-speed core - our core charge is high for two reasons. First,
because so many 2002 owners want to convert, 5 speed cores are increasingly
hard to find. Second, the prospect of reducing costs by so much will
hopefully encourage those purchasing this conversion kit to locate
a 5-speed core in their area. Any BMW 5-speed core from any model,
'80 and later (USA) and '77 and later (EURO), will qualify.
- 4-speed core - If the 4-speed transmission you are replacing is
“rebuildable" (see Question and Answer Section), it is
worth additional reductions in the overall price.
- 4-speed driveshaft - as long as your driveshaft is still in one
piece it has value to us and would therefore be worth returning.
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