Transmission

[theratdude64]

My car acts like a 2 speed or something. its an auto, but when i floor it , it doesnt shift until 50 and about 6000 RPM or a little higher, goes to redline... is this normal? is it skippin a gear or something? cause when i floor it i only hear it shift once. it shifts nice n firm n takes off even faster right after the shift, but it just seems a little odd to me used

[M-technik-3]

The older BMW autoboxs are know weak link. Suggestion is to drain the fluid take the filter out and put new fluid and filter back in that may help.

Good luck as auto boxs are $400 used.

[Speedy-325is]

spunds like saftey mode... when something goes wrong on a car w/auto, the tranny goes in saftey mode and starts in 2nd or 3rd so u cant hurt the car.
my girls car just did this and the only fix was a new tranny ecu box...

it really sux, but it is something u can change urself if thats the prob... have it checked if the fluid thing doesn't fix it.

Mark

[theratdude64]

holy crap these things are advanced! LOL

ya it does take off dead freakin slow from a stop, as if its from a diffrent gear... how much would it be to fix? How can I figure out what tripped safety mode? Wow these cars amaze me

[Speedy-325is]

have a shop or someone read the code...

[M-technik-3]

E21's don't have a tranny ECU. It is a 70's based simple automatic. Just based on valves and fluids, and a torque converter.

[Speedy-325is]

i did not know that... im not too great w/the auto tranny...

what controls the tranny then the ecu or is there something else?

Mark

[M-technik-3]

Go hear to read up on autoboxes http://auto.howstuffworks.com/automa...nsmission1.htm

[Speedy-325is]

nice...

thanks, thats good stuff.

Mark

[xxxlegionaire]

There are two kinds of transmissions.
1) Mechanical - no electronics and use a valve body to determine shifting pressure..does not throw a code due to it not being electronic to diagnose it youll need to open it up.
2) Electronic - uses eletronics to control and shift the tranny, these can be modded to change line pressures and will throw codes when broken.

Mechanicals are more reliable due to less working parts to go wrong. Also in a race application, drag perf., mechanical trannies can be built to high extremes much like on top fuel dragsters and ect. These trannys are solid and are usually built for racing. Electronic trannies are in newer cars and use a control box/ecu to control shifting point, shifting pressure and so on. These arent ideal to race with because you have to use a shift kit to alter line pressure which isnt that consistant and could ruin the car.

As for your car, there could be several things wrong.
Your stall convertor is going out, and its not keeping your tranny idled right.
You have a crack in your bellhousing and its leaking oil, but i doubt that..unless you revved it up and then dropped it into drive. This would also lead to bad planetary gears which would have been grinded down from bump shifting it.

Greg Heart