525 e34, transmission differences - BMW Forum

wesku · 07-02-2008, 02:57 PM

Friend has a 525 e34 -92, engine m50, auto transmission 5hp18. Original transmission went out of order (no drive forward). He bought one for replacement from junkyard. It should be from 525 e34 as well but appears different.

Some photos:

Both transmissions, original on left side.

Markings of the replacement one:

And the original one:

Does somebody know about possible differences and about what should be checked when purchasing a repplacement trasmission to ensure compatibility ? There are some transmissions for sale nearby (in Sweden) but would not like to drive around the country with original one to compare. Any help greatly appreciated.

darkhorse737 · 07-02-2008, 05:54 PM

should be the same. the difference is only in the production #'s(origin) and the manufacture date.

wesku · 07-03-2008, 07:35 AM

Holes for mounting to engine are different. It can be clearly seen when click the image to get larger image. Also it seems that engine angle is slightly different. Maybe it is from different body or engine anyway.

darkhorse737 · 07-03-2008, 10:01 AM

Quote:

Originally Posted by wesku

Holes for mounting to engine are different. It can be clearly seen when click the image to get larger image. Also it seems that engine angle is slightly different. Maybe it is from different body or engine anyway.

yes, i just noticed... apparently, it's from a different engine but 5HP18, nonetheless.

Take a look at the mounting bolts on the rear of the bell housing. You just might be able to swap bell housing and it should work.

Also pay close attention to the size of the torque converter. same?

*When u say no drive forward... 2 things come to mind. TC issue or tranny issue. Have you changed ur tranny filter at all?

wesku · 07-03-2008, 05:26 PM

Quote:

Originally Posted by darkhorse737

*When u say no drive forward... 2 things come to mind. TC issue or tranny issue. Have you changed ur tranny filter at all?

Could it be TC issues as it moves fine with reverse ?

I do not know about the filter as this is a friend's car but will ask. Could filter change help ?

darkhorse737 · 07-04-2008, 02:00 AM

TC and OIL PUMP issues are possible because the torque req'd for reverse wd be much less than moving fwd owing to the big difference in gear ratio.(if the tranny was still on the car, u can prove that by shifting into 1st or the lowest gear ans see if it will indeed move.

Then, internal in the tranny is the issue of bands. just like brake shoes, they wear out over time. sometimes, they are adjustable, and sometimes, they just burn out from heavy use.

Consider also... the valve body. a number of solenoids and ball valves that play and move around to shift the direction of ur tranny oil based on the gear that has been selected for the car to run on.... oil supply to these valves are coursed through a transmission filter... clogging of which results in oil starvation, and resultantly... no operation, partial operation, or faulty operation.

Diagnostics(from basic to complex) include:
1) measurement of oil level;
2) color of oil(darker brown colors indicate burnt bands/clutches
3) smell of oil - burnt oil will smell differently than fresh oil
4) resdue found in oilpans... i.e. metal bits in the oil???
5) oil pressures measured at different RPM's (for advanced tech's)

I don't have a lot to go by from what's been said concerning your plight... read on an see if ur prob is anything like the above, or expound more on ur issue. am sure someone here is always willing to help

fonker2889 · 07-09-2008, 01:42 PM

So im kind of having the same problem. 91 e34 525i and my transmission recently went out. Im not gettin a connection in some gears and the engine will just rev just like its in neutral. Do you think I should even waste my time by changing my transmission filter and oil? Or do I just need a rebuilt tranny?