Cajas de cambios 5 velocidades para M10

Fernando

Board Admin
Miembro del equipo
21 Nov 2007
19,043
423
83
Bogota
Para empezar una buena discusión, esto dice Mike Macartney

2002 Transmission History
The vast majority of all 1600's and 2002's leaving Munich came with a 4 speed transmission. While the four speed was offered throughout the production run, there were some minor changes made along the way. An important change in the four speed transmissions used in the 2002 occurred in mid 1971. The facotry began using the Borg-Warner type synchros in the 2002 transmissions. All the earlier transmissions used the Porsche style baulk-ring synchonizers. Of the two designs, the Borg-Warner style synchros are considered superior, because they last longer, provide smoother shifting, and can withstand faster, harsher shifts. From a mechanical standpoint, they are more durable, and are preferred by rebuilders. The internal gears underwent a slight design change to complement the Borg-Warner synchros, and the gear ratios were also slightly changed in the process. Overall, the Borg-Warner transmissions are more plentiful, and more desirable. However, both transmissions are still suseptible to synchronizer wear, although it is much more pronounced in transmissions sing the Porsch synchros. Second gear is usually the first to show signs of wear from abusive shifting. Synchro wear is characterised by the "cruching" noise made when attempting to shift from 1st to second gear in a rapid motion.

Here's a quick rundown of the ratios available for the 4-speeds and 5-speeds that easily fit the 2002.

Four Speed Transmissions

Getrag 232, pre-'71 2002 4-speeds with the Porsche style synchros:
1st: 3.835
2nd: 2.053
3rd: 1.345
4th: 1.00



There were several minor changes made to this transmission over its lifespan. Pre-'69 examples came with a 3-bolt output flange, to match the smaller, 6-bolt flex coupling used on the earlier driveshaft. Later cars had a 4-bolt output flange, with an 8-bolt Guibo flex coupling. The selector shaft length was also changed with the flange change, so trying to install a 4-bolt flange on a transmission originally equipped with a 3-bolt will result in a problem of the flex coupling hitting the selector shaft.


Getrag 242, '02s from mid-'71 on, most 320i 4-speeds, Borg-Warner synchros:
1st: 3.764
2nd: 2.02
3rd: 1.32
4th: 1.00


There was also a change made to the output flanges on this transmission. Early examples (pre-'76) were infamous for having the splines on the output shaft and flange wear down, sometimes to the point of shearing off, resulting in a stranded car. The fix came on late '75 cars, with a redesigned shaft and flange featuring finer splines. Most of these transmissions will have exhibited this problem by now and should have been fixed (by updating to the newer style flange and shaft). Occasionally, you can still find one of the rare ones that haven't suffered from the problem. Also, in '78, some internal modifications were made (wider first gear, etc.) to this transmission. It should be noted that the 2002 and 320i versions can be interchanged, although the clutch slave cylinder mounts differently, depending on the version. The 2002 clutch slave cylinder is pressed into a bore cast into the bellhousing, and has an exposed pushrod that pushes towards the rear of the car, while the 320i clutch slave cylinder is bolted into a lug on the side of the bellhousing, with a pushrod that is hidden inside the bellhousing, pushing towards the front of the car.

Five Speed Transmissions
The Getrag 235/5, optional close ratio 2002 5 speed:
The 235/5 gearbox was the factory optional close ratio five speed gearbox for the 2002. These units are fairly rare. A guess is that there were perhaps 2000-3000 of these units produced. This transmission was an option even on the 2002 Turbo. If you have one, or know where one is, consider yourself lucky! If you have one, and it needs rebuilding, prepare to spend some money and encounter lots of frustration! This gearbox is used primarily for track type events and for people searching for the best performance and overall gear selection. It is well suited to cars with heavily modified motors which have a narrow powerband. Most street applications are more suited to the five speed overdrive gearbox. Some parts can be found for the 235/5, but most of the rebuild items that still exist have to come directly from Germany. Unfortunately, a large amount of core parts for these gearboxes are NLA. If you are in need of major parts for this transmission, you may be out of luck. These transmissions are 3.0625 (3 and 1/16) inches longer than the 4-speed, and need the associated hardware adjusted accordingly. The clutch slave cylinder is mounted in the same manner as a standard 2002 four speed.

There are several easy ways to identify a transmission as a close ratio five speed. First, the front housing is identical to a 2002 four speed. There is an added cast aluminum section sandwiched between the front housing, and the rear cover. On the top of the transmission located on this additional sandwiched housing, there will be some numbers stamped. The first is a serial number, ending with a /5 (to designate five gears). There will also be a 235 or 238 number stamped on the cast sandwiched housing nearby. This gearbox also uses the racing style shift pattern, with first gear to the left and down, under reverse.

Apparently, there were additional gearsets available from the factory (or Getrag) for racing applications. These are extremely rare (even more so than a regular 235/5 box). Nevertheless, they represent some interesting gearing possibilities for a 2002. The race version uses dog type synchros, much like the racing Hewland gearboxes. With this setup, you just bang it into gear and go. They're not very forgiving, though. The ratios for all three gearsets are listed below.


Getrag 235/5, optional close-ratio 5-speed for the 2002:

street version: rally version: race version:
1st: 3.368 2.71 2.30
2nd: 2.16 1.84 1.56
3rd: 1.58 1.38 1.28
4th: 1.24 1.13 1.09
5th: 1.00 1.00 1.00


The street version is the one that is commonly (relatively speaking) available. Another thing to note, in perhaps a bit of irony, is that the 235/5 has not proven itself to be a very strong transmission. Broken gear teeth are not all that uncommon on 235/5 units that have led a hard life. The typcial mode of failure is a synchro will fail (usually as a result of over-exhuberant speed-shifting during a competition event), and parts and pieces of the synchros go through the gear mesh, taking out gear teeth in the process (this happened on the 235/5 transmission I have). Bearings (esp. layshaft) can fail as well.

More common 5 speeds:

The Getrag 245/4 overdrive five speed from the 1980-1982 320i is the most popular transmission used when installing a five speed into a 2002. The gear ratios are:


Getrag 245/4, '80-'82 320i overdrive 5-speed
1st: 3.68
2nd: 2.00
3rd: 1.33
4th: 1.00
5th: 0.81


The overdrive 5th really helps on the highway. This transmission is 3.5625in longer than the 2002 4-speed. (note that it is longer than the CR 5-speed) The clutch slave cylinder is mounted "backwards", in the 320i style. With a 3.64:1 final drive, and 185/70-13 tires (a theoretical diameter of 23.2 inches) this combination will give 2560 rpm at 60 mph. A nice relaxed cruise speed. Even better, at 80 mph, the engine will be turning at only 3400 rpm. (of course, we always drive at the posted legal speed limit!) This transmission can be coupled with a 3.90:1 final drive, to mimic the '80-'83 320i's. Acceleration through the gears will be better, and the overdrive 5th brings the revs back down to sane levels on the highway. This setup will, of course, rev higher in any given gear than with the 3.64:1 final drive. Using a 3.90:1 final drive and 185/70-13 tires, 60 mph will theoretically give 2750 rpms in 5th, and 80 mph will give 3660 rpms.

The Getrag 245/10 close ratio 5 speed can be found on some european 320's. Nowadays, this is usually the close ratio gearbox of choice for conversions.

Getrag 245/10, close-ratio 5-speed found on some european 320's:
1st: 3.764
2nd: 2.325
3rd: 1.612
4th: 1.229
5th: 1.00


This is probably the better of the two close ratio transmissions to use, as it is of the newer, stronger 242/245 series design. It uses the stronger Borg-Warner style synchromesh. Plus, parts for this transmission will very likely be easier and cheaper to get in the future. The catch is finding one in the first place. This transmission is very much like the 245/4 OD trans, except that it is 3.125 inches longer than the 242 4-speed, not 3.5625in.

Not listed here is the Getrag 240 overdrive 5 speed found on the '83 320i and '84-'85 318i, as it is almost identical, ratio-wise to the 245/4. It is also of a lighter, weaker design than the 245/4. It is therefore not a good choice when mated to a modified performance engine. Installing one in a 2002 is also slightly more of a challenge, due to it's extra width and lack of an available 4 bolt output flange.

It is also noteworthy to point out that the newer E36 318is gearbox is not a close-ratio unit. The first 4 gears are shortened such that 5th can be made direct and push through a relatively high-geared final drive, simulating a wide ratio overdrive 5-speed pushing a regular final drive. This improves overall efficiency in 5th gear by reducing frictional and gearing losses




Pues a mi nunca me han acabado de convencer estas referencias:

Esta es la caja 5 sport que yo tengo para montar en el ALPINA, es original de un 2002 motor M10, con los complicados syncros tipo Porsche. Las tres piezas estan grabadas con el mismo numero serial, por consiguiente nunca le han cambiado la la tapa trasera donde esta grabado el siguiente numero...

100_5878.jpg


close-ratio.jpg


y acabo de revisar la caja de 4, con syncros borg warner, y el número es identico, excepto por el inferior a la izquierda:
está estampada con los siguienbtes numeros:

232.0.139.00
3,1 225
 
Y esta es una caja de 5ta ECO, overdrive, retirada de un E21 320i, las diferencias exteriores son bastante evidentes:
bombin del embrague: switch de luz de reverso, tapa posterior y por supuesto la disposicion de las marchas.

getrag5speedECO03.jpg


getrag5speedECO04.jpg




El número que viene grabado en la parte posterior es el siguiente:

getrag5speedECO01.jpg




Veo claramente el primer numero, 245, que coincide con la descripción de Macartney, pero ... donde esta el 235 que llevan las close-ratio?. La tapa es practicamente idéntica a una de 4, salvo por un numero... que pasa de 3,1 en la caja de 4 a 4,1 en la caja de 5...

Alguien sabe mas información al respecto?
 
Unas fotografias de la referencia de la caja de 5 velocidades close-ratio que tengo para montar en el 2002ti.....
Verificando que las tres carcazas externas no han sido intercambiadas, el numero 302 esta grabado en las tres...

100_8520.jpg




y miren la diferencia de la tapa trasera:

100_8523.jpg


los numeros dispuestos en otro sentido!!!!, pero en efecto es una close-ratio
 
--Alpina-- dijo:
Miro las fotos y todavia no puedo creer que la caja esta en Colombia :o.

Hoy de tarde estuve trabajando debajo de mi auto y tiene exactamente esos numeros, mañana si puedo le saco fotos y las pongo.

dale... porque me doy cuenta que el famoso 235... no existe!!, al menos no lo he visto en ninguna
 
Fernando dijo:
--Alpina-- dijo:
Miro las fotos y todavia no puedo creer que la caja esta en Colombia :o.

Hoy de tarde estuve trabajando debajo de mi auto y tiene exactamente esos numeros, mañana si puedo le saco fotos y las pongo.

dale... porque me doy cuenta que el famoso 235... no existe!!, al menos no lo he visto en ninguna

Yo tampoco nunca vi ese famoso 235 :P
 
Creo que pasa lo mismo que con las close-ratio de los 323i. Según todas las informaciones deberian tener gravado 245, pero todas las que conozco ponen 242 ???
 
si, eso parece.... entonces porque tanto Macartney como la web de E21.net mencionan esos numeros???
 
En una subasta de una caja en ebay encontré este par de fotos...

76af_1.jpg


7935_1.jpg



En ésta última se ve claramente el 235... que va estampado en el interior de la campana de la caja, junto al eje principal que acopla al embrague. Yo aun no he revisado la mia... parece que la famosa combiancion 235/5 es otra je je je... ya está teniendo lógica el tema de la nuemracion 235 (5ta close-ratio), 242(4 cambios) y 245 (5ta ECO)

Alguien ubica este numero en su caja?.. mas tarde revisare la mia
 
Algo mas para discutir el tema de la numeracion de las cajas para M10.

Numero estampado en una getrag 245 (5ta ECO de E21) en la tapa trasera
tranny4.jpg


y ésta foto, de la misma caja, aparece un 242 en el interior de la campana, donde esta el estampado el 235 en la caja de 5ta close-ratio
e-21trannymarks.jpg
 
bueno pues como de momento el frances no me ocntesta con lo de la caja de 5v de e21, he estado mirando y en esta pagianq ue debe estar escrita en arameo (sueco noruego o lo que sea)el tipo este de 2002 turbo.com pone una caja de 518i que imagino igual a la de un e 30 318i dice que le pone la parte de atras de no se que caja para que funcione con lo del cuenta km del 2002 , esa punta trasera de la caja , seria de 2002 por ejemplo? http://www.2002turbo.com/02driveline.htm
 
En efecto es la caja de un 518, con bloque M10, pero los soportes son bastante diferentes, menudo trabajo para instalarla. Esa caja es una ECO
 
osea que no es como la de un 318i e30 es mas bien como la de un e21? es que he leido algo por ahi de que se puede poner la punta trasera de la caja de 2002 en la caja del e30 para solucionar lo de el reenvio del cuenta km
 
Miilor, respecto al reenvio hay un post en el que Jan comentaba que por lo menos en la caja del M3 se puede instalar el piñon del velocímetro.
 
Miky dijo:
Miilor, respecto al reenvio hay un post en el que Jan comentaba que por lo menos en la caja del M3 se puede instalar el piñon del velocímetro.

Cierto, ya que la caja del M3 E30 tiene un tapon donde va el piñon que conecta la guaya del velocimetro..., pero no se como va en las cajas del E30 318, tendriamos que ver fotos en el lado donde va el piñon
 
Hola a todos! les paso mi inquietud, hace pocos dias hice el mantenimiento a una caja 235/5 close ratio, le cambie rodamientos y revise todo el funcionamiento y esta muy bien, ya e reparado varias cajas de E21 pero obviamente con sistema Borg Warner, en muchas ocaciones ya e reparado cajas con sistema de syncro Porsche y la verdad que es bastante frustrante hacer ese tipo de cajas pues es muy dificil que el syncro quede perfecto, tambien busque mucho por internet y todos coinciden en lo mismo, hasta en los foros de Porsche tienen el mismo problema.
Tengo libros que hablan de este sistema y dicen que el sincronizado es mas suave y preciso, pero la realidad es que a dado muchos dolores de cabeza.
Estoy enterado que por ahi en Colombia hay carreras de velocidad con 2002 y me imagino que deben de usar esta caja de cambios, en Argentina tambien corren con estos autos y esas cajas pero le quitan los frenos y le ponen sistema de clanes como las que tienen las cajas de las motos, pero en caso de usarlo con syncro Porsche, este en realidad es efectivo?
Desde ya me gustaria leer sus opiniones e inquietudes ya que me gustaria y estoy dispuesto a encontrar solucion a este sistema de sincronizado.

Desde ya gracias a todos!!
Adolfo Chelle.
 
Hola Adolfo. Aqui todas las cajas conservan los syncros tipo Porsche, incluso los de carreras. Cual es el verdadero problema de tu caja?
 
La gran incognita es el sistema Porsche, la verdad es un sistema no muy confiable ya que es dificil que quede con una presicion similar a los Borg Warner, me gustaria saber experiencias que tengan con este tipo de sistema y que opiniones tienen, por ejemplo la presicion que tienen los cambios al entrar y al rebajar.
Y otra cosa, cuando se hace una reparacion en estas cajas tambien es complicado que el acionamiento de el sincronizado quede 100% bien incluso con todos los repuestos nuevos.

que opinan?

Gracias.