engine and drivetrain Was the Getrag 242 EVER in a New 2002?

[thehackmechanic]

I thought I knew the answer to this ("2002 four-speeds were 232 gearboxes with the clutch slave mounted through a hole on the edge of the bell housing; 320i four-speeds were 242s with a side-mounted clutch slave"), but now I'm not so sure.

 

I'd always thought that ALL 2002 four-speed transmissions were the Getrag 232 with the clutch slave held into a hole on the circumference of the bell housing by two circlips, and a big rectangular hole in the side of the bell housing for the clutch fork. I thought that the 232 went from Porsche synchros to Borg Warner synchros in 1971, and went from a coarse-splined output flange to a fine-splined flange in mid-74. Here is a photo of a 232 showing the clutch slave and the big rectangular hole (the clutch fork isn't in

place):

 

 

 

I'd always thought that the Getrag 242, with its bolt-on clutch slave and the clutch fork inside the bell housing (hence no hole in the side) came in with the 320i, and that any that was in a 2002 had been installed as a bolt-in replacement since they're the same size. Here is a photo of a 242. The clutch slave isn't attached, but you can see where it mounts (to the right of the word "Getrag"), and you can see the absence of the hole for the clutch fork. (Note that the coveted 320i 245 5-speed also has the side-mounted clutch slave and no hole, but is longer, with an extra spacer between the case and the rear cover):

 

 

The info on the Metric Mechanic web site supports this, listing the 2002 as having the 232 and the 320i as having the 242. I trust Jim Rowe on this, as he probably knows more about transmissions than most people:

http://www.bmw2002faq.com/applications/core/interface/file/attachment.php?id=25326.

 

But then I was looking at the (now 19 year old) transmission information on the old Bimmers site, and Ben Thongsai refers to the change from the 232 to the 242 as occurring when the synchros changed. Another post here on the FAQ referenced this, but it was never followed up on:

http://www.bimmers.com/02/faq/transmission.html

 

I thought... HA! Ben is never wrong about anything, but he's wrong about this!

 

But then I checked the Macartney book, and he uses the same convention as Ben, saying that the Getrag 232 had Porsche synchros, which changed in mid-1970 to the 242 with Borg Warner synchros (page 88).

 

I looked in the factory 2002 repair manual and... imagine my surprise when I saw this, which I have no idea what to make of:

 

 

 

Note that all of the illustrations in 2002 factory parts catalog (the blue books) clearly show the 232 case, with the holes for the clutch slave and the shift fork:

 

 

So, what do we think?

Is it a misunderstanding of what we mean by a "2002 242 transmission?"

Is this a difference between the transmission model number and the numbers stamped into the transmission case, which have been the source of much confusion over the years?

Am I reading the factory manual wrong?

Is it some strange Euro-only thing?

 

I've owned 30 2002s; I've seen coarse and fine-splined output flanges, but the only side-mounted clutch slaves I've ever seen have been on retrofitted 245 5-speeds.

 

--Rob

 

 

Edited September 15, 2016 by thehackmechanic
clarity

[TobyB]

The side- mount slave started with the 320- or almost exactly at the same time, anyway.  Knowing BMW, there's no guarantee

at all that they didn't stick one or 2 in the last of the 1502's in Europe, OR grab a 2002- style trans for one of the first 316's.

But the hydraulic/mechanical ratio is different, so it's not the best idea ever.

 

As to 232/242- I think it's a nomenclature problem.  Getting a solid number onto a transmission is never easy with BMW.

So the B/W synchro box in a 2002 may very well be referred to as a '242' and a B/W 320 trans as a '242/4' or some similar foolishness.

 

It would be a big deal if this thing was a Datsun, as getting parts would be (and often is, for Datsuns) stupidly hard.  They go by the box designation.

But this is BMW, run by Germans, and Das Part Number is DAS PART NUMBER and if DIS part number is different than DAT part

number, then it's a different part, full stop.  Now, it might be SUPERSESSION, and Der New Part replaces (or is supposed to anyway) Dat Old Part,

and they seem to get that wrong occasionally, but the NAME of Der Transmission isn't too critical, as long as you're looking at the right picture in the parts system,  however you view it.

 

Personally, I have thought that the B/W 4- speed was a 242- it shares the end case with the Porsche box, so the CASTING is a 232, but Der Guts can be 242.

Goes back to the casting number rant I had a few months back.  But I never gave it TOO much thought, as Der Guts seem to be Der Same as Der 4- speed 320 trans...

...thus, Der Later 4 Schpeed is a 242-something, depending on which style clutch actuation it uses.  Based on what's in the box...

 

no answers here,

 

t

 

[Son of Marty]

I've not seen all the 1600-2002 variants but I've never seen 1 with the 242 tranny the wasn't added as a replacement, and very few of those, because if your going to change all the clutch gear why not go with a 5 speed  as most did.

[Conserv]

Rob,

 

My '76 (April 23, 1976) has its original 232. (EDIT: Guess not! It’s a 242/6 based on the combination of the factory service manual Rob attached above and the Owner’s handbook references that I cite in my next post!) My understanding is that all U.S. 2002 transmissions were 232's, but there were lots of improvements and changes along the way, e.g., Porsche-to-BW synchronizers, coarse-to-fine spline output shafts.  If there is a single fact I'm pretty darned comfortable with, however, it is that the change in synchronizers did NOT signal a change from the 232 to 242.  (It's scary to contradict Toby but, every once in a while, I must contradict him to keep him at the top of his game!)

 

Since the housings are dated, it's easy -- once the transmission is out -- to see the year of the housing (which doesn't guarantee the innards, of course).  I'm betting there are more than a few 242's (from e21's) that have worked their way into the '02 population by now, but post-date the manufacturing date of their present car.

 

I will admit that the overlap between '02 production (into 1977 with the Euro-only 1502) and e21 production (beginning spring 1975 with the Euro models) does make me wonder if (a.) very early e21's used the 232; (b.) 1502's used a 242; or (c.) the 232 was purely the '02 transmission and the 242 was purely the e21 transmission.

 

Now I am hoping that you will unravel the mystery for once and all!

 

Best regards,

 

Steve

 

Edited May 15, 2019 by Conserv

[thehackmechanic]

I'm willing to bet that the use of the term "242" in the factory manual is simply not what we mean by a "242" in the 2002/320i sense, and that Ben Thongsai and James Taylor were going by the manual rather than implying that 2002s had the same four-speed as the 320i with the side-mounted slave.

[Hans]

Interesting to see the slightly different gear ratios, which might explain the different acceleration/speen in gear graphs discussed in another thread (stock vs tii).

[Conserv]

Rob,

 

I believe I need to return to '02 Camp for intensive "re-education"!

 

The sales brochures and owner's handbooks make no mention of 232 or 242, but they do, of course, reflect the change in gear ratios, and that change does appear -- based on my few owner's handbooks -- to accompany the change from Porsche to Borg-Warner synchros!

 

The owner's handbook, dated July 6, 1969, from my very early 1970 refers to Porsche synchronizers and that 3.835:1 first gear.  The next owner's handbook in my collection, dated October 15, 1971, refers to Borg-Warner synchronizers and the 3.764:1 first gear.  And that change in gear ratios appears to follow the change from 232 to 242 that is represented in the page you show from the service manual.  So maybe my '76's trans is a 242/6; it's different, however, from a 242 in an e21.

 

So is the version of the 242 in an e21 simply another "improvement" to the line that WAS a 232 in 1966 and became a 242 with the change in synchronizers and gearing?

 

Interestingly, or perhaps un-interestingly, the owner's handbooks, which point to the differences among the various sub-models -- 1600-2, 2002, 2002tii, etc. -- note absolutely no differences among the transmissions used in the various sub-models, even though they note differences in engines, clutches, and differentials.  The service manual, however, notes that different versions of the 242 are fitted based on sub-model:  242/6 for most '02's, but 242/4 for tii's and 242/14 for 1502's.  As if we need more complexity in this area!

 

Does someone have the analogous page from the e21 factory service manual?

 

I'm trusting you to straighten out this big ol' mess!

 

And I'm sorry I contributed to the historical mis-information!

 

Best regards,

 

Steve

 

Edited September 16, 2016 by Conserv

[HBChris]

And it was my understanding that the Porsche synchro units had a smooth top case, not ribbed.  I have only ever seen one of these.  Regardless of 232 or 242 all slaves were mounted on the bell housing. 

[Tommy]

8 hours ago, thehackmechanic said:

I'm willing to bet that the use of the term "242" in the factory manual is simply not what we mean by a "242" in the 2002/320i sense, and that Ben Thongsai and James Taylor were going by the manual rather than implying that 2002s had the same four-speed as the 320i with the side-mounted slave.

I believe in this explanation and claiming the answer in original post wrong. The numbering tells about what's inside the box, the basic construction as the gears and synchros. External differences like the slave cylinder type are then expressed by the numbers after slash. I have experience about 1502's that are the latest euro models and I think the slave type goes strictly according to body (-02 to e21) but internally the same box was used in both bodies.

 

Inspired by Hans I entered the ratios in my gears-excel. I'd bet there is no effect in acceleration unless tested as in formula one level.  

[TobyB]

Quote

Interesting to see the slightly different gear ratios, which might explain the different acceleration/speen in gear graphs discussed in another thread (stock vs tii).

Nah, it's just that both driving and driven gears are different sizes, and thus, the tooth counts are different.  Since you have to have a finite number of teeth,

any time you change the diameter of gears in a ratio,  the actual numerical ratio changes a tiny bit. 

Like a 4.10 and a 4.11 diff have effectively the same ratio, but they get there with a different number of teeth on both the pinion and the ring.  Same thing happens

when you change tooth count on the same size gears...  make them "fine tooth", for example.

 

And, I have torn down B/W 2002 transmissions and one B/W E21 4- speed transmission:

they are darned near identical.  Very much unlike the Porsche style syncro box. 

So while I don't really care very much what number's assigned to each, I can easily see the 242 designation

being from 4-71 to 9-80 or even beyond- since the box changed very little on the inside.

I'd have a harder time justifying how the Porsche and BW boxes  can be called the same...

 

But Rob's the one who NEEDS answers- I just need the darned countershaft bearings to be quiet!

 

heh

 

t

 

[thehackmechanic]

The thick plotkins...

[Conserv]

Rob,

 

If the following source is correct, the version of the 242 in early e21's might have been a 242/9, 242/18, or the memorably-named 242/18.30!  Sorry, I'm not kidding.

 

http://www.bmwe21.net/?page_id=124

 

I'll leave you to untangle this business! ?

 

Best regards,

 

Steve

 

Edited September 16, 2016 by Conserv

[Mike Self]

The only difference I can tell externally between the OEM gearbox in my Feb '69 2002 and my Dec 72 build date '73 is that the '69 has an adjustable slave cylinder pushrod and the 73 doesn't.  The '69 gearbox definitely has the Porsche synchros--which I have babied since new, and 2nd gear still doesn't crunch--and the '73 definitely has the B-W synchros--a much nochier feel (ameliorated by using Redline MTL).  They both have the side-mounted slave-cylinder and hole for the throwout bearing arm.

 

mike 

[Preyupy]

I always considered the change from 232 to 242 as the change from the Porsche to BW synchros.  The 232 cast into the housings is just a casting number and has nothing to do with the internals.  The 235 CR boxes have 232 series casting numbers. 

[thehackmechanic]

So, do we collectively think that (and I'm going to use labels no one else does so we don't get wrapped around the axle of 232 and 242)

 

--At the change from Porsche to BW synchros, the guts of the 2002 box changed from "Type A" to "Type B," but the case stayed the same with the slave-through-the-hole-in-the-bell-housing and the clutch-fork-through-the-square?

 

--At the change from the 4-speed 2002 box to the 4-speed 320i box, the guts remained "Type B," but the case changed to support a slave bolted to the side with an internal clutch fork?

 

Rob