Member
Hey guys,
Having some doubts about an e36 ZF transmission I am refreshing. Installed the output shaft seal, torqued the output flange nut to 140ft lbs - backed it off with an impact - re torqued to 89ft lbs per spec. Seems like there is quite a bit of drag on when I try to spin the flange by hand. So much so that I can't spin the input shaft by hand in third or higher gears. What are your thoughts on the normal amount of drag for a new seal? It seemed to spin ok with the old seal.
Member
Fresh seals will drag some. Hopefully you reassembled correctly. You may want to back off the nut, pull the yoke, and see what the box feels like (in 4th and 5th) for reference.
Member
Box feels ok with the flange off. All gears are good. Going to try again with a new seal unless there is some different input on how to install. Someone said leave the seal about 4mm from flush with the case before running the flange down to help it seat better in the flange. Thoughts?
Member
Yes. It is NOT to be bottomed out, nor flush. Not sure what spec is, but IIRC is is somewhere around 3-4mm. That is about the thickness of a penny.
Member
Mine had some drag to it, whined a bit too when it was fresh... didn't leak though!
Member
BMW E36 M3 Expert
A US penny is 1.52 mm thick.Originally Posted by snaponbob
Neil
Member
Snaponbob was giving his 2 cents, hence 3mm (or 3.04mm)
Member
Yeah. THAT !!!!
Member
lol Costco
Cant find an actual torque spec for the ZF box. The procedure I used came from the Bently manual supposedly for cars that use the ZF, but seems likes its the procedure the manual references is actually for a getrag box because its talks about a 30mm not 36mm flange nut. Can anyone verify the actual torquing procedure? Local BMW dealer wouldn't release any service manual info to me
Last edited by Traffic; 12-09-2014 at 02:27 AM.
Member
As a dct development engineer we use a specific "turning torque" procedure. It's an industry standard verification that everything was put together correctly. The techs at the dealer would have no knowledge of it because the manufacturers don't publish these tests.lol Costco
Cant find an actual torque spec for the ZF box. The procedure I used came from the Bently manual supposedly for cars that use the ZF, but seems likes its the procedure the manual references is actually for a getrag box because its talks about a 30mm not 36mm flange nut. Can anyone verify the actual torquing procedure? Local BMW dealer wouldn't release any service manual info to me
Here it it, basically:
1: Put gearbox in gear.
2: install torque wrench on input shaft. Beam type with max value indicator is best or electronic wrench, clicker will not work.
3: output shaft is free to turn.
4: turn input with torque wrench to approximate speed of 60 rpm (1 rev/sec)
5: observe peak torque on wrench and record
6: continue with every other gear engaged.
There are established "turning torque" specs for every transmission. I can tell you the values for many, many gearboxes. I'll see if I have specific data for you.
In 1st gear you're looking at a value of no more than 100 in*lb.
This test measures: bearing drag, synchro drag, seal drag and gear drag.
Last edited by jhott66; 12-09-2014 at 09:30 AM.
Member
Interesting information. Im familiar with the concept from setting differential bearing preload. The procedure and specs are actually laid out pretty well in older service manuals for cars that came with LSD. Have never seen it for a transmission though. It would be very cool to have!
Need to keep in mind though that specs are probably for all new components: bearings, races, seals, etc. If only replacing seals, the actual measurement will be different than spec because the bearings and races are worn in.
Member
Spent some time at the BMW dealership today. They didn't want to help, but an independent shop was kind enough to print me the spec page from the factory service manual DVD. I haven't seen this info listed anywhere on the forum so here goes if you're interested:
Transmissions S5D200G, S5D250G, S5D260Z, S5D310Z, and S6S420G = locktite nut, pretension to 190Nm, release, tighten 120Nm
Transmissions S5D280Z and S5D320Z = locktite nut, pretension 170Nm, release, tighten 130Nm
Translation- If you have a 96 or later e36, the bentley has the wrong torque specs.
Member
Yeah, this is an old thread, but I searched all over for this info two years ago and couldn't find it. This is great info for ZF owners, and the turning torque is a good guide for anyone with an old car that may not work well with the stated torque values. I couldn't even turn my output shaft at 80 ft lbs. I'd like to think I wound up somewhere in the 100 in lb range using my best judgement, but I'll find out soon enough.
Somehow I missed the loctite info, and have had a tranny leak since I did the output seal. I'll be remedying that and checking everything else tonight with the data provided here.
Thanks!
[Edit] Oooh, torque wrench on input shaft. Yeah, that's not happening, at least not tonight. But the loctite is - finally! Good info nevertheless...
Last edited by blckstrm; 05-22-2018 at 05:57 PM.
-Josh: 1998 S54 E36 M3/4/6 with most of the easy stuff and most of the hard stuff. At least twice. 271k miles. 1994 E32 740il with nothing but some MPars. 93k miles.
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