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Thread: Driveline upgrade M635csi

  1. #1
    Join Date
    Dec 2005
    Location
    Melbourne, Australia
    Posts
    1,903
    My Cars
    E24, E34 x2, E36

    Driveline upgrade M635csi

    After I reckon a 4 year hiatus I’m finally doing some works on my m635csi.

    some time ago my 280 gearbox failed so I quickly replaced it with the dogleg box and a changed the diff to a more reasonable 3.46. Clutch has been slipping past few years progressively getting worse to the point it needs to be changed. As the gearing was still pretty short (approx 2950rpm@100kmh).

    Originally I was going to use a 260 getrag with the stock 3.73 diff but both first and 2nd looked short with a big gap to 3rd. I had my old large case ratio 3.23:1 from my m3 so doing the maths it matches well to the dogleg, and 100kmh at a more reasonable 2650rpm with a taller first and 2nd making them more usable. Like everything one small job snowballs into multiple jobs. A quick summary:

    Gearbox: getrag 265/5dogleg with uuc adjustable shifter
    Clutch: custom Spring centre segmented with altered pressure plate using 11lb flywheel

    Diff: large case with 3.23 ratio, altered ramp angles on pressure ring, shimmed clutches, new bearings & seals.

    Driveshaft/cv joints: all refreshed with new dust boots, degreased, new bearings

    Shocks: rear shocks rebuilt bilstein HD

    Bushes: new adjustable urethane control arm bushes to finally correct the toe and -3.5deg camber


    These upgrades should make a world of difference and really enhance the enjoyment of the car.
    BMW’s
    90 E34 M5
    84 E24 M635csi standalone ecu with coil on plug
    94 E34 540i/6 SC 5-17psi Flex fuel/standalone ecu
    97 Z3 2.8
    97 E36 M3 euro SC still u/c


    OTHERS
    11 Audi S5 APR stg2
    19 Volkswagen Amarok V6


  2. #2
    Join Date
    Apr 2008
    Location
    Scottsdale, Arizona
    Posts
    4,885
    My Cars
    81 euro 635, 4.4 X5
    Gazz that sounds like a very short ratio for a dog leg. I have a 3:07 and first gear ifelt really short the little bit I drove it before tearing it down. Since I haven't driven the car since restoration yet, but if as short as I think, I may look for a 2:90 I will see as our hiway speeds average 65 and in some places you can get away with 80
    81 Euro undergoing total nut and bolt restoration
    pictures at: flickr.com/photos/bertsphotos

  3. #3
    Join Date
    Aug 2008
    Location
    Sydney Australa
    Posts
    2,482
    My Cars
    1x633, 1x E3 2 DR Racer
    I've got a dogleg in my racer with a 3.46 LSD. Nice and racey. My 6'er has the 3.73 LSD and I'll put the 6 speed in it getting that overdrive 6th for the highway. Otherwise, to be fair, you do want close and racey. Glad you are getting her back on the road Gaz.
    1977 633 CSi RHD Euro. S38B38 3.9L M5 Transplant. 5 Speed Getrag Dogleg. 3.73 LSD. 417hp, 369lb/ft
    1971 3.0CS E3 2dr Alpina Special Coupe Racer, 347hp, 295lb/ft

  4. #4
    Join Date
    Dec 2005
    Location
    Melbourne, Australia
    Posts
    1,903
    My Cars
    E24, E34 x2, E36
    It’s always been on the road just not driven much due to the deterioration in the clutch. It will be great Josh to have it work with a tight lsd and nice feeling rear end. Yes 3.23 with dogleg is close to 3.73 with Overdrive with dogleg 100kmh cruise is 2650rpm instead of the 2500rpm with the 3.73/280 gearbox combo. Actually first and 2nd are slighly taller than before. Don’t forget I run the m88 so it’s a little more rev happy than the m30. I thought about 3.15 but it would have made first a little too tall at close to 80kmh@7000rpm. The 3.23 gives me just over 70kmh in first I think is a happy medium.
    BMW’s
    90 E34 M5
    84 E24 M635csi standalone ecu with coil on plug
    94 E34 540i/6 SC 5-17psi Flex fuel/standalone ecu
    97 Z3 2.8
    97 E36 M3 euro SC still u/c


    OTHERS
    11 Audi S5 APR stg2
    19 Volkswagen Amarok V6


  5. #5
    Join Date
    Feb 2009
    Location
    Pittsburgh, PA
    Posts
    1,718
    My Cars
    '86 635CSi, '08 128i
    Looking forward to updates, not sure about ratios, but it all sounds like a solid plan to me.
    Save the manuals!
    '08 128i 6MT, '86 635CSi 5MT (B32, Motronic 1.3, WBO2, G265, 18# FW, 3.46 torsen)
    Past projects:
    '96 318iS, sold 4/23 '90 535iM, RIP 1/23 '90 535iA RIP 6/22 '91 318i, sold 7/19 '97 M3 sedan, sold 11/18 '85 735i, RIP 2/18 '92 325iC, sold 7/16 '91 318iS, sold 6/16 '84 745i, sold 10/14 '82 633CSi, traded 9/12 '90 325i, RIP '87 325 sold '89 525i, traded '87 325iS, RIP

  6. #6
    Join Date
    Aug 2008
    Location
    Sydney Australa
    Posts
    2,482
    My Cars
    1x633, 1x E3 2 DR Racer
    There's a spreadsheet on this somewhere. Where you input the gearbox, tyre size and diff ratio and it calculates speed at rpm. Do you want me to dig it out for you Gaz?
    1977 633 CSi RHD Euro. S38B38 3.9L M5 Transplant. 5 Speed Getrag Dogleg. 3.73 LSD. 417hp, 369lb/ft
    1971 3.0CS E3 2dr Alpina Special Coupe Racer, 347hp, 295lb/ft

  7. #7
    Join Date
    Aug 2010
    Location
    West Nyack, New York
    Posts
    1,391
    My Cars
    86 635csi 98 740i 96 MB

  8. #8
    Join Date
    Dec 2005
    Location
    Melbourne, Australia
    Posts
    1,903
    My Cars
    E24, E34 x2, E36
    All good chaps. Ratios I’m confident with. Just gotta do with the normal car stuff. Diff guy taking forever, kMac sending early style bushes for an 84 model car etc etc. lucky it’s a spare car I don’t use often.
    BMW’s
    90 E34 M5
    84 E24 M635csi standalone ecu with coil on plug
    94 E34 540i/6 SC 5-17psi Flex fuel/standalone ecu
    97 Z3 2.8
    97 E36 M3 euro SC still u/c


    OTHERS
    11 Audi S5 APR stg2
    19 Volkswagen Amarok V6


  9. #9
    Join Date
    May 2020
    Location
    hermosa beach
    Posts
    4
    My Cars
    e 24 1987
    I agree. I have the 3:07 with dogleg. 1st gear is Tooo short. 2:90~~would be perfect

  10. #10
    Join Date
    Dec 2005
    Location
    Melbourne, Australia
    Posts
    1,903
    My Cars
    E24, E34 x2, E36
    Too short with a 3.07 diff? Must be pulling 50mph in first almost which is where 2nd would be when I had the 3.73 diff
    BMW’s
    90 E34 M5
    84 E24 M635csi standalone ecu with coil on plug
    94 E34 540i/6 SC 5-17psi Flex fuel/standalone ecu
    97 Z3 2.8
    97 E36 M3 euro SC still u/c


    OTHERS
    11 Audi S5 APR stg2
    19 Volkswagen Amarok V6


  11. #11
    Join Date
    Apr 2008
    Location
    Scottsdale, Arizona
    Posts
    4,885
    My Cars
    81 euro 635, 4.4 X5
    Quote Originally Posted by gamerco View Post
    I agree. I have the 3:07 with dogleg. 1st gear is Tooo short. 2:90~~would be perfect
    Agree. I have thought of this for a long time and am sort of always looking A hard item to find
    81 Euro undergoing total nut and bolt restoration
    pictures at: flickr.com/photos/bertsphotos

  12. #12
    Join Date
    Dec 2005
    Location
    Melbourne, Australia
    Posts
    1,903
    My Cars
    E24, E34 x2, E36
    If you wanted taller gears in large case the 540i e34 has 2.93 ratio which all the chaps with them throw them in the bin so the gearset would be cheap.

    all starting to take shape. Diff is back and in, shocks back in, kMac bushes installed, rear cv’s done and in car, new centre bearing with bracket sourced from USA and in our hands. Pretty well just waiting now for the custom clutch to be returned. I’m getting the pressure plate modified, new segmented clutch plate, throw out bearing, flywheel slighly lightened and machined(currently 12lb one) and all balanced as an assembly. We will probably see the clutch late next week and then back on the road.

    Diff guy said to use Castrol 80w140 syntrax lsd oil. What about for the dogleg gearbox?

    It makes a nice change works done in a timely and comprehensive manner with good communication.
    BMW’s
    90 E34 M5
    84 E24 M635csi standalone ecu with coil on plug
    94 E34 540i/6 SC 5-17psi Flex fuel/standalone ecu
    97 Z3 2.8
    97 E36 M3 euro SC still u/c


    OTHERS
    11 Audi S5 APR stg2
    19 Volkswagen Amarok V6


  13. #13
    Join Date
    Dec 2005
    Location
    Melbourne, Australia
    Posts
    1,903
    My Cars
    E24, E34 x2, E36
    Well got car back and after a few adjustments including proper phasing of the driveshaft to remove annoying hitting the body.

    Firstly gearing feels much better. Nice to have a few legs in first and 2nd. The 3.23 combined with the dogleg seems to be a good combination. Rebuilt shocks feel great. The kMac adjustable bushes fit up well but the cups don’t have much overlap.

    It’s going for a full alignment on Thursday morning so this will tell if I can dial out some of the negative camber at the rear. Aiming for around -1.5deg each side with around 1.5mm of toe in pet side. I’ll retain the -2deg at the front end and just a tiny bit of toe in say 0.3mm per side just to look after the inside edges.

    Yes it’s been some time the 6 has had some loving. Probably 3 years. Been busy doing other cars so it’s hard to focus on 3 builds at once. The others are pretty well sorted so hopefully some more activity for the e24.

    It really needs a standalone computer to get the best out of it. Being hearing abit of noise that ecu master have a plug and play m30 motronic 1.1 plug and play loom. Uses an e36 variable tps with wideband sensor, intake temp sensor and map sensor. It will be nice to have an adjustable ecu so it will allow easy upgrades when changes to the engine. I played with one of the 123ignition distributors and the dramatic change you can make to how a car drives with optimised ignition timing.
    BMW’s
    90 E34 M5
    84 E24 M635csi standalone ecu with coil on plug
    94 E34 540i/6 SC 5-17psi Flex fuel/standalone ecu
    97 Z3 2.8
    97 E36 M3 euro SC still u/c


    OTHERS
    11 Audi S5 APR stg2
    19 Volkswagen Amarok V6


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