M635 Gear Shift Restoration

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Boggie
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M635 Gear Shift Restoration

Post by Boggie »

Hi All,

My 1985 M635 has a vague gear shift, it selects gears perfectly well but has just got a little sloppy with age (haven't we all...). I have been looking at the picture below, trying to identify likely culprits. So, I have a couple of questions for you guys:
  • Do I simply need to replace the bearing sleeves (No.4 x2), shift lever bearing (No.9) and shift arm bearing (No.10/11)?
  • Is this all possible from within the car or will I have to remove the gearbox?
I appreciate that until I get a proper look it is hard to know exactly what the cause may be but are there components that commonly need replacing? I don't want to upgrade the shift, I just want to restore it to original action.

Thanks,
Ian

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1985 M635CSI
Classic Car and Bike Collector & Restorer.
CSGuy
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Re: M635 Gear Shift Restoration

Post by CSGuy »

Just bought an 85 M635 that I think should shift better.
Seems to me that Ireland eng or someone makes a urethane replacement for
#'s 10 & 11...Too many other projects and I can't remember
All three look like they could get sloppy but there may be a reason
for the aftermarket part.
brickwhite
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Re: M635 Gear Shift Restoration

Post by brickwhite »

- 12 535i
- 92 325ic
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Boggie
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Re: M635 Gear Shift Restoration

Post by Boggie »

Thanks Chaps!
I might drop the box out to restore the linkage more easily and stick a new clutch in whilst I am at it.
Ian
1985 M635CSI
Classic Car and Bike Collector & Restorer.
cjarvis
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Re: M635 Gear Shift Restoration

Post by cjarvis »

Replace #21. It will make a big difference in shifter feel. You will laugh when you see it, but install it anyway. Pretty sure it has to be done from underneath as it is where the shift linkage attaches to the trans. The bushes last a long time. 21 not so long as it is just a foam pad.
Craig in MI
85 745i
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hornhospital
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Re: M635 Gear Shift Restoration

Post by hornhospital »

+1 on replacing #21 (yellow foam pad). You'll think "that can't make much difference", but it does.
Shifter linkage refurbishment is something you want to do once. Do all of it.
Last edited by hornhospital on Mon Jul 30, 2018 5:29 pm, edited 1 time in total.
Ken Kanne
'84 633CSi "Sylvia"; '85 635CSi "Katja";'85 325e "Hazel Ann"; '95 M3 "Ashlyn"
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Re: M635 Gear Shift Restoration

Post by wattsmonkey »

Brucey posted in this a while back, advocating a small spring to replace that ridiculous piece of foamy stuff.
"Most of it necessary; all of it enjoyable." LJKS
'84 635CSi, dogleg...itbs and supercharger????? Eaton Mess
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Brucey
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Re: M635 Gear Shift Restoration

Post by Brucey »

yep, there is just room for a small (but rather stiff) spring in the back of the knuckle housing, that preloads the joint nicely, but (unlike the rubbishy foam thing) doesn't just disintegrate at the first sniff of gearbox oil. The spring needs to have a single turn only, and the assembly should be built up with a load of good MS2 grease in it.

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Boggie
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Re: M635 Gear Shift Restoration

Post by Boggie »

I have the car up on the ramps / stands to replace the complete braking system. Whilst I was under there applying penetrating oil to all the unions, I had a wiggle of the shift mechanism. The only significant play I could find was in the union between the lower gear stick and the selector rod (14). However, the play I was feeling was lateral, rather than longitudinal so foam pad preload might not be the issue.

Firstly, do I understand this correctly; removing the tension bush/clip (20), pushing out the dowel pin (19), removing the foam rubber washer and pushing in a new one, secured by reinsertion of the dowel pin will apply pressure between the pin and selector rod, preloading the knuckle joint? If so I don't think this will solve my lateral play but is probably worth doing (especially liking Brucey's spring idea).

I need to spend some time tomorrow having a proper look at where the lateral play is. It might be the bearing (9) or the connection between the gear stick and the shift mechanism. What I cannot tell from the two separate drawings (the one below and the other showing the Gear Shift) is; how does the gearstick end attach into the mechanism below? Does it connect at the RH end of the selector rod, held in place by 12 and 13? If so, I assume our foam buddy cannot be replaced without dropping the transmission...?

Cheers all. I love this forum....
Ian
1985 M635CSI
Classic Car and Bike Collector & Restorer.
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Brucey
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Re: M635 Gear Shift Restoration

Post by Brucey »

I think you have it in mind quite well how the parts go together. The main problem with rebuilding the front knuckle in situ is seeing what the heck you are doing, and reaching into the right place too. All this is a lot easier if you have the gearbox out of the car....

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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