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6.3

Reverse problem and other malfunctions on K4B
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Just to let you know. I was able to fix reversing issue by tightening reverse brake belt by 1/4 turn (it's 3 minute job).
Also new bushings on shifting rod helped a lot. No "gear hide and seek" is necessary anymore.

The remaining issue I have is very late shift from 2 to 3 (around 50-60 kmh even with just a little throttle). The shift from 2 to 3 is so stiff that my wife is rejecting driving with me as her neck hurts. Modulating pressure is 0.5kpcm2 (just a little under specification 0.6±0.05).

It seems to me that there is something set incorrectly but have no idea what. I will try measuring step pressure to see if the pump is fine.

I'm now trying to get #5346 awake and check its transmission to decide about possible swap.


300SEL 6.3 #1285 (1969 EURO version)
300SEL 6.3 #5346 (1971 US version with engine KO)
I just bought #5346 (US version - reduced compression) to source transmission and differential. Hope this will solve my problems.
#5346 engine is not running (it's turning, but no joy) but the rest should be OK.

300SEL 6.3 #1285 
300SEL 6.3 #5346
off the top of my head, try Neil at Star motors. Also, Mike at Morris Motors. Both run shops and are members of this forum. -CTH
PS. that means he killed it or it was dead before he got it.  A full and expensive rebuild could in theory repair it.
The situation about differential is getting more complicated. The previous owner used standard CASTROL AXLE EPX 90W hypoid MB 235.0 oil and he told me that the car has open differential (there is no SPEICAL OL sign mounted on it).  Based on his suggestion I used the same oil too.
Now it seems that according (https://www.m-100.co/content.aspx?page_id=2155&club_id=406485&item_id=823880&message_id=2075253&fs=1#req) all cars #1202+ had LSD from factory. I believe that using standard oil means that LS function is dead forever. 

I don't have original engine (I should have engine 12-001195). I have 12-000986.
It's really confusing as I was told that they used 6.3 #4990 (I have copy of contract from 2002 for buying #4990) as donor for restoration in 2007.

I can imagine that I can have diff from #4990 or original from my #1285 or even one that came with engine no. 12-000986 (probably not from #4990 as the number is quite low).

Is there any way to recognize diff visually? Shall I contact MB and get datacards for #4990 and car with engine 12-000986?

BTW I believe that there is no chance to repair both gear noise and LS function.
Well does anybody have spare NOS or used LSD for sale?

Filip

PS: Both previous owners are dead so I can't ask ... 

300SEL 6.3 #1285
Thanks for suggestion about lapping on differential. I will try to do it.

Regarding transmission I just had a call with https://www.klaus-automatikgetriebe.de/automatikgetriebe/ and they told me that they already done some number of K4B for 600s and that they have all spare parts on stock. He noted that some parts are custom made in US on some special laser machines and also that they know how to repair the brake belts. I think I will give it a go.

Filip
If the ring and pinion are not damaged and the case hardening is intact you can have them lapped and the preload set, that and a set of bearings through it may suffice. 

300SEL 6.3 #2723, my first classic Benz 3.5 #8659, my second. 2 to go...
I'm based in Prague, Czech Republic so Holland is reachable for me (will send Paul PM). I also found some company in Germany that claims to be able to repair K4B (link). Just the price 4690 EUR is quite high.

And yes I mean differential. I have standard one without limited slip feature (at least there is no sign of special oil on it). Do you think it's worth of opening it? I mean are there some spare gear parts still available to reduce the noise?

Filip
Filip, where are you based?  Paul in Holland may know a shop to help you.  Also, when you refer to your "rear gear", are you talking about the differential in the rear axle?  If so, the differential is specific to the 6.3.
Art

Hello

I just returned from 500 km Regularity rally (pic) where my transmission started to fail. I have to admit that reversing was not easy already for some time and increased rpm was needed to make car start moving backwards. It’s much worse now. I’m unable to reverse at all. The car is only moving slowly backward on perfectly flat tarmac and pushing throttle makes no difference. Also I lost kick-down and ability to manually force 1st and 2nd gear. Shifting to D directly doesn’t put the gear in. I have to do L (or S) wait for about a second for gear to kick in and shift to D. Also shift from 2 to 3 is like and shot that almost brakes you neck – very rough. It’s complete mess. I think I definitely need somebody with K4B experience to give it a look or most probably a complete refurbish. Is there any recommended person/company in Europe that knows these transmissions?

Also my rear gear is very noisy despite recent oil change (old oil was like coal black). Is there a way to repair it or shall I look for replacement from some other W108/W109?


Regards


Filip

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