Mercedes 410D gearbox sequence mystery

Discussion in 'Tech/Mech General' started by veevee, Nov 18, 2011.

  1. veevee

    veevee Funster

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    Just collected our 1992 Hymer 670 MH on a Mercedes 410D base, manual gearbox.

    It being all new to me I was startled a few hundred yards down the road when I selected 3rd and not 5th gear.

    As mentioned it's all new to me, the beginning of rush hour traffic and I keep missing the 5th gear. No fun I thought as I have to drive this about 600 miles that evening and the following day.

    After about 30 minutes of driving and settling in I tried to watch what happened on changing from 4th to 5th, it looked as though I had positioned the lever in about the right slot but still missed 5th.

    After around an hour pulled into a services and tried in the almost empty parking area to pull away in 3rd and guage the response, then in 4th, then 5th. All gears were in the right place and all had differing resistance.

    Concluded there was a selector problem when changing from 4th to 5th, this was a problem for much later as had to move the MH to central France that day but was quite unhappy that we had been caught out with this purchase. Also central France was a long way from Dorset via Folkestone with 4th as my top gear.
    Told Rosie that we may have a major gearbox problem (she was following in our car), we weren't very happy for a while.

    Remembering what had happened on one of my works Fiat Ducato vans when the selctor mechanism partially failed, I had had to change gears out of sequence.

    So tried from 3rd to 5th, as possibly the route via 4th was the problem? It worked although the gear was hardly as high, maybe not as high as 4th?

    So it transpired that all gears were there but 4th and 5th had been transposed, here is the sequence -

    1st - left and back
    2nd - right and forward
    3rd - back directly in line with 2nd
    4th - right and back, yes that's back
    5th - forward, directly in line with 4th

    Please someone tell me that this isn't correct, rather it's a regular sequence starting at 1st.

    If it's not correct how was it done?

    I had been changing gear in the sequence, 1st - 2nd - 3rd - 5th - 4th, no wonder I thought I was selecting 3rd in place of 5th every time.

    Have written in another thread that the comfortable cruising speed for this model feels too low, so if someone has altered? the gearbox then maybe the ratios are wrong too?

    Got to France but it was painful as all logical thought (for gear changing) had to be abandonned, help please...
     
  2. G4GMO

    G4GMO Read Only Funster

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    I've just taken a look at the merc base vehicle manual and 4th and 5th are the opposite way round to how you appear to find yours, ie, they should be: 4th right and forward with 5th back in line with 4th.

    Sorry can't be of any more help as mine is a 4 speed automatic transmission. I've never heard of anything like this before. Maybe 4th and 5th have such close ratios as to be difficult to distinguish between them, I don't know.
     
  3. pappajohn

    pappajohn Funster Life Member

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    the only way that's possible is if the box has been rebuilt and 4th and 5th gears have been installed in reverse order on the main and lay shafts.

    a lot would depend on the internal case castings whether this would be possible.

    the one we used as a wrecker truck didn't need first, even with a transit on the spec lift, and was just a crawler gear.
    set-off in second was around the same as doing it in first on most vehicles
     
  4. pudseykeith

    pudseykeith Read Only Funster

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    Like sturing a pudding

    Hi
    The gearleaver do's not go directly into the gearbox. It works though a linkage on the side of the box which wears badly and makes gear changing difficult [ just like sturring a pudding :Rofl1:]. It wont cost much to replace the worn parts. A Merc dealer should carry the spares,and if not in stock they can ussualy be avallable in a day or two. :thumb:
    Pudseykeith
     
  5. veevee

    veevee Funster

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    Pretty sure the problem has just been found, some of the answer is in pappajohn and pudseykeith's reply.

    Was sent a diagram of the gear selector layout this afternoon which as said is fitted to the LH outside of the gearbox.

    3 external levers operate the internal gear clusters, one each for reverse/first - second/third - fourth/fifth. Two levers point upwards, the third points downward! The third lever is for fourth and fifth!
    If it is turned through 180o it will operate fourth and fifth in the opposite direction to how it is set up now...

    To make this appear more probable the gearbox looks new/reconditioned with a (re)manufacturers quality black paint. The two levers pointing upwards have the paint coating, the 4/5th pointing downward is slightly rusted and unpainted.

    Got to work for the rest of this week and then get back to the UK, but in around 2 weeks will turn the lever round and hope.
    Still a little puzzled as to why a new gearbox should be required after 67,000 kms, especially a Mercedes commercial one at that.
    Did think to check that the mileage was correct and found a TuV certificate for 2002 for 34,500 kms and recent MoT's that show a regular 4000 km each year.

    Thanks to everyone as each bit of info, it all adds to the answer.
     
  6. pappajohn

    pappajohn Funster Life Member

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    i reckon you've cracked it there VeeVee.

    obviously not a merc dealer repair and an easy mistake to make if the same guy who fitted the box didnt remove it, or a crap mechanic if did remove and replace it.

    hopefully now it will sound a little less destructive at cruising speeds...and a little more economical. :thumb:
     
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