R30 4141 Auto - no 1st
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  1. #1
    Tadpole
    Join Date
    Sep 2005
    Location
    Bristol UK
    Posts
    6

    Icon5 R30 4141 Auto - no 1st

    Not sure if this should go in the technical area or here - hope this is okay.

    My '78 30TS Auto has not used first gear since I got it and the changes between 2 and 3 were very poor. It's a low mileage car and I don't believe there's much wear in the 'box. I suspected the governor computer to be at fault and followed some very useful instructions on one of the DeLorean sites to replace the capacitors in the unit that apparently are always blown (http://www.dmcnews.com/Techsection/transputer3.htm). I also replaced the transistors that control the two gear change solenoids.

    The result is very encouraging - I now have lovely smooth changes at the correct speeds - but sadly still only between 2 and 3 - no first gear (not in Drive, 2 hold or 1 hold).

    From a study of the Renault workshop manuals, I think I've either still got a problem in the governor (either a poor joint on one of the the transistors I replaced or 'something else') or the solenoid valve for first is not working correctly. From what I've read though - this solenoid is also opened when Reverse is selected, and that gear works fine.

    Has anyone out there experienced a similar fault and fixed it? What to check next - I need to change the fluid so perhaps check the solenoid first before pulling the governor apart again?

    Many thanks for any help,

    Tim.

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  2. #2
    farmerdave
    Guest

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    You need to check that both of the solenoids are working electrically and hydraulically. I forget the specs but I'll PM them to you.
    1st gear is selected by applying power to both of the solenoids, Reverse is manually selected in the valve body if I understand correctly.
    Do you have the 4141 manual?

    Farmerdave
    Last edited by farmerdave; 30th November 2005 at 01:52 PM.

  3. #3
    Tadpole
    Join Date
    Sep 2005
    Location
    Bristol UK
    Posts
    6

    Default

    Thanks farmerdave,

    Yes, I have a 4141 manual - I thought it showed both solenoids in use for reverse - that's why I wasn't too sure about the solenoid operation since reverse is okay on the car. My manual seems a little short on detail compared to the one I have for the 4139. I used both in trying to diagnose the problem - I believe the fundamentals of the operation of the two boxes are the same? I have probably misinterpreted the diagrams. If, as you say, reverse is all down to manual selection, then I guess that '1st' solenoid must be the prime suspect. I need to change the fluid soon, so that'll be an opportunity to take a look.
    The impression I get of these boxes is that the mechanical components are pretty robust, it just seems to be the control system that is a little flakey as delivered by Renault. The changes that are available on my R30 have been vastly improved just by beefing up the governor as described on that DeLorean site.

    Thanks again - I'll report back when I have had time to take a look at the 'box (weather allowing - we're well into winter here in the UK!)

  4. #4
    farmerdave
    Guest

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    Yes, I have a 4141 manual - I thought it showed both solenoids in use for reverse - that's why I wasn't too sure about the solenoid operation since reverse is okay on the car.
    Yes, both solenoids are grounded (this is what the transistors do- switch to ground) but the manual valve has shut off all the ports except the reverse one. Pressure is much higher in reverse than in any foward gear.

    My manual seems a little short on detail compared to the one I have for the 4139. I used both in trying to diagnose the problem - I believe the fundamentals of the operation of the two boxes are the same?
    Yes, they use the same type of controls. The (4)139 section of the R16 manual goes into great detail, probably because the system was totally novel at the time.

    I have probably misinterpreted the diagrams. If, as you say, reverse is all down to manual selection, then I guess that '1st' solenoid must be the prime suspect.
    The 4141 manual gives heaps of info on tests, don't be too worried about the BV control box, it's all doable with a couple of test lamps and a multimeter.

    The impression I get of these boxes is that the mechanical components are pretty robust, it just seems to be the control system that is a little flakey as delivered by Renault. The changes that are available on my R30 have been vastly improved just by beefing up the governor as described on that DeLorean site.
    Yes, the mechanicals are fine. The controller has a few problems- Capacitors go bad as they were electrolytic, Tantalum ones are best for replacement as they are stable. Stranglely, there is no bypass capacitor on either of the IC's and no protection from the voltage spike caused by cutting the power to the solenoids- which is happening everytime it changes gear.


    Farmerdave

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