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vacuum pump / drive shaft

Discussion in 'General Technical / How To' started by ajmackie, Oct 2, 2004.

  1. ajmackie
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    ajmackie Member

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    [Oct 2, 2004]
    I'm looking to fit the Waeco MS-50 cruise control kit with a standard audi cruise control stalk, as I want to retrofit cruise control to my 99 A4.
    The servo is vacuum operated and requires a vacuum source, presumably there is an existing pump.
    Is this easily accessibly on a 1.8 A4 and is it a constant vacuum source or does it vary depending on the load, e.g. brakes?

    Also how easily accessibly is the drive shaft as it requires a magnetic speed sensor to be attached to it.

    Not too sure so thought I would check first!!

    Thanks!
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  3. audi5e
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    audi5e Member

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    [Oct 2, 2004]
    Mackie, my 100 gets its vacuum from an electrical pump under the bonnet. It is behind the coolant bottle. The ECU increases or decreases vacuum to vary the servo size and hence move the throttle to the correct position. You would have to see if the Audi switches work with the MS-50 control unit, then wire it up.
    I would imagine fitting the speed sensor is probably the easy part. you will need to place the sensor either close to the suspension/wheel hub or close to the gearbox as the pickup needs to stay within a certain distance. If for example you put it in the middle of the driveshaft then the sensor will move too far away from the pickup as your suspension moves up and down or worse get snagged on the driveshaft as it rises and falls when going over bumps.
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  4. ajmackie
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    [Oct 3, 2004]
    Yeah!! good thinking!!! i will try and mount the sensor nearest to the rngine as psossible to avoid any dynaimc discrepancies.

    Just wondering about the vacuum, so it changes with respect to the load and time. if it needs a constant vacuum, would this not be available?

    Don't want to order the MS-50 if it won't work as for an extra £80 I can order the MS-700 which is motor driven and uses the speedo sensor off the clock or radio which saves fitting the sensore.

    Hmmmmm.... decisions!!!
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  5. ajmackie
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    [Oct 3, 2004]
    Ok, i just have 1 question left.
    I understand that the vacuum pump is used for the brakes as well as other devices, so does the vacuum pump operate at a continous speed? Is it therefore only the devices that vary the use of the vacuum.

    Just need to make sure as I don't want to fit this cruise control servo and then have a variable vacuum input!

    Thanks!!!!
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  6. audi5e
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    [Oct 3, 2004]
    On my 100 there is a mechanical vacuum pump mounted on the cylinder head and driven off the camshaft that gives extra vacuum for the brakes.
    There is a seperate electrical vacuum pump that controls vacuum to the cruise control servo. The ECU controls this electrical pump to vary vacuum to make the servo expand or collapse and hence move the throttle in/out to maintain speed. The Audi cruise control takes the speed reading from the speedometer, so I suppose it would make sense to rather buy the MS-700. Also then you know you will get the correct vacuum.

    I would not use the same vacuum that the breaks use, also keep it seperate from the inlet manifold cause if you mess with that.... I know.. :)
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  7. ajmackie
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    [Oct 3, 2004]
    Thanks for that info! I may have to consider buying the electrical servo one then. Costs an extra £100, but might well be worth it!!

    Might email Waeco and see what they suggest.

    Well want to get this cruise control, but £90 is a lot cheaper than £200!!

    Thanks for the help!
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  8. audi5e
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    [Oct 3, 2004]
    OK, hope you come right. I agree with your suggestion to conact Waeco, always better to confirm.
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  9. ajmackie
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    [Oct 4, 2004]
    Well waeco haven't replied!
    I've looked under the bonnet and can see the drive shaft. if i put it up on some ramps then i should easily be able to mount the sensor. just down to this vacuum thing now!

    Checked ETKA parts catalogue thing and it says £120 for a vacuum pump!!! Hope I can get one cheaper if i do need one!
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  10. audi5e
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    [Oct 5, 2004]
    Where do you guys get hold of this ETKA catalogue?
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  11. ajmackie
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    [Oct 5, 2004]
    I've found this extract on the requirements for the vacuum actuator. Should this therefore work on my 1999 Audi A4?

    "The standard vacuum systems are designed for use with petrol (non-turbo) and diesel or turbo diesel (fitted with standard vacuum pump for power assisted brakes)."

    Does my car have this standard vacuum pump for power assisted breaks? Is the power assisted breaks a recenct invention or has it been around for about 10 years on all cars?

    Thanks
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  12. audi5e
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    [Oct 6, 2004]
    ha ha ha
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  13. ajmackie
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    [Oct 7, 2004]
    i've heard back from them! well i gave them 7 hours to call me back and then gave up!!!

    it runs off the brakes for the vacuum supply. the engineers in germnay reccommended the electric one for mine, but then they would as it's the most expensive!!! he said the ms-50 cheap vacuum one will still work so am just going to get that one and if it's **** then i can always sell it on ebay!!!!

    Will post about what it is like! Can't be too bad for £90 delivered from germany!
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  14. ajmackie
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    [Oct 7, 2004]
    doubt it!!!!!
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  15. audi5e
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    [Oct 7, 2004]
    which means lots of work ahead... :) good luck!
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  16. ajmackie
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    [Oct 7, 2004]
    naaa won't be too bad. i'm quite mechanically and electrically minded (doing engineering degree).

    I've looked at where the sensor goes, just need to put it on my mates ramps to get access - that's easy.

    Mounting the servo and connecting to throttle is easy.

    Wiring is easy.

    Only hard thing will be connecting the vacuum up. might let a garage do that as i'm a wee bit lazy!!!

    It's real hell trying to source a cruise control stalk from a scrap yard. No one has them and don't want to pay £70 for a new one!!

    Cheers for your help, really appreciate it /ubbthreads/images/graemlins/beerchug.gif
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  17. audi5e
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    [Oct 7, 2004]
    Cheers Mackie!
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  18. audi5e
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    [Oct 8, 2004]
    [ QUOTE ]
    ajmackie said:
    but then i wouldn't unless i wanted to strip the engine and rebuild a gear box!!!


    [/ QUOTE ]

    Ha ha ha, I know exactly what you mean...

    I am guessing they are talking about the pipe that runs from the brake booster to the inlet manifold. The non-return valve normally plugs into the brake booster, and the pipe onto that. They probably suppy a T-piece that you can use to join the brake pipe. ie either cut the brake pipe into two then use the t-piece to join, or get an extra piece and plug the t-piece into the end of the brake pipe without cutting then simply add the other pipe to join to the booster and non-return valve. wahlah you have an extra vacuum line for your servo.
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  19. ajmackie
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    [Oct 9, 2004]
    Yeah that is right, they supply ** 3 ** different size t-pieces, bet i still won't get one that fits!!!

    The brake booster is the big circular diapragm by the brake fluid filler i think, isn't it!

    Where is the intake manifold? Is it after the airbox and before the throttle? Not too sure!!

    That is a darn good idea of yours to add a pipe instead of cutting!!! Think I shall be doing that!!

    thanks again!
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  20. audi5e
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    [Oct 9, 2004]
    I hope the big circular diaphragm is the brake booster, otherwise I've been living in never never land... :)

    Position of the intake manifold? If you do a handstand on the front lip of the bonnet, then poke yourself in the eye, you should notice a big block of metal, that's the engine, the top part of the engine is called the cylinder head and the intake manifold bolts to this. /ubbthreads/images/graemlins/laugh_roll.gif

    where exactly your vacuum pipe goes, I am not sure. I would not worry about it, since you only need to join the new pipe to the t-piece, the rest is academic.

    Good luck fitting it.
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