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Thread: How to fix speedometer issues

  1. #1
    Uncensored Hypocrite stevedmc's Avatar
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    How to fix speedometer issues

    While visiting Darren Decker's house Lexington, NC I had a chance to look at Brandon Barber's speedometer issue. We have resolved it since then, but here is the information I posted on Google Groups regarding how the system works.

    Here is a quick video explaining how the speedometer system in a Delorean works.



    First his speedometer dust cap is missing. He will need to order a new one from a vendor such as DMCMW or DPI. I don't think John Hervey sells this part.
    http://store.delorean.com/p-7273-dust-shield.aspx

    Next we discovered that his angle drive does not work. I verified this by disconnecting it from the lower cable and turning the angle drive by hand. The angle drive did not turn on both sides when I turned it by hand. Something is broke inside of it and the angle drive will need to be replaced. I highly recommend the one John Hervey is selling.

    DMCMW-DMCH Angle Drive (I've gone through several of these)
    http://store.delorean.com/p-7325-spe...gle-drive.aspx

    John Hervey -I've probably put 20k miles on mine. I'm not really keeping track but I installed it back in 2011. I drove 15,000 miles back in 2013 without any speedometer issues other than a dust cap.
    http://specialtauto.com/delorean-par...ngle-drive.jpg
    http://specialtauto.com/delorean-par...e-with-nut.jpg
    http://www.specialtauto.com/Merchant...Category_Code=
    http://www.specialtauto.com/Merchant...Category_Code=

    Keep in mind the nut will need to be transferred from your old angle drive to the new one. It is a big pain to do if you have never done something like this before. I don't mind transferring the nut myself but it can be worth spending a few extra dollars for the convenience of having an angle drive that is ready to go.

    The next mind boggling thing we discovered is the inner cable in his lower speedometer cable is completely missing. At a minimum he will need to replace the inner cable. I would recommend replacing the entire cable assembly (lower and upper) with a longer cable. This will allow him to bypass the counter box (there is a fancy word for it but I don't know how to spell it) and will make his speedometer less likely to fail in the future.

    I got my longer speedometer cable from John Hervey and am very happy with it. I believe PJ Grady sells the same thing. I'm not sure if Josh Bengston has it or not. Bill Robertson claims you can buy a $9 cable at AutoZone and transfer the ends from your old cables to the new one. This would be an interesting way to save money.

    Anyway, here is a link to John Hervey's longer speedometer cable.
    http://specialtauto.com/delorean-par...er-cable-1.jpg
    http://www.specialtauto.com/Merchant...t_Code=101412L

    Hopefully this information helps someone. As you can see there are a lot of components to go wrong in a Delorean speedometer system. Fortunately, it is very simple to diagnose speedometer problems.
    Rest assured, we have a backup of Farrar's car blog and it will be restored in the near future. (Steve Rice - March 2016)
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  2. #2
    Uncensored Hypocrite stevedmc's Avatar
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    This video shows Bill bragging about his $15 cable. In reality, it cost me almost $20 to buy the parts.



    The background noise in this video is terrible. When I have the time, I will make my own cable and document the process.

    Below are the necessary part numbers to make this cable. You will need to transfer the angle drive connector from an old cable to the new one.

    Part Number: CA-3005
    Alternate Part Number: 03101
    Cross Reference Vehicle: 1988 Chevrolet Monte Carlo 4.3L TBI 6cyl
    http://www.autozone.com/autozone/par...fier=1666_0_0_


    Part Number: 03369
    Universal part. No cross reference information.
    http://www.autozone.com/autozone/acc..._&target=shelf
    Rest assured, we have a backup of Farrar's car blog and it will be restored in the near future. (Steve Rice - March 2016)
    Rest assured, we have a backup of Shep's posts and all of them will be restored in the near future. (Steve Rice - March 2017)

  3. #3
    I'd be interested in hearing some other owner's opinions on something with my speedometer system.

    My speedo has not been working well for quite some time. I have replaced the dust cap a couple times, the angle drive a couple times (as well as the nut the last time around) and the lower speedo cable a couple times. My service counter currently has the guts taken out of it. I do not have my speedo cable bracket (the original wire type one) installed yet as I'm going to put it on when I do some front brakes work. In the meantime, I have the simplified bracket and the little plastic clip and some zip ties trying to secure it in place. I have never gone in behind the instrument cluster to do much inspecting back there at the upper connection.

    Mine appears to be very much affected by alignment and whether it is "perfectly" connected and tight. The part I was wondering what others have seen is that if I have no lower speedo cable connected, but the angle drive is in place and I spin the end of the cable on the dust cap side (dust cap removed when doing this), it rotates fairly easily and you can do it with your finger tips and not need a pair of pliers or drill to make it rotate. When I insert the tip of the lower cable however, it almost immediately becomes very difficult to spin with your fingers, borderline impossible. I get the feeling that it is either the lower cable end that is getting inserted too far somehow, or otherwise is creating some misaligned interference that ultimately doesn't let the speedo needle move in the cluster.

    Anyone else see this change from freely spinning to terribly hard to spin once you insert the lower cable connection? Or better yet, know what I can do to correct it or which part might be the cluprit and worth replacing?

    Thanks.
    "Life moves pretty fast. If you don't stop and look around once in a while, you could miss it."

  4. #4
    Uncensored Hypocrite stevedmc's Avatar
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    Can you turn the cable inside the lower cable when it is still connected to service counter?
    Rest assured, we have a backup of Farrar's car blog and it will be restored in the near future. (Steve Rice - March 2016)
    Rest assured, we have a backup of Shep's posts and all of them will be restored in the near future. (Steve Rice - March 2017)

  5. #5
    Quote Originally Posted by stevedmc View Post
    Can you turn the cable inside the lower cable when it is still connected to service counter?
    I believe so, but not for certain... let me do that test and report back shortly...
    "Life moves pretty fast. If you don't stop and look around once in a while, you could miss it."

  6. #6
    Be very gentle using a drill to test your speedometer setup. Spindle cable is wound backwards from forward wheel rotation. If your setup binds, you run a very real risk of unwinding the spindle cable -- uber bad on Houston's angle drives (non-replaceable spindle cable). If you can't spin the spindle cable with your fingers, don't try a drill.

    I've always considered the rust/breakage prone lower cable support to be a "silver bullet" panacea. What ails the angle drive has nothing to do with lower cable support:
    - very shallow gear teeth (hardly any engagement between them -- like 1/32")
    - unequal number of teeth between the gears
    - forward wheel rotation turns gears into each other rather than away from each other (you can feel the angle drive bind in your hand in forward rotation, then break free when turned backwards).

    That said, the lower cable always proved problematic for me. The inner cable would occasionally fall out of the Lambda box. Also the outer sheath would pull to maximum length when I turned right, then fail to shove back when I turned left (probably what caused the inner cable to be too short).

    Since I made my own single piece speedometer cable I haven't had a single inner cable engagement issue.

    I made my single piece cable the same length as the OEM cables with Lambda box, but now consider it too long:

    It makes a pretty wicked S bend under the dash. If that bend ever causes the inner cable to bind I will definitely make another shorter one.

    On Brandon's car we attached the outer sheath to the speedometer gauge, made a nice gentle bend through the firewall, then marked it at the wheel before cutting -- a much better approach.

    Bill Robertson
    #5939

  7. #7
    Since I brought up angle drives:

    Be advised that Hervey's angle drive has a 1:1 gear ratio. OEM drives, reproduced by Houston, have an 8:9 gear ratio. I don't know what Josh's drive ratio is.

    Houston's drive reproduces OEM speedometer accuracy (however accurate that in fact may be). Hervey's drive spins the gauge approximately 12% slower.

    Bill Robertson
    #5939

  8. #8
    Uncensored Hypocrite stevedmc's Avatar
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    Quote Originally Posted by content22207 View Post
    Since I brought up angle drives:

    Be advised that Hervey's angle drive has a 1:1 gear ratio. OEM drives, reproduced by Houston, have an 8:9 gear ratio. I don't know what Josh's drive ratio is.

    Houston's drive reproduces OEM speedometer accuracy (however accurate that in fact may be). Hervey's drive spins the gauge approximately 12% slower.

    Bill Robertson
    #5939
    I can testify that Josh Bengston's angle drive is perfect. We installed one for Brandon Barber about a month ago and one of the first things we did on the road was compare his speedometer to a GPS. It was 100% correct. I don't know how well his angle drive will hold up long term but it appeared to be very well built. It has the removable shaft that connects to the dust cap and frankly, the unit looked identical to Herveys.

    I have been running a Hervey unit for about 18 months and as many of you know, I put tons of miles on my car. The Hervey unit has not failed yet but unfortunately it is about 12% off. This means I have to do math in my head to figure out what my speed is.

    I've gone through several angle drives from DMCH. Lets not go there. When they have a good product, I brag about it. Angle drives aren't one of their best products.

    I actually talked to Josh a week ago about getting one of his angle drives. Unfortunately he is out of stock and he said it would be 6 weeks until he has more. He mentioned that his angle drive kit was about $110 but they were going to see about having a large quantity produced to get the cost down.

    $110 is a lot for an angle drive when Hervey has them for $55 and Houston has them for $60 but based on what I saw with Brandon's car, I will be purchasing an angle drive from Josh at DPI as soon as they are available again. I'm cheap, but when a product is good I cough up the money.
    Rest assured, we have a backup of Farrar's car blog and it will be restored in the near future. (Steve Rice - March 2016)
    Rest assured, we have a backup of Shep's posts and all of them will be restored in the near future. (Steve Rice - March 2017)

  9. #9
    I've been running a Houston unit for 16,000-24,000 miles no problem. The first one showed up with a manufacturing flaw -- receiver for the lower cable was totally round. Its replacement has a flat crimp, not a square shape. I squished my lower cable end in a vise to match. Not 100% prototypical, but the unit hasn't failed yet. If I can get 40,000 or 50,000 miles out of it I will be satisfied.

    Bill Robertson
    #5939

  10. #10
    If I had a lot of money for experimentation, I'd find angle drives from similar cars of the era (Jaguar, etc.) and check their gear ratios.

    It's a shame our speedometers are mechanical, otherwise you could try something like this, and the ratio wouldn't even matter -- just calibrate the gauge and you're good to go. Maybe one of the electronics geniuses out there can work something up eventually, but in the meantime it's a good thing there are proper angle drives available from more than one vendor, in my opinion.

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