May 28, 2009 at 7:40 pm #232636
I’m the second owner from new of an ’85 British Coach Works ( BCW )
Looking around the vehicle, I’d say the car has covered about 10k miles, the word ‘about’ is key here, as the speedometer, a white faced ‘Classic Instruments’ unit, stopped working both needle and odometer at 702 miles.
Now, in my search for a BCW I came across two others before I closed the deal on the one I bought, both of which had speedos which had stopped working at less than 1000miles.
Sounds like coincidence is not a factor for consideration here, so is anyone familiar with what goes wrong with the speedos on BCWs? Of course I could trace the fault to source, but I’m imagining the BCW knowledge base has come across this before. Any assistance would be greatly appreciated.May 28, 2009 at 8:03 pm #238994Steve CritesParticipant
I’m sorry if I missed it, but what drive train are we talking here?
Is it a mechanical or elctric speedo?
Oh, and welcome to the gang!
Ringo39961.8366435185May 28, 2009 at 9:08 pm #238995Dan RosaParticipant
Peril , The first thing to check is the cable to the transmishion from the spedo after sitting a long time or limited use the spining part inside the cable gets bad you can try replacing the inside, all auto parts stores have them cheep and a quick fix it is universal part simple replacement. Best of luck, Dan RMay 29, 2009 at 11:41 am #238996
We need to know if it’s cable or electronic and if it’s VW or Chevette driveline.
I hope it’s not what happened to my former Pink MG…The drive gear (worm gear) on the transmission tail shaft disintegrated. This is common and happens because it’s nylon and when it sits in gear oil for a long time, the nylon swells…really swells.
So, at some point, the nylon drive gear (worm gear) on the tailshaft and the nylon speedometer cable drive gear (spur gear) mesh/clearance gets way too tight. The thinner worm gear then cracks and disintegrates leaving nothing but a black mark of burnt nylon debris cooked on to the tail shaft. See the huge picture where the tailshaft meet the gear case.
This is the problem that caused me to have to remove the floor tunnel, engine and transmission from the Pink MG that Larry Murphy just bought.
I hope this is not your problem.June 1, 2009 at 4:40 pm #238997
Thank you for the welcome and the responses – I omitted to add that my BCW is indeed the Chevette powertain and the speedo is electronic.June 1, 2009 at 6:51 pm #238998Steve CritesParticipant
First, if there’s a cable from the tranny to the sending unit, pull that and see if it’s broken. If no cable, start at the wiring and work back to the tranny to check the sending unit.
Check the wiring from the sending unit up to the speedo with a continuty tester. Double check the ground(s)! If OK, pull the sending unit. Take a pencil and shape the point to a square the same size as the one in the unit. Chuck the pencil in variable speed drill and spin the unit to see if the speedo moves. (with power on). If no go and you’re sure of the wiring, , it’s probably the sender. If the speedo moves with the drill, it’s probably a broken mechanical connection (cable) to the unit from the tranny. After that the problem would be in the tranny. Hope its not the same as Marks!
On Fords it’s a short speedo cable from the tranny to the unit. Don’t know if Chevettes are set up the same, but basically it’s either wiring to the sender, the sender, or the mechanical link to the sender. If none of that, it’s inside the tranny.
Hope this helps.
Ringo39965.796087963June 2, 2009 at 1:59 am #238999GeoffreyParticipant
Damn Ringo! You must have done this before! Nice tips…. Now tell me how to retire at 30!June 2, 2009 at 2:02 pm #239000
Amen…you’d better hope it’s not the same problem that the Pink MG had.June 2, 2009 at 3:02 pm #239001
I’ll put her up on ramps in the next couple of days and report back the findings. Thanks Ringo for the tips…. and yes, let’s hope it’s not the nylon gear. If that’s the case, I’ll look at it this winter as Summer is for driving not spinning spanners!
RogerJune 3, 2009 at 10:59 am #239002
If you know the diameter of your tires and have a working Tachometer, you can determine your speed in any gear.
I built an Excel spreadsheet table that I can send to you. Just change the tire diameter and final gear ratio (in any gear) and it’ll automatically change the table to tell you the actual speed at a given RPM.
Otherwise…drive at the speed of the traffic around you is always a safe bet…unless there is no traffic!
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