[DML] Re: Time for a new Speedo mechanism ...

["Dave Swingle" <swingle@xxxxxxxxxxx>]

Nice idea but economics gets in the way. I've been involved in some 
aftermarket parts work and we've actually thought thru this a bit, 
and this requires :

-- a weatherproof electrical sender, either on the trans or front 
wheel that can take the abuse;
---a servomotor to continue to turn the speedo cable in time with the 
transducer OR a new speedo head that is electronic rather than 
mechanical, but can still run the odometer;
---some electronics to translate the sender pulses to a servomotor 
control OR an electronic gauge (but something still needs to run the 
mechanical odometer, or that needs to be replaced too!);
---someone to design, engineer, and test all this, who is willing to 
invest thousands up front for production, and then sell it for less 
than or equal to the price of the current angle drive ($60)

Here's a made-up business case analysis - yeah the numbers are made 
up but it's close enough for this excercise:
-----
After spending many hours doing the design, sourcing the parts, 
building the kit etc. and building the inventory, say the investment 
is $5000 in engineering and testing(probably a lot more) and $40000 
in the first 200 units ($200 each set for a pulse drive, custom 
control circuit, and a speedo head or servomotor.)

So our developer ties up $45000 in time and money.  Assuming he can 
sell all 200 of them over 2 years and wants to make his investment 
back in that much time (no profit yet) it has to sell for $225 each. 
AFTER two years he gets to make a gross profit of 13% per unit for 
all this trouble and investment. Not much of a business plan. Add 
marketing costs in there too. 

In addition, probably 3/4 of the target purchasing audience would 
have to pay someone another $100 to install it, more if the dash has 
to come apart.

How many $225 (+ install) speedo setups do you suppose someone would 
sell, given that I can continue to buy angle drives for $60? Even if 
I'm off by 50% in all the numbers, it doesn't work.

That's why nobody has done it, at least commercially. I hope someone 
will do one and prove me wrong. BTW this is exactly how BMW 
speedometers have worked since about 1983, driven from the rear axle.
 So - maybe there's a design that you can start with.

Dave Swingle



--- In dmcnews@xxxxxxxxxxxxxxx, "Nick Kemp" <nkemp@xxxx> wrote:
> The speedo on my D is a pain.  I just pulled the wheel and found 
the cable
> end that goes into the plastic hub shredded.  The speedo is 
relatively new
> (Most of the inches put in it were in the garage) as is the plastic 
cap.
> The speedo rotates freely as do the cables. (The lower cable is new 
as
> well).  When it did sorta work the speed jumps/pulses.
> 
> Here's my idea ... We need an electrical transducer that attaches 
to the
> front wheel.  






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