Speedometer Question (General)

[Huw Powell]

> I have a 5000 TD gauge cluster that I'm planning to install as part of 
> my conversion from gas to diesel in an 86.5 Quantum Syncro. I already 
> have plans in place to rearrange everything so the three-gauge cluster 
> will fit in the two-gauge Quantum, but... I need to know if the 
> speedometers are compatible.
> 
> Are there different internal gearings for different differential ratios, 
> thus making speedometer swaps a tricky business that will require a 
> custom cable? The Syncro has a 4.11:1 where the 5k TD I think had a 
> 4.5:1 (Correct me if I'm wrong).

OK, I don't know.  But I'm going to yap away anyway.  I am going to 
assume the 5k td has a mechanical speedo drive (later Audis start using 
electronic signals).

Here is how to play around and get your answer, assuming all the cables 
will hook up nicely later.  Take an electric drill, and use it to drive 
the two speedos in question - the old Q one and the 5k td one.  In this 
I take as an assumption that the drill speed will be the same, as the 
speedos are an easy load.

If the needles deflect the same amount (ie, read the same mph), you are 
golden.  If they don't, you'll need aspirin.

> Does "speedometer ratio" merely indicate relationship of transmission 
> output RPMs to cable RPMs? I'm not sure how all this works, so I ask.

Good question, but you sound right.

-- 
Huw Powell

http://www.humanspeakers.com/audi

http://www.humanthoughts.org/