inst cluster K number ...

#1

my speedometer is reading way off and the current theory is that the instrument cluster from an eta car was put into my 325i car. The way to tell is by looking at the K number in small print at the bottom of the instrument cluster. Would someone who has an 89-90 325i please tell me what the K number on your instrument cluster is?
thanks,
bruce

#2

leggwork wrote:

[quote]my speedometer is reading way off and the current theory is that the instrument cluster from an eta car was put into my 325i car. The way to tell is by looking at the K number in small print at the bottom of the instrument cluster. Would someone who has an 89-90 325i please tell me what the K number on your instrument cluster is?
thanks,
bruce[/quote] If you have an ETA cluster, the tach only goes up to 4500 redline

#3

that’s a good point …

#4

I think the speedo sensor is the one in the diff. How different are your tire sizes from stock?
Bigger question…How does the car know if the final drive ratio changed…like from an open 4:10 like the auto tranny cars had to a 3:73… maybe the ECU is hard coded in the eeprom for the type of diff that was original.

#5

Hi Sean,
the tires are close to stock, and the speedometer is way off - when it reads 80, I am only going about 60 (via GPS). It has a 3.73 diff in it - that speedometer discrepancy could be accounted for by it thinking there is a 2.93 diff installed. I haven’t tracked down how the ECU or inst. cluster is programmed with the current diff ratio yet.

thanks,
bruce

nasaregistrar wrote:

[quote]I think the speedo sensor is the one in the diff. How different are your tire sizes from stock?
Bigger question…How does the car know if the final drive ratio changed…like from an open 4:10 like the auto tranny cars had to a 3:73… maybe the ECU is hard coded in the eeprom for the type of diff that was original.[/quote]

#6

leggwork wrote:

[quote]Hi Sean,
the tires are close to stock, and the speedometer is way off - when it reads 80, I am only going about 60 (via GPS). It has a 3.73 diff in it - that speedometer discrepancy could be accounted for by it thinking there is a 2.93 diff installed. I haven’t tracked down how the ECU or inst. cluster is programmed with the current diff ratio yet.

thanks,
bruce

nasaregistrar wrote:

[quote]I think the speedo sensor is the one in the diff. How different are your tire sizes from stock?
Bigger question…How does the car know if the final drive ratio changed…like from an open 4:10 like the auto tranny cars had to a 3:73… maybe the ECU is hard coded in the eeprom for the type of diff that was original.[/quote][/quote]

Is is an e to i swap? I don’t think any i cars came with any diffs besides 4:10 or 3:73

#7

what rpm indicates 80 but actual 60?

#8

it is a 325i from birth, but I don’t know what might have been monkeyed with in the instrument cluster. It was serving duty as a parts car for a while so the seller might have put non-standard bits back on.
thanks,
bruce

#9

find an online gear calculator and put in the variables to see if you can figure out what variables to change to get a match to your situation

#10

gear Calc, try this one

http://www.unixnerd.demon.co.uk/revs.html

#11

the engine is turning almost 3000 rpm in 5th at 60mph.

thanks,
bruce

nasaregistrar wrote:

#12

leggwork wrote:

[quote]the engine is turning almost 3000 rpm in 5th at 60mph.

thanks,
bruce

nasaregistrar wrote:

80 mph in a car with 195-60-15 tires a 3.73 rear and a .81 5th gera should be turning 3269.6 mph

#13

nasaregistrar wrote:

[quote]leggwork wrote:

[quote]the engine is turning almost 3000 rpm in 5th at 60mph.

thanks,
bruce

nasaregistrar wrote:

80 mph in a car with 195-60-15 tires a 3.73 rear and a .81 5th gera should be turning 3269.6 mph[/quote]
60 actual in same car should be 2452 rpm’s
Do you have access to a tach/dwell meter? if you can figure out exactly what the rpm;s are you can use the math to find the culprit which I suspect is the rear gear

#14

I’ll try that, thanks Sean
bruce

#15

just an update on the resolution of this issue.
Nothing obvious was wrong to cause the inaccurate speed reading and then the odometer stopped working also. A used speedometer came up on ebay so I bought it cheap, installed it, and, presto, the speed is now accurate and the odometer works.

It was odd though - I installed it an put it all back together. When I first took it out for a drive the speedometer was dead and I thought - I’ve either installed it wrong or I’ve just wasted some money … - but after a couple of miles it came to life and was accurate.

cheers,
bruce

#16

good enough…if you don’t mind saying…how much did you pay for the cluster?

Also, a place called North Hollywood Speedometer can repair these things.

#17

it was $35

#18

leggwork wrote:

Sweet for you… I have an e and an i as spares now. crazy what these actually cost back in the day.

#19

Got that right - I did the circuit board swap on an `88 535is and it cost me $200+