speedo off?

[turnofftheradio]

so, as cars fly by me, I couldn't help but think that everyone is an asshole, then, I passed a speed check station and I was 10 mph off. 'DOH! I had swapped an entire cluster from a 318 into my 325e. would that cause it to be off? I figured the coding plug took care of that. I do have the origional speedo, but don't want to swap it if it makes no difference. anyone know?

[r0l4n]

If i'm not wrong, the speedo counts how many impulses it receives from the rear diff in a period of time, so I don't know why you are wrong. Different impulse sending wheel in rear diff, wrong speedo (I don't think so) or maybe different diameter wheels?

[nando]

maybe your tires are too big? that would make it read low. I have undersized tires so it reads about 5mph high. wheel diameter has nothing to do with it..

[turnofftheradio]

If i'm not wrong, the speedo counts how many impulses it receives from the rear diff in a period of time, so I don't know why you are wrong. Different impulse sending wheel in rear diff, wrong speedo (I don't think so) or maybe different diameter wheels?

I have the stock bottlecaps and standard dia. tires :? I do not know if the rear end has been swapped out before I got it. hmmmm

[nando]

diff swap shouldn't make a difference, the sensor measures the axel speed after it's gone through the diff anyway.

what size tires do you have?

[r0l4n]

If you're running stock tires your speedo is not in good shape or your rear diff has different impulse sending wheel than the 318i had.

[turnofftheradio]

diff swap shouldn't make a difference, the sensor measures the axel speed after it's gone through the diff anyway.

what size tires do you have?

185/60/r14
supposed to be 195/60 but I thought the 60 was the height?

[Beej '86 325es]

Keep in mind that the speedos are 4mph fast. If you maintain a consistent speed and reset the average speed on the OBC, it should show about 4 mph slower than the speedometer. I believe BMW used to do this to prevent people from speeding so much. I don't know if they still do this or not.

[KenC]

Keep in mind that the speedos are 4mph fast. If you maintain a consistent speed and reset the average speed on the OBC, it should show about 4 mph slower than the speedometer. I believe BMW used to do this to prevent people from speeding so much. I don't know if they still do this or not.

Is this true for all e30s? Are you just basing this off of the OBC measurement, or have you read documentation regarding it? I've noticed when driving past the police radars that they'll read a bit slower than my spedo shows.

[nando]

diff swap shouldn't make a difference, the sensor measures the axel speed after it's gone through the diff anyway.

what size tires do you have?

185/60/r14
supposed to be 195/60 but I thought the 60 was the height?

actually it should be 195/65-14, 185/60 is waaaay undersized. the 60 is actually a percentage of the width so the height is different for a 195 vs a 185 tire.

[Digitalwave]

diff swap shouldn't make a difference, the sensor measures the axel speed after it's gone through the diff anyway.

what size tires do you have?

185/60/r14
supposed to be 195/60 but I thought the 60 was the height?

actually it should be 195/65-14, 185/60 is waaaay undersized. the 60 is actually a percentage of the width so the height is different for a 195 vs a 185 tire.

A lot of the early models had 195/60-14 from the factory.

[Rob]

with 195/60s on my car (65 is stock), my speedo was off 10-12mph @ 80mph (based on GPS), so it could definitely be your tire size.

[AndrewBird]

Did you ever think that the needle may not be in the exact right position on the needle shaft? If it was turned, then it won't read right. Just take your car out with the plastic lense off the cluster, find a radar and adjust it until it reads right.

[nando]

Did you ever think that the needle may not be in the exact right position on the needle shaft? If it was turned, then it won't read right. Just take your car out with the plastic lense off the cluster, find a radar and adjust it until it reads right.

it could be but 185/60 is definetly undersized.

[turnofftheradio]

Did you ever think that the needle may not be in the exact right position on the needle shaft? If it was turned, then it won't read right. Just take your car out with the plastic lense off the cluster, find a radar and adjust it until it reads right.

I wouldn't doubt it, but knowing my luck, It would be 20 off when I'm done. I can deal with it so long as I remember....