Speedometer accuracy issues again....

douglas vincent · Post by **douglas vincent** » Tue Feb 28, 2006 5:30 am

On the drive back down from Aberdeen Washington, I was following Ralliteck in a 60 mph zone.

He was driving about 60 mph exactly and EVERYBODY was passing us. I called him up and asked him was his speedo read. 65 mph.

hmmm..... 5 faster than mine.

I asked him what his tachometer read. Withen 100 or so of mine.

hmmmm....and mine is about 150 faster than the Perfect Power reads.

So I once again started timing myself as I drove down the freeway in cruise control.

62 seconds to go a mile at 60mph (real speed = 58 mph)

50 seconds to a mile at 75 mph (real speed = 72 mph)

46.5 seconds to go a mile at 80 mph (real speed = 77.5 mph)

So it seems my speed is off about 2-3 mph (or 3%). Rallitecks speedo is off ALOT more, about 7 mph, or 6-7%.

I am using stock WRX rims and RE92s. Ralliteck is using some 17" with low profile tires that are almost 1" smaller in circumfrence.

So after doing this again, I once again through serious doubt onto those claiming to have really truly cross your heart and die gone 130-140 in our cars if they are using anything smaller than 16" rims and/or weird giant truck style tires.

JasonGrahn · Post by **JasonGrahn** » Wed Mar 01, 2006 5:30 pm

Tacoma Speedometer can recalibrate that for you.

Post by **Legacy777** » Wed Mar 01, 2006 7:28 pm

Jason,

What do they do to recalibrate the speedo on a mechanical speedo setup?

JasonGrahn · Post by **JasonGrahn** » Wed Mar 01, 2006 7:37 pm

Dunno, but I bet if you called they could tell ya at least a little bit. They've got all sorts of tricks.

http://tacomaspeedometer.com/

evolutionmovement · Post by **evolutionmovement** » Thu Mar 02, 2006 12:31 am

Going by the police radar speed display signs, my speedometer was most accurate with my 15's (dead on), but the 16's are close and still more accurate than the OEM 14's.

douglas vincent · Post by **douglas vincent** » Thu Mar 02, 2006 6:52 am

I was the worst on my 14" rims. 10% off. 100 was truly only 90.

Post by **Legacy777** » Thu Mar 02, 2006 7:49 pm

Called them up.

Talked to Mark. (Seemed like a really knowledgable & nice guy)

What they do is take a speed reading on a dyno at 60 mph. Take that, and build an adapter, which is about 3" in length to go in line on your cable. Parts wise, he said the adpater is about $60, and cable stuff is around 30.

If they were to do the whole thing, including the dyno stuff I think he said around 150-170.

If I were going to do, I'd have to get a dyno reading down here in Houston @ 60 mph and send him that information as well as my speedo cable for him to modify.

Once I pick the size tires I want to use, I'll probably look into doing this.

wiscon_mark · Post by **wiscon_mark** » Thu Mar 02, 2006 8:14 pm

sorta off topic here...all 1st gens have speedo cables then? They're not electronic?

Post by **Legacy777** » Tue Mar 07, 2006 8:36 pm

Well....they have speedo cables, but the speedo is electronic. The cable drives a speed sensor....not the speedo directly.

scottzg · Post by **scottzg** » Tue Mar 07, 2006 10:54 pm

whats the point in regearing it? The speedo jumps at 80 and 90 mph anyway. You have to watch the tach to have an accurate speed reading.

Post by **Legacy777** » Tue Mar 07, 2006 11:26 pm

I asked the guy about the speedo reading at higher speeds....and he said regearing it would fix it across the entire range. I don't know if was intending/implying it'd be accurate at 100 mph.

wiscon_mark · Post by **wiscon_mark** » Wed Mar 08, 2006 12:34 am

Legacy777 wrote:Well....they have speedo cables, but the speedo is electronic. The cable drives a speed sensor....not the speedo directly.

Interesting. I wonder if the OBDI Imprezas also had a cable, because my OBDII Legacy is all electric wiring.

Post by **Legacy777** » Wed Mar 08, 2006 1:06 am

wiscon_mark wrote:
Legacy777 wrote:Well....they have speedo cables, but the speedo is electronic. The cable drives a speed sensor....not the speedo directly.
Interesting. I wonder if the OBDI Imprezas also had a cable, because my OBDII Legacy is all electric wiring.

I'm pretty sure this is how it works. Vikash would probably be able to confirm whether I'm right or wrong.

I would probably venture to say the OBD1 imprezas are the same as the OBD1 legacies.

vrg3 · Post by **vrg3** » Wed Mar 08, 2006 4:02 pm

Actually, I think all Imprezas use the electric setup, with the VSS threaded into the transmission. I could be mistaken though.

BAC5.2 · Post by **BAC5.2** » Wed Mar 08, 2006 5:43 pm

I know the 1994 WRX had the VSS threaded into the transmission.

JuhaKankkunen · Post by **JuhaKankkunen** » Fri Mar 17, 2006 2:36 am

My 93 Legacy tell me in the spedometer 160 km/h (100 mph) when i was really driving at 150 km/h (93.75 mph). Can anybody tell me if there is a solution for that??? Thanks.

Post by **Legacy777** » Sun Mar 19, 2006 6:05 am

Yes....the website posted above can fix that.....

legacycentral bbs

A forum for 89-94 BC-BF(BJ) Legacy Owners and Fans

Speedometer accuracy issues again....

Speedometer accuracy issues again....