Crupper Posted August 28, 2007 Share Posted August 28, 2007 Just bought a 92 Loyale wagon AWD with a 3 sp auto and 185 tires and I see it came out with 165's and the speedo is 10 MPH off. Can you change gears in the trannie? The 185's are about new so didn't want to change back to 165's. Any suggestions? Link to comment Share on other sites More sharing options...
j2coe Posted August 28, 2007 Share Posted August 28, 2007 1/8" white pinstriping tape and put new bolder marks on the speedometer for the actual readings? probably have to check with a specialty tranny or racing shop I haven't heard if a speedometer gear changer for soobies, maybe there are universal ones? Link to comment Share on other sites More sharing options...
Manarius Posted August 28, 2007 Share Posted August 28, 2007 It'd probably be more expensive to pull the transmission than it would to just buy new tires. 185 tires shouldn't really make the speedometer wrong though. It would be having 50 series vs 75 series tires that would mess with the speedo. Link to comment Share on other sites More sharing options...
mikeshoup Posted August 28, 2007 Share Posted August 28, 2007 Actually, changing just the width while maintaining the same aspect ratio (the series) will effect rolling diameter. The series is what percentage of the width the tire is tall. So if you had 100mm wide tires with a 70 series, they'd be 70mm tall. Ergo, a 165/70 tire will have a smaller rolling diameter than a 185/70 tire. However, 10mph off is not correct. A 165/70/13 tire will have an overall diameter of 22.09 in. A 185/70/13 tire will have an overall diameter of 23.19 in. The overall difference is around 5%. What does this mean? Your speedometer reads about 5% slow. When you're traveling 100mph, your speedometer will read 95mph. When you're traveling 10mph, your speedometer will read 9.5mph. Extrapolate from there. 10mph off? hardly. Link to comment Share on other sites More sharing options...
Crupper Posted August 28, 2007 Author Share Posted August 28, 2007 Actually, changing just the width while maintaining the same aspect ratio (the series) will effect rolling diameter. The series is what percentage of the width the tire is tall. So if you had 100mm wide tires with a 70 series, they'd be 70mm tall. Ergo, a 165/70 tire will have a smaller rolling diameter than a 185/70 tire. However, 10mph off is not correct. A 165/70/13 tire will have an overall diameter of 22.09 in. A 185/70/13 tire will have an overall diameter of 23.19 in. The overall difference is around 5%. What does this mean? Your speedometer reads about 5% slow. When you're traveling 100mph, your speedometer will read 95mph. When you're traveling 10mph, your speedometer will read 9.5mph. Extrapolate from there. 10mph off? hardly. OK. then this car's tire plate on the door post says 165 SR 13 and doesn't have a series. The the Goodyear tires on it are 185/ 80 R 13. Would that make it read more than 5%? I was driving my 90 sub at 55 MPH and the wife was following with this 92 and she was going 45 MPH. thanks for the comeback! Link to comment Share on other sites More sharing options...
Tom63050 Posted August 29, 2007 Share Posted August 29, 2007 OK. then this car's tire plate on the door post says 165 SR 13 and doesn't have a series. The the Goodyear tires on it are 185/ 80 R 13. Would that make it read more than 5%? I was driving my 90 sub at 55 MPH and the wife was following with this 92 and she was going 45 MPH. thanks for the comeback! Most speedometers read fast with stock tires, by about 5%. I also have 185/80x13 tires on my lifted 91 Loyale. I verified that these tires only make the odometer read 2.5% slow, and figure the speedo is affected by about the same amount. The stock tires on my car were probably making the speedo read 2-3 MPH fast. The easiest way to check the odometer is to drive on a highway with mile markers for 20-50 miles, and compare the tripmeter reading with the distance you have driven on the highway. You need the tripmeter because it has tenths, for more accuracy. The easiest way to check the speedometer is to drive at an indicated 60 MPH for however long it takes to go from one mile marker to the next. If it takes 60 seconds, your speedo is exactly right; 66 seconds, it's reading 10% high; 54 seconds, 10% low; 57 seconds, 5% low, etc. So to calculate gas mileage I just add 2.5 miles per 100 (since it reads 2.5% slow) to whatever the tripmeter reads, then reset it when I fill up. Link to comment Share on other sites More sharing options...
Ross Posted August 29, 2007 Share Posted August 29, 2007 easiest solution is just to remember roughly how many % out it is and use the speedometer accordingly. As long as you know what the speedo should be reading, thats all that matters! Link to comment Share on other sites More sharing options...
ausubaru92 Posted August 29, 2007 Share Posted August 29, 2007 I pulled appart a speedo a while ago and noticed an adjustable spring connected to the needle shaft, this might allow adjustment of the speedo Link to comment Share on other sites More sharing options...
j2coe Posted August 29, 2007 Share Posted August 29, 2007 that would be cool if you could adjust it, but how would know where to set it? isn't something that you can pull out the meter and tweak while driving having your instrument cluster handing loose. thats most likely for initial calebration. I suppose if you just played around with it marked the starting point and adjusted it say 1/4 turn at a time and tried it again to see what difference it made in the speedo readings you could make a chart. Right turn and Left turn will slow or speed or whatever and by how much. be a major hastle if I recall trying to get into a dash though taking it out and putting it in to check the changes. there are shops that do speedometers repair aren't there? maybe they could tell you. Link to comment Share on other sites More sharing options...
bratgrl Posted August 29, 2007 Share Posted August 29, 2007 Or....if you have access to a handheld GPS, set it to the "speed" page, take it in the car with you, drive at 60mph (or whatever) and see what the "speed" on the GPS says. I did this with my Jeep after I put the bigger tires on it. My Jeep is 11% off of what the speedo says, (i.e. if I'm doing 65mph according to the speedo, I am actually doing around 72 mph). Then you will be able to calculate the difference and you will know exactly how fast you are going, and knowing is half the battle. Link to comment Share on other sites More sharing options...
mikeshoup Posted August 29, 2007 Share Posted August 29, 2007 The speedometers don't have any calibration on it themselves. The difference is that the transmissions use a different speedometer gear ratio for the tire sizes. You *might* be able to pull apart a transmission from one of the cars that 185/70/13 was stock and swap the speedo gears. Link to comment Share on other sites More sharing options...
Loyale 2.7 Turbo Posted August 29, 2007 Share Posted August 29, 2007 Just for Share Info: Last Week, I was changin` the Oil on my White Wagon, and while it was drainin` the old oil, my Boss asked me for some info I got on my PC, so I took a Taxi, (here cost around $3.ºº an Average Taxi Ride) and the Taxi I got, was a 1988 Loyale... ...So (Obviously) I Started talkin` with the Taxi Driver about his Subie. I Inmediately Noticed that the Speedometer was doing a Wrong count, Because the car just Started at first Gear, and the Speedometer did Show 35 Mph... Then it Raised soo Fast, untill the Needle was markin` 75 Mph, and the car was just on Third Gear, at Around 30 Mph... I Asked him about the Speedometer Malfunction, and he said something about that the car did have a bad Short Circuit, and he sent it to a Car Electrics Repairs Shop, Then it came just like That!... :-\ ... Why? ... He said that there, the Master Electrician said that it was an "Internal Damage" on the Speedometer itself... Well... is That Possible? ... might be that the Speedometer has some way to Adjust it? ... What do you Think About? Link to comment Share on other sites More sharing options...
ezapar Posted August 29, 2007 Share Posted August 29, 2007 The speedo on my Brat is on and off. Usually it pegs at about 40 actual miles per hour. But once and a while, it works properly. Link to comment Share on other sites More sharing options...
Hodaka Rider Posted August 29, 2007 Share Posted August 29, 2007 Well... is That Possible? ... might be that the Speedometer has some way to Adjust it? ... What do you Think About? I don't know about adjusting it, but I believe that the cable input at the speedo head is turned into a pulse signal, which is then used to drive the motor that moves the needle. Link to comment Share on other sites More sharing options...
misledxcracker Posted August 29, 2007 Share Posted August 29, 2007 Mine's so screwed up, and I can hear the speedometer clicking and ticking inside the dash cluster... it tends to stick and read low... Speedometer cable loose, maybe? I don't know. BTW crupper, your 92 aint winning any races any time soon... Why even make a big deal out of it? Link to comment Share on other sites More sharing options...
j2coe Posted August 29, 2007 Share Posted August 29, 2007 the rotation drives a magnet that is picked up by coils that drive the needle. kind of a little generator. fiddly and complicated. so the faster the rotation the higher the output voltage the stronger the signal the higher the needle reads. 0 rotation 0 needle movement, really fast really big signal. fried electrical that fuses some coils = reads way off makes sense. I doubt the calibration adjuster discussed earlier would compensate for tire diference any way, unlikely to have enough adjustment, just for fine tuning / calebration. Link to comment Share on other sites More sharing options...
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