Ranman72 Posted January 29, 2012 Report Share Posted January 29, 2012 Does any one know how to adjust a stock 68 510 speedo car is all original stock motor stock 4 speed etc speedo reads 60 when doing around 48 by GPS tires are 195 50 15 Thanks Randy Quote Link to comment
ggzilla Posted January 29, 2012 Report Share Posted January 29, 2012 Speedometers are not adjustable per se. The normal procedure is to change the speedo gear at the transmission. Especially when using different diameter tires. Go from the stock 17T gear to a 20T gear. Quote Link to comment
Ranman72 Posted January 29, 2012 Author Report Share Posted January 29, 2012 Speedometers are not adjustable per se. The normal procedure is to change the speedo gear at the transmission. Especially when using different diameter tires. Go from the stock 17T gear to a 20T gear. OK thanks I wasn't sure if the metal piece that is kind of c shaped was an adjuster or just some kind of balance part I know there is a thread on here somewhere that has the gear colors for number of teeth do you know Quote Link to comment
Zeusimo Posted January 29, 2012 Report Share Posted January 29, 2012 I Guess I Have The Same Question How Do You Know What Is The Right Teeth? When I Go 40 It Feels Like 50 :huh: 1 Quote Link to comment
ggzilla Posted January 29, 2012 Report Share Posted January 29, 2012 Stock gear on a 510 or 1200 is 17T. So if you go up one more tooth that is 18/17 or 106%. In Ranmans case he needs to go up by 20% (60/48mph) so he needs to go up a bunch. For the 620 there is a bunch of gears, start by pulling your gear and count the teeth. You can buy the gears at Nissan for about $10. Quote Link to comment
datzenmike Posted January 29, 2012 Report Share Posted January 29, 2012 Stock 510 tires are 5.60 x 13 or about 185/70R13. going to 195/50R15 is only 1.3 mph different at 60. I would suggest you verify your readings with another car. Quote Link to comment
ggzilla Posted January 29, 2012 Report Share Posted January 29, 2012 He checked it with GPS, but yes, having a third check will clear it up. I've seen Datsun speedos off by 15% with stock tires and stock gears. Quote Link to comment
Ranman72 Posted January 30, 2012 Author Report Share Posted January 30, 2012 Stock 510 tires are 5.60 x 13 or about 185/70R13. going to 195/50R15 is only 1.3 mph different at 60. I would suggest you verify your readings with another car. I will check it with another car but with the gps at multiple speeds it is about the same off at 40 on the speedo feels like I could run faster I was doing 27 on GPS It is also possible the speedo cog in the tranny had the gear changed before I owned it Mike you seem to be the encyclopedia of Datsuns is the gear the only way to change the speedo Quote Link to comment
ggzilla Posted January 30, 2012 Report Share Posted January 30, 2012 Oh I forgot ... but with the gps at multiple speeds it is about the same off So at 40mph it's 12mph off, and at 60mph it's still 12mph off? If so that's not a gear problem, that a problem with the speedometer itself. See Speedometer Calibration. Quote Link to comment
datzenmike Posted January 30, 2012 Report Share Posted January 30, 2012 I will check it with another car but with the gps at multiple speeds it is about the same off at 40 on the speedo feels like I could run faster I was doing 27 on GPS It is also possible the speedo cog in the tranny had the gear changed before I owned it Mike you seem to be the encyclopedia of Datsuns is the gear the only way to change the speedo Each tooth increase or decrease will adjust by aprox. 5%. This is 5mph at 100mph and only 2.5 at 50. It's not a set amount and varies by speed. 75 would be 3.5 out. If you have a constant amount out at all speeds then see ggzilla's post. Quote Link to comment
Ranman72 Posted January 30, 2012 Author Report Share Posted January 30, 2012 Each tooth increase or decrease will adjust by aprox. 5%. This is 5mph at 100mph and only 2.5 at 50. It's not a set amount and varies by speed. 75 would be 3.5 out. If you have a constant amount out at all speeds then see ggzilla's post. ok Thanks a bunch Randy Quote Link to comment
thetimanator Posted January 30, 2012 Report Share Posted January 30, 2012 Meh. My speedo is bouncing between 85-100 mph going down the interstate. Meanwhile cars are passing me. I just gave up Quote Link to comment
Ranman72 Posted January 30, 2012 Author Report Share Posted January 30, 2012 Meh. My speedo is bouncing between 85-100 mph going down the interstate. Meanwhile cars are passing me. I just gave up NEVER GIVE UP Quote Link to comment
wayno Posted January 31, 2012 Report Share Posted January 31, 2012 This is all I could find. I beleave there are more colors, but I have not a clue what they are. Quote Link to comment
datzenmike Posted January 31, 2012 Report Share Posted January 31, 2012 Meh. My speedo is bouncing between 85-100 mph going down the interstate. Meanwhile cars are passing me. I just gave up Loosen the transmission end of the cable, it's actually an outer protective sheath with a small tightly coiled spring inside that is very floppy. It has a ferrule on that end that locks it to the drive pinion inside. Pull it out and out of the sheath from the speedometer. Watch out it is very floppy and easily dropped. Lube with a dry graphite powder ir anything with molybdenum dy-sulphide in it for speedo cables. Installation is the reverse. Be sure the outer sheath is not tightly bent or kinked and be sure there is no damage to it that will let water or dirt in. 1 Quote Link to comment
metalmonkey47 Posted January 31, 2012 Report Share Posted January 31, 2012 Do different transmissions have different speedo drive gears? Mine is off by exactly 10mph and I'm using 195/75/14's Quote Link to comment
ggzilla Posted January 31, 2012 Report Share Posted January 31, 2012 Yes, different transmissions have different gears. You can't go by the color as there are different blue gears for different transmissions. Find out: 1. What series transmission do you have 2. Pull out the gear and find out which one you already have Quote Link to comment
thetimanator Posted January 31, 2012 Report Share Posted January 31, 2012 Loosen the transmission end of the cable, it's actually an outer protective sheath with a small tightly coiled spring inside that is very floppy. It has a ferrule on that end that locks it to the drive pinion inside. Pull it out and out of the sheath from the speedometer. Watch out it is very floppy and easily dropped. Lube with a dry graphite powder ir anything with molybdenum dy-sulphide in it for speedo cables. Installation is the reverse. Be sure the outer sheath is not tightly bent or kinked and be sure there is no damage to it that will let water or dirt in. wow... your datsun/mechanical knowledge is great!! Thanks! Quote Link to comment
Ranman72 Posted September 23, 2014 Author Report Share Posted September 23, 2014 I know this is an old thread but I changed the motor and tranny about 2 years ago and the speedometer became very accurate now I have changed tranny to a zx one and ran into the speedometer being off again what I found is the zx tranny had a black or I believe 17 tooth gear and the tranny that was in my car has a 23 tooth gear so I am going to put the 23 tooth gear in the zx tranny the 23 tooth gear is green I have also been told they have a 24 tooth gear but I dont know the color Quote Link to comment
DanielC Posted September 23, 2014 Report Share Posted September 23, 2014 The speedometer is made of two parts. The odometer, and the speedometer. The odometer measures the miles, and has a direct mechanical geared connection to the transmission, and rear axle. The odometer has to be corrected first. This is done with the different pinion gears, to match the rear axle ratio, and tire size. The speedometer is an aluminium cup, with a magnet spinning inside it. The spinning magnet induces an electric current inside the aluminium, and drags the speedometer needle higher the faster it goes. There is a spring that returns the speedometer to zero. If there is dirt, inside the aluminium cup, or the cup is bent, it will drag on the spinning magnet, and make your speedometer read too high. Dirt or crud on the outside of the return spring, or the bearings that hold the speedometer needle can make the speedometer read slow. Quote Link to comment
HRH Posted September 25, 2014 Report Share Posted September 25, 2014 I've been through this a million times with the 510. The best easiest way to get your speedo accurate is to buy a programmable speedometer. The different gears are all obsolete, so if you change gearing much or tire size, you'll never find the right one, much less you have to rely on pick n pull for the magical transmission that came with the gear you need. You will have to figure out where and how to mount a pickup but it's not that hard. (He says, having not done it himself.) The other option is you can remove the needle carefully (usually the older they are, the more they break off) and reset the needle to the speed to get it more or less correct in a given range of speed. 1 Quote Link to comment
Nuclear Water Boy Posted September 25, 2014 Report Share Posted September 25, 2014 You first have to know the differentials ratio before doing any manual speedo calibration otherwise you'll be chasing a fart in the wind. True in that tire size does change gear ratios and can either slow down or speed up the speedo. If I remember correctly each extra or less tooth in the speedo pinion cog is around 3mph. Can't exactly remember but I do have this, increasing the tooth count on the pinion will decrease MPH readout. 16t Pinion is Yellow, 17t is black, 18t is blue, 19t is white, 20t is red, 21t is purple, 22t orange and 23t is green Quote Link to comment
kelowg Posted September 25, 2014 Report Share Posted September 25, 2014 come on randy, just get the speedhut gps speedo. just doesnt work in tunnels Quote Link to comment
Ranman72 Posted September 26, 2014 Author Report Share Posted September 26, 2014 come on randy, just get the speedhut gps speedo. just doesnt work in tunnels AND DOESENT FIT IN A 68 510 DASH i PUT THE 23 GEAR COG IN THE ZX TRANNY AND sorry for caps i am not re typing and now the speedo reads 40 and the gps reads 40 at 80 on the gps the speedo reads 78 PRETTY F----ING CLOSE and good enough for me Quote Link to comment
kelowg Posted September 26, 2014 Report Share Posted September 26, 2014 Mayb the gps version,but someone on here has used them in a 510 with GREAT results. Quote Link to comment
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