Ron1200 Posted January 22, 2014 Report Share Posted January 22, 2014 I'm having issues with my speedometer and am looking for some help... especially with part numbers. I have a 620 with an L16 and a pre-1980 280zx 5 speed. The speedo has been wrong since the day I bought it. At an indicated 60 MPH, I'm actually traveling 66 MPH according to my GPS (about 10% off). Recently my speedo died due to a failed Pinion gear (a red, 20 tooth gear). So now I hope to fix both the speedometer and correct the speedometer error at the same time. :) From the research I've done on this site the red 20-tooth gear indicates a 4.11 rear end. I have no idea what ratio the real rear end is geared for (but it doesn't really matter for what I'm doing here). As stated, I'm running about 10% faster than indicated on the speedo, So to get things right, I think I need a blue 3.70 18-tooth gear for a 10% correction. I believe that a smaller gear will turn the cable faster and catch the speedo up to the truck. My problem is that my 620 is a mix and match truck and the part numbers that I've located on this site aren't matching up with what I think is correct. As the old pinion is a 20-tooth gear, any smaller pinion needs a different sleeve. According to this post http://community.ratsun.net/topic/19081-speedometer-gear-issues/?p=265015 , I need part number 32707-78000 for speedometer pinions with 16 to 19 teeth. However, checking with the dealer (Nissanparts.cc) that part number is for a automatic 280zx. They suggest either 32707-P9000 (12/80 thru 8/81 5 spd 280zx) or 32707-58500 (79 620 5spd). I have no idea which part I need. I thought that the 280zx, Maxima and pickup used the same 5 speed transmissions. Any suggestions that I could have them search for? Anyone have a part (pinion & sleeve) I could buy from them? I've also read these helpful posts: http://community.ratsun.net/topic/19081-speedometer-gear-issues/ http://community.ratsun.net/topic/26704-matching-speedo-gears-after-rear-end-swap/?hl=%20speedometer%20%20gear Quote Link to comment
ggzilla Posted January 22, 2014 Report Share Posted January 22, 2014 Since yours is a pre-1980 gearbox, go with the pre-1980 part number. They use the same transmission series, but parts change slightly from time to time. the dealer ... suggest either [/font][/color]32707-P9000 (12/80 thru 8/81 5 spd 280zx) or 32707-58500 (79 620 5spd). Quote Link to comment
EatLag Posted January 22, 2014 Report Share Posted January 22, 2014 I just corrected my speedo by finding out how far it's out, then pulling the plastic cover off, pulling the needle of and putting it back on lower ;) works for me haha Quote Link to comment
ggzilla Posted January 22, 2014 Report Share Posted January 22, 2014 Reading 60 when actually going 66 could mean it is 10% off. Or it could be 2mph off + 7% off. They key to knowing which is to measure it at 30 indicated and 60 both. Quote Link to comment
datzenmike Posted January 22, 2014 Report Share Posted January 22, 2014 First year zx pinions are totally different fom the other years and the Maxima. You want an 18 tooth from any 4 or 5 speed '74 and up 620/280z/'79 280zx or early 810. Has to be before '80. I'll get you a part number. Quote Link to comment
Ron1200 Posted January 22, 2014 Author Report Share Posted January 22, 2014 They key to knowing which is to measure it at 30 indicated and 60 both. good advice Zilla... but my gear is stripped. So I can't do the 30 mph check. :) Quote Link to comment
Ron1200 Posted January 22, 2014 Author Report Share Posted January 22, 2014 First year zx pinions are totally different fom the other years and the Maxima. You want an 18 tooth from any 4 or 5 speed '74 and up 620/280z/'79 280zx or early 810. Has to be before '80. I'll get you a part number. thanks Mike... Besides the pinion, I need the Sleeve. My understanding is the the off-set changes with 19-tooth gears and smaller. The one I have is a 20-tooth, which is a different Sleeve. Quote Link to comment
DanielC Posted January 22, 2014 Report Share Posted January 22, 2014 The speedometer and the odometer are different, even though they are both in the same instrument. The odometer has a solid mechanical geared connection to the rear wheels, the speedometer uses a magnet, in an aluminium cup, to move a needle against a spring. There is not a solid connection on the speedometer needle. You need to check the actual distance traveled, against what the odometer says, to get the pinion right. Then the speedometer needs to be adjusted by a speedometer shop to get the speedometer to read right. Quote Link to comment
ggzilla Posted January 22, 2014 Report Share Posted January 22, 2014 Or, one can adjust it at home, using the same methods the speedometer shop would use. Quote Link to comment
datzenmike Posted January 23, 2014 Report Share Posted January 23, 2014 If the key that retains the speedometer sleeve assy is at the top like this... Then the '79 810 has an 18 tooth assembly that should work... THIS... 32703-78102..... 18 tooth pinion gear FITS INTO THIS...32707-R5600..... pinion sleeve assy Quote Link to comment
MikeRL411 Posted January 23, 2014 Report Share Posted January 23, 2014 The speedometer and the odometer are different, even though they are both in the same instrument. The odometer has a solid mechanical geared connection to the rear wheels, the speedometer uses a magnet, in an aluminium cup, to move a needle against a spring. There is not a solid connection on the speedometer needle. You need to check the actual distance traveled, against what the odometer says, to get the pinion right. Then the speedometer needs to be adjusted by a speedometer shop to get the speedometer to read right. Quote Link to comment
Ron1200 Posted January 23, 2014 Author Report Share Posted January 23, 2014 The speedometer and the odometer are different, even though they are both in the same instrument. The odometer has a solid mechanical geared connection to the rear wheels, the speedometer uses a magnet, in an aluminium cup, to move a needle against a spring. There is not a solid connection on the speedometer needle. You need to check the actual distance traveled, against what the odometer says, to get the pinion right. Then the speedometer needs to be adjusted by a speedometer shop to get the speedometer to read right. Thanks for the insight Daniel. My pinion gear is stripped so no working odometer. If the key that retains the speedometer sleeve assy is at the top like this... Then the '79 810 has an 18 tooth assembly that should work... THIS... 32703-78102..... 18 tooth pinion gear FITS INTO THIS...32707-R5600..... pinion sleeve assy Yup that's my tranny. Thanks Mike that's exactly what I was looking for. Quote Link to comment
Ron1200 Posted January 23, 2014 Author Report Share Posted January 23, 2014 Just an update... Dealer had the Pinion in stock. Sleeve is in Mass. It should be here in 7 to 10 days. Quote Link to comment
Ron1200 Posted February 9, 2014 Author Report Share Posted February 9, 2014 Installed new blue pinion & new sleeve. Had to swap the roll pin from the old sleeve as the new one didn't have one. Works great!... At 30 mph speedo is spot-on, at 60 mph indicated is actually doing 59 MPH... GPS verified. Thanks Mike x2... 1) for the part numbers and 2) have a drain pan handy to catch the gear oil draining out once the sleeve was removed. :) Quote Link to comment
datzenmike Posted February 9, 2014 Report Share Posted February 9, 2014 Damn, sorry forgot about that. I should have remembered this happened when I pulled mine out. That oil comes out fast. Quote Link to comment
Ron1200 Posted February 9, 2014 Author Report Share Posted February 9, 2014 No.. were good... I got that info via an other post you made. It was only mentioned in one thread I read on the forum... and I read many :)... I'm glad you mentioned it in that post... truly. :) Quote Link to comment
datzenmike Posted February 10, 2014 Report Share Posted February 10, 2014 Yeah I installed the 5 speed empty, then put the speedo sleeve in and filled it. Later I needed to change the gear to correct the speedo and took it out... sploosh. Quote Link to comment
Ed-datsun521 Posted February 11, 2014 Report Share Posted February 11, 2014 This wouldn't happend on a 521 4 speed would it think it's kind of high up on the side I need to change Mine also Quote Link to comment
datzenmike Posted February 11, 2014 Report Share Posted February 11, 2014 You probably have an over size tire on the truck. Find a mile marker on the freeway and mark down your odometer reading. Drive 10 miles and record the difference, it won't be very much so be as accurate as you can. Very roughly each tooth change is about 5% or 2 1/2 MPH at 50 MPH Quote Link to comment
MicroMachinery Posted March 23, 2014 Report Share Posted March 23, 2014 I'm experiencing a similar issue. At 60, the speedo reads 80. At 30, the speedo reads 40. Seems like it reads 33% higher than it actually is.. pretty sure it's the later style ZX 5spd, because the 5th gear is really tall. It's with a 3.70:1 rear end, I believe..(whatever was in the 69' 510 4spd). Would this be correctable by installing the pinion from the 4spd into the 5spd?.. or am I missing something.. Quote Link to comment
ggzilla Posted March 23, 2014 Report Share Posted March 23, 2014 What it needs is a 5-speed pinion which has more teeth than what's already in there. For example if you have 16-tooth gear now, fit a 21-gear tooth So start by finding out which gear is in there now. Quote Link to comment
datzenmike Posted March 24, 2014 Report Share Posted March 24, 2014 Each tooth change is about 5.5% change. Keep in mind 5% is only 2 1/2 MPH at 50 16 to 17 is 6.25% 17 to 18 is 5.8% 18 to 19 is 5.5% 19 to 20 is 5.2% 20 to 21 is 5% 16 to 21 is 31% but if you are already at 19 there are no 25 tooth pinions. All you can do is change to a 3.545 or 3.364 diff to make it right. Maybe. Quote Link to comment
ggzilla Posted March 24, 2014 Report Share Posted March 24, 2014 ,There are several options, including larger diameter tires and speedometer cable ratio changers. Quote Link to comment
MicroMachinery Posted March 24, 2014 Report Share Posted March 24, 2014 Right on, figured the answer was that. Just didn't know exactly how much each tooth added percentage wise. Thanks, you guys are awesome. Quote Link to comment
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