My speedo is abuot 8-9mph off reading too fast through entire range. 88 n/a is auto to manual swap by prev owner. 4.30 lsd W58. Could the W58 have come from a car with a different speedo gear than the supra, or one with a different GR in the rear. I have a new stock speedo gear ready to put in I ordered from toyota. That is assuming an 88 n/a man trans had 4.30lsd.
Speedo, gearing question
- Thread starter mikeoc1
- Start date
Manual and auto trans have different gears in the transmissions I believe. DM has an option for buying either manual or automatic speedometer cables:
http://store.driftmotion.com/static/i-spedometercableformk3supra.php
http://store.driftmotion.com/static/i-spedometercableformk3supra.php
I have the manual trans cable I was wondering about the speedo driven gear which is what the cable connects to on the tranny in the w58. Was wondering how likely my w58 came out of a car without 4.30lsd. Which I think would mean a different speedo driven gear.
there are 3 different diffs used in na cars with 3 different ratios, the lsd is pretty rare on na as they go. The cable itself dosent matter it spins at the speed the driven gear runs at. So you difference will be caused by the diff the trans or the cluster or a combination of the 3. Also if you have larger tires than stock that will affect it too.
metaphysico;1599262 said:
No, there is two differentials available. Open and LSD clutch pack are the only choices on a US model. And there is only one ratio for the n/a.
OK, so the instrument cluster CAN make a difference? I just put in a 5sp cluster two days ago and have not checked the speedo yet for accuracy. Didn't think the acutal speedo in the cluster would be different, I just swaped the cluster out so I wouldnt have to look at the ect stuff and the o/d off light blinking. Not sure where the w58 came from as it was a Prev Owner swap and PO never finished the smaller details of the swap. I have a stock speedo driven gear from an 88 n/a 5sp but didnt want to put it in if they were all the same.
The one question that anybody has failed to ask, is HOW do you know that your speedo is off in the first place? Tire size, differential ratio, transmission, and rpm in whatever gear you choose. Plug this info into here:
http://akb.norbie.net/Public/Gearing.aspx
Really easy gearing calculator to use, and should give you your actual speed. Take what this gives you and compare to what your speedo tells you you're going at XXXXrpm in X gear...
http://akb.norbie.net/Public/Gearing.aspx
Really easy gearing calculator to use, and should give you your actual speed. Take what this gives you and compare to what your speedo tells you you're going at XXXXrpm in X gear...
Actually depending on the year of the car there are 3 diffs for na an 86.5-88 had one the 89-92 had another both non lsd then the lsd that the later had. Unless the gearing is the same between the lsd and non lsd of the later years but I cant find the page I was on the other day to look up vin code. Anyways if the donor car was the same year as yours you can narrow it down some. Two of the codes are G284 and G285, dont know the third, but I know there is one, whether or not we got it here I am not sure.Nick M;1599272 said:
Found it hopefully this will help and clear things up some.
G284 = 4.30:1 4-pinion 8.0" pre-89 N/A Diff (no-LSD, USA Only)
G282 = 4.30:1 2-pinion 8.0" 89+ N/A Diff (no-LSD, USA Only)
G285 = 4.30:1 4-pinion 8.0" N/A Diff (with-LSD)
G315 = 3.91:1 4-pinion 8.0" pre-89 Turbo Diff (with-LSD)
G305 = 3.73:1 4-pinion 8.0" 89+ Turbo Diff (with-LSD)
G284 = 4.30:1 4-pinion 8.0" pre-89 N/A Diff (no-LSD, USA Only)
G282 = 4.30:1 2-pinion 8.0" 89+ N/A Diff (no-LSD, USA Only)
G285 = 4.30:1 4-pinion 8.0" N/A Diff (with-LSD)
G315 = 3.91:1 4-pinion 8.0" pre-89 Turbo Diff (with-LSD)
G305 = 3.73:1 4-pinion 8.0" 89+ Turbo Diff (with-LSD)
te72;1599574 said:
Being almost 10mph off I could tell I was reading too fast based on traffic around me. That led me to use a gps. I dont know how accurate gps are but using the same gps in my jeep my speedo pretty much matches the gps. So I know my supra is off. And after checking it with the gps today. The new cluster didnt make much of a difference. So I will use the calculator link above to confirm and will switch out the speedo driven gear. When I pull it and compare it with the new one I have I will know for sure. thanks.
I swapped my na(4.3 lsd) auto for an r154 and my speedo reads about 10mph faster too. I'm wondering how easy it is to swap the speedo gear with the transmission still in the car. I'm hoping there's an r154 speedo gear to match the read end.
mikeoc1;1600190 said:
I used to think that about my Mk2 until I realized that everybody else just drives their cars/trucks like assholes around here. I'd say the GPS is probably a bit more reliable than your 20 year old speedometer. Does your needle 'bounce' as well?