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General Forums => The Mess Hall => Topic started by: Jeffy on May 09, 2011, 11:41:43 AM
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Well, I'm on the look out for a 39T gear. I can't believe how much these things have jumped in price. When I bought my 35T and 37T, they were around $15-18 at the Dealership. Now they're $118. You can find them online for around $39 but I think that's still a hell of a lot. Especially since they're imported from Taiwan. Anyone have one they want to trade or sell outright? It need to be a 4.5" long shaft and not the 2.5" short shaft the TJ's use. The part number is #52068061.
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Good luck finding one, the 39 and 40 tooth gears are pretty hard to come by.
The 50 dollar converter box might be a better bet in the long run
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Good luck finding one, the 39 and 40 tooth gears are pretty hard to come by.
The 50 dollar converter box might be a better bet in the long run
I've seen a few places with them for $39. There is another company, PPR, that makes them. I think it's the actual company that makes them or else imports them from Taiwan.
Here's the part number for the 39T - PPR-3091-0639L
The cheapest electronic option is Dakota Digital.
http://www.dakotadigital.com/index.cfm/page/ptype=product/product_id=126/category_id=287/home_id=59/mode=prod/prd126.htm
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I know how much the are, 2 gear changes or tire changes and the dakota unit paid for it self
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I'm just surprised the price jumped $100. I'll probably just get the right gear. I don't see myself getting it regeared or changing tires anytime soon... maybe.
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I still have to correct the wiring on my Dakota Digital unit....I did notice that at some point they did update them so that once it is wired in you simply hit "up" or "down" to correct the speed...I just need to wire into my new sensor and too lazy to crawl under there and do it.
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I still have to correct the wiring on my Dakota Digital unit....I did notice that at some point they did update them so that once it is wired in you simply hit "up" or "down" to correct the speed...I just need to wire into my new sensor and too lazy to crawl under there and do it.
you can always do it in the engine bay where the wires join the main wiring harness (not sure where that is on your TJ but if I were to do it that would be my choice rather than going with another set of wires all the way to the sensor).
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I've got a whole bunch of speedo gears, but the closest I have to what you need is a 36t or a 41t.
Have you checked with www.tacomaspeedometer.com ?
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I've got a whole bunch of speedo gears, but the closest I have to what you need is a 36t or a 41t.
Have you checked with www.tacomaspeedometer.com ?
Sent them an email. I have a 35T, 37T and a 41T. Currently I have the 41T installed and it's about 4-5MPH off at 65 mph. I'm pretty sure the 37T was about the same.
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Sent them an email. I have a 35T, 37T and a 41T. Currently I have the 41T installed and it's about 4-5MPH off at 65 mph. I'm pretty sure the 37T was about the same.
1/41.....65mph
1/37.....72mph
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1/41.....65mph
1/37.....72mph
So you're saying it should be correct with the 41T?
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It means that with the 37 it would only be off by 2 or 3.
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So you're saying it should be correct with the 41T?
i'm saying that if now it shows 65mph with 41T at the same speed with 37T will be showing 72mph (neale got it right).
if you meant that at 65mph real speed and with 41T the speedo displays 60mph then with 37T at the same real speed would display 66.5mph
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I had both in there and both were off but on the other side of correct.
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I had both in there and both were off but on the other side of correct.
not saying it's correct, just gave you the impulse equivalent speeds based on what you provided. Not sure what the stock size tires you had initially on your jeep but if i take 28'' as stock and 33 what you have now at 65mph real speed (and displayed with 28'' stock tires) with 33'' tires would display 55mph (with stock gears) - you however have 4.56 gear ration compared to 4.10 so that would make the speedo display 61.3mph (so that is about 4mph lower than real speed and consistent to what you are reporting) - at this point swapping the 41T with the 37T would make the speedo display 68mph
so according to my math in your configuration at 65mph real speed with 41T = 61mph, 37T=68mph (-4/+3) - that is based on 28'' stock tires and 4:10 stock gears (if different then the numbers will be different) - seems to be in the same ballpark to what you were seeing before, 37T is a little bit closer to reality but still off and not much of a difference
Also, different speeds result in different mph offset, percentage based would be the accurate way to measure it (same at any speed).
Sounds like the dakota digital would be the best option if you plan to play around with the tires in the future, one time payment and call it a day
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I'm just using the gut feeling calculator since I've done this a few times. :lol: About 4mph off with either pinion gear at 65mph is about right. So that should mean 39T would get me within 1mph or better. I don't really feel like wiring another box under the hood when I can just swap a gear in 1-2 minutes. My stock tires were 205.75R15's not the 215.75R15's. 205's were the stock tires and most 2.5's had them with the option for 215's. Over the years people probably end up with 215's eventually as that's the base tire for the 4.0L's. The optional tire was the 225.75R15's.
Funny thing about these gears is that they are the same ones that are used in cars going back into the 60's.
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in that case
205/75R15 = 27''
at 65mph with 33'' tires and stock 4.10 gears, 41T speedo gear = 53.2mph :yikes:
at 65mph 33'' tires with 4.56 ratio
> 41T = 59.14 mph
> 37T = 65.54 mph :blbl:
doesn't get any better than that i would think
unless the tire size is 28'' and not 27'' (which is more on the lines with your calculations).
and just for the record
at 65mph 33'' tires and 4.88 ratio and stock speedo gear (considering the stock tires 27'') = 63.3 mph speedo reading
EDIT: if the stock tires are 28'' then the same setup would display 65.64mph on the speedo.
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Nope, 37T was off by almost the same amount as the 41T I have in there now. I ran the 37T with my 35's and was pretty much 'on'.
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Nope, 37T was off by almost the same amount as the 41T I have in there now. I ran the 37T with my 35's and was pretty much 'on'.
for 35s vs 27 stock
true speed / tire / R&P ratio / speedo gear / indicated speed
65mph / 27'' / 4.10:1 / 41T / 65.0 mph
65mph / 35'' / 4.10:1 / 41T / 50.1 mph
65mph / 35'' / 4.56:1 / 41T / 55.8 mph
65mph / 35 / 4.56:1 / 37T / 61.8 mph
35 vs 28 stock
65mph / 28'' / 4.10:1 / 41T / 65.0 mph
65mph / 35'' / 4.10:1 / 41T / 52.0 mph
65mph / 35'' / 4.56:1 / 41T / 57.8 mph
65mph / 35 / 4.56:1 / 37T / 64.1 mph
so it's either the stock tires were not 27, the stock speedo gear is not 41 (i have no idea), the speedo calibration was off from factory (maybe they did not have different gears for the 205s and 215s), or the 35s were maybe 34 real diameter (would come to 64mph indicated speed in that case) - so not sure
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got to remember a lot of tires come up short on reported size. When I went shopping for speedo gears in early 97 I paid 15 bucks at the dealer. The last one I bought for my other Jeep was 30 bucks. So truthfully to get it accurate and be flexible the wizbang box is the way to go.
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:lol: I'll go with the gut feeling. Math is good but experience says I need a 39T. Hard to believe the Dealers are charging $90-120 for the gears now.
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39 tooth for $40
http://www.jeep4x4center.com/jeep-speedometer-gears/
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I run the Dakota Digital unit, but kinda had to since I installed the SS SYE with the Rubi speedo pickup, no more speedo gear.
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39 tooth for $40
http://www.jeep4x4center.com/jeep-speedometer-gears/
Yeah, I've seen them on ebay for about the same. I talked to PATC - http://www.transmissioncenter.net/speedometer_calibration_______va.htm
For completeness, here are some electronic signal modifiers/calibrators on the market. The Dakota, while the cheapest is the most complicated since covers a wider range of vehicles. Feel free to post links to others out there as I'm sure there are more.
Superlift Tru Speed - http://www.superlift.com/accessories/truspeed.asp
Jet Accuspeed - http://www.jetchip.com/JET_Transmissions.asp
Dakota Digital's SG-5 - http://www.dakotadigital.com/index.cfm/page/ptype=product/product_id=126/mode=prod/prd126.htm
Healtech Electonics SpeedoHealer - http://www.bluemonkeymotorsports.com/products_ht_apps.html
Yellow Box - http://www.yellr.com/
TS Performance ReSpeed - http://www.thoroughbreddiesel.com/ts-performance/respeed.htm
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I run the Dakota Digital unit, but kinda had to since I installed the SS SYE with the Rubi speedo pickup, no more speedo gear.
X2
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Took the Jeep on the highway again and was able to check the speedo against the GPS. At about 40mph it's off by 2mph. When I get to 65 it's off by 4 mph. Each tooth is supposed to be worth 2-3 mph at 65 mph, IIRC.
Haven't decided on what I'll actually do just yet.
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Took the Jeep on the highway again and was able to check the speedo against the GPS. At about 40mph it's off by 2mph. When I get to 65 it's off by 4 mph. Each tooth is supposed to be worth 2-3 mph at 65 mph, IIRC.
Haven't decided on what I'll actually do just yet.
just leave it as it is, not worth it - mine was off by about 10mph at 65 so you're in much better shape than i was with only 3mph (i don't think it's worth the effort to be honest).
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just leave it as it is, not worth it - mine was off by about 10mph at 65 so you're in much better shape than i was with only 3mph (i don't think it's worth the effort to be honest).
I kinda got used to having an accurate speedo after a decade of it being off.
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I kinda got used to having an accurate speedo after a decade of it being off.
well, if you're at 65 and your speedo shows exactly 61 and you currently have 41 tooth gear in order to bring it to precisely 65 you need 38.47 teeth so obviously you'll need to take your pick between 39 or 38 (not sure if the latter is available). this is unrelated to the tire size since you already have the values and you'll be using the same tires but mind you for 33s will vary a bit based on the tire pressure as well, so if you have the pressure lower you'll see more speed indicated.
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well, if you're at 65 and your speedo shows exactly 61 and you currently have 41 tooth gear in order to bring it to precisely 65 you need 38.47 teeth so obviously you'll need to take your pick between 39 or 38 (not sure if the latter is available). this is unrelated to the tire size since you already have the values and you'll be using the same tires but mind you for 33s will vary a bit based on the tire pressure as well, so if you have the pressure lower you'll see more speed indicated.
Choosing the correct gear is never exact. There are too many variations with tire size, pressure, wheel size, vehicle weight, etc... I found many of the charts out there to be inaccurate. Some are closer then others though but it's really a gut feeling sort of thing. I've done enough of then to know what I need though.
If I had known there would be a rise in the price I would have bought a set of them. Or at least 35-41 as that's what I'm usually swapping to for one reason or another. Although, if someone was going to do this for the first time I'd probably recommend one of the electronic pulse modifiers.
On another note supposedly, 1993 was a change from the 4.5" speedometer gear to the 2.5" gear. I don't think there is any difference in the transfer case. It looks like you can take the VSS a part and swap the upper for one that will take a shorter gear. The only problem with that would be having to swap the plug on the transfer case harness. Seems doable though. Probably won't even have to cut the plug off but just take the plug apart and swap the pins.
And if the 4.5" gear supply dries up you can take a heat gun and remove the gear off a 2.5" shaft.
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Choosing the correct gear is never exact.
since you know the real speed, indicated speed and the current tooth count it is an exact figure as long as you keep the same tire pressure and weight of course.
On another note supposedly, 1993 was a change from the 4.5" speedometer gear to the 2.5" gear. I don't think there is any difference in the transfer case. It looks like you can take the VSS a part and swap the upper for one that will take a shorter gear. The only problem with that would be having to swap the plug on the transfer case harness. Seems doable though. Probably won't even have to cut the plug off but just take the plug apart and swap the pins.
And if the 4.5" gear supply dries up you can take a heat gun and remove the gear off a 2.5" shaft.
i don't think the connector is different, i have both styles, i can have a look and let you know if you want. There's no difference in the t-case mounting, as a matter of fact the 95 YJ fit in the CJ D300 (did that and no problem as long as you clock it properly)
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since you know the real speed, indicated speed and the current tooth count it is an exact figure as long as you keep the same tire pressure and weight of course.
i don't think the connector is different, i have both styles, i can have a look and let you know if you want. There's no difference in the t-case mounting, as a matter of fact the 95 YJ fit in the CJ D300 (did that and no problem as long as you clock it properly)
The TJ plug looks to be a bit different though.
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The TJ plug looks to be a bit different though.
maybe TJ is different, i was talking about 95YJ vs earlier style electronic senders -the early ones were a signal gen adapter that was screwing in where the speedo cable used to go, the one i had on the Jeep was 1 piece. seemed to me that the connector was the same but didn't look close enough to see if they are keyed differently or not.
EDIT:
this is the earlier style, don't have pics of the one that was on my np231, i swapped the one in the pics below with the one that was on the Jeep as it is shorter so never had a chance to check if the connectors are the same (the green gear is the one that was in the D300 - disregard it).
(http://i57.photobucket.com/albums/g222/sharpxmen/Drivetrain_Upgrades/Test_Fit_D300_NV3550/Speedo_1.jpg)
(http://i57.photobucket.com/albums/g222/sharpxmen/Drivetrain_Upgrades/Test_Fit_D300_NV3550/Speedo_2.jpg)
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The connector looks to be different.
(http://www.stu-offroad.com/engine/speedo/speed1.jpg)
(http://www.dailydriventj.com/images/speedo/12.jpg)
Also found that AA sells the speedometer pinion gear for the cheapest at $43.05 shipped.
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The connector looks to be different.
it's the same just doesn't have the guide for the clip, should fit.
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Ended up buying a 39T speedometer gear from AA. Should be here by the end of the week if not sooner.
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Got the new gear and installed it. Now the speedo is pretty much dead on!
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Glad to hear it is fixed. I'll be going through this soon (also with 4.56 and 33s and stock speedometer gear).