Is my gearing messed up? (1JZ W58 Low Speeds, High RPMS! - 5speed SC owners plz come)
06-06-13, 01:22 PM
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Is my gearing messed up? (1JZ W58 Low Speeds, High RPMS! - 5speed SC owners plz come)
Hey all.
SC300, 1JZ W58.
Would of added this to my previous thread, but felt that it was overloaded with questions and that this needed it's own thread since I'm sure it could help a lot of people when searching for this individually since I can't find anything on it.
Even since I had my 2JZ swap in my car, I've always had a strange issue. I haven't given it much thought until now though. On highway speeds for example, my car will be doing about 80-85MPH at 6k RPM range in FIFTH GEAR! This is completely unnaceptable, the top speed on this car is horrible. I don't know where to look into this or how to find out if perhaps my differential was swapped out or has been tampered with.
I just wanted to know from your experience, what could I swap out or experiment with to change my gearing to something more reasonable? This high rpm with low speeds is pretty killer when you think of it in terms of gas mileage as well. The short little speed boosts are fun but I never feel like I can really squeeze out power, everything has very short gears. I miss how my old 240's sr20 would be able to hit 70mph in third gear at redline.
Any thoughts on this?
SC300, 1JZ W58.
Would of added this to my previous thread, but felt that it was overloaded with questions and that this needed it's own thread since I'm sure it could help a lot of people when searching for this individually since I can't find anything on it.
Even since I had my 2JZ swap in my car, I've always had a strange issue. I haven't given it much thought until now though. On highway speeds for example, my car will be doing about 80-85MPH at 6k RPM range in FIFTH GEAR! This is completely unnaceptable, the top speed on this car is horrible. I don't know where to look into this or how to find out if perhaps my differential was swapped out or has been tampered with.
I just wanted to know from your experience, what could I swap out or experiment with to change my gearing to something more reasonable? This high rpm with low speeds is pretty killer when you think of it in terms of gas mileage as well. The short little speed boosts are fun but I never feel like I can really squeeze out power, everything has very short gears. I miss how my old 240's sr20 would be able to hit 70mph in third gear at redline.
Any thoughts on this?
06-06-13, 01:30 PM
#2
Was your car an original automatic? If so you still have the original 4.27 rear end. I just swapped my 4.27 out to an 3.92 rear since my MPG sucked.
Look for an 4.10 5speed diff or an 3.92 rear. These are open diffs to after you do a little more research you'll learn about the LSD rear ends.
There should be a bunch of threads on here just search
Look for an 4.10 5speed diff or an 3.92 rear. These are open diffs to after you do a little more research you'll learn about the LSD rear ends.
There should be a bunch of threads on here just search
06-06-13, 02:04 PM
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Was your car an original automatic? If so you still have the original 4.27 rear end. I just swapped my 4.27 out to an 3.92 rear since my MPG sucked.
Look for an 4.10 5speed diff or an 3.92 rear. These are open diffs to after you do a little more research you'll learn about the LSD rear ends.
There should be a bunch of threads on here just search
Look for an 4.10 5speed diff or an 3.92 rear. These are open diffs to after you do a little more research you'll learn about the LSD rear ends.
There should be a bunch of threads on here just search
And thanks for the info I'll do another search again with this info, maybe I wasn't using the right terms to find what I needed! But still, please chime in if you have any info!
06-06-13, 02:09 PM
#4
It isn't a could be the cause, that is 100% the cause. your final ratio is the ratio of the gear you are in X the rear end ratio.
so you have changed to a manual, you need to change the diff to get your ratio back to where its supposed to be.
There are alot of near plug and play options for the SC, from some cars it involves just swapping out the front flange on the diffs before installing.
I have a stock w58/rear end and In the ballpark of 80 I think its close to 4k hard to remember, but if you like to drive a little faster I would suggest going even lower than the stock 5 spd diff as I feel the n/a setup is just a little too close ratio for a turbo motor.
so you have changed to a manual, you need to change the diff to get your ratio back to where its supposed to be.
There are alot of near plug and play options for the SC, from some cars it involves just swapping out the front flange on the diffs before installing.
I have a stock w58/rear end and In the ballpark of 80 I think its close to 4k hard to remember, but if you like to drive a little faster I would suggest going even lower than the stock 5 spd diff as I feel the n/a setup is just a little too close ratio for a turbo motor.
Last edited by Ali SC3; 06-06-13 at 02:16 PM.
06-06-13, 02:15 PM
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It isn't a could be the cause, that is 100% the cause. your final ratio is the ratio of the gear you are in X the rear end ratio.
so you have changed to a manual, you need to change the diff to get your ratio back to where its supposed to be.
I have a stock w58/rear end and In the ballpark of 80 I think its between 3 and 4k, but if you like to drive a little faster I would suggest going even lower than the stock 5 spd diff as I feel the n/a setup is just a little too close ratio for a turbo motor.
so you have changed to a manual, you need to change the diff to get your ratio back to where its supposed to be.
I have a stock w58/rear end and In the ballpark of 80 I think its between 3 and 4k, but if you like to drive a little faster I would suggest going even lower than the stock 5 spd diff as I feel the n/a setup is just a little too close ratio for a turbo motor.
)-and note, I didn't change my car to manual. it came like that but I know for a fact that it wasn't an original 5speed so more than likely they kept the same diff.
06-06-13, 03:22 PM
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What do you recommend instead of the stock 5speed diff then Ali? (You've always been so insightful in my previous threads )
-and note, I didn't change my car to manual. it came like that but I know for a fact that it wasn't an original 5speed so more than likely they kept the same diff.
)-and note, I didn't change my car to manual. it came like that but I know for a fact that it wasn't an original 5speed so more than likely they kept the same diff.
06-06-13, 03:29 PM
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Also to the OP a diff change (gear change) even to a 3.13 TT 6 spd Supra diff is not going to remove 2000 + rpms your tach is off.
Last edited by blk&blu*j; 06-06-13 at 03:34 PM. Reason: spell
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06-06-13, 07:08 PM
#8
I think you are right about the cluster if they didn't swap it out it takes into account the original rate with the trans and the diff, you should verify it with a gps speed if you have one. its prob that and also has the original diff not everyone swaps it out maybe once you fix that it will be a little better.
also the r154 had a little different 5th gear ratio but not a huge difference.
also the r154 had a little different 5th gear ratio but not a huge difference.
06-06-13, 07:34 PM
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crap... you guys are awesome. I really appreciate your input, you have no idea how much. I'll give you a call tomorrow blk, since it's sort of late and I don't wanna bug ya My shop told me one time that my tach is off but I never believed him. lol. But would this account only for acceleration and not idle? Basically my idles are accurate but my acceleration isn't up to match is what you guys are saying?
Ali, I'd like to add that I have a 5speed cluster, not the auto.
My shop told me one time that my tach is off but I never believed him. lol. But would this account only for acceleration and not idle? Basically my idles are accurate but my acceleration isn't up to match is what you guys are saying?I think you are right about the cluster if they didn't swap it out it takes into account the original rate with the trans and the diff, you should verify it with a gps speed if you have one. its prob that and also has the original diff not everyone swaps it out maybe once you fix that it will be a little better.
also the r154 had a little different 5th gear ratio but not a huge difference.
also the r154 had a little different 5th gear ratio but not a huge difference.
Last edited by Bleak; 06-06-13 at 07:41 PM.
06-06-13, 07:53 PM
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Guys I think you all are missing the point the engine has nothing to do with the rpms showing 6000 nor does the trans not in this issue,. again my sons W-58 in a mk3 Supra with 4.30 lsd diff
is doing 3700-3900 at 80 in 5 gear. on a 16inch wheel.
My Supra with 3.26 TRD lsd 6spd (jdm = 3.26 ratio) at 80 in 6th I'm doing about 3400-3500 rpms
Supra 6 Speed V160 ratio's
First: 3.827:1
Second: 2.360:1
Third: 1.685:1
Forth: 1.312:1
Fifth: 1.00:1
Sixth: 0.793:1
R154 ratio's
First 3.25:1,
Second 1.95:1,
Third 1.31:1,
Forth 1:1
Fifth 0.75:1
W-58
First 3.28:1,
Second 1.89:1,
Third 1.27:1,
Forth 1:1
Fifth 0.78:1.
Hope this helps
is doing 3700-3900 at 80 in 5 gear. on a 16inch wheel.
My Supra with 3.26 TRD lsd 6spd (jdm = 3.26 ratio) at 80 in 6th I'm doing about 3400-3500 rpms
Supra 6 Speed V160 ratio's
First: 3.827:1
Second: 2.360:1
Third: 1.685:1
Forth: 1.312:1
Fifth: 1.00:1
Sixth: 0.793:1
R154 ratio's
First 3.25:1,
Second 1.95:1,
Third 1.31:1,
Forth 1:1
Fifth 0.75:1
W-58
First 3.28:1,
Second 1.89:1,
Third 1.27:1,
Forth 1:1
Fifth 0.78:1.
Hope this helps
06-06-13, 08:07 PM
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I'll do a speed test tomorrow morning on my way to work with a phone gps app I just downloaded. I will post the results when I get to the office! Thanks! (And good night! Gotta wake up early! )
)
06-06-13, 08:19 PM
#12
your rpm's will read the same with an auto or manual sc300 cluster, that signal is from ignitor/ecu.
your rpm's will be higher at a given speed with the auto diff than if you have a manual diff, which is why at certain speeds you feel like the engine is revved too high.
to add to that problem above, you also have the issue that the speedo could be reading off because it assumes the stock ratio. if you had an auto cluster you would have the wrong trans and throw it off. with the 5 spd cluster you still have the wrong diff that throws it off.
So you are seeing a higher than usual rpm's at a speed directly duw to your diff, and that speed on your cluster that you are looking at could be slower than you are actually going... or faster I don't really feel like figuring that out you should try and test it with a gps app or something.
your rpm's will be higher at a given speed with the auto diff than if you have a manual diff, which is why at certain speeds you feel like the engine is revved too high.
to add to that problem above, you also have the issue that the speedo could be reading off because it assumes the stock ratio. if you had an auto cluster you would have the wrong trans and throw it off. with the 5 spd cluster you still have the wrong diff that throws it off.
So you are seeing a higher than usual rpm's at a speed directly duw to your diff, and that speed on your cluster that you are looking at could be slower than you are actually going... or faster I don't really feel like figuring that out you should try and test it with a gps app or something.
06-06-13, 08:28 PM
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He is not doing 6000 rpms even at 100 mph his TACH CLUSTER IS WRONG!!!!
If somebody removed the needle and tried to reinstall this could be a problem among many other issues but the answer is the same!!!!!!!!!!
If somebody removed the needle and tried to reinstall this could be a problem among many other issues but the answer is the same!!!!!!!!!!
06-06-13, 09:42 PM
#14
As the guys above have mentioned: cluster inaccuracy and a 4.27 auto rear end cause what you're describing.
I have a 5-speed W58 car with a 4.27 rear diff (I changed out my stock 4.08) running 255/40R-17 rear tires and a YellowBox correcting the minor inaccuracy the 4.27 gave me over stock.
Even with that gearing, in 5th you should be turning about 3,000rpm @ 70mph and about 3,500rpm @ 80mph. 85-90mph should be around 4,000rpm or very slightly above but NOT 6,000rpm. Ali SC3 is right. Try using a GPS to verify your actual speed and those should be the numbers you're actually getting.
As for what's optimum, 4.08 or 3.92 should be good for a 1JZ. 4.08 was the standard ratio for manual Soarers. 4.272 is a bit too aggressive for turbo. As Ali SC3 mentioned, the W58 has a 0.783:1 fifth gear while the R154 has a 0.753:1 fifth.
I have a 5-speed W58 car with a 4.27 rear diff (I changed out my stock 4.08) running 255/40R-17 rear tires and a YellowBox correcting the minor inaccuracy the 4.27 gave me over stock.
Even with that gearing, in 5th you should be turning about 3,000rpm @ 70mph and about 3,500rpm @ 80mph. 85-90mph should be around 4,000rpm or very slightly above but NOT 6,000rpm. Ali SC3 is right. Try using a GPS to verify your actual speed and those should be the numbers you're actually getting.
As for what's optimum, 4.08 or 3.92 should be good for a 1JZ. 4.08 was the standard ratio for manual Soarers. 4.272 is a bit too aggressive for turbo. As Ali SC3 mentioned, the W58 has a 0.783:1 fifth gear while the R154 has a 0.753:1 fifth.
Last edited by KahnBB6; 06-06-13 at 10:03 PM.
06-07-13, 06:21 AM
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So I did the speed test today using a GPS.... 
It all matched up. My tach is accurate as can be. It must be the differential at this point. Is there a way to tell if I actually have an auto diff and not a 5speed diff? Differences in appearance or anything?
In 5th gear at ~4.5k rpms I was 70MPH.
In 5th gear at ~5.2k rpms I was 80MPH.
This sucks. lol
It all matched up. My tach is accurate as can be. It must be the differential at this point. Is there a way to tell if I actually have an auto diff and not a 5speed diff? Differences in appearance or anything?In 5th gear at ~4.5k rpms I was 70MPH.
In 5th gear at ~5.2k rpms I was 80MPH.
This sucks. lol
Last edited by Bleak; 06-07-13 at 08:41 AM.