Pros/Cons of Changing from a 3.26 to 3.113 LSD Ratio
07-06-07, 09:58 AM
#1
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Pros/Cons of Changing from a 3.26 to 3.113 LSD Ratio
Thinking about "lowering" my ratio a little bit from a open 3.26 to Supra 3.113 limited slip diff.
I know that the car will be a little slower off the line, albeit not much. But that can actually help reduce traction loss and increase line times.
What I am unsure about is how this will affect highway speeds and acceleration on a roll.
What pros and cons am I looking at?
This is much cheaper than going with a TRD LSD, even though it will be a 1.5 way diff. Supra 98 turbo LSD should bolt into our pumpkin w/o a problem.
Suggestions?
I know that the car will be a little slower off the line, albeit not much. But that can actually help reduce traction loss and increase line times.
What I am unsure about is how this will affect highway speeds and acceleration on a roll.
What pros and cons am I looking at?
This is much cheaper than going with a TRD LSD, even though it will be a 1.5 way diff. Supra 98 turbo LSD should bolt into our pumpkin w/o a problem.
Suggestions?
07-06-07, 10:35 AM
#2
Your top speed in each gear will increase, your off the line performance will decrease slightly. In fact, all around acceleration will be reduced since the ratio stays the same throughout the RPM range.
The only thing you'll be increasing will be gas mileage (assuming you are cruising and not doing heavy stop and go traffic.)
The only thing you'll be increasing will be gas mileage (assuming you are cruising and not doing heavy stop and go traffic.)
07-06-07, 10:52 AM
#3
I feel that the difference between a 3.26 and a 3.113 is negligable. The main difference is you are getting an LSD now along with its benefits. I feel that acceleration/top speed/gas mileage will not be as noticable as you might think. For example, I recently went from 3.26 to 3.73 gearing and my RPMs are roughly 300rpms higher at any given speed; and that's by moving up about .50 in terms of gearing! Your only going down about .15 so if the calculations stay constant you should only be at "maybe" 100rpm lower at any given speed. You will save on gas but maybe 1mpg; if that. All in all it sounds like a great mod because you will get the new benefit of an LSD. GL!
07-06-07, 10:55 AM
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Your top speed in each gear will increase, your off the line performance will decrease slightly. In fact, all around acceleration will be reduced since the ratio stays the same throughout the RPM range.
The only thing you'll be increasing will be gas mileage (assuming you are cruising and not doing heavy stop and go traffic.)
The only thing you'll be increasing will be gas mileage (assuming you are cruising and not doing heavy stop and go traffic.)
Too bad the LS400 3.6X diff wont bolton
07-06-07, 11:20 AM
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Tough cookie to swallow.
I am still considering it though.... Thanks.
The question is if a TRD LSD (stock) gearing is worth the extra $700 in price.....
07-06-07, 12:07 PM
#6
Rock-a-lex, your RPM will not be 300rpm higher at any speed. the gear ratio is just that, a ratio. Its a corellation between the input drive shaft and the output driveshaft. At idle, you're not 300rpm over what you normally are you? 
If you want to go faster, get the 3.76 LSD diff. I think the TRD is worth it, if you're going FI and not wanting to increase fuel consumption. Your turns will be better though since you have LSD. but the problem is labor. Its very expensive and the not exactly easy to install. You'll end up paying the same amount as buying a brand new supra differential.
If you want to go faster, get the 3.76 LSD diff. I think the TRD is worth it, if you're going FI and not wanting to increase fuel consumption. Your turns will be better though since you have LSD. but the problem is labor. Its very expensive and the not exactly easy to install. You'll end up paying the same amount as buying a brand new supra differential.
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07-06-07, 12:22 PM
#8
GSteg,
I am now always at a higher RPM now that I have changed from the stock 3.26 to 3.73 gearing at all speeds. For example, at 80mph with my stock rear I was around 2700rpm. Now, with my new 3.76 Supra LSD I am at around 3000rpm at that same speed. The same goes for other speeds that I have done this test with. I am burning more fuel than I was before "at any given speed" all the time no matter what gear I am in. In Lex*Toy's example it will be the opposite effect of mine but his will not be as noticable; hence, 3.26 vs. 3.11.
I am now always at a higher RPM now that I have changed from the stock 3.26 to 3.73 gearing at all speeds. For example, at 80mph with my stock rear I was around 2700rpm. Now, with my new 3.76 Supra LSD I am at around 3000rpm at that same speed. The same goes for other speeds that I have done this test with. I am burning more fuel than I was before "at any given speed" all the time no matter what gear I am in. In Lex*Toy's example it will be the opposite effect of mine but his will not be as noticable; hence, 3.26 vs. 3.11.
Last edited by Rock-a-Lex; 07-06-07 at 12:26 PM.
07-06-07, 12:58 PM
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Could the 3.62 R&P from the 95-97' LS400 could be installed with the TRD LSD unit in the stock GS400 pumpkin? I'm wondering if the issue is just the difference in the LS & GS pumpkins mounting points. If I were to go with LSD I would atleast reuse the stock 3.26 R&P.
07-07-07, 05:21 AM
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Looks like this thread got better attention than this one: https://www.clublexus.com/forums/sho...d.php?t=263418
According to a link in above thread, the Supra would be 3.133.
I have attached a spreadsheet showing rpms for each of the 3 gearsets mentioned above in all gears.
According to a link in above thread, the Supra would be 3.133.
I have attached a spreadsheet showing rpms for each of the 3 gearsets mentioned above in all gears.
07-07-07, 12:42 PM
#13
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Something else occurs. At certain speeds you will have BETTER gearing than stock or 3.77 ratio.
The 3.77 upshifts from 1st to 2nd at 38mph but the stock 3.27 gearing holds first until 44 and the 3.13 until 46mph. So stock cars will have better gearing from 38 to 44mph and 3.13 will be superior from 44 to 46mph.
This occurs at each gear change and grows.
3.77 1-2 = 38 2-3 = 59 3-4 = 90 4-5 = 128
3.27 1-2 = 44 2-3 = 68 3-4 = 104 4-5 = 148
3.13 1-2 = 46 2-3 = 71 3-4 = 108 4-5 = 154
So, the 3.77 car will shift to 4th at 90mph but the 3.13 car will be in 3rd until 108mph. In a 90-110 pull the 3.13 will have much better gearing.
Same in 2nd with the 3.77 car changing to 3rd at 59 but the 3.13 geared car staying in 2nd until 71. From 59 to 71 the 3.13 pulls harder.
Furthermore. When changing to 3.77 gears (3.769) the top speed drops from the limited 149mph to 130 or so. It is possible that the reverse is true and the 3.13 gears will raise the speed limiter to maybe 155mph
Obviously the 3.13 car will run away from the 3.77 car from 130 up
The 3.77 upshifts from 1st to 2nd at 38mph but the stock 3.27 gearing holds first until 44 and the 3.13 until 46mph. So stock cars will have better gearing from 38 to 44mph and 3.13 will be superior from 44 to 46mph.
This occurs at each gear change and grows.
3.77 1-2 = 38 2-3 = 59 3-4 = 90 4-5 = 128
3.27 1-2 = 44 2-3 = 68 3-4 = 104 4-5 = 148
3.13 1-2 = 46 2-3 = 71 3-4 = 108 4-5 = 154
So, the 3.77 car will shift to 4th at 90mph but the 3.13 car will be in 3rd until 108mph. In a 90-110 pull the 3.13 will have much better gearing.
Same in 2nd with the 3.77 car changing to 3rd at 59 but the 3.13 geared car staying in 2nd until 71. From 59 to 71 the 3.13 pulls harder.
Furthermore. When changing to 3.77 gears (3.769) the top speed drops from the limited 149mph to 130 or so. It is possible that the reverse is true and the 3.13 gears will raise the speed limiter to maybe 155mph
Obviously the 3.13 car will run away from the 3.77 car from 130 up
Last edited by JBrady; 07-08-07 at 08:20 AM.
07-07-07, 08:41 PM
#14
Thinking about "lowering" my ratio a little bit from a open 3.26 to Supra 3.113 limited slip diff.
I know that the car will be a little slower off the line, albeit not much. But that can actually help reduce traction loss and increase line times.
What I am unsure about is how this will affect highway speeds and acceleration on a roll.
What pros and cons am I looking at?
This is much cheaper than going with a TRD LSD, even though it will be a 1.5 way diff. Supra 98 turbo LSD should bolt into our pumpkin w/o a problem.
Suggestions?
I know that the car will be a little slower off the line, albeit not much. But that can actually help reduce traction loss and increase line times.
What I am unsure about is how this will affect highway speeds and acceleration on a roll.
What pros and cons am I looking at?
This is much cheaper than going with a TRD LSD, even though it will be a 1.5 way diff. Supra 98 turbo LSD should bolt into our pumpkin w/o a problem.
Suggestions?