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Discussion Starter #1
I have a F283 (4.30) in my car and found a F293 (4.10) and T372 (3.757) in the junk yard today and am wondering if it's worth getting one of them.

Thanks for the help!

ps - is a junk yard diff really worth $150???
 

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i'm not sure, but I'd like to ask you a question about your 4.30, namely, how high are your rpms at highway speed?
 

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The differece between a 4.10 and a 4.30 is 5% give or take. So expect to be going 5% faster at any speed. You'll lose a fractional amount of snap off the line as well. If there is nothing really wrong with your 4.30s its not really significant enough to call it an upgrade. I would say $150 is a tad on the expensive side. It depends what type of yard it is. If it a full service new car type yard $150 is probably pretty cheap. If it is a U'pull'it type place its high. Pick'n'pull around here is $45 IIRC. Of course make sure it works at any price.
 

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Highway speeds / RPMs with my 4.30 differential:

90MPH @ 4k RPM (definite)
65MPH @ 3,400 RPM (memory - not exactly sure)

These are with a 5-speed manual trans.
 

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SilverMk2 said:
I would say $150 is a tad on the expensive side. It depends what type of yard it is. If it a full service new car type yard $150 is probably pretty cheap. If it is a U'pull'it type place its high. Pick'n'pull around here is $45 IIRC. Of course make sure it works at any price.
I would agree with that... 150 for the whole diff is expensive... down here is a fix price of 60 for the diff and it is a u wrench it place. with 100% money back gauranteed in 30 days....

If you are not into serious go fast performance like turbo... and just love with the almotor... go with the 4.10 so that the highway driving won't suck
 

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[email protected] - Can someone get me a better differential?

I have all of my parts together for the 7MGTE swap, except MHG & intercooler piping, and figure I can start in about 1 month. Is 3.73 best for turbo or should I go lower or higher? Would it be safe to reduce the size of the ring gear (like from 7.5 down to 6.5)?

I have the Lexus AFM and will use it and larger injectors down the road...
 

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go with the 3.727 set-up with or taller gears like 3.42 etc if you are really looking for gas mileage and you cannot cnage the ring gear size for it is imposible to... and it is not worth the trouble of modding the whole rear section for it
 

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Generally speaking you go to larger ring gear sizes for added strength. So going the opposite way really is contradictory to make the car better.
 

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According to the tranny/gear/rpm calculator I have, with the W58 and stock tires, these are the top end speeds of different rear ends:


4.30 (F-283)
130.6 mph @ 6000 rpm
152.3 mpy @ 7000 rpm

4.10 (F-293)
137.0 mph @ 6000 rpm
159.8 mph @ 7000 rpm

3.73 (F-303)
150.7 mph @ 6000 rpm
175.8 mph @ 7000 rpm

3.42 (F-383)
164.3 mph @ 6000 rpm
191.7 mph @ 7000 rpm


If anyone is interested in this program, email me and I'll send it along - it's got the specs for most Toyota tranny's and diff's, and you can enter custom tire sizes.
 

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Dudezxt,

90MPH @ 4k RPM (definite)
65MPH @ 3,400 RPM (memory - not exactly sure)

These are with a 5-speed manual trans.
The numbers from your 4.30 ratio are half correct.

90mph @ 4K rpms is indeed correct. I found it odd that 100mph @ 4,400 rpms, which is right at peak torque, rather interesting.

65mph, you should be right at 3K rpms. 3,400 rpms would be 75 mph.

On the 4.30 ratio (AND ASSUMING that you are still on the stock 225/60/14 tires), the general rule of thumb (in 5th gear), is that every 5mph, the tach should go up 200 rpm's.
 
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