Final Drive Discussion

[Hawk77FT]

Originally Posted by mrk1

MFactory just sells the ring and pinion, Ive never seen whats in the box with Cusco but wouldnt be surprised if its the same

Cusco would sell some clips, new pinion nut, new bolts. It is basically the same kit that Toyota sells (in a Cusco box). I got mine for half the price Cusco sells it.
Still waiting for some other parts atm but it will be a while

[Hawk77FT]

Ok, here it is...Almost ready to be sealed and installed!

[Mild2Wild]

Perhaps we could also include a comparison of final drives in this thread; more specifically, how the longer final drives compare. I am very interested in lowering mine to either the 3.73 or 3.91, but am finding it almost impossible to locate one of the 3.73s short of ordering new from a dealer (yes, I've been in contact with shops who specialize in this). The 3.91 is very easy to obtain, but with 500whp on tap, I'm unsure it will make enough of a difference. For example, the stock car tops out 3rd at 83mph, the 3.91 at 91, the 3.73 at 96; fourth is maxed at 104 on the stock FD, 116 with 3.91, and 121 with the 3.73. Of course, the numbers are only numbers, and without having experienced either of the other final drives, I would appreciate some advice. The increased effort required during in-town cruising and accelerating from a stoplight is one thing to think about, too... Can anyone help me?

[Wayno]

You know it comes with 6 gears, not 4, right?

Originally Posted by Mild2Wild

Perhaps we could also include a comparison of final drives in this thread; more specifically, how the longer final drives compare. I am very interested in lowering mine to either the 3.73 or 3.91, but am finding it almost impossible to locate one of the 3.73s short of ordering new from a dealer (yes, I've been in contact with shops who specialize in this). The 3.91 is very easy to obtain, but with 500whp on tap, I'm unsure it will make enough of a difference. For example, the stock car tops out 3rd at 83mph, the 3.91 at 91, the 3.73 at 96; fourth is maxed at 104 on the stock FD, 116 with 3.91, and 121 with the 3.73. Of course, the numbers are only numbers, and without having experienced either of the other final drives, I would appreciate some advice. The increased effort required during in-town cruising and accelerating from a stoplight is one thing to think about, too... Can anyone help me?

[Mild2Wild]

Originally Posted by Wayno

You know it comes with 6 gears, not 4, right?

......

Third is over in the blink of an eye, and fourth doesn't last too much longer. The extra time in gear would really be helpful and often mean that trying to shift quickly into 5th is not necessary. Your response makes it seem like you have no first hand experience with what I'm describing. Considering most other cars of similar power have something longer than a 4.10, your quip reeks of ignorance.

[BRZoomTX]

Originally Posted by Mild2Wild

......

Third is over in the blink of an eye, and fourth doesn't last too much longer. The extra time in gear would really be helpful and often mean that trying to shift quickly into 5th is not necessary. Your response makes it seem like you have no first hand experience with what I'm describing. Considering most other cars of similar power have something longer than a 4.10, your quip reeks of ignorance.

Go with 3.73's. 3.90's won't be worth it enough. With 3.73's and stock tire height, my 4th gear tops out at over 120. Forgot the exact number, depends on how high I'd rev it up.

No issues at all putting around town with 3.73's. I run a m85 LSD diff on my car like many others. Direct bolt on replacement, find one to use out of an is300.

Reference below. 3.73 rear, stock tire height, 15psi was about ~370whp for me on a dynojet.

[ame="https://www.youtube.com/watch?v=LpatSEF0aH0"]3rd to 4th / 15psi - YouTube[/ame]

[Mild2Wild]

[QUOTE=BRZoomTX;2626797]Go with 3.73's. 3.90's won't be worth it enough. With 3.73's and stock tire height, my 4th gear tops out at over 120. Forgot the exact number, depends on how high I'd rev it up.

No issues at all putting around town with 3.73's. I run a m85 LSD diff on my car like many others. Direct bolt on replacement, find one to use out of an is300.

Reference below. 3.73 rear, stock tire height, 15psi was about ~370whp for me on a dynojet.


Damn that video was a pretty great demonstration of exactly what I wanted to see--thanks a lot; I hadn't been able to find anything on youtube. It's been problematic to locate even an m85: only one is on eBay, but it's from Quebec and looks a bit sketchy. The video solidifies 3.73 as a much better choice though it seems.

[BRZoomTX]

Originally Posted by Mild2Wild

Damn that video was a pretty great demonstration of exactly what I wanted to see--thanks a lot; I hadn't been able to find anything on youtube. It's been problematic to locate even an m85: only one is on eBay, but it's from Quebec and looks a bit sketchy. The video solidifies 3.73 as a much better choice though it seems.

No problem. I actually took that video specifically for rear end reference as I also had problems finding videos of a longer rear ratio. You can calculate the numbers, but its not the same as seeing the longer gears on the tach. I have other videos on my Instagram, linked in my sig.

I'll tweak the title and description so others can find it more easily.

[Riftur]

How much does it usually cost to install it. Also is it a complicated process for someone who has never done it and would only have jacks to work with and not a lift?

[Mild2Wild]

Originally Posted by BRZoomTX

No problem. I actually took that video specifically for rear end reference as I also had problems finding videos of a longer rear ratio. You can calculate the numbers, but its not the same as seeing the longer gears on the tach. I have other videos on my Instagram, linked in my sig.

I'll tweak the title and description so others can find it more easily.

I should try and link a copy of spreadsheets of both options with speeds calculated all the way from 0 to 9000rpm in 250rpm increments.

I'm having to settle for now...couldn't locate a 3.73, but then saw that a complete IS300 3.91 pumpkin popped up on eBay and jumped at the chance to even try it out since it was a good price. I'll still be on the lookout for the former, though.

[KoolBRZ]

Originally Posted by Mild2Wild

I should try and link a copy of spreadsheets of both options with speeds calculated all the way from 0 to 9000rpm in 250rpm increments.

I'm having to settle for now...couldn't locate a 3.73, but then saw that a complete IS300 3.91 pumpkin popped up on eBay and jumped at the chance to even try it out since it was a good price. I'll still be on the lookout for the former, though.

Weir performance has used ratios down to 3.58 for our differentials. Call Spence at his shop, http://weirperformance.com/contactus.html. Don't email, call. Ask about the used FD ratios 3.73, and even 3.58 for Toyota Supra's 1986.5-92. Those are the ones that fit our FD's. Are you going to use the stock drive line?

[Mild2Wild]

Originally Posted by KoolBRZ

Weir performance has used ratios down to 3.58 for our differentials. Call Spence at his shop, http://weirperformance.com/contactus.html. Don't email, call. Ask about the used FD ratios 3.73, and even 3.58 for Toyota Supra's 1986.5-92. Those are the ones that fit our FD's. Are you going to use the stock drive line?

Does anyone have any real info on if, and by how much, the IS300 differential is stronger than ours? I could pop the 3.91 pumpkin in and send out the stocker, but if there's a big disparity in strength that might not make sense.

It's all stock driveline--apart from the clutch--for now; I have replaced the left stock axle with a used OEM part after going to the strip for fun on my previous setup (430whp) and subsequently getting a little clicking from it, but I was almost 2" lower at that time and got some bad wheel hop on one run in particular. Crossing my fingers I am not forced to upgrade this year, as I'd rather wait and tackle that for next season. A friend has a 450whp ls1 240 that's been happy to rip donuts, burnouts, and go drifting on the stock driveline, so here's to hoping I will be so fortunate.

[BRZoomTX]

Originally Posted by Mild2Wild

Does anyone have any real info on if, and by how much, the IS300 differential is stronger than ours? I could pop the 3.91 pumpkin in and send out the stocker, but if there's a big disparity in strength that might not make sense.

It's all stock driveline--apart from the clutch--for now; I have replaced the left stock axle with a used OEM part after going to the strip for fun on my previous setup (430whp) and subsequently getting a little clicking from it, but I was almost 2" lower at that time and got some bad wheel hop on one run in particular. Crossing my fingers I am not forced to upgrade this year, as I'd rather wait and tackle that for next season. A friend has a 450whp ls1 240 that's been happy to rip donuts, burnouts, and go drifting on the stock driveline, so here's to hoping I will be so fortunate.

People claim to have ran low 10's on is300 forums with the stock LSD M85. There is a guy on here with a 2j swap who ran the m85 that grenaded on him around 500hp I believe. I ran mine at 470whp but didn't do any hard launches as that would be an immediate axle killer with my 285 Yokohamas.

If you're staying under 500whp the m85 will be plenty strong. Its when you go in to the 550-600+ range that they start to fail catastrophically on hard launches. If you roll in to it, they're pretty good.

[Mild2Wild]

Originally Posted by BRZoomTX

People claim to have ran low 10's on is300 forums with the stock LSD M85. There is a guy on here with a 2j swap who ran the m85 that grenaded on him around 500hp I believe. I ran mine at 470whp but didn't do any hard launches as that would be an immediate axle killer with my 285 Yokohamas.

If you're staying under 500whp the m85 will be plenty strong. Its when you go in to the 550-600+ range that they start to fail catastrophically on hard launches. If you roll in to it, they're pretty good.

I'm at 500 already, so there's only one way to go... But I don't use the car for hard launches. Spoke with Weir today and he didn't think the m85 was any stronger than the stock unit; he suggested that I find a 3.73 from the non-locking diff and send it all to him for a refurbish.