4.88 Final Drive review / Spencer Fabrications

[Z06ZN6]

Originally Posted by 86TOYO2k17

Since it was bumped, might as well add my experience.

Disclaimer: This is for general all purpose fun spirited driving (if you are tracking/autox specific then deciding on an FD has a specific method to align gear/rpm with the track and specific usage to get the most benefit from it, but i wont go into further detail in this post)

2017 AT
When i was NA full bolt ons, custom tune, full drag reduction, 100+lbs weight loss, etc... Switching from 4.1 to 4.56 was up there with ace header / custom tune in terms of performance and acceleration feel. header/tune and then FD swap in that order is what i would do for NA. Highly recommended for NA. Personally i wouldn't go more aggressive though, if i was MT i would probably do 4.44.

Then i went FI probably at around 285whp/220ftlbs. and 4.56 was just too short now. Traction in 1st was an issue, 4th (1-1 gear same as MT 5th gear) topped out around 114mph which came up way too quickly, always wishing for a little more gear. If i was cruising at 75mph+ (common cruising speed since FI) and floored it, it would either only shift to 4th because it was too close to topping out 3rd (83mph) it wouldn't bother shifting to it, or i would shift it to 3rd but then about 1/2second later it would top 3rd and shift to 4th, so the start of my pull was either wasting time shifting back and forth or trying to pull in 4th at lower rpm. NA wasn't a big deal since it pulled slower the time between downshift/upshift was longer and i usually cruised around 70mph instead of 75mph. (that low end torque makes your foot heavy...)

Then i swapped back to 4.1 and went from a 225 tire to 255 tire at the same time which solved my 1st gear traction problem (still couldn't launch at all though) and i liked the higher MPH per gear but not the slower acceleration feeling despite the power pulling to almost 130mph in 4th now (with 255 tire) felt kind of slow. so Finally settled on a 4.3FD. Can still hit 120mph in 4th (1-1 gear), 3rd gear with the 255 tire shifts at about 89mph so i am not just double shifting or bogging down at start of pull. and the 5% more mechanical torque to wheels made acceleration that much better. 40/60-120mph pulls are awesome now. Seems perfect for 250-300whp range on an AT.
I would probably stick to 4.1 with MT at 260whp-300whp range, maybe 220-260whp a 4.3 would be great. Below 220WHP a 4.44FD. would pair well. Again all for general purpose fun spirited driving.

Agreed on the 4.30 being an excellent all around gear for an AT in a street/highway environment. I went straight to the drop in 4.30MT diff after the Edelbrock SC (340rw) for several reasons and would not want any more or less gear.

1. OEM direct swap, reliability and quiet with OEM like behaviours.
2. I tend to drive a bit slower for normal driving so mainly I wanted the extra bit of RPM to bring the engine completely out of the "bog" range. This helps the pick up in the upper gears which is now instant, (and brutal with the e85 SC...and my other car has a 600hp LS7 just for reference), even in 6th gear it absolutely moves the moment you press the accel and the power takes over from there. When I had the 4.10s still, I would have about 150rpm to "climb out of" first.
3. Great bang for buck. Cost a few hundred off ebay for a low mileage unit, plus new seals, axle clips and oil and a couple hours of my time.

The AT really doesn't need a whole lot more rear gear with enough power and HP but even around the mid-300 level, a small gear increase can overall improve the driveability of the car in everyday situations without any compromises. Of course, every user will have different needs but the 4.30 is perfect for me too.

[norcalpb]

I was debating between 4.3, 4.56 and 4.88 on my 2013 6mt. I’m glad I only went 4.3, because the cars rpms would be absolutely screaming on the freeway if it was even higher.

[DarkPira7e]

Part of me really wants to have absolutely savage gearing with about 350WHP and a lot of grip. I wish someone could put in some 4.5 or 4.88 gears and tear through them just to show how dumb it'd be. I know it'd be next to useless...but I'm still curious.
I'm very much contemplating a swap to 4.3 from the 4.1. I don't care about highway RPM, I have a beater for groceries and trips to Home Depot

[Dr. BRZ]

I have an 2018 MT and I have ace headers/overpipe, tuned, giken lsd with 4.88 gears. I love the gears, the car is so peppy. When you give it throttle, you can feel the car just wants to go more and more. I am pleased with the gears and I can say, at 4.88 it can be a daily. Just depends where you want your speed/rpms.

[nextcar]

Originally Posted by norcalpb

I was debating between 4.3, 4.56 and 4.88 on my 2013 6mt. I’m glad I only went 4.3, because the cars rpms would be absolutely screaming on the freeway if it was even higher.

I run 4.56 on a 2013 MT. At 80MPH I am at 4K RPM... does not bother me in the least and I often think I should have gone 4.88. If you are driving 65MPH, it is about 3200-3300 RPM.

Opinions differ, but not exactly screaming... it is only about a 11% RPM increase over stock.

And BTW - Although a bit of a hassle to import, my 4.56 gears are Toyota OEM from a Crown!

[86TOYO2k17]

Originally Posted by Dr. BRZ

I have an 2018 MT and I have ace headers/overpipe, tuned, giken lsd with 4.88 gears. I love the gears, the car is so peppy. When you give it throttle, you can feel the car just wants to go more and more. I am pleased with the gears and I can say, at 4.88 it can be a daily. Just depends where you want your speed/rpms.

You swapped again from your 4.56 to 4.88?

[86TOYO2k17]

Originally Posted by nextcar

I run 4.56 on a 2013 MT. At 80MPH I am at 4K RPM... does not bother me in the least and I often think I should have gone 4.88. If you are driving 65MPH, it is about 3200-3300 RPM.

Opinions differ, but not exactly screaming... it is only about a 11% RPM increase over stock.

And BTW - Although a bit of a hassle to import, my 4.56 gears are Toyota OEM from a Crown!

4.88 will be 19% higher RPM vs 4.1 at same speed/gear.
4.88 will be 19% lower max MPH per gear vs 4.1.
100mph before is 81mph now in the same gear at same rpm.
5th gear (1-1 gear) will hit about 103mph. 6th gear is way too long to accelerate in. you'd need a 5.1 to have any amount of mechanical torque to accelerate at any reasonable rate in 6th gear.
Very track/autox specific. Terrible for HWY pulls, good for city driving and city acceleration if your into speeding around town.

4.56 is a good FD for NA, still hit about 113mph in 5th. Not bad for 40/60-110mph hwy pulls.

[NoHaveMSG]

Originally Posted by norcalpb

I was debating between 4.3, 4.56 and 4.88 on my 2013 6mt. I’m glad I only went 4.3, because the cars rpms would be absolutely screaming on the freeway if it was even higher.

Same here. I was looking at a 4.44 and 4.56 setups. Glad I went 4.3 and I was able to get the complete diff from a 2018 car for 580 with shipping. Most of the tracks I have been to it is pretty spot on, I would be in between gears in a lot of places with the other two options. That is the only reason I went away from 4.1 to begin with.

[nextcar]

Originally Posted by NoHaveMSG

Same here. I was looking at a 4.44 and 4.56 setups. Glad I went 4.3 and I was able to get the complete diff from a 2018 car for 580 with shipping. Most of the tracks I have been to it is pretty spot on, I would be in between gears in a lot of places with the other two options. That is the only reason I went away from 4.1 to begin with.

At the time I did the swap, the factory 4.3 option was not available or I might have gone that way as a cheaper OEM (read quiet) gear option... I spent $480 on new OEM gears, $250 on a complete 4.1 differential from a salvage yard (20K miles on it!), about $150 on seals, bearings, gear oil, etc. to take my time doing the setup and then do a quick complete diff swap.

If you are serious about racing, you need to worry about matching the track...

For a daily driver, within the last 10 posts there have been members saying they are happy with 4.3, 4.56, and 4.88 swaps...

my point is you hear a lot of hyperbole about "screaming revs on the highway" when 4.56 gears are only an 11% difference from 4.1 stock, and if you are comparing to 4.3 are only a 6% difference. It just is not that big of a deal on the street.

To this day my 4.56 gears bring a smile to my face in 3rd gear on an empty cloverleaf onramp... but I always want a little more acceleration - hence my wondering about 4.88s!

[NoHaveMSG]

Originally Posted by nextcar

At the time I did the swap, the factory 4.3 option was not available or I might have gone that way as a cheaper OEM (read quiet) gear option... I spent $480 on new OEM gears, $250 on a complete 4.1 differential from a salvage yard (20K miles on it!), about $150 on seals, bearings, gear oil, etc. to take my time doing the setup and then do a quick complete diff swap.

If you are serious about racing, you need to worry about matching the track...

For a daily driver, within the last 10 posts there have been members saying they are happy with 4.3, 4.56, and 4.88 swaps...

my point is you hear a lot of hyperbole about "screaming revs on the highway" when 4.56 gears are only an 11% difference from 4.1 stock, and if you are comparing to 4.3 are only a 6% difference. It just is not that big of a deal on the street.

To this day my 4.56 gears bring a smile to my face in 3rd gear on an empty cloverleaf onramp... but I always want a little more acceleration - hence my wondering about 4.88s!

The only reason I quoted who I did is because they also went with 4.3, the whole screaming revs on the highway I could give a shit less about. If 4.88 was the "solution" then that is what I would have went with. For me 4.3 works for 95% of what I want it to. I only needed to shift the revs a few hundred RPM to get it to where it was good enough.

[Dr. BRZ]

Originally Posted by 86TOYO2k17

You swapped again from your 4.56 to 4.88?

I still have the 4.56 gears.
Long story short. I totaled out my 2013 brz but I took off the 4.56 and added the stock 4.1 back on.
Then I purchased a 2018 brz ts with 4.88 gears installed and i have the 4.3 diff with it too lol.

[86TOYO2k17]

Originally Posted by nextcar

For a daily driver, within the last 10 posts there have been members saying they are happy with 4.3, 4.56, and 4.88 swaps...

my point is you hear a lot of hyperbole about "screaming revs on the highway" when 4.56 gears are only an 11% difference from 4.1 stock, and if you are comparing to 4.3 are only a 6% difference. It just is not that big of a deal on the street.

In the last 2 pages I don’t see any mention about cruising rpm (besides 1 member saying the opposite of your “hyperbole” statement and actually praising and appreciating the higher rpm when cruising.

Otherwise you are the only one that mentions cruising rpm in regards to FD. Don’t think many people care about 6-11% more cruising rpm which translates to about 2-300 rpm. Hence the lack of any mentioning of it.

The concern is in regards to top speed by gear, what speed 5th gear or 1-1 gear tops out at as acceleration in 6th is useless. And on track/autox having to go to 5th instead of 4th or 4th instead of 3rd and then losing any mechanical advantage the swap had and actually being slower now because of it.

[nextcar]

Originally Posted by 86TOYO2k17

In the last 2 pages I don’t see any mention about cruising rpm (besides 1 member saying the opposite of your “hyperbole” statement and actually praising and appreciating the higher rpm when cruising.

Then you didn't read too well. My initial post #47 was mainly to counter the post #44 by norcalpb, which stated:

"I was debating between 4.3, 4.56 and 4.88 on my 2013 6mt. I’m glad I only went 4.3, because the cars rpms would be absolutely screaming on the freeway if it was even higher."

I object to the assertion that FD greater than 4.3 "would be absolutely screaming on the freeway". The difference is, as I pointed out, just not that big.

[norcalpb]

Originally Posted by nextcar

I run 4.56 on a 2013 MT. At 80MPH I am at 4K RPM... does not bother me in the least and I often think I should have gone 4.88. If you are driving 65MPH, it is about 3200-3300 RPM.

Opinions differ, but not exactly screaming... it is only about a 11% RPM increase over stock.

And BTW - Although a bit of a hassle to import, my 4.56 gears are Toyota OEM from a Crown!

I’m not saying the difference between 4.3 and 4.56 is “screaming vs not screaming”, I’m saying even with the 4.3 diff the RPMs @ 80mph are very high. Going from 4.1 to 4.3, I personally wouldn’t want the RPMs to be any higher than they currently are driving 80+mph down the highway.

I never said this is something that would bother everybody else lol I speak for no one but myself.