My BRZ is Alive!! Upgraded Final Drive

[mrk1]

Originally Posted by stevesnj

So where did you get the gears? cost, install pricing....thanks for any info!

I got the gears from MFactory, $750.
Install kit with solid pinion spacer from Weir Performance $380.

I did the labor myself so that saves me money there as its not a quick job, setting up the backlash, pinion height and preload. There are a bunch of shims you need to set the back lash, this is really what makes this not a drive way install. I bought one of every size, not cheap. There are only 2 of these shims in the diff when its done but I had to try a few to get the back lash just right. If you have a shop do the gear set up they would have to have these shims.

[linkmaster_13]

Where's the like button lol


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[Carlitoz3]

Originally Posted by linkmaster_13

Where's the like button lol


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No likes just thanks 😋

[ck-GT86]

Originally Posted by mrk1

I got the gears from MFactory, $750.
Install kit with solid pinion spacer from Weir Performance $380.

I did the labor myself so that saves me money there as its not a quick job, setting up the backlash, pinion height and preload. There are a bunch of shims you need to set the back lash, this is really what makes this not a drive way install. I bought one of every size, not cheap. There are only 2 of these shims in the diff when its done but I had to try a few to get the back lash just right. If you have a shop do the gear set up they would have to have these shims.

Damnit why do you have to be so far away? Ever considered moving to Cali?

++kudos for the mod!

.ck

[Ultramaroon]

Originally Posted by linkmaster_13

Where's the like button lol


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You'll see it after 10 posts.

[Bobblehead]

Originally Posted by Carlitoz3

What are the drawbacks?

Higher RPM at cruising speed and engine/exhaust noise, possibly lower MPG, and possible warranty issues.

[misooscar]

Intrigued...how would this feel on a vortech superchargered model?

[Captain Snooze]

Originally Posted by churchx

Smaller tires .. good 'tune' for this particular car, as in addition to lower weight/rotational mass [1], some say that it's suspension was developed with 16" in eyes, some even prefer resulting handling with smaller rim size [2]. And some say that it even looks better with meatier tires. Daily drivability/comfort may increase. And of course one will save $$ on tires (which are eaten rather quickly, when drifting). About the only caveat for going 16" - most bigger brake kits won't fit.

1/ As I mentioned above fitting 16" wheels is not a guarantee that you are going to end up with a lighter wheel.

2/ The difference in static diameter is approximately 2mm. I do not know what the difference is on rolling diameter but I am suggesting it is not the panacea that some people claim.

Originally Posted by stevesnj

I am going with 16" wheels eventually to bring the final drive down to the true ratio.

True ratio? What is that?
17" 45 profile vs 16" 50 profile: When speedometer reads 60mph (96.6km/h) actual speed will be 59.8mph (96.3km/h): 0.3% slower on the 16". Once again this is static diameter.
Negligible difference in ratios.

I am hypothesing that given the increase in sidewall height a 16" tyre has more angular momentum than a 17" tyre.

[stevesnj]

Originally Posted by Bobblehead

Higher RPM at cruising speed and engine/exhaust noise, possibly lower MPG, and possible warranty issues.

Not that dramatic a change in RPM but there is enough to notice. Warranty should not be affected at all. Would like to know for sure though.

[mrk1]

Originally Posted by misooscar

Intrigued...how would this feel on a vortech superchargered model?

Any Centrifugal SC car would love a higher final drive. More RPM more power with a centrifugal SC so a higher FD will keep you in those higher more powerful rpms

[Kostamojen]

Originally Posted by Captain Snooze

17" 45 profile vs 16" 50 profile: When speedometer reads 60mph (96.6km/h) actual speed will be 59.8mph (96.3km/h): 0.3% slower on the 16". Once again this is static diameter.
Negligible difference in ratios.

Try a 225/45/16 tire with those calculations. Thats what im running.

[Captain Snooze]

Originally Posted by Kostamojen

Try a 225/45/16 tire with those calculations. Thats what im running.

My apologies.
That is not something I have considered given how few choices TireRack offers in that size.
I do not doubt there are savings to be made with that size.

[churchx]

Originally Posted by Captain Snooze

1/ As I mentioned above fitting 16" wheels is not a guarantee that you are going to end up with a lighter wheel. ...

Guarantee? Certainly not. But on average similar rim and tire models more often then not turns out lighter. Of course there are exceptions to rule (for example available mostly only in 15" size, rarely in 16" max, very strong rally grade rims - mostly heavier then even some heavy 18-19" rims) and of course one can always artificially choose worse/heavier ones of smaller size and compare with ones on lighter scale part of bigger size.
But how about other bits? Like to some preferable handling changes, daily driving comfort, tire cheapness (imho should matter a lot in this car, as going sideways eats through rubber quickly), wider choice for that size? In my eyes pros/cons of 16" outweigh those for 17", except maybe for BBK fitments bit.

[churchx]

BTW, that speedometer reading .. does it matter much at all, if even on oem 17" rims & oem prius tyres (and at air pressure as per manual) i saw difference of almost 8-10% vs what i saw on gps? As in 65kmh on speedo, 59 @gps. Yes, with different final drive difference will grow, but if there wasn't any precision to begin with, and main thing - real drive-ability/performance will increase no matter what is displayed on speedometer. And vice versa, putting bigger diameter wheels on car to get speedometer report right numbers will decrease performance of it except maybe top speed, almost no one almost never needs.
P.S.
Great pitty that those rally grade rims are mostly available as 14-15" (those that are 16" look somewhat interim between them and average rims, with much longer spokes/smaller center dish, +usually are for 4x100 nut pattern, except maybe this) almost never as 17" and even greater pitty - that they are THAT heavy. Design-looks wise i prefer them to most other designs (#1, #2, #3). They simply look much meaner then thin spoke "normal" lightweight rims. I know that weight is there for strengthening/rigidity at heavy abuse .. but if there were of such design && lightweight (i'm willing to sacrifice extra durability), i'd jump on purchase right away.