CUSCO 4.55 FINAL DRIVE installed. - Page 19 - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

Suzaku · 08-11-2013, 02:35 PM

Racecomp, quick question for ya.

I just got the Cusco 4.556 final drive installed on my car last week, and since then I've noticed quite a bit of thumping and popping sounds coming from the rear end; at its worst, it sounded like I left a couple of bowling balls rolling loose in my trunk. Usually at parking lot speeds, but on a few hard right turns it's been noticeably noisy too. Has yours been like this? Not sure if you're still running the stock limited-slip differential on your car or not, but that's what I've got on mine.

wootwoot · 08-11-2013, 02:57 PM

NOT normal. I have one installed and it doesn't do that.

troek · 08-11-2013, 10:42 PM

Maybe they accidentally installed a cusco limit slip

Opposed · 08-11-2013, 11:16 PM

Quote:

Originally Posted by Suzaku

Racecomp, quick question for ya.

I just got the Cusco 4.556 final drive installed on my car last week, and since then I've noticed quite a bit of thumping and popping sounds coming from the rear end; at its worst, it sounded like I left a couple of bowling balls rolling loose in my trunk. Usually at parking lot speeds, but on a few hard right turns it's been noticeably noisy too. Has yours been like this? Not sure if you're still running the stock limited-slip differential on your car or not, but that's what I've got on mine.

Sounds like it may not have been shimmed properly.

fooyc · 08-11-2013, 11:38 PM

the sound is like u have a straight cut gear?

Tye300 · 08-12-2013, 02:48 AM

Quote:

Originally Posted by Suzaku

Racecomp, quick question for ya.

I just got the Cusco 4.556 final drive installed on my car last week, and since then I've noticed quite a bit of thumping and popping sounds coming from the rear end; at its worst, it sounded like I left a couple of bowling balls rolling loose in my trunk. Usually at parking lot speeds, but on a few hard right turns it's been noticeably noisy too. Has yours been like this? Not sure if you're still running the stock limited-slip differential on your car or not, but that's what I've got on mine.

I think you have to get that checked.

37 · 08-12-2013, 10:32 AM

Definitely not normal. I now have an MFactory 4.67 in mine and the gears are silent. The Cusco 4.56 uses OEM MKIII Supra gears so it's not likely a manufacturing defect.

Racecomp Engineering · 08-17-2013, 11:17 PM

Yeah I get some of that at times under certain circumstances. I now have 6k on this set up I think...and its no issues.

Adding WL rear diff and cradle bushings makes it sound like a racecar when you put a sequential box in gear ! Yes at times you think you are in a very prepared car, but its normal to some degree DEPENDING on the bushings you have.

Stick a go pro back there and let me hear and I can confirm.

Myles

PantsDants · 08-26-2013, 12:31 AM

This thread inspired me to go with a shorter final drive ratio, which I'm now in the process of acquiring the parts for. Already have my IS300 carrier, just got to source the gears and then it's off to the diff shop.

One thing I've noticed is that people are concerned about running really high rpms on the highway after installing shorter gears. That may be true for the manual, but for those of us with automatics, swapping to a 4.556 final drive has you running right around 2500 rpm at ~70 mph. The reason for this is the AT (which is an Aisin A960E) has a really tall 6th gear (.582).

I got started researching this because I noticed that on the stock final gear, I run < 2000 rpm at 60 mph, so I realized the gearing between the MT and AT had to be different, if only for 6th gear.

Long story short, I may be looking at going to 4.88. 65 mph at 2500 rpm, I can live with that.

zoomzoomers · 08-26-2013, 12:39 AM

Quote:

Originally Posted by PantsDants

This thread inspired me to go with a shorter final drive ratio, which I'm now in the process of acquiring the parts for. Already have my IS300 carrier, just got to source the gears and then it's off to the diff shop.

One thing I've noticed is that people are concerned about running really high rpms on the highway after installing shorter gears. That may be true for the manual, but for those of us with automatics, swapping to a 4.556 final drive has you running right around 2500 rpm at ~70 mph. The reason for this is the AT (which is an Aisin A960E) has a really tall 6th gear (.582).

I got started researching this because I noticed that on the stock final gear, I run < 2000 rpm at 60 mph, so I realized the gearing between the MT and AT had to be different, if only for 6th gear.

Long story short, I may be looking at going to 4.88. 65 mph at 2500 rpm, I can live with that.

Keep us AT drivers updated with your results!

PantsDants · 08-26-2013, 12:53 AM

Quote:

Originally Posted by zoomzoomers

Keep us AT drivers updated with your results!

Will do, it'll probably be a few weeks before I have it all installed as I'm taking a road trip for Labor Day. I'll post a new thread with my results.

Racecomp Engineering · 11-04-2013, 10:43 PM

Quote:

Originally Posted by Grimlock

I'm starting to like this idea. A very good mod that would be stealthy.

Once I return from SEMA next week we start un modding my car. If you are interested in this we could maybe swap rear ends plus some. Just a thought. Doesn't get any easier than that.

if email me.

Myles

yoruck · 11-07-2013, 02:26 PM

hello , have some question who somes could answear
i have now Mfactory 4.67 FD in my car install.
but that whistle like straight cut gear, my mechanical say it s like his subaru rally with competion gear box he says not normal, is this need a break in time or not.
the back lash was set like the original one.
is it bad or not

fooyc · 11-07-2013, 10:17 PM

more or less is the factory cutting the gear tooth no match enough. that's why hv the sound. for track is ok but for street used they should try to cut the sound off.

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08-11-2013, 02:35 PM	#253
Suzaku Junior Member Join Date: May 2013 Drives: 2013 FR-S Location: Las Vegas, NV Posts: 1 Thanks: 0 Thanked 1 Time in 1 Post Mentioned: 0 Post(s) Tagged: 0 Thread(s)	Racecomp, quick question for ya. I just got the Cusco 4.556 final drive installed on my car last week, and since then I've noticed quite a bit of thumping and popping sounds coming from the rear end; at its worst, it sounded like I left a couple of bowling balls rolling loose in my trunk. Usually at parking lot speeds, but on a few hard right turns it's been noticeably noisy too. Has yours been like this? Not sure if you're still running the stock limited-slip differential on your car or not, but that's what I've got on mine.

08-11-2013, 02:57 PM	#254
wootwoot Senior Member Join Date: Jul 2012 Drives: FRS Location: Cali Posts: 1,558 Thanks: 188 Thanked 462 Times in 264 Posts Mentioned: 9 Post(s) Tagged: 0 Thread(s)	NOT normal. I have one installed and it doesn't do that.

08-11-2013, 11:38 PM	#257
fooyc Member Join Date: Jul 2013 Drives: GT86-JDM Location: MY Posts: 54 Thanks: 8 Thanked 9 Times in 7 Posts Mentioned: 0 Post(s) Tagged: 0 Thread(s)	the sound is like u have a straight cut gear?

08-12-2013, 10:32 AM	#259
37 degrees Join Date: Mar 2013 Drives: 6MT BRZ Location: Shifting Posts: 157 Thanks: 132 Thanked 141 Times in 72 Posts Mentioned: 10 Post(s) Tagged: 0 Thread(s)	Definitely not normal. I now have an MFactory 4.67 in mine and the gears are silent. The Cusco 4.56 uses OEM MKIII Supra gears so it's not likely a manufacturing defect.

08-17-2013, 11:17 PM	#260
Racecomp Engineering Join Date: Nov 2011 Drives: 2016 BRZ, 2012 Paris Di2 & 2018 STI Location: Severn, MD Posts: 5,520 Thanks: 3,542 Thanked 7,416 Times in 3,034 Posts Mentioned: 311 Post(s) Tagged: 9 Thread(s)	Yeah I get some of that at times under certain circumstances. I now have 6k on this set up I think...and its no issues. Adding WL rear diff and cradle bushings makes it sound like a racecar when you put a sequential box in gear ! Yes at times you think you are in a very prepared car, but its normal to some degree DEPENDING on the bushings you have. Stick a go pro back there and let me hear and I can confirm. Myles

08-26-2013, 12:31 AM	#261
PantsDants Senior Member Join Date: Jul 2013 Drives: Scion FR-S A/T, Whiteout Location: Seattle Posts: 334 Thanks: 57 Thanked 221 Times in 90 Posts Mentioned: 16 Post(s) Tagged: 2 Thread(s)	This thread inspired me to go with a shorter final drive ratio, which I'm now in the process of acquiring the parts for. Already have my IS300 carrier, just got to source the gears and then it's off to the diff shop. One thing I've noticed is that people are concerned about running really high rpms on the highway after installing shorter gears. That may be true for the manual, but for those of us with automatics, swapping to a 4.556 final drive has you running right around 2500 rpm at ~70 mph. The reason for this is the AT (which is an Aisin A960E) has a really tall 6th gear (.582). I got started researching this because I noticed that on the stock final gear, I run < 2000 rpm at 60 mph, so I realized the gearing between the MT and AT had to be different, if only for 6th gear. Long story short, I may be looking at going to 4.88. 65 mph at 2500 rpm, I can live with that.

11-07-2013, 02:26 PM	#265
yoruck Member Join Date: Jan 2012 Drives: ford fiesta st 150 Location: belgium Posts: 13 Thanks: 0 Thanked 1 Time in 1 Post Mentioned: 0 Post(s) Tagged: 0 Thread(s)	hello , have some question who somes could answear i have now Mfactory 4.67 FD in my car install. but that whistle like straight cut gear, my mechanical say it s like his subaru rally with competion gear box he says not normal, is this need a break in time or not. the back lash was set like the original one. is it bad or not

11-07-2013, 10:17 PM	#266
fooyc Member Join Date: Jul 2013 Drives: GT86-JDM Location: MY Posts: 54 Thanks: 8 Thanked 9 Times in 7 Posts Mentioned: 0 Post(s) Tagged: 0 Thread(s)	more or less is the factory cutting the gear tooth no match enough. that's why hv the sound. for track is ok but for street used they should try to cut the sound off.

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