Final Drive Comparisons

In the never ending quest to maximimize performance, one of the most overlooked parts are the final drive gears. Also referred to as the ring and pinion, this simple 2 gear system converts the mechanical torque output of the engine, and emits it to the wheels. The higher that ratio, the more the torque is multiplied – at the expense of top speed per gear. Picking the right ring and pinion is a function of many things, such as the torque curve of the engine, the rpm range of the engine, the wheel and tire combination, and the vehicle weight, and how those all operate within the confines of your intended useage. A car that has a very high specific torque may opt for a lower overall final drive ratio, to help put it’s power to the ground without uselessly spinning the wheels. Vehicles that have exceptionally high rev limits and make comparitively less torque than they do horsepower may opt for a higher overall final drive ratio, which helps overall acceleration and general engine responsiveness. It’s the never-ending balancing act.

In looking at what final drive is right for you, it’s often beneficial to examine what ratios other cars use. Will start this off by looking at the various final drive ratios of notoriously “quick/fast/powerful/desirable” Rear Wheel Drive Sports cars. If interested, we can expand this in future series to examine front wheel drive and AWD vehicles as well.

If any of the figures below are incorrect, please let me know!

996 series Porsche 911 GT3: 3.44:1 final drive, car weighs 2970 lbs, 8200 rpm redline, 355 crank hp, 284 ft/lbs
997 series Porsche 911 GT3RS 4.0: 3.89:1 final drive, car weighs 2998 lbs, 500 hp, 339 ft/lbs
Ferrari 360: 4.44:1 final drive, car weighs 3197 lbs, 8500 rpm redline, 400 hp, 275 ft/lbs
Ferrari 430 Scuderia: 4.30 final drive, car weighs 2976 lbs, 8640 rpm redline, 510 hp, 347 ft/lbs
Corvette C6 Z06 (2013 2LZ): 3.42 final drive, car weighs 3175 lbs, 7000 rpm redline, 505 hp, 470 ft/lbs
Laborghini Gallardo LP550-2 Balboni: 4.06 final drive, car weighs 3153 lbs, 8500 rpm redline, 550 hp, 397 ft/lbs
Viper GTS SRT Track Pack (2013): 3.55 final drive, car weighs 3374 lbs, 6250 rpm redline, 640 hp, 600 ft/lbs

Tp help you calculate how various options will affect your car, use the online gear calculator we posted. Click here for final drive calculator

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Adam’s Project Z33: Bringing up the Rear Part II

Got some new updates on my bastardized rear that we’ve discussed here last month.

The goals were simple – the execution, has proven anything but! Today I’ll show off some pics of the more of the guts that are needed to make this 4.3 ring and pinion work.

First, notice the picture of the Quaife LSD all dismantled Quaife Helical LSD

Quaife LSD for 350Z Exposed

The Quaife is a helical differential, which means it transmits power via a series of intermeshing gears.

This diff has never been used, but we wanted to make sure it was absolutely perfect. It has been sitting around though for a few months, unsealed, so we wanted to make sure it was free of any oxidation, etc. It’s been fully taken apart, cleaned, and prepped and is now ready to go back in.

Last time, we showed how the custom sleeves were done to allow the correct pinion bearings. The next hurdle to tackle was the actual pinion flange. The problem with the 4.3 final drive I got is the pinion diameter is smaller than the factory 350Z units – the length is correct, but the difference in diameter is why we had to sleeve the shaft in the first place. In order for the rear to work, it has to somehow bolt to the driveshaft. This is what the flange’s job is – it joins the driveshaft and pinion together so all that power can effectively turn the pinion, which turns the ring, which is bolted to the differential, and then output to the rear axles/wheels. What we ended up having made was a bit of a hybrid. It uses the splined carrier for the 4.3 ring gear, mated to a custom machined flange that matches the correct outer diameter of the original 350Z pinion flange.

Custom Machined Flange for 4.3 ring and pinion into 350Z

Stock on the right, new flange on the right. This will allow everything to work together in harmony, and bolt up without us having to modify the driveshaft in any way. Next thing to do is get it on the drill press and put the holes in to allow it to mate to the driveshaft, and then high speed balance it to make sure it is 100% true, so there are no unwanted vibrations.

Last things to do are press on the new bearings to the differential, and then microfinish and cryo the ring and pinion. More updates coming soon!