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| Since the diff runs really hot at the track, we will use Motul 75/140 Competition synthetic gear oil, a bit on the thick side, but at high temps, it will be fine. |
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| For serious track use we are going to need a diff cooler. For now, we will limit our hot laps and hopefully the diff cover will help keep things cool enough. |
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| To make things easier we added the oil off the car. |
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| Our diff is ready to go, Buttonwillow here we come! |
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| For this track event we changed our wheel and tire setup from 18×9.5 front with a 275/35-18 and a 18×10.5 with a 295/35-18 in the rear to a 18×10.5 Enkei wheel all around with 285/35-18 Nitto NT05 tires all around. Going from staggered to square made the car a little more balanced. The NT05's had a little more grip than the Continentals we had to run for the Modified Magazine shootout. The bigger front tires makes our car look better too! |
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| Congratulations Brenda for taking the worst action pictures to ever grace our site! Out on the track our car was turning laps in the consistent low 2:02 range, 4 seconds a lap faster than it had gone previously. We feel that the diff contributed to more than half of the improvement by totally eliminating wheelspin on corner exit which was really bad at Buttonwillow. Not bad for a 100% street car with no aero and basically a stock engine. We did have to adjust our driving style as the locking of the diff into the corners made the car want to rotate under trail braking. We had to change to more of a brake in a straight line, then turn, driving style. The car also wanted to drift on corner exit a little more than we wanted to. As it is now, the diff would probably be perfect for an R-Compound tire , for a street tire we might need to deactivate one more set of clutches for optimal traction. We decided to leave it for now and focus on some suspension tuning as it looks like we need more adjustment than the Kinetix links we have will allow. We need stiffer suspension and more negative camber. |
Stay tuned, in the next installments of Project 370Z we will be focusing on getting more power and more grip out of Project 370Z. Our goal is to break into the sub 2 minute range at Buttonwillow with a total daily driver street car with no aero and no R-compound tires.
Sources
6 comments
Thank you for your really excellent explanation of how these components work.
One question: Gear type differentials (Torsen), appear to me to offer perfect distribution of power at all time. They are strong and require essentially no maintenance or replacement of parts.
What is the advantage of the Salisbury clutch type that you chose?
If the car was to be used exclusively on the street, would you have made the same choice?
They work better, torsens are really not that great.
Great write up, what lock rate was selected 60%, 80% or 100% for your build?
A youtube channel mentioned cusco recommended to leave it at 100% and only mess with the spring preload because with lower lock up rates the disc tend to run hotter. is this true?
Hey Mike – would you be able to do a detailed article on LSD tuning in all aspects?
1) Initial Breakaway torque
2) Ramp angles
3) Belleville thicknesses and spring rates
4) Different clutch plate treatments and surfaces
5) Different clutch plate materials (steel/carbon)
6) Tuning with different oils and additives
From the rabbit hole that i’ve gone down, it seems that most people only focus on the initial breakaway torque and that’s it. But having different spring rate bellevilles (cone washers) or stacking these washers also effect the LSD and how it behaves and reacts.
For example, the ATS carbon LSD needs ~250ftlb breakaway torque, but yet it doesn’t cause the wheels to skip/chatter in the parking lot. But a metal LSD with 80ftlb breakaway torque can skip/chatter with small steering input.
Something as simple as removing one of the belleville/cone washers and replacing it with a spacer and setting the same breakaway torque. How will that effect the LSD and driving?
Cheers, Mike
We did a few already, a couple of youtube video too. search is your friend.
We have several, use the search function. Videos too on youtube. We have never tuned an ATS diff before except for drifting and we didn’t like it and ended up going back to a spool.