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Driving Hard with a ATB Diff


260DET

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First run on a circuit with the R180 Torsen type LSD diff and CV jointed half shafts last Saturday. Quite different to the former R200 Nissan plate type LSD, get the back end out and hold it there :) Very predictable and smooth.

 

Thinking about some changes to the driving technique. With third gear sweeping corners, 120 to 180 degrees, an off power/on power blip seemed to work to get the front in tighter and drive out in a fairly straight drift.

 

Track time is fun, mostly, any tips or comments?

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  • 2 months later...

260DET, what fluid do you run in the Torsen? I have one in one of my non-Z cars (Maserati) and I'm changing the fluid. I'm planning on using Quaker State synthetic 75W-90 GL-5 which states it is formulated for LSD diffs as well as open diffs.

 

I read in the link you posted that the manufacturer of your Torsen recommends Penzoil 90 synthetic plus LSD additive. I had wondered if, based on the non-clutch operation of the Torsen, if an LSD additive/modifier would even be necessary or useful.

 

Any recommendations, and have you had temperature problems? I'm not going to spend the $850 for the large sump with pump available for my car (for street use), but it doesn't seem difficult to add a small oil cooler/reservoir plumbed into the drain plug hole as a passive system to disperse fluid heat. Thanks in advance, DAW.

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The diff place which installed the ATB and new bearings throughout suggested a 140 in our hotter climate. But after its done a bit more work it will probably be changed to a full synthetic 90 of some sort, particularly as a synthetic is more stable at higher temps. My Z does five lap sprints so gross overheating should not be a problem.

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Richard, I went with the 75W-90 synthetic and I put in half of a tube of LSD additive. I'll go to 140 if I autocross it next summer.

 

One thing that has me wonderring...I was under the car turning the crank to get the timing mark visible (yes, it's on the flywheel viewed through an opening in the bottom of the flywheel cover)...and there was a huge amount of motion of the driveshaft possible without any movement of the wheels. My first impression was that there was excessive backlash of the ring/pinion and I dreaded looking inside. When I pulled the cover and checked the lash it was reasonable (under 0.010"), but I noted the Torsen helical gears seemed to have a lot of up-and-down movement which allowed lash before the side gears moved and this is where the "slop" came from. The car drives fine and makes no noise from the diff. Maybe this is normal for a Torsen and I'll have to resaerch it further but I wondered if you have noted something similar? DAW

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The side gears need to drive the worm gears on their little axles until they hit the inside of the case. This is quite a bit of movement in a Quaife, and from the pictures and descriptions I've seen of the type II Torsen it should be more movement before the gears engage the case.

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Thanks, Jon. I'm relieved to hear that and it just doesn't seem like something catastrophic is wrong because it drives fine, makes no noise, and doesn't feel like there's any excess driveline lash when driving. This is the first Torsen design LSD I've driven so I don't know what to expect.

 

BTW, when running a viscous LSD is there any reason or justification to using a LSD additive/modifier to the differential fluid? My impression is that there is no need to use an additive since the LSD function is accomplished by silicone viscosity properties within a self-contained case and is independent of the properties of the diff fluid used (re LSD properties). Naturally, you'd want a high quality diff fluid to manager heat/friction in the diff, but LSD additives? DAW

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VLSD's are sealed and have their own internal fluid that determines the LSD characteristics. Additive not necessary. FWIW, SWEPCO 201 goes in all my diffs (and John Coffey used it in his Quaife too), and you don't need additives with 201 anyway.

 

I'll second that emotion......Swepco 201 is great stuff! Use it in my R200 LSD as well as my 5 speed gear box. I've been told by a reputable source that Swepco 201 is the only gear oil Porsche will use in their race cars....sounds good anyway!!! And it's a nice blue color...BFD!

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260DET' date=' what fluid do you run in the Torsen? I have one in one of my non-Z cars (Maserati) and I'm changing the fluid. I'm planning on using Quaker State synthetic 75W-90 GL-5 which states it is formulated for LSD diffs as well as open diffs.

 

I read in the link you posted that the manufacturer of your Torsen recommends Penzoil 90 synthetic plus LSD additive. I had wondered if, based on the non-clutch operation of the Torsen, if an LSD additive/modifier would even be necessary or useful.

 

[/quote']

 

Agreed. I was always under the assumption that only reason the LSD additive would be needed is for LSD's which use clutch discs. It is a friction modifier for proper clutch operation.

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