TD_05

I got a new aftermarket LSD installed (997.2 GT3 street car). I haven't put a ton of spirited miles on it yet. There is a fair bit of chatter, vibration, shutter on low speed, tight radius corners. Installer and manufacture don't seem super concerned yet, and have suggest a LSD friction modifier additive to be added to the gear oil. Do any of you have opinions on this initial strategy and perhaps a product that you have had luck with eliminating LSD clutch chatter?

TD

Hella-Buggin'

Yeah, they do that. I have a guard's and it chatters most noticeably in parking lots and getting out of the driveway.

VPD255M

Same here, I have guards in a 997.1 (with 996 ramps) and does the same

RAudi Driver

I too have a guards and never realized it chatters at all. What's this chatter sound like? Is it similar to the SM flywheel sound?

Hella-Buggin'

Exactly.

MKIVdan

I guess I have all sorts of chatter going on with a guards diff and LWFW lol.

Car sounds like a bag of marbles at at stop light.

Spyerx

What oil did they put in the trans?

I've run Delvac and Motul 140w in mine (without friction mods) and I don't get much chatter, maybe a little. I have a guards diff.

I noticed it much more on my 964 which also have a GT diff.

If it bothers you you can use the Motul for LSD which does have friction modifiers in it, just be aware this makes the diff slightly less effective as it will allow more slip.

Hella-Buggin'

It's probably the LFW at idle and the diff when slowly maneuvering. I don't have a LFW so I don't get the idle marbles but do get the clacking when first engaging the clutch, especially when I'm cranking the steering wheel.

TD_05

Sorry I have been away from RL for a few days. I am confident it is not the LWFW. I hear the chatter around low speed, tight corners, and you can also feel it resinate thru the car a bit. I've added a friction modifier to see if it makes a difference in terms of chatter, and the vibration associated with chatter and any unwanted, noticeable increase in diff slip. Life has been busy since then, still haven't driven it. More to follow.

Hella-Buggin'

When I moved I went to a new shop that put redline in instead of the delvac that I'd been using. And was told by the previous owner to use. I was concerned so I called guards. They told me that I should get it out of the box and put the delvac in. That the redline is slippery and will feel smooth but the modifiers will calcify in all the nooks and crannies.
The chatter is just part of the deal for the performance the LSD brings to the table.

MJFDDS

I remember reading the long post by Matt at GT stating he recommends not using any friction modifier with his LSD.

Belinko

^^^^ X2

Guards diff here no noticeable chatter with Motul gear LS 75W90. Perhaps some audible creaking/tire grabbing while making a low speed u-turn, but nothing else and no LWFW in the car.

GEAR 300 LS from Motul is a 100% synthetic ester based transmission and differential lubricant formulated for racing. It is suitable for all types of manual transmissions, transaxles, and differentials. The "LS" stands for Limited Slip. GEAR 300 LS is formulated to be less slippery than standard GEAR 300 oil, making it a great choice for transmissions with worn synchros and clutch-type limited slip differentials where increased lockup is desired. The GL-5 gear lube rating allows its use with both hypoid and straight-cut gears (perfect for racing transaxles). The 75W-90 viscosity offers excellent low-temperature flow for easy cold shifting, while the zero shear loss formula ensures that the hot viscosity will not stray from 90 weight, even under extreme conditions. GEAR 300 LS is compatible with all seal materials and is non-corrosive to bronze parts (shift forks, synchros, etc). Note that street-driven clutch-type limited-slip differentials may experience increased chatter due to the reduced slippage. Motul GEAR 300 LS meets API GL-5 standards. It is tinted green to distinguish it from standard Motul GEAR 300.
https://shopmotul.com/product/gear-300-ls-75w-90
https://www.pegasusautoracing.com/pr...?Product=MT202

TD_05

Sorry @Spyerx I didn't answer your question. They used Mobil 1 Delvac, not sure of weight of the top of my head.

I removed a bit of the gear oil to allow for some Amsoil Slip Lock at the recommended rate.

Minimal audible chatter remains during the slowest, tightest radius maneuvers. There used to be a vibratory component as well, this is totally gone. I plan to replace gear oil after about 1000 miles per some recommendations. I will iniitally skip the additive, if the chatter returns, I'll plan to repeat what I've done. I'll post my .02 of the mods performed in the next days. Thanks to all for helping out!

jreifler

Just got my car back with rebuilt trans w/ RS 4.0 spec and new Guards unit. I can't isolate noise to the diff, but it's certainly a bag of rocks now. It was chattery before, but even more so now. I do notice a little more mechanical noise right at clutch engagement crawl (i.e., no throttle), but it all melts away into angry bliss once things get going.

powdrhound

I've had numerous Guard LSDs including the GT3 Club and the GT2 Pro. None have ever made any noise or chatter and they are set up pretty tight for track use. Delvec 75W90 used exclusively.