^^^ 09.09—09.11 @ LS? What is going on that weekend, schedule says MTY CO. Parks Cherry Jubilee??? I'll be at Infineon that weekend.

Daren

 

Hey Daren, it's a 3 days track event run by PCA. Cherry Jubilee is just a side show in the paddock where people show off their muscle cars. Very interesting crowd and weather should hold up ...

Mike

 

Mike,
You better be at Sears Point Sept 24-25. I want to meet you face to face...

 

Yes, you can count on that. Should I bring my beat up Cup sequential so you can give it a proper GTgear blessing?

 

I know you are joking, but I will be there with Bullet Racing. If you wanted to arrange to have your gearbox serviced, it's actually something we could consider. I'd just need to schedule and arrange it in advance with them to have Bernie work on it. I can't 100% guarantee that he could do it, but as of yesterday they were planning on running Pirrelli Driver's Cup that weekend and ALMS the previous weekend. It's feasible that he would have time between the two events to do your gearbox.

 

Hey Matt, yes, I was joking but that joke my turn into OMG esp when I have 4 more track events before meeting you at SP. I hope the joke will remain that way but appreciate the possibility of a on site service if needs arise

Will call and look for ya at SP in couple weeks

Cheers

Mike

bullet racing ... Canadians. I seen them around Northern California before

 

Mikymu, did you have a manual before you tore into this project? Amazing write up. Thanks for taking the time to share this with all of us.

~A

 

Hello, everybody!

As most of you have said - it's VERY informative thread you have made here. Now I know why my LSD has "<5Nm slip torque"...
Thank you all - especially Matt and Mike

coes mentioned "generic 4061-lsd manual" - does it have more specific name, location of manual, whatever information?
I'm asking this because I disassembled my LSD and now I want to assemble it properly, but unfortunately - either I made some mistakes measuring or Opel TIS(technical information system) has some errors in it - long story short - by measuring various dimensions I should have had
number indicating "play" (free movement of details) inside LSD. According to TIS - if that number is 0..0.1mm - that's good, if it's more - you have to take action... but what I got was negative value

If I can get that generic manual - I might figure it out by myself, if not - may be I can post excerpts from TIS with measurements I took from LSD?

 

Don't know how a negative value would be good. That would suggest to me that you've got an internal stack height that's greater than the body. Stock OEM GT3 LSDs tend to have a 1.9mm to 2.3mm internal gap. Cup Cars have around 0.6-0.0.8mm internal gap. Most of the LSDs we're sending out to people are in the 1.6mm range+/- depending on spec and application.

 

No manual ... just plow ahead with the DIY and ask Matt when I get stuck

 

I have been out of the loop on this thread for a long time. I just need more postings so I can PM someone

 

I have had my guards in for about 2K miles now. Just did a round trip over the loop today, I'm loving life right now. A big thanks to you Matt and the Sharkwerks gang!

 

While I'm waiting for my parts from Guards to arrive, I thought I'd bump this wounderful thread with another question I cannot recall having been asked:
When does the LSD in these cars UNlock after locking up? The ramps are pressed out based on difference in wheelspeed, but as soon as the LSD locks, the speed of both wheels are forced to be the same but I would be very surprised if the diff unlocks as soon as the speed of both wheels are the same?
Does anyone (Matt?) have a good description on how this side of a LSD works?

 

i'll try to explain as i think the lsd works...
first, the ramps are not pushed outwards based on difference in wheelspeed but on the applied force to the lsd carrier via the engine (acceleration or motorbrake).

an lsd with preload is locked in general and as you mentioned right, both wheels spin in the same speed when the lsd is locked.

the lsd will unlock, when a certain difference in wheeltorque (not wheelspeed) of the left and right wheel is exceeded!
if the car is cornering, the outside wheel can handle more torque as the inside wheel. and during cornering, when the difference of l+r torque exceeds that max locking factor (that depends on the lsd setup... rampangles, clutches... and the force applied from the engine), the lsd opens up, the clutches slip and the wheels can rotate at different speeds! but as there is sliding friction then, it still doesnt handle like an open diff in that case but still transmits more torque to the outer wheel... but when it has opened, the torque ratio transfered to the outer wheel remains constant and cannot rise any more!

 

Hello,
While wheelspeed and wheel torque is often used somewhat interchangeably in these discussions, Coes is correct that what causes the LSD to lock is a difference in wheel torque. When one wheel is spinning at different speed than the other, it will exert a different amount of force on the drive gears and pass that on to the spider gears. It is that force that rotates the pins the spider gears run on, and it's those pins that slide up the edge of the ramps, pushing the pressure rings apart, thereby locking the differential.

With respect to the question of when does it unlock? It unlocks once that load is released. So, let's take the example of a tight 2nd gear corner. You bury the throttle and your inside wheel starts to slip and spin. This locks the LSD. At this point, the outer wheel, which has traction, is in essence trying to slow the loose spinning wheel down to the same speed as it is travelling. Once it has managed to slow the wheel down enough that the tire is able to regain traction, the force on the cross pins will be released, they'll slip back down into the bottom of the ramp, the pressure rings will unclamp the clutches and the diff. will open up. This is a very generalized description and ignores ramp angle, the exact locking factor and whatever static preload is built into the unit. Make sense?