997,1 GT3 LSD refurb/upgrade options

[Diggermeister]

Well it's not a job I'm going to do between sessions on a track day at any rate.

 

[Cunno]

Cunno and diggermeister,

I am not good at multi quoting... but here are my 2c...

Opening the diff on our cars is very easy (relatively speaking) as you don't need to remove driveshafts from the car. Once they are down from the diff output flanges, you can remove the former. Since you aren't changing bearings, as long as you keep the shims as you found them, there should be no changes to the backlash of the diff. Once the flanges are off, then you can remove the diff covers, once they are off, the LSD casette with the crown wheel can be removed. Splitting it open isn't difficult and then you can inspect the plates. Having a good bearing puller is helpful, but not essential.

if you are rebuilding, having a precise vernier depth gauge and basic maths skills is all that you need. All torque values are in the WSM. The beauty of the 996/7 transaxle is that it's old school. It is designed to be rebuildable, or that ratios/LSD can be swapped in the field. Hence it allows even oiks like me to have a play...

As for the ramp angles - both of you are spot on. 996.1 and 2 have 40/60 diffs, while 997.1 and 2 are much weaker at 28/40, expecting the ABS and rear brake calipers to do much of the work... we know how that worked out in real world...

.
Well that's way beyond my skill set, brave man than me and clearly are a lot more hands on than me. Be good to see a how to guide for jobs like these

 

[Senoj]

Are we absolutely sure, talking 997 here, that Rear brakes are active in the diff's behaviour with TC off, or TC and PSM off in the case of the 7.2

I have to say I'm not convinced they are. I have run with it all off most of the time and rear pads lasted forever for me so if they're doing anything it's not much.

 

[Cunno]

Are we absolutely sure, talking 997 here, that Rear brakes are active in the diff's behaviour with TC off, or TC and PSM off in the case of the 7.2

I have to say I'm not convinced they are. I have run with it all off most of the time and rear pads lasted forever for me so if they're doing anything it's not much.

Clearly Dan your car is broken :grin: or you just need to driver quicker.

Yes sure on 997.1 don't know for 7.2 to answer your question

 

[Roro]

Are we absolutely sure, talking 997 here, that Rear brakes are active in the diff's behaviour with TC off, or TC and PSM off in the case of the 7.2

I have to say I'm not convinced they are. I have run with it all off most of the time and rear pads lasted forever for me so if they're doing anything it's not much.

Clearly Dan your car is broken :grin: or you just need to driver quicker.

Yes sure on 997.1 don't know for 7.2 to answer your question

Eh... am I misunderstanding something here, I thought TC off meant I wouldn't use my rear brakes? But we're saying off doesn't really mean 'off" are we? What's the solution, would that be steeper ramp angles with a Guards diff then?

 

[Diggermeister]

I was definitely under the impression, on the 997.1 GT3, that TC off meant the rear brakes no longer played a part in the correction of the diff.

Furthermore, FWIW, when TC is left on, switching to "sport" mode (loud exhaust and different throttle response) also increases the point at which the TC will step in.

Someone please correct me if I'm wrong.

 

[Roro]

I was definitely under the impression, on the 997.1 GT3, that TC off meant the rear brakes no longer played a part in the correction of the diff.

Furthermore, FWIW, when TC is left on, switching to "sport" mode (loud exhaust and different throttle response) also increases the point at which the TC will step in.

Someone please correct me if I'm wrong.

Re the TC button, what I'm hearing here is off doesn't really mean off. I always turn off my TC when I'm on track, but I had a trackday check up the other day and was told my rear pads were slightly more worn than the fronts. Nothing major, and I didn't think anything of it, until I read this thread afterward. So the wear-rate isn't as drastic, but TC off in 997.1 GT3s does seem to still use the rear brakes a little more than the fronts. At least on my car, but i don't see what else could be causing the greater wear on the rear pads than the front, unless that's just how the cars are set up anyhow with a rear brake bias. No idea...

Re Sport mode, I'm not sure it does anything to the TC, I don't think it's that sophisticated

 

[Senoj]

I was definitely under the impression, on the 997.1 GT3, that TC off meant the rear brakes no longer played a part in the correction of the diff.

Furthermore, FWIW, when TC is left on, switching to "sport" mode (loud exhaust and different throttle response) also increases the point at which the TC will step in.

Someone please correct me if I'm wrong.

I knew we'd been here before. This was my take on it a while back. Not changed my mind since :floor:

http://www.911uk.com/viewtopic.php?...start=20&sid=e791f54af565d5ebe85f4203025b4ab8

 

[Roro]

I was definitely under the impression, on the 997.1 GT3, that TC off meant the rear brakes no longer played a part in the correction of the diff.

Furthermore, FWIW, when TC is left on, switching to "sport" mode (loud exhaust and different throttle response) also increases the point at which the TC will step in.

Someone please correct me if I'm wrong.

I knew we'd been here before. This was my take on it a while back. Not changed my mind since :floor:

http://www.911uk.com/viewtopic.php?...start=20&sid=e791f54af565d5ebe85f4203025b4ab8

Ha! That explains the deja vu :grin:

 

[Cunno]

I was definitely under the impression, on the 997.1 GT3, that TC off meant the rear brakes no longer played a part in the correction of the diff.

Furthermore, FWIW, when TC is left on, switching to "sport" mode (loud exhaust and different throttle response) also increases the point at which the TC will step in.

Someone please correct me if I'm wrong.

So I'm no expert here but from what I've read the 7.1 TC is off when turned off but the ABD (Active Brake Diffirential) part remains on, otherwise you lose part of the diff workings when you turn off TC. First page on this thread that we have discussed before.

https://www.pistonheads.com/gassing/topic.asp?h=0&f=48&t=1250316&i=8

From personal experience with my car I never found that having the TC off actually helped the rear brake wear a great deal. It was only when I changed ramp angles to 40/60 that the rear brakes stopped aiding the mechanical diff and rear brake life doubled. For me this confirms Fioran0 comments.

 

[Diggermeister]

I was definitely under the impression, on the 997.1 GT3, that TC off meant the rear brakes no longer played a part in the correction of the diff.

Furthermore, FWIW, when TC is left on, switching to "sport" mode (loud exhaust and different throttle response) also increases the point at which the TC will step in.

Someone please correct me if I'm wrong.

So I'm no expert here but from what I've read the 7.1 TC is off when turned off but the ABD (Active Brake Diffirential) part remains on, otherwise you lose part of the diff workings when you turn off TC. First page on this thread that we have discussed before.

https://www.pistonheads.com/gassing/topic.asp?h=0&f=48&t=1250316&i=8

From personal experience with my car I never found that having the TC off actually helped the rear brake wear a great deal. It was only when I changed ramp angles to 40/60 that the rear brakes stopped aiding the mechanical diff and rear brake life doubled. For me this confirms Fioran0 comments.

As Roro says, it's deja vu all over again! I do now remember the thread Senoj mined from the archives.

Yes, I stand corrected on the diff braking. You are also definitely right (I found this too) that rear brakes intervene less with revised diff ramps.

I am pretty certain I was told TC threshold does change in sport mode though.

 

[GTTommy]

Anyone got any experience of the RPM technik clutch pack?

Seems they are offering their own plates these days

 

[NXI20]

Anyone got any experience of the RPM technik clutch pack?

Seems they are offering their own plates these days

Think you'll find they use the Gripper plates BICBW.

This seems to confirm it:

https://gripperlsd.com/product/porsche-997/

 

[GTTommy]

Anyone got any experience of the RPM technik clutch pack?

Seems they are offering their own plates these days

Think you'll find they use the Gripper plates BICBW.

This seems to confirm it:

https://gripperlsd.com/product/porsche-997/

Ah good find, thanks for the info!

Does anyone have any experience of gripper vs guards?

I was originally planning on guards 40/60 :dont know:

 

[tb993tt]

I was originally planning on guards 40/60 :dont know:

I have a Drexler LSD part number DSD-100-100-00027

This diff is used by Ruf and 9ff who used to use the Guard stuff but now use the German built Drexler.

Similar to the Guard GT Pro I had, I found the Dexler too aggressive on the over run and in my road car set up caused too much understeer for my liking, I now run a Wavetrac which has nothing like the tractive benefits but suits my road use better.

The Drexler unit has done less than 500 road miles and I will sell it if anyone interested ? I have full spec sheets etc.