GTgears

Actually it's closer to 30 including practice time. Regardless, one of the common questions we get is how frequently am I going to need to rebuild my LSD if I use your parts. I think it's a valid question, though in the last couple of years the nature of the question has been skewed by certain other manufacturings talking about how more plates is better and that according to them their infinity plate LSD never needs rebuilding as a result. Well, here's some empirical show and tell for you.

These are the actual friction discs that were used in Bullet Racing's car that competed in the Rolex 24 Hours of Daytona at the end of January.

You can go back to page one of Mike's install if you want to see what they look like when brand new. Obviously they are no longer new. However, when measured, the friction discs show .01mm of wear on them. And while they are showing swirl marks, the hardened steel plates show no measurable wear. I pulled these out, and if it weren't for the fact that I've completely rebuilt the gearbox and sold it to a new client, I would put them right back in and keep running them. On one of BGB's LSDs in one of their Conti cars, we saw more than 80 hours of dedicated motorsports usage on their unit before we serviced it. I'll be sending these off to Bullet to keep in their kit of spares and next time they have a worn out LSD in one of the cars in their fleet, these parts can go right in with the expectation of another 50 or 60 hours of use before they need to be retired.


Just for grins, I measured the clutches from the 2010 Cup Car LSD that was initially part of the donor box for this build. I was told by the previous owner that it had 18 hours on it. Like mine, the steel plates showed no measureable wear. The clutches were .05mm off of their new spec. Quite a bit more wear.

Aerokitted

What a monster thread. Many thx, gents!

It looks like I will be getting the guards unit. My service guys didn't sound all that enthusiastic about testing my LSD. Now I know why?

I had no idea. This should be stickied.

Aerokitted

Got the 40-60 unit installed and could notice a diff even on an aggressive street turn. Rear end slid out in a nicely contolled manner and the traction light flashed. Never happened before.

Dealer said my LSD checked out fine, but my best guess says it was marginal at best. My car is pure street use, never tracked, sunny day warrior.

My wallet is $2500 lighter.
Thanks, all!

savyboy

Adding my two cents about how great it is to deal with Matt at Guard Transmission. Super knowledgeable, high-quality parts, great service. Anyone looking for LSD/transmission work or parts needs to support this business. I put my money where my mouth is.

P.J.S.

+1

Mvez

Now I need some lower gearing......perhaps the 3.89 R&P?

Can't handle watching the 3.8's jump off the 3rd gear corners, and leave me sitting there. Mid-Ohio is not very friendly for the 3.44...

P.J.S.

8:33 (4.125) ring and pinion from guard is a work of art

In my experience, a properly geared for your track/s 3.6 RS is every bit as quick as a 3.8 RS with stock gears... certainly at corner exit when they start to gap a 3.44 R&P 3.6 RS

I did 8:33 and first thru fourth -- this is not the cheapest way as it reuires a new mainshaft but it is divine.

When I regeared, the 3.89 ring and pinion was not available for purchase unless you bought the whole box...

Mvez

Hi Matt,

Any changes regarding the availability of the 3.89 R&P ?

AudiOn19s

3.6 cars with 3.44 need to use 2nd gear in keyhole, carosel and T 8-9 at Mid Ohio for ultimate lap time. I don't particularly like using it in the Carosel because you have to do the 2-3 shift in the left hander onto the straight. I also tend to over-slow going over the top of the hill in madness when downshifting there but I"m working on that currently.

I was on lesser tires than several 3.8 RS's (Nittos vs. Hoosiers) a couple weeks ago and was able to hound them all the way down the straight using 2nd on exit of the keyhole despite my 80hp disadvantage. They have to stay in 3rd for that exit.

Exit of 11 and run through thunder valely is where the 3.89 really shines as we all have to use 3rd through there.

Andy

Mvez

I know, but that's pretty hard on the gearbox for just a DE, and makes for a ton of shifting. I experimented with 2nd gear in the keyhole and carousel, and don't like the 2-3 shift out of the carousel either, it's literally right in the middle of the track out.

Problem with the keyhole is that I carry 4th gear into it using the club course, so you have 2 downshifts in a very compact braking zone, unless you grab 3rd going into T3 first, which tends to scrub off even more speed, and that's an area where I am really good at carrying alot of speed through.

I agree about the exit at T11, but where the 3.89 also quietly adds up alot of pace is from T7 through T11. Every corner is a point and squirt. It's great practice trying to carry crazy speed into each corner to keep revs up and actually get some launch in 3rd at 7-8-9-10-11...but you simply can't match the consistency of the lower gearing. My stock M3 gearing at 3.62 feels way better, so I can only imagine what 3.89 feels like. Grrr.

Porsche Motorsport 4.0 is an option, but I really don't want to be geared that low either. 3.89 really is a great all-around gearing, that balances gearbox wear with some good grunt.

GTgears

Not from us. But Porsche issued a part number late last year and the dealer should be able to order it for you. We don't plan to manufacture it. Not enough demand. There have also been a few kicking around the used market from guys who removed them and installed our 4.125

Regards,

Matt

Mvez

word

Mvez

Suncoast has it priced at $2695. Haven't seen any in the used market, but if you know of anybody wanting to get rid of theirs, send them my way. Thanks again Matt, you are the man.

GTgears

Hello,
I figured this would be the best place to put this with a bump on this thread since so many people reference it. Guard Transmission is in the process of relocating. I will not be rebuilding any LSDs in house until further notice. You guys can still get them done at any number of respected RL sponsors, like Sharkwerks, Autometrics, Body Motion and many others. But during the move, which is going to be done in stages and have me working out of two facilities simultaneously, we just don't have the infrastructure to juggle LSD rebuilding at this time. Thanks in advance for your understanding.

Regards,

Matt

PhilMorrison

Just wanted to say thanks very much to the OP for the how to. It made pulling the LSD a lot less daunting. I think you should edit it a little to emphasise a little more just how much of an ******* it is to get the unit out past the drive shaft and rubber hoses though .
Also thanks to Matt for the Guard parts. replacing the internals myself turned out to be a very easy job.