Elise787

Hi Guys,
New to the forum. I just purchased a Wavetrac LSD for my 981 Cayman S 6sp manual. The Wavetrac comes as a core so would have to transfer the ring gear from the stock unit. However, there is no installation instructions from Wavetrac and looking at the factory service manual there anything about this either. The only thing related to this is the replacing the half shaft flanges where the differential is just lifted out and reinstalled without any shimming or adjustment to the mating clearance between the the pinion and the ring gear. If I were to install a new carrier bearings for the new Wavetrac LSD, how do I know the clearance between the gears are correct?
Does anyone had any experience in this area? Most of the discussion I saw are on the 987.
Thanks

Bernie930

A differential swap can not be done unless you have special tools and knowledge and even then some screw it up!

TMc993

I absolutely love everything about my 981 Cayman base but the interior noise is nasty...Much worse than my 993...Porsche should be ashamed...

marques

Right. I have not done one on these cars, but have done it on others. For starters, you will want to check/adjust the preload on the output bearings (before you swap the ring gear). If the new LSD doesn’t have bearings, you will need to source new ones and press them in without damaging anything. If they are too loose with play you can feel, you will need to tighten things. If they are too tight (takes higher than normal force to spin the diff), you will need to loosen things. There are different specs if you are reusing old bearings or new ones.

Then you will need to swap the ring gear. They are typically an interference fit (in addition to all the bolts that are torqued to a high value + Locktite). So, not trivial to remove, and not trivial to install.

Then you need to put things together again and check the backlash. If it’s too lose you need to move the ring gear in (closer to the pinion gear). If it’s too tight, you need to adjust in the opposite direction. Without changing the preload on the output bearings. Once that’s set, you need to put some special paint in the gears and spin it forward under load to check the mesh pattern.

Then you need to fill with the appropriate fluid and go for a test drive in the parking lot and make sure there are no bad noises or vibrations. If that all checks out, you will need to put a few hundred miles on it and change the fluid again.

So this is a long, tedious process where you are assembling / disassembling / checking / adjusting multiple times. And you will need access to some special tools and maybe a helper. Hopefully this explains why not too many people are swapping in LSD’s in their driveway.

Elise787

I am going to use use new carrier bearings. Provided if the mating surfaces on the new diff is the same as the original one, I would imagine the clearance should be within tolerance as the one removed. Check the shop manual, and parts list there are no shims for adjustment. The only place Diff is even mentioned anywhere is when you need to replace the drive shaft flange on the car. And even then the instruction is just to remove the diff and reinstall them after you are done. Nothing about clearance, preload and back lash is mentioned.
BTW, the carrier bearing is not tapered but regular ball race type. so in theory no preload should be check or adjust if all the mating surface is of the same dimension to the old one.

Dutchman69

Had a wavetrac installed in my 981 BS transaxle last year by Bill Rader Motorsport when the spider gears in my OEM open differential went bad. Highly recommend them, very fair pricing for probably the top Porsche transmission expert in the country. Special tools and test rig is required to lock the pinion, set the backlash, etc. they also test the gear synchros. This is not a DIY install and not really doable correctly with the tranny still in the car, was highly recommended by both Bill and the race shop who removed the trans to not attempt an install on the car. Can very easily damage the pinion and diff if not done correctly.

colnagoG60

I'd check with Deman Motorsports (frequently performs shorter gear installs), BMC & G (Ohio...they do the Autoquest shorter final drive installs), or TPC Racing for guidance.

nhnguy12

How much did they charge you to get this done? Also what are your impressions of the wavetrac differential?

Dutchman69

Labor to remove transaxle, ship to Bill Rader Motorsports to install differential, set backlash and pre-load, ship back and reinstall transaxle into car: around $3000
Night and day from the standard open diff. puts down power smoothly and rotates on power, also much easier to invoke a slide.

nhnguy12

Thanks for the reply.

How much was just the shipping part? I'm close enough to just drive to Vegas.