Wave Trac Diffs. Any Issues
 

I put a new Wave-Trac in our 915 gearbox and ran it for a few laps on the track. The symptom was a feeling of drag after shifting it into 5th after a few laps. Before the gear box heated up, it seemed to be ok and the 3rd and 4th gears seemed ok until it was shifted to 5th.
Disassembly of the gearbox found some greyish colour in the oil( was new Swepco201) and what appeared to be friction material. I can only think it is coming from the Wave-Trac.
I am hoping others may have a view on this. I am planning to call Wave-Trac on Monday morning
The car is a full race spec 914
Thanks Geoff

I am FAR from an expert, but if I understand the Wavetrac it is essentially a Torsen-type diff with a clutch-type device that activates under very low load / no load.

Therefore you have friction materials sliding against each other like a more traditional clutch diff.

While the plates seat / break in with each other, they're going to grind down a bit. Pretty sure that's why oil looked dirty. Most aftermarket clutch diff manufacturers recommend a diff (or in the case of a transaxle, gearbox) oil swap after break-in.

Perhaps the debris from the break-in affected your synchro action?

To my understanding of it, there aren't any clutches in a Wave-Trac. The part that mimics an LSD is the pressence of pressure rings that push on the gears to lock them together. See video:

Wavetrac® Differential - A torque biasing differential with a difference

Thanks Matt. No matter how many videos I watch, helical diffs are witchcraft to me. Throw in an extra complication and I'm totally lost.

No expert here, but I do have a Wave-trac in a 915 box with 4 track days so far with no issues. Lot of variables in the transmission including assembly that could be causing your issues. Friction material in a fresh 915 could just be the synchros wearing in.

How do you guys like the wavetrac? Is it a noticeable improvement over an open diff?

I like the Wavetrac. My use is street, track and autocross. I chose the Wavetrac based on cost and thought a torque biasing differential would be a good compromise for street and autocross. On the street it is transparent. Big improvement at autocross over an open diff, power down out of corners is now dependant on the grip of both rear tires. On the track it’s hard for me to tell the gain over an open diff since I wasn’t having any wheel spin or handling problems with the open diff. My car with upgraded suspension handles well on the track, threshold braking is very stable even with the TBD. Many other threads on TBDs vs. LSD, really depends on your intended use. My understanding is the Wavetrac does Not lock under braking (like all TBDs). They say it locks during the brief transition from accel to decel. I can’t really feel that, the car just feels stable.

Wavetrac
 

Hey Geoff, I too have a wavetrac in a 915 behind a 3.6 varioram in a 2000lb 914. It is a full time track car that i have been building for 2 years and will be on the track in August. Anyway I was wondering if you heard anything from wavetrac about the grey mucus? Thanks!

Wave Trac Follow-up
 

Thanks to all who provided comments to my original post concerning Wave-Tracs. We did call Wave-Trac and they were very helpful. My race mechanic spoke to them at length covering the principals of how the Wave-Trac works, why the oil turned a greyish colour, how to test the diff unit etc. Based on the discussions and testing of the unit we are satisfied that it is operating as its supposed to. The real test , of course, will come in the next on-track test after we re-assemble the gearbox.
As for the source of the problem we went looking to solve, noise and a drag in 5th, I have to say we haven't found anything that was not the way it should be in the trans or clutch assembly. So then, only thing to do is try it.
I will try to circle back and close this thread after we have tested it with some further comments.
Thanks again for your responses.
Geoff

I have not heard of any recommendations to change oil...what does Wave-Trac say?