Rear Suspension Questions
12-21-2016, 07:17 PM
#21
You're familiar with the advantages of Strange Engineering's S-Trac, right?
12-21-2016, 08:41 PM
#22
Those have a good reputation but I wasn't aware of anything they would do to make a "1200HP" axle live so far beyond its means. I'm here to learn above all else so please educate me.
Thanks.
12-22-2016, 08:54 AM
#23
Wait, tell me again why MN_V was wrong? The 8.8 is readily available, maybe not more but probably equally as available as a 9". Especially since everyone knows to look for the 9" and gobbles them all up. Where as the 8.8 more so slides under the radar not to mention it can be had for way cheaper.
And as he said it is also well proven? Go ahead and look up broken 8.8's because I know where this is going but be warned, I know I can google more broken 9" rears then 8.8's.
OP either rear end will work. Maybe the 9" can hold a little more power, but the 8.8 as a whole in the V1 will be easy 1k cheaper. Just depends on your pockets.
And as he said it is also well proven? Go ahead and look up broken 8.8's because I know where this is going but be warned, I know I can google more broken 9" rears then 8.8's.
OP either rear end will work. Maybe the 9" can hold a little more power, but the 8.8 as a whole in the V1 will be easy 1k cheaper. Just depends on your pockets.
12-22-2016, 09:06 AM
#24
Wait, tell me again why MN_V was wrong? The 8.8 is readily available, maybe not more but probably equally as available as a 9". Especially since everyone knows to look for the 9" and gobbles them all up. Where as the 8.8 more so slides under the radar not to mention it can be had for way cheaper.
And as he said it is also well proven? Go ahead and look up broken 8.8's because I know where this is going but be warned, I know I can google more broken 9" rears then 8.8's.
OP either rear end will work. Maybe the 9" can hold a little more power, but the 8.8 as a whole in the V1 will be easy 1k cheaper. Just depends on your pockets.
And as he said it is also well proven? Go ahead and look up broken 8.8's because I know where this is going but be warned, I know I can google more broken 9" rears then 8.8's.
OP either rear end will work. Maybe the 9" can hold a little more power, but the 8.8 as a whole in the V1 will be easy 1k cheaper. Just depends on your pockets.
12-25-2016, 08:43 AM
#27
I have read about it in the past. It is a Quaife type of affair right? I can't remember why I landed on the Trutrac..Either wasnt available for the 8.8 with the right spline count or I was in a cheap-a$$ mood that day. Still the TT isn't cheap per se so I would like to think $ wasn't the only factor.
Those have a good reputation but I wasn't aware of anything they would do to make a "1200HP" axle live so far beyond its means. I'm here to learn above all else so please educate me.
Thanks.
Those have a good reputation but I wasn't aware of anything they would do to make a "1200HP" axle live so far beyond its means. I'm here to learn above all else so please educate me.
Thanks.
These three units are all helical gear, preloaded, non-locking, torque-biasing LSDs, but the TruTrac doesn't put any power to ground if you lift a wheel or significantly unload one. The Wavetrac and S-Trac can still put power to the ground, but I don't understand how the S-Trac does it without using spring packs. Inside the Wavetrac there are these machined wave profiles that are locked together while the axles are loaded. When the axles are unloaded, they slip against each other, driving the halves of the center section apart. This loads the differential and ends the axle no-load condition.
Wavetrac Under Load:
Wavetrac Under No Load:
In terms of torque rating, the TruTrac is definitely the loser here. There are articles on the materials used--basically, the TruTrac's gears and fasteners are inferior and generic whereas the WaveTrac and S-Trac use case-hardened 9310 gears and ARP fasteners where applicable. In photos showing destruction of TruTrac differentials, you can see significant wear along the tooth profiles of the sun gear and chips or shearing on the planetary gears.
The most common theme is that you can break the 31-spline TruTrac with 450-500 RWTQ (equivalent to about 600 RWHP) and the 33-spline unit with 550 RWTQ. But there are also photos of broken TruTracs with their users claiming that they were broken with sticky tires and a lot less horsepower. By comparison the 35-spline Wavetrac is good for 700-800 RWTQ and the 35-spline S-Trac is good for almost 1000 RWTQ. You have to be careful looking at Wavetrac breakage stories because a lot of the broken units were first-gen products and the design has been updated since then. In general, it's important to try to control for case design--aluminum cases break a lot more easily than nodular iron--sometimes people will say "I broke my [insert product here]" when they only broke the case.
To get an idea of the price, the 31-spline 8.8" TruTrac costs $485, whereas the 35-spline 9" Wavetrac and S-Trac cost $995 (they're direct competitors). Likewise, the TruTrac is warrantied for 1 year, whereas the Wavetrac and S-Trac have a lifetime warranty on breakage due to excessive horsepower. When I bought my Gforce 9" kit, I noticed that they stopped offering the Wavetrac and asked them about it. They said that they had a lot of users breaking the Wavetrac but had far fewer problems with the S-Trac. Since they're the same price, with the same feature set (plus S-Trac is made in Chicago), and the S-Trac is a few pounds lighter, they had no problems only offering the S-Trac.
Hope that helped! I'm sure the torque numbers will be controversial but that's the nature of the game... factors like sticky tires and user error are almost always left out when people are complaining about breakage.
Last edited by FuzzyLog1c; 12-25-2016 at 11:22 AM.
01-11-2017, 11:49 PM
#28
Sorry it took so long for me to see your very thoughtful and detailed response. Looks like there does exist a Cobra IRS kit which would work for a 8.8 V swap with Wavetrac. Maybe I just cheaped out. 
Thought: I see in the pics that the gears(machining angle) are all aimed inwards...Is it possible that the inward pressure is accomplished through the loading of said gears when the rear is loaded, providing the inward pressure allowing the Wavetrac to compress around the center section? Would keep the "waves" in the center design compressed against each other. Does this perhaps explain what you say is questionable? Just my non-engineer guess.
Thought: I see in the pics that the gears(machining angle) are all aimed inwards...Is it possible that the inward pressure is accomplished through the loading of said gears when the rear is loaded, providing the inward pressure allowing the Wavetrac to compress around the center section? Would keep the "waves" in the center design compressed against each other. Does this perhaps explain what you say is questionable? Just my non-engineer guess.
Last edited by Mercier; 01-12-2017 at 08:36 AM.
01-12-2017, 01:06 AM
#29
Thought: I see in the pics that the gears(machining angle) are all aimed inwards...Is it possible that the inward pressure is accomplished through the loading of said gears when the rear is loaded, providing the inward pressure allowing the Wavetrac to compress around the center section? Would keep the "waves" in the center design compressed against each other. Does this perhaps explain what you say is questionable? Just my non-engineer guess.
When the wheels are driven by the motor, the thrust load is directed inward, forcing the wave profiles together. This diagram might help a bit:
