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To lock, or to limit the slip?

sloopy

2-digit whp
Joined
May 25, 2020
Location
Dallas, Texas
Hello everyone. I'd like to get some of your feedback on a g80 vs the wavetrac for a high performance street application.



My suspension setup is bone stock save for a factory 23mm front and 21mm rear anti-roll bar setup. I have enkei 14x6 inch wheels with 215/70R14 cooper cobra radial g/t tires. I'm going to be experimenting with softer rear bars to see what it does to the rear grip.



My plans as far as power are to build a hot n/a B230F which will likely never exceed 200 hp unless I get really ambitious :^)



The g80 seems great for having fun launching the car and doing some low speed sliding. However, I also enjoy sending my car into hard turns at anywhere from 30 mph to 60 mph and I'm not sure if an effectively open diff will allow me to put the power down coming out of the turn.


I would love to go out and do some testing, but it's hard to tell with the bone stock b230f since I can barely break traction anyway.


What do you guys think? If some simple suspension tuning and adjustment of my driving style can mean effectively putting power down in hard 30-60 mph turns, then I think I'd be happy with the g80 and the money saved.
 
Remove the governor function on the G80 and it will work great for what you want to do. The G80 is a hybrid design and doesn't really lock. It is a clutch type limited slip unit that acts like an open differential until it engages and clamps down on the friction discs. No pre-load like other clutch type limited slip units.
 
Yeah, it locks OPEN in some situations vs. locking. When it's not locked open it's using clutch packs like a regular LSD.

It has two different spring-weight gixmos that control the locking:
1) The one that spins based on relative differences left to right - IIRC once they get to around 100 RPM difference it will allow the LSD function to engage
2) The flyweight mentioned above that measures the rotation of the diff itself - above roughly 25 MPH it engages and prevents the diff from engaging. You can cut this flyweight off and it won't ever engage and lock out

FWIW I put a well used (190K miles??? I can't remember) junkyard G80 in my 240, and while it's certainly functioning as designed (you can jack it up and spin the rear wheel, it acts like a normal open diff until you spin it hard enough and *LOCK* it engages. I can't turn it by hand at that point, but on the road it def slips. Going around a tight low-speed corner and give it some throttle and the inside tire will spin without the outside one spinning. But it transfers enough torque to make 2 black marks on straight, flat pavement.
 
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From what I have read the flyweight locks out the engagement above 35 mph. The modified G80 Greg Ervin runs in his 740 Autocross car does not lock out at any speed.
 
ANd it's a pretty easy mod to make on the G80 - no real disassembly required. Well, I'm not sure if you can do it with the diff still in the axle housing or not.
 
G80 diffs work ok, but a proper LSD is a huge upgrade.
My biggest complaint with the G80 was the inconsistency with open vs lock when driven hard. This only gets worse as they wear out. Long sweeping corners were the worst ones. 85mph sweeper, apply throttle, any wheelspin means diff goes full lock, car then goes sideways. Fun-ish on a race track, not fun on the street at legal speeds.
 
Sir Culberboner,

That's exactly what I'm worried about with the G80. I'd rather not have an incident because my diff unexpectedly locked up. I'm imagining a dark and stormy night... This car is intended to be my daily driver although I plan on entering it into some autocross events for fun.

I'm not sure why, but it seems like the truetrac is nearly $600 at this point. Makes it not quite worth it especially considering it'll be nearly useless on hairpins where my inside rear wheel unloads almost completely.
 
I guess when not locked out, a nice fresh G80 (acts like it) has a lot of preload.

Mine's just always been soft and easy, but probably just because it's half worn out.
 
G80 diffs work ok, but a proper LSD is a huge upgrade.
My biggest complaint with the G80 was the inconsistency with open vs lock when driven hard. This only gets worse as they wear out. Long sweeping corners were the worst ones. 85mph sweeper, apply throttle, any wheelspin means diff goes full lock, car then goes sideways. Fun-ish on a race track, not fun on the street at legal speeds.

It just depends on what you are used to and your style of driving. A regular clutch type limited slip is definitely more predictable. I like the Torsen differentials the best. My GT has one and is totally predictable. The 99 Z28 I used to Autocross also had a Torsen in it.
 
Sir Culberboner,

That's exactly what I'm worried about with the G80. I'd rather not have an incident because my diff unexpectedly locked up. I'm imagining a dark and stormy night... This car is intended to be my daily driver although I plan on entering it into some autocross events for fun.

I'm not sure why, but it seems like the truetrac is nearly $600 at this point. Makes it not quite worth it especially considering it'll be nearly useless on hairpins where my inside rear wheel unloads almost completely.

With the truetrac getting close to $600, I'd just spend the extra money on something better.

If you have the funds to spend on a $1000-1300 diff, go for it.
Gripper makes a great clutch type LSD.
https://gripperlsd.com/product/volvo-all-rwd-models/

The wave track looks like a nice Torsen with a built in locker. I haven't driven a car with one, so I can't really comment on what they are like.
 
That gripper looks very nice and the variety of preset configurations are great. It is a good bit more expensive than the wavetrac and I don't see myself benefiting from the gripper over the wavetrac. Once ben has the wavetracs back in stock, I believe they will be on sale for $800.
 
After reading culberro’s post I have to agree with him. I’m used to driving cars sideways, therefore, for me, the sudden lock is not an issue. When Autocrossing we would force the G80 to lock right at the beginning of the turn with a sudden throttle blip. Then, it would stay locked through the entire turn. It is a bit tricky to drive really fast with one without a lot of experience.
 
G80:
Bend the spring on the flyweight weight/mod it to 'basically always locked/locks with minimal difference at low speeds?'
Great for pulling out of your snowy/gravel driveway/ way better than nothing, no special oil required, doesn't generate a lot of heat/wear out the oil as fast, allows you to use your donut spare tire.
Doesn't twist off your axle splines/cushions things a bit more than welded/spool/maybe save your suspension bushings or tires on pavement/make the car movable?
Should be fine for straight line stuff too, obviously.

Interesting engineering mechanical compromise/no electronics :e-shrug:
Works real nice in the front of a jeep that's mild/for slushy stuff where the D30 would break regardless for outright boulder crawling? :lol:
As culberro sez, for higher speeds/consistency required, don't care for it so much as a performance application thing.
But DD/crawl out of your slushy gravel driveway/job sites, sure/doesn't hurt?

Clutch LSD is real nice, but forged cross shafts to make them viable and some way to deal with the heat and keep both tires exactly the same diameter is another thing to worry about/potentially break/wear item that requires adjustment/inspection.

The Torsens aren't junk, just don't care for them/not my thing.
There are fancier torsens like the wavetrac that probably are decent, but not exactly cheap. Bolt-in yes though!

Rather loosen up the clutch LSD for snow (but no rock crawling)/different courses or have it be basically welded once you get on the gas at all for pavement & have the option.

Everyone laughed at me (with some justification IMO) when I had the 4-pinion clutch LSD in the back of the ford, D60 power-lock front & lockable center.
I was like 'what, I don't crawl over boulders, I just want to get out of my snowy/icy driveway predictably!"
Air or e-lockers would be less fussy/lower wear though, just expensive/weren't popular/period correct k@@l-@id for a 1978 truck.
Less to go wrong/low speed/precise handling not a concern there.
 
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After reading culberro?s post I have to agree with him. I?m used to driving cars sideways, therefore, for me, the sudden lock is not an issue. When Autocrossing we would force the G80 to lock right at the beginning of the turn with a sudden throttle blip. Then, it would stay locked through the entire turn. It is a bit tricky to drive really fast with one without a lot of experience.

They're fine most of the time, but at ORP in long sweepers mine would lock/un-lock. Not what I would want in a performance setting.
 
We had to actually think about what we were doing in order to make it drive correctly. You don’t need that extra element to pay attention to. With my Torsen differential I just drive the car.
 
Culberbone put it best though; straight line / pull out of your ditch/slushy driveway:?
G80s fine/cheap/easy/good engineering compromise for what it is.

Expecting higher speed predictability and ridiculous multi-surface rally abuse, not-so-much/more likely to kill you maybe? :lol:
 
Exactly. My brain switches back-and-forth from TB cheap bastid to real world ideal situations. In the real world of high performance driving you want a proper clutch type limited slip or Toreson differential. My GT is so seamless it can be driven “near” its limit almost immediately. It’s limit is set so high it will take me years to get to that point.
 
I was of the impression that volvo g80 was the same as GM RPO G80. They look the same. GM has teeth, no clutches. You did NOT want to put friction modifier in one, and correct me if i?m wrong, but volvo is the same. They sure act the same.
I have one on the shelf, i can look inside. And i can do a breakaway torque test on it in a car. My bet is once it locks there is zero slip.
 
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