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Wed Feb 06, 2013 10:42 am

Yep, it is hard to tell regular folks we just installed a "torque biasing differential" and not come off sounding wonky and elecit funny replies.

Wed Feb 06, 2013 10:45 am

Madspaniard is technically accurate, Vanagons have TBD, not LSD.

And I agree the colloquial term for TBD is LSD

more about the differences between TBD and LSD
http://www.thesamba.com/vw/forum/viewtopic.php?t=347063&postdays=0&postorder=asc&start=0

Wed Feb 06, 2013 10:55 am

I use the term "limited slip" when talking to non-Vanagon folks.

But this is a technical forum for Vanagons and it would be technically accurate to use the term "TBD" if discussing the Pelequin unit... not "LSD", "Posi".. or any other.. unless referring to those other units for other vehicles.

Wed Feb 06, 2013 10:55 am

Just call it a grippy diff

Wed Feb 06, 2013 11:20 am

Semantics aside, what is it about the TBD that causes the van to tend to slide sideways downhill on slick off-camber (sidehill) surfaces?

Wed Feb 06, 2013 11:33 am

teej wrote: Yep, it is hard to tell regular folks we just installed a "torque biasing differential" and not come off sounding wonky and elecit funny replies.

Wonky? Sounding like you know what you're talking about is preferable than further bastardizing the terminology, IMHO. As someone who's been selling both LSDs and TBDs for over a decade, I have seen this cross-terminology grow primarily in VW circles .. ever since TBDs became available for VWs. It suggests a lack of understanding, while the differences really aren't that difficult to grasp. The Porsche crowd has no problem differentiating between the terms, so from a more "hands-on" crowd, why would it be so difficult for us?

Around the same time Porsche and ZF were developing the LSD for rear-engined Porsche race cars, the TBD was being developed by Gleason for (I believe) the trucking industry (1940s?). Two different paths of development, and neither ever called their product using the other's terminology. Only in the last few years has the term "LSD" been embraced by companies that only make TBDs (or something less sophisticated) .. this muddying of the terminology has been on purpose IMO.

Wed Feb 06, 2013 12:35 pm

SCM wrote: Semantics aside, what is it about the TBD that causes the van to tend to slide sideways downhill on slick off-camber (sidehill) surfaces?

It's wheelspin at both rear wheels that causes the rear to go sideways. With a TBD and non-winter tires this will be an issue. As soon as tires start to spin, even if it's just a little, the side to side grip is lost. The reason this doesn't happen so much with an open diff is that one tire is more likely to spin (the uphill one) and the other one maintains side to side grip. This isn't a deal-breaker for a TBD. You just need to use winter tires that have enough grip that wheelspin is minimized.

D

Wed Feb 06, 2013 12:37 pm

D Clymer wrote: SCM wrote: Semantics aside, what is it about the TBD that causes the van to tend to slide sideways downhill on slick off-camber (sidehill) surfaces?

It's wheelspin at both rear wheels that causes the rear to go sideways. With a TBD and non-winter tires this will be an issue. As soon as tires start to spin, even if it's just a little, the side to side grip is lost. The reason this doesn't happen so much with an open diff is that one tire is more likely to spin (the uphill one) and the other one maintains side to side grip. This isn't a deal-breaker for a TBD. You just need to use winter tires that have enough grip that wheelspin is minimized.

D

Just for clarification, this can also happen with an LSD or a locker as well I believe?

Wed Feb 06, 2013 12:49 pm

Zeitgeist 13 wrote: Just call it a grippy diff

In casual interactions with non-mechanical types I call it a traction differential. In this forum I call it what it is: TBD.

Wed Feb 06, 2013 2:00 pm

dobryan wrote: D Clymer wrote: SCM wrote: Semantics aside, what is it about the TBD that causes the van to tend to slide sideways downhill on slick off-camber (sidehill) surfaces?

It's wheelspin at both rear wheels that causes the rear to go sideways. With a TBD and non-winter tires this will be an issue. As soon as tires start to spin, even if it's just a little, the side to side grip is lost. The reason this doesn't happen so much with an open diff is that one tire is more likely to spin (the uphill one) and the other one maintains side to side grip. This isn't a deal-breaker for a TBD. You just need to use winter tires that have enough grip that wheelspin is minimized.

D

Just for clarification, this can also happen with an LSD or a locker as well I believe?

Yes, of course - its having both rear wheels spinning that causes the slide. Fix that with good winter tires and/or chains if you're in really extreme conditions.

With my old Jeep Cherokee I could spin all four wheels and travel downhill sideways. ;)

Wed Feb 06, 2013 3:58 pm

teej wrote: Zeitgeist 13 wrote: Just call it a grippy diff

In casual interactions with non-mechanical types I call it a traction differential. In this forum I call it what it is: TBD.

I love calling it what it is, a torque biasing differential, and educating whomever is listening the details on how it works, and the difference between an open diff, LSD and TBD.

What I don't understand is why Go Westy has decided to market Mr. Gary Peloquin's superior TBD as something that it is not - a Posi-Traction. My Chevelle had Posi-Traction, my Vanagon does not!

Wed Feb 06, 2013 9:41 pm

"Grippy DIff" .. I like it. Perhaps Go Westy's choice of "Posi" was their way of saying "Grippy Diff". They correctly avoided the term "LSD".

Thu Feb 07, 2013 7:27 am

gears wrote: "Grippy DIff" .. I like it. Perhaps Go Westy's choice of "Posi" was their way of saying "Grippy Diff". They correctly avoided the term "LSD".

Wasn't he (Grippy Diff) on the Andy Griffith show or one of those other '60's TV shows?. I think he is the one who went to jail for selling LSD and tested posi for TBD.

Thu Feb 07, 2013 9:41 am

I think you guys are getting bored. Here are some more pics and scenery with the peloquin.
For me it is the extra places you can go with confidence.
I would not try some of these rough dirt roads alone without a TBD LSD or a diff lock. Alone anyway.

Thu Feb 07, 2013 9:53 am

Very bored :sleeping:

Thu Feb 07, 2013 11:27 am

Christopher Schimke wrote: gears wrote: "Grippy DIff" .. I like it. Perhaps Go Westy's choice of "Posi" was their way of saying "Grippy Diff". They correctly avoided the term "LSD".

Wasn't he (Grippy Diff) on the Andy Griffith show or one of those other '60's TV shows?. I think he is the one who went to jail for selling LSD and tested posi for TBD.

Bad Chris! Muddying up Opie's legacy like that... ;)

Thu Feb 07, 2013 1:01 pm

davevickery wrote: I think you guys are getting bored.

Were some of those shots (around the 10 second mark mostly) of the trail to Knowles Canyon Overlook near Fruita by any chance?

Thu Feb 07, 2013 1:15 pm

Close. Rabbit Valley enter on south side of 70 at exit 2. To the right, the trail crosses over the border into Utah. Cool place, lots of BLM land and free widely dispersed campsites, or just find your own.

Thu Feb 07, 2013 1:15 pm

Really enjoyed the video clips. Way to bring the thread back to what it was intended to be about- getting your 2wd Vanagon out on the the trail and into some awesome places- not a semantics lesson on differentials.
I actually just dropped my 88 Carat weekender off at the shop this morning to have a Peloquin "TBD"! installed on our van. I am excited to have the extra off road traction to get us where we want to go. Really looking forward to some awesome spring back country trips.

Thu Feb 07, 2013 9:19 pm

davevickery wrote: Close. Rabbit Valley enter on south side .

Yep, we been there a few times.
Last time (2009) we decided the Jetta didn't didn't have quite enough clearance any more.

I think the Westy will be dialed-in enough to take it there next spring though. Clearance is the key.