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Tue Jan 20, 2015 11:40 pm

I plan to have my well-used 2wd Westy transaxle rebuilt prior to an engine conversion (Bostig). I do some logging-road and mountain road driving around New Mexico and have from time to time experienced the drawbacks of 'one-wheel drive' in the winter. I'm thinking about the AA Transaxle Peloquin option. I've read the extensive discussion on the TBD vs LSD thread here and the Peloquin sounds like a worthwhile upgrade for my driving needs.

My question: what are the drawbacks, aside from the cost? Are there frictional losses that show up in the gas mileage? Is there a reliability question? Is there anyone out there in a position to comment from experience?

Thanks.

Tue Jan 20, 2015 11:55 pm

There are no drawbacks and no measurable effect on gas mileage. Audi uses TBD's in centre diffs and in rear diffs of road-going cars that are expected to get good gas mileage. A TBD is not a limited slip differential (LSD) and the confusion sometimes leads people to think TBD's can affect gas mileage the way that LSD's can.

Note that you can actually use a TBD and a diff locker together if you wish.

Wed Jan 21, 2015 12:33 am

There's no real drawback. The van will behave a little differently when you're spinning on ice, but most folks won't experience that!

Wed Jan 21, 2015 5:02 am

I can't speak for others but my gas mileage dropped.

Wed Jan 21, 2015 8:05 am

Brad4 wrote: I can't speak for others but my gas mileage dropped.

Any idea how much? I had AA install a Peloquin at the same time the transmission was being regeared for the TDI. All was installed at the same time, so I have no idea of the effect of the TBD on mpg.

This hasn't come up in past threads which leads me to believe the effects are negligible.

Wed Jan 21, 2015 8:08 am

Not the greatest performance in ice and snow.

Wed Jan 21, 2015 8:31 am

insyncro wrote: Not the greatest performance in ice and snow.

I have the exact opposite view point. With studded tires I now make it to my local ski resort with out losing any traction where before I did. You can't drive like a goon with a lead foot, or the back end will come around. If you adjust your driving style, a TBD is well worth the cost. I also took my van up to a 6000' base camp this fall in varying wet, muddy, rocky and dry conditions where the two suburbans I was traveling were stunned I made it with out 4WD.

Wed Jan 21, 2015 8:45 am

Franklinstower wrote: insyncro wrote: Not the greatest performance in ice and snow.

I have the exact opposite view point. With studded tires I now make it to my local ski resort with out losing any traction where before I did. You can't drive like a goon with a lead foot, or the back end will come around. If you adjust your driving style, a TBD is well worth the cost. I also took my van up to a 6000' base camp this fall in varying wet, muddy, rocky and dry conditions where the two suburbans I was traveling were stunned I made it with out 4WD.

When the vehicle and driver are put into a very dangerous situation, on ice/snow and the driver lifts off the throttle quickly, the vehicle will counter rotate.
Yes, studs help, but many States and tire sellers are trying to talk vehicle owners out of studding tires.

I personally do not think of this transmission upgrade as one I would want seeing the amount of ice and snow that I do.
With that said I drive a Syncro in fowl weather and the OP seems to be in a warm climate.

Just sharing my experience with this product in winter conditions.

Wed Jan 21, 2015 9:27 am

Reck wrote: what are the drawbacks

Welcome to Samba

not much drawback, and TBD in a Vanagon makes a 2wd much more capable on dirt hills and ruts.

limitations: TBD will NOT do anything IF you get a rear wheel completely in the air.

TBD has the potential to dig the rear tires down deeper in sand than an open diff.

TBD has the potential to cause the rear of the van to slip sideways on sideslope terrain that is slippery, more than an open diff.

TBD can NOT be turned off.

Yes I think TBD is a great addition to a 2wd, go for it!

Wed Jan 21, 2015 10:06 am

Everything has positives and negatives. Years ago we were trying to get our vehicles up a wet grassy hill that we had to angle up. The regular 4wd's with open differentials had no problems at all and people with regular 2wd street vehicles could make it up if they gunned it hard enough. The only vehicle that couldn't make it on its own was a Jeepster with a limited slip up front and some form of locker in the back. It just would turn off the hill and end up at the bottom of the slope again no matter what the quite experienced driver tried.

At other times the same Jeepster that couldn't make it up that grassy hill would typically get through mud holes with ease the rest of us would likely end up getting winched through.

Wed Jan 21, 2015 12:58 pm

I am going to revise my comments a bit. The TBD design is not really intended or designed to assist with traction in extreme conditions. The reason is that it biases torque to the wheel with grip, but only if there is some drag on the slipping wheel. So, any case where one wheel is in the air, for example, or one wheel is on ice and the other not, is going to result in no torque going to the wheel with better traction.

On roads, with all wheels on the ground, the TBD can assist a lot in wheel spin situations like hard acceleration starts, heavy throttle in hard cornering, and especially, hard acceleration on wet roads. So, my TBD-equipped Audi S4 gets great wet-road starts (and cornering) as a result of the TBD centre and rear diffs. I agree with Dylan's comments on Vanagons in the snow, but only with low-powered Vanagons. My SVX-powered Syncro will slide the rear all over the place in snow with open diffs with just a bit of throttle (230 horsepower, ya know).

For a 2WD Vanagon, my personal preference for adding off-road and logging road traction would be to add a locking diff. I have experimented a fair bit with my syncro with the front diff de-coupled, but the rear diff locked. It is amazing how much traction the rear locker adds! Even when one wheel is off the ground, the locker helps a lot. But in fairness, the locker cannot be used at all on dry roads, at least not without damaging the driveline. Oh, and it's, expensive to add to a 2WD.

It's a compromise. So the choice will come down to deciding when and where you want to add the traction. The ideal 2WD solution would be a controllable Haldex rear diff, but nobody makes one for the Vanagon AFAIK and it would not be cheap.

Wed Jan 21, 2015 1:50 pm

I don't have experience with the Peloquin TBD, but I would think the parking brake should add sufficient load to the unit for it to function with one wheel off the ground.

Wed Jan 21, 2015 1:56 pm

AA installed a TBD in our 2WD in 2012.

Have noticed better handling in day to day driving, and definitely more traction/stability in mud, rough ice, and snow. Good Yoko Geo tires (not studded).

Can't comment on MPG because we had a Suby 2.5L put in at the same time.

It wasn't cheap, but a good mod and I'm glad we have it.

Mon Jan 26, 2015 5:14 pm

Hey, welcome to the Samba! I've seen a lot of Westies around Santa Fe the last few weeks, which one is yours? Mine is the white/yellow one...

Just for information for the rest, Santa Fe is at >7000ft. There is snow off and on from October to May, mountains to 13,000ft on the north and classic southwest desert at 5000ft to the south, each less than an hour away.

I found this thread 'cause I'm thinking about the same thing: locker, Peloquin, LSD or "mini-locker". Most of the camping is on dirt/sand/mud/some snow, but there is often enough snow on the pavement to NOT WANT something that makes driving on that more dangerous.

Mon Jan 26, 2015 7:19 pm

I had mine out the other day in some snow. If I were buying one, I would get the one with the locking option. To buy just a TBD for a Vanagon is a waste in my opinion. There is some benefit but parts and labor do not equal a good bang for the buck to me. I have a Syncro with front and rear TBD. I much prefer my other Syncro with front and rear diff locks. When I had my two wheel drive Westy a diff lock would have helped me where my current $yncro decoupled with TBD is not much better then my previous 2wd open diff in steep low traction rutted terrain. As long as you keep momentum the TBD does help you out but not that much. When running baja style, or high horsepower car on asphalt, a TBD does wonders.

Tue Jan 27, 2015 9:04 am

I like mine. Helps on wet inclines, silent and out of the way the rest of the time.

Stephen

Tue Jan 27, 2015 10:28 am

I absolutely love my Peloquin! I no longer get stuck on slight inclines with wet grass and snow is a breeze to drive in, not to mention loose, gravelly hills.

Yes, its snappier on glare ice if you lift off the throttle suddenly but you can learn to control that pretty easily.

Tue Jan 27, 2015 12:05 pm

Sounds like we can have a little Vanagon meetup in Santa Fe.

Tue Jan 27, 2015 12:12 pm

Oh, so that's YOU in the orange two-tone? I think the only place I've seen more Vanagons/Westies than here is Santa Cruz... A spring meet-up would be nice, maybe a new thread.

Tue Jan 27, 2015 12:25 pm

Yeah that’s me, but officially its brown not orange. Assuan Braun, to be Germanlike about the nomenclature.

BTW, I have a transmission in the shop (Mr GAS) in Colorado Springs getting rebuilt and am also weighing the advantages of a TBD. Can’t speak from experience but after following this discussion I think I’ll go for it.