Care & Feeding of a Locked Diff

[S2_ITBVW]

I am happily on my way to Chicago where, among other much less important business/family things, I will be picking-up my tranny with a locked differential. I have zero experience with this and do not want to break anything, so sage advice on the care and feeding of this "configuration" would be much appreciated. What do I need to be careful of in the paddock? What will I need to change on the track?

Thanks!

[joeg]

Don't turn tight...need wide turns to prevent CV breakage.

Normal tranny fluid. The diff is locked so does not require special lubricant.

[JLawton]

What will I need to change on the track?


You'll have much better turn in when you're on the throttle. More push when off. I think big sweepers is where you'll feel the affect the most. You have to feather the throttle a little to keep your bite. I liked a welded diff better than a Torsen or Quiafe. And better traction when you're up on two wheels...... ;)

Baby it when driving around the paddock..........

[Knestis]

In terms of on-track performance, you're going to figure out pretty intuitively how it drives. You'll want to be FULLY on the throttle when it's time, and that's where you get the greatest return for the locked diff.

If you find yourself with any push sneaking into your life, you'll find that turning down toward the apex will haul you that direction. It'll cost you some speed but it will keep you from falling off the outside. If you are inclined to be a curb jumper, you'll get some return from the diff there as well, as the outside tire will keep dragging you around the corner rather than spinning away energy into the air.

Locked diffs have an undeserved reputation for being evil in the wet but I've found if you just let them have their head, they are actually a benefit. If you hit a puddle with one front wheel, it will move laterally a bit but if you don't try to chase it around, it will settle right down when both wheels grip again.

In the paddock, it's particularly easy to get "diff whip" when reversing. Go slow and plan way ahead. Don't use full lock at all when going slow.

K

[shwah]

Turn the wheel as little as possible when backing up. That is when you break outer CVs.

On track, it will be intuitive. Kirk is right on with the early aggressive throttle application. If you need to tighten the line, left foot braking is a good way to tighten it up. In addition to curb hopping, the track is wider when you need it to be. If the car is loaded up in a turn, the inside tires will actually "free up" a bit if you drag them through the grass.

I have not ever broken a drive shaft or CV with the locker.

[Knestis]

You didnt' just tell him to drive in the grass, did you Chris? It's not only contrary to the rules, it's my secret weapon. :)

K

[dhardison]

You didnt' just tell him to drive in the grass, did you Chris? It's not only contrary to the rules, it's my secret weapon. :) K
Uhh, you don't say? :D

http://www.danhardison.com/ITFest2011/2.jpg

[Knestis]

<blushing>

That IS a good picture though, huh?

K

[mossaidis]

yeah... it is.

[shwah]

You didnt' just tell him to drive in the grass, did you Chris? It's not only contrary to the rules, it's my secret weapon. :)

K

If the tire is in the air, it is not in the grass is it?

[shwah]

But yeah...
http://i220.photobucket.com/albums/dd262/chois_photos/ITB%20GTI/BHFaggressiveapex.jpg

Of course the car IS on the course.

[S2_ITBVW]

So, let me get this straight. I need to not turn the wheel a bunch when I back-up in the paddock and, based on the photos, I need to bolt a mower deck onto the bottom of the car??

I learn so much from you folks. I didn't even know VW made lawn mowers?!? :shrug:

[JLawton]

Uhh, you don't say? :D

http://www.danhardison.com/ITFest2011/2.jpg

That is TOO funny!!! I like the grass getting thrown in the air like one of the old style reel mowers!!

[dhardison]

<blushing> That IS a good picture though, huh? K

Come on Kirk, at least be a professional landscaper and blow the clippings off the track when you're done. :D Maybe a rear bumper blower attachment to go along with that mower deck?

http://www.danhardison.com/ITFest2011/5.jpg

[Sandro]

If you thought driving your car on the track was fun before, you will have 10 times as much fun with a locker. First time I came off track with the locker I had a grin from ear to ear for a week straight. You can change what the car does mid corner just by varying the amount of gas you give it. :026::026::026::026:

To get around the paddock, when turning smash the peddle the inside tire will slip and you will turn on a dime. If you just go slow you will end up with a mile wide turning radius.

[jimbbski]

I would think that the only time a locked diff causes problems in the paddock is on the paved part. On grass, dirt, sand, or gravel it should not be an issue. Correct?

[dhardison]

I would think that the only time a locked diff causes problems in the paddock is on the paved part. On grass, dirt, sand, or gravel it should not be an issue. Correct? That's an even better reason for Dave to paddock up on the grassy hill with the "cool kids" vs. down in the lower/paved paddock with all the bad element.... :p

[S2_ITBVW]

We're back. We have the tranny and my crew chief is getting ready to install it. However, he had the funniest look on his face when I told him that we needed to run to our local Cub Cadet dealer to get some additional parts . . .

More importantly, I am beside myself with joy over the possibility that I might get to paddock with the cool kids. Gosh, I'll be more nervous about that than I will be about racing in front of a few thousand fans. GOSH!

As always, thanks for the help. I'm looking forward to trying this thing out.

[Flyinglizard]

Bring some softer rear springs. If the car was neutral before, it will be way loose locked. About 100# less will be close
The locker makes a lot more front grip. Dont know why, just does. The optimal camber may be a little less @ the front also.
Have fun with it. MM

[S2_ITBVW]

That's not at all what I expected. I thought the locked diff would cause the car to push more. My car is neutral to loose now. I thought this change would make it dead neutral. Maybe not.

DE