Gripper Limited Slip Technical Thread

[airsweden]

30 sounds good!

If they are to be shipped to you (Jennifer) just let us know where to send the appropriate payment to cover the washers and mail forwarding.

Thankyou

[allessence]

Hello, I have emailed Tom and asked for 30 washers. Luke asked that I give Tom Lukes address so the stuff could be shipped to Lukes since he needed the out drivers asap.


I haven't heard back yet. I'll give you guys the update once I hear anything.

[TheAlien1980]

I red through almost all posts of this thread, but I fail to understand what you guys are trying to do here. Why not just use a quaife LSD ?


offtopic:
Who in god's name can read stuff like this ???? I so hate these registering forms. Took me for ever to register here.

[Jordan]

I red through almost all posts of this thread, but I fail to understand what you guys are trying to do here. Why not just use a quaife LSD ?

A quaife is a torque sensing type LSD and is not really used that much in rally as it only transfers power to one wheel if the other wheel has some sort traction. For slippery surfaces ,a clutch-type LSD is much more effective and probably easier to drive. Torsen difs seems to be better suited for pavement. They just work completely different. The other benefit of a clutch type is that if damage one side of the drivetrain, axle shaft, cv, wheel etc, you should be able to keep driving.

offtopic:

Who in god's name can read stuff like this ???? I so hate these registering forms. Took me for ever to register here.

4UE77RXM?

[Luke]

If you are green/red color blind I could see that could be a hard one, but not too bad otherwise.

[TheAlien1980]

Interesting. Thanks.
So with a gear type LSD the wheel that has 0 traction "receives/wastes" all the power ?
I wonder how important that really is in a fast rally. I mean we are not talking about slow 3mph hill climbs in 4x4, right ?
OT:
Probably just my screen then that produces colors that are a tad of... No chance to get it right, and I am not color blind.

[Crazyswede]

Interesting. Thanks.
So with a gear type LSD the wheel that has 0 traction "receives/wastes" all the power ?
I wonder how important that really is in a fast rally. I mean we are not talking about slow 3mph hill climbs in 4x4, right ?
OT:
Probably just my screen then that produces colors that are a tad of... No chance to get it right, and I am not color blind.

The gear type requires that both wheels be in contact with the ground....a properly setup clutch type does not care if one wheel is off the ground or not. In loose terrain this is preferable. Both are better then an open diff.

[DrewP]

The portion of torque that a diff can send to a single wheel of the total torque is referred to as Torque Bias Ratio, or TBR. The TBR determines how much torque can be sent to one wheel or the other before that wheel starts to spin.

The lesser-laden wheel will start to spin when the torque sent to the wheel exceeds the traction at that wheel.

With a TBR of 4:1 a diff supplied with 100 lb-ft can send as much as 75 lb-ft to the wheel with more available grip as long as the unladen wheel can transmit the 25 lb-ft. If the unladen wheel can only support 15 lb-ft, it will start slipping. Even though the wheel is slipping, it may still be able to transmit 15 lb-ft, in which case the laden wheel will still receive 45 lb-ft of torque, for a total 60 lb-ft transmitted of the supplied 100 lb-ft.

Open diffs usually have small slightly positive TBR's, something like 1.1:1 or 1.2:1 is common.

Torque-sensing / torque-biasing helical diffs (Quaiffe and Torsen) usually have TBR's in the 3:1 - 5:1 range and not much more than that.

Clutch pack / Salisbury diffs can have very high or even infinite TBR for at least some torque transmitted because they are usually pre-loaded to be completely locked up to some level of torque transmitted. Up to say 50 lb-ft the diff is completely locked, until it has to allow some slip, and then will revert to whatever TBR is built into the unit.

Some cam-and-pawl diffs can be set up like a clutch-pack but usually don't differentiate as smoothly, but they are cheaper.

The advantage of torque sensing helical diffs is that when you release the throttle or under small throttle openings the diff is essentially 'open' and the two driven wheels can spin freely at different speeds, so that under braking or coasting around a corner the wheels don't tend to 'lock' like a Salisbury, which in a road car can cause the car to feel like it doesn't want to turn (with a RWD car it will add some understeer, with FWD it will add oversteer).

That same issue is an advantage on slippery or rough surfaces because you can transmit more total torque to the ground with one wheel off the ground or over bumps, or like Luke mentioned, if you break a drive component on one side, not a likely occurrance on a road car.

Clutch pack diffs also generate a lot more heat, and usually require special lubricant.

In several types of LSD's you can tune the TBR by swapping components and materials, and can fine tune a small amount with lubricant selection.

Best,
Drew

[TheAlien1980]

Interesting stuff.
I have a quaife. Not adjustable, correct ?

[Crazyswede]

Interesting stuff.
I have a quaife. Not adjustable, correct ?

correct

[allessence]

I use mine on the street just about everyday, and I have to say it rocks. Only time there is a problem is when you are trying to hook up when you have one tire in the dirt (snow, sand ,etc) and one on the pavement.

The one on the slippery stuff doesn't do much but the one on the pavement does it's best to push the car off line since it is getting more grip.

As to sharp corning, J turns etc. the clutch/plate type is far superior since even with one tire up in the air you still can put power down to the road.

With the Quaiffe gear type you still end up with no drive power till the tire comes back down.

I've also found this to be problematic when on really slippery stuff like glare ice. With the Gripper diff, doesn't make a bit of difference. More power applied, tighter the plates lock.

[allessence]

heard from Tom today. They just got back from holiday so will be getting the needed parts up and going sometime this week.

[Luke]

Update!

22 washers and the spare driver arrived last week, they look the same to me as the old ones dimensionally, but they could have different metalurgical properties I suppose.
I will bring them to Black River this weekend so Geoff can grab some, if anybody needs some sent right away just let me know. Otherwise I see most everyone that has one at least a few times a year so I can hand deliver...
We should definatly thank Tom, definatly went out of his way to get these to us and didnt charge a dime.

[Geoff]

cool!
Tom's email address for thanking: dreng@dsl.pipex.com (or has it changed?)

Yeah, I'll pick mine up this weekend. You can also give Seth his and Seth might be able to get Chris R.'s set to him.

[allessence]

its changed. dreng21@gmail.com is the current affair.