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Spool 100 % locked diff

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Spool 100 % locked diff

Postby naylon » Sat Oct 15, 2016 2:09 pm

Spool in differential:

Drag only car with limited slip differential. Limited slip has 4 discs and 4 metal plates. Brakeaway torque is set to 150 lb-ft (20,7 kg).

Tracks have no preparation. 28" slicks on all 4 corners, as it is an all wheel drive car.

At around 50 mph and 60 mph one of the rear wheels spin much faster than the opposite rear wheel. @ 60 mph power is 1200 @ wheels.

Option A: Keep LSD but Increase brakaway torque from 150 lb-ft to 200 lb-ft.

Option B: Remove limited slip and put a spool, 100 %.

Car is drag only. Will it be difficult to correct the car in case the back of the car goes loose?

What are the pros and cons of a spool?
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Re: Spool 100 % locked diff

Postby MadBill » Sat Oct 15, 2016 10:47 pm

1200 HP, that's serious grunt!
As is common on S/T, you ask a simple question but get a short essay instead of an answer:
Can you increase the RR corner weight to load the tire more?
Probably easiest to just up the breakaway torque, but if not, why not go with a Detroit Locker instead of a spool? It locks up like a spool under straight line power, but ratchets to allow you to turn without chattering tires or risking a broken axle...
Felix, qui potuit rerum cognscere causas.

Happy is he who can discover the cause of things.
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Re: Spool 100 % locked diff

Postby naylon » Sat Oct 29, 2016 3:43 pm

Installed spool, went to track. Car is much stable off the line till 330 feet.

But there still is some unhappy acceleration meaning that the car is not like a straight arrow.

Went to wheel alignment after track, both of the rear wheels are misaligned, TOE and CAMBER are found to be wrong.

Moreover, corner weighed and found out the following:

Right rear tire 837 lbs
Left rear tire 753 lbs

Do the corner weights tells us something?
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Re: Spool 100 % locked diff

Postby John Wallace » Sat Oct 29, 2016 5:49 pm

Here are some calculators by Billy Shope:

Calculators

Haven't heard from Billy in a while?

:?:
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Re: Spool 100 % locked diff

Postby naylon » Sun Oct 30, 2016 4:01 pm

John Wallace thank you.
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Re: Spool 100 % locked diff

Postby MadBill » Sun Oct 30, 2016 4:15 pm

naylon wrote:...At around 50 mph and 60 mph one of the rear wheels spin much faster than the opposite rear wheel.


Which wheel? in a conventional RWD solid axle car, torque reaction unloads the right rear and so drag cars can have the RR weight increased to compensate. On the other hand, if yours, as it appears, is an independent rear this reaction force is resisted by the the differential mounts and the light LR weight could be causing it to spin more.
Felix, qui potuit rerum cognscere causas.

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Re: Spool 100 % locked diff

Postby joe 90 » Sun Oct 30, 2016 6:39 pm

Adjust the tyre pressures?
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Re: Spool 100 % locked diff

Postby MadBill » Sun Oct 30, 2016 7:36 pm

John Wallace wrote:Here are some calculators by Billy Shope:

Calculators

Haven't heard from Billy in a while?

:?:


There's a phone # (407) 385-5470 on his site: http://www.shopeshop.org/
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Re: Spool 100 % locked diff

Postby pdq67 » Fri Nov 25, 2016 8:29 pm

Don't have a clue here but I would look into Detroit Lockers! And the mini-lockers like it.

Or those worm gear drive posi-trac jobbers...

Right, pre-load the chassis so that all corners plant the same by T&T.

I hope this is of help??

Personally I like the 12- bolt Eaton clutch posi, but can it be, "disc/plate", or shimmed enough to hold your power levels?

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Re: Spool 100 % locked diff

Postby jacksoni » Sat Nov 26, 2016 8:12 am

Are tire diameters the same static and at speed? How much do they grow?
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Re: Spool 100 % locked diff

Postby pdq67 » Sat Nov 26, 2016 6:56 pm

^^^^^^^^^^^^^^^^^

Good point, jacksoni!!

Same batch new tires all the way around?

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