Garage

Customer Service Center

Talk to an expert at RANDYS:

1-866-631-0196 Live Chat

Shop by Category Shop all

Shop by Diff Shop all

Calculators

Warranties

Knowledge Center

Our Company

Shop by Category

Shop by Diff

My Account
Hello, Sign In

Customer Service Center
Talk with an expert at RANDYS:
1-866-631-0196 Live Chat
- Returns
- Policies

Spartan Helical Limited Slip Diff - positraction | RANDYS Worldwide

Name: SL D30-4-27-LSD
Brand: USA Standard Gear
SKU: SL D30-4-27-LSD
Price: 420.71 USD
Availability: InStock

Spartan Helical LSD Worm Gear Limited Slip Differential, Dana 30 Front 27 Spline

Product Details

The Spartan Helical LSD’s helical-cut worm gears seamlessly funnel torque to the tire with the best grip. Its 10-pinion design is stronger than 6- or 8-pinion units because it has more points of contact to deliver optimal load distribution.

Fits Dana 30 front differentials
27 spline
3.73-and-up ratio
Forged 8620 steel alloy case and internals for superior durability
Recommended gear oil: Non-synthetic 80W-90 GL-5
Use of friction modifiers not recommended
Maintenance free, no worry performance
Smooth engagement and linear traction

Technical Notes

Warranty Information

Warranty information unavailable

Compatible Make / Model

Compatible Differentials

Specification

Brand	USA Standard Gear
Prop65 Warning	WARNING: This product can expose you to chemicals including arsenic, which is known to the State of California to cause cancer. For more information, go to www.P65Warnings.ca.gov.
Keywords	27spl,3.73,30,D30,DANA,DIFFERENTIAL,GEAR,GRIP,HELICAL,LIMITED,POSITRACTION,SL,SLIP,TT,UP,WORM
UPC	883584103837
ProxyNumber	10383
Width	9.00 in
Length	9.00 in
Depth	9.00 in
Weight	14.0000 lb

FAQs

The primary function of a limited slip differential (LSD) is to effectively distribute torque as needed. During regular driving conditions, a positraction LSD is engaged, ensuring equal traction is provided to both wheels. However, when the throttle is aggressively pressed, tight corners are taken, or when navigating through loose gravel trails, the LSD kicks in to limit wheel spin across the drive axle. It achieves this by allowing the axle shafts to spin at different speeds while continuously attempting to balance the distribution of torque between the two axles. Consequently, power is transferred to the wheel that has the best traction, thereby improving grip, control, and overall predictability of the vehicle.

Learn more about limited slip differentials in our How It Works blog article here.

Watch our “Are Posis Worth It?” video to get more info about limited-slip differentials.

Are Posis Worth It?

When traveling in a straight line where wheel speeds are identical on both sides, all LSDs continuously provide equal traction to both tires. The difference between LSD types has to do with how this occurs and what happens when additional traction is needed.

In a clutch-type unit, the spring array applies pressure to the side gears which puts pressure on the clutch packs in the outer part of the carrier. Both axles get equal pressure and both tires get equal traction. When a tire starts slipping, the clutch packs are engaged with different resistance. The clutches work to maintain synchronization between the tires, transferring more torque to the tire that has the best grip while reducing torque transfer to the tire that has less grip.

A gear-type LSD has no frictional surfaces to initiate torque transfer. It uses floating helical-cut worm gears that operate in pockets and mesh together. Under normal driving conditions this type of LSD acts like an open diff. When acceleration or wheel slippage occurs, axial and radial thrust is applied to the helical gear pinions in their pockets. Under these loads, more torque is transferred to the tire with the best traction in a progressive manner as torque is withheld from the tire that is slipping.

Yes. Your ride will drive better than ever because both wheels will receive traction. When things get hot the Spartan Helical LSD will limit wheelspin across the drive axle by permitting the axle shafts to spin at different speeds while continuously trying to balance the application of torque between the two axles. This results in transferring more power to the wheel with the best traction. This improves vehicle control and performance. Mashing the throttle, taking a tight corner aggressively, or working through loose gravel or challenging sections of trail will actuate the unit’s gear array to increase your traction.

Get for more information on the Spartan Helical LSD and LSDs in general in our Stengths & Advantages Of The Spartan Helical LSD blog article.

Some are, some aren’t.

Clutch-type LSDs, like our Dura Grip, can be rebuilt. Rebuilding involves replacing the clutches in the unit. The clutches can be replaced to bring the unit back to its original performance level, or non-stock clutches with different friction characteristics and springs with custom compression rates can be used to fine tune the Dura Grip’s performance to better match the style of driving/racing you are doing.

Gear-type LSDs, like our Spartan Helical, do not require rebuilding because there are no clutches to replace, there is nothing to rebuild. The unit’s internal worm gears should last the life of your vehicle.

Using non-synthetic 80W-90 GL-5 will produce optimum performance in our Dura Grip clutch-type units.

Learn more about LSD oils, and drivetrain lubrication in general, by watching our “Tech Talks, Oils and Additives” video.

Tech Talks, Oils and Additives

First, this product is for clutch-type differentials only, not gear-driven limited slips like our Spartan Helical LSD. Friction modifiers are all about chatter. They guard against abnormal clutch engagement and/or disengagement (source of the chatter), ensuring the proper friction characteristics between clutch discs are maintained.

For a normal, daily driven, vehicles we advise that you change the differential oil every 50,000 miles. For vehicles that are hard worked, such as trucks that do a lot of heavy towing, we advise that you change the differential oil every 15,000 miles.