Simple, light, attractive... just a few of the reasons why this 1 5/16" (33.3mm) threaded Spidertrax Filler Cap assembly is a great solution for custom off-road builds. Our Spider engraved 6061T6 billet aluminum filler cap has an o-ring seal to keep oil where it belongs and keeps the filler cap from loosening up. In addition, our double anodize protection will keep your filler cap from corroding even in the harshest terrain. Our weld-in steel sleeve has a large 1 5/16" (33.3mm) diameter opening making filling easy. Our Spidertrax Axle Filler Assembly Kit contains one steel sleeve, aluminium cap, and o-ring.

In the spirit of everything getting bigger in the world of Ultra4 racing... we are very excited to release the Spidertrax 2 1/4" (57.2mm) Thread Aluminium Fill Cap & Steel Bung Assembly. As the title gives away, this massive 2 1/4" (57.2mm) opening lets you easily peak inside the axle housing, great for gear inspect and easy filling.

CNC machined from billet 6061T6, the Spidertrax cap is both sexy and held to high tolerance. A stepped shoulder on the cap makes threading quick & easy, and the larger outer filler cap indents provide a comfortable grip. Assembly comes complete with aluminium cap, steel bung, and o-ring.

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Protect the underside of your Spider 9 housing with our Spider 9 Housing Skid Plate. This laser cut, CNC formed, 4130 heat treated 3 piece skid plate provides superior underside protection. At .120 thickness, we're keeping the weight down with minimal compromise to ground clearance as well.

This skid plate is designed specifically for 3½" 88.9 Ultimate & Pro Series Spider 9 Housings.

Protect the underside of your Spider 9 housing with our Spider 9 Housing Skid Plate. This laser cut, CNC formed, 4130 heat treated 3 piece skid plate provides superior underside protection. At .120 thickness, we're keeping the weight down with minimal compromise to ground clearance as well.

This skid plate is designed specifically for 4" 101.6mm Ultimate & Pro Series Spider 9 Housings.

Strengthen your inner Ultimate and Pro Series Knuckles with our Knuckle Gussets. These laser cut, CNC formed, 4130 gussets provides superior strength without compromising weight.

These gussets are designed specifically for 3½" 88.9mm Spider 9 Housings running Ultimate or Pro Series Knuckles. These gussets are not heat treated. Spidertrax recommends the heat treated option for all rock racing and competition based applications.

Strengthen your inner Ultimate and Pro Series Knuckles with our Knuckle Gussets. These laser cut, CNC formed, 4130 gussets provides superior strength without compromising weight.

These gussets are designed specifically for 3½" 88.9mm Spider 9 Housings running Ultimate or Pro Series Knuckles. These gussets are heat treated. Spidertrax recommends the heat treated option for all rock racing and competition based applications.

Strengthen your inner Ultimate and Pro Series Knuckles with our Knuckle Gussets. These laser cut, CNC formed, 4130 gussets provides superior strength without compromising weight.

These gussets are designed specifically for 4" 101.6mm Spider 9 Housings running Ultimate or Pro Series Knuckles. These gussets are not heat treated. Spidertrax recommends the heat treated option for all rock racing and competition based applications.

Strengthen your inner Ultimate and Pro Series Knuckles with our Knuckle Gussets. These laser cut, CNC formed, 4130 gussets provides superior strength without compromising weight.

These gussets are designed specifically for 4" 101.6mm Spider 9 Housings running Ultimate or Pro Series Knuckles. These gussets are heat treated. Spidertrax recommends the heat treated option for all rock racing and competition based applications.

Strengthen your Spider 9 housing with our Spider 9 Truss. This laser cut, CNC formed, 4130 truss provides superior strength with virtually no compromise to ground clearance. At .120 thickness, we're keeping the weight down as well.

This truss is designed specifically for 3½" 88.9mm Ultimate & Pro Series Spider 9 Housings with a Ta/Tb range of 21"-29" 533.4mm-736.6mm. This truss is not heat treated. Spidertrax recommends the heat treated option for all rock racing and competition based applications.

Strengthen your Spider 9 housing with our Spider 9 Truss. This laser cut, CNC formed, 4130 truss provides superior strength with virtually no compromise to ground clearance. At .120 thickness, we're keeping the weight down as well.

This truss is designed specifically for 4" 101.6mm Pro Series Spider 9 Housings with a Ta/Tb range of 21"-29" 533.4mm-736.6mm. This truss is not heat treated. Spidertrax recommends the heat treated option for all rock racing and competition based applications.

Strengthen your Spider 9 housing with our Spider 9 Truss. This laser cut, CNC formed, 4130 truss provides superior strength with virtually no compromise to ground clearance. At .120 thickness, we're keeping the weight down as well.

This truss is designed specifically for 3½" 88.9mm Ultimate & Pro Series Spider 9 Housings with a Ta/Tb range of 21"-29" 533.4mm-736.6mm. This truss is heat treated.

Strengthen your Spider 9 housing with our Spider 9 Truss. This laser cut, CNC formed, 4130 truss provides superior strength with virtually no compromise to ground clearance. At .120 thickness, we're keeping the weight down as well.

This truss is designed specifically for 4" 101.6mm Pro Series Spider 9 Housings with a Ta/Tb range of 21"-29" 533.4mm-736.6mm. This truss is heat treated.

The Spidertrax High Performance Inboard Oil Seal Kit is the perfect solution for sealing up your Spider 9 housing. We start with billet 6061T6 and machine a fully rebuildable seal housing that accommodates three external o-rings and two high performance axle shaft seals (both o-rings & seals are pre-installed). With up to five total sealing surfaces, this kit ensures oil stays where it belongs, inside the housing. Seal is designed to install on the inboard side of your Spider 9 (installs near your diff).

Please note, this Inboard Double Seal works with ALL Spider 9 housings LESS our legacy 3" 76.2mm OD x 3/8" 9.5mm wall Spider 9. If you are in need of an inboard seal for this legacy housing, please click on the Contact Us tab located on the bottom of this page and we'll be happy to help you out.

This is the same seal housing as the 40-45 spline version but with a smaller seal (SLIINSERT).

Inboard Seal
for 40-45 Spline Shafts

The Spidertrax High Performance Inboard Oil Seal Kit is the perfect solution for sealing up your Spider 9 housing. We start with billet 6061T6 and machine a fully rebuildable seal housing that accommodates three external o-rings and two high performance axle shaft seals (both o-rings & seals are pre-installed). With up to five total sealing surfaces, this kit ensures oil stays where it belongs, inside the housing. Seal is designed to install on the inboard side of your Spider 9 (installs near your diff).

This is the same seal housing as the 35-40 spline version but with a larger seal (SLI120).

The Spidertrax Inboard Seal Housing Rebuild Kit is designed to completely rebuild your Spidertrax in-board seal housings. Each rebuild kit comes with 2 seal inserts, 3 o-rings, and a new seal retaining set screw.

Please note, this rebuild kit is designed specifically for Spidertrax model no. SLI212D.

The Spidertrax High Performance Outboard Oil Seal Kit provides an easy and clean solution for installing seals on the outboard side of your Spider 9 housing (wheel side). Each kit comes complete with steel seal housing and two rubber seal inserts. Steel seal housing is designed to be welded in place.

The Spidertrax High Performance Outboard Oil Seal Kit provides an easy and clean solution for installing seals on the outboard side of your Spider 9 housing (wheel side). Each kit comes complete with steel seal housing and two rubber seal inserts. Steel seal housing is designed to be welded in place.

Designed around NASCAR technology, this stretchy Seals-It brand seal insert performs like no other seal around. This one insert will work with shafts of diameters up to 40 spline and will keep oil where it belongs, inside your housing.

These seal inserts are designed to be installed in the Spidertrax High Performance Oil Seal Kit.

The Spidertrax Spider 9 ARP 3^rd member bolt kit come with ten ARP studs, ten 3/8-24 Grade 8 Nylok hex head nuts and stud installation hardware.

Please note, this 3^rd member bolt kit works with all Spider 9 housings with press in style studs. If you are in need of screw in style studs for our legacy housings, please click on the Contact Us tab located on the bottom of this page and we'll be happy to help you out.