When it comes to drives for my 1400 HP gas turbine, I can count the choices on one hand. Very few will stand up to the torque of a T-58 turbine.

Simple and reliable, Arneson Surface Drives are absolutely bulletproof! Featuring a bronze thrust tube and 2" stainless shaft, this monster is rated to handle 1400 HP.

These are the 'before' photos my Arneson ASD8. This particular ASD8 drive unit was manufactured in 2000 by Twin Disk. This Twin Disk ASD8 surface drive is identical to the Arneson ASD8 bronze inline surface drive.

Weighing under a couple hundred pounds fully installed, the Arneson Drive (ASD8) features a full 40º of steering swing and allows the operator to power trim up to 15º while making power and underway.

Here's the trim pump, associated lines, and some wiring.

It's obvious all the components (including these Twin Disk steering and trim cylinders) are engineered for reliability in high performance and extreme applications.

Here's the stainless steel hardware, backing plate, and drive-line. This Arneson ASD8 was the one part of I was very concerned about being able to locate (within my budget). You just never see these available used (unless they are incomplete or garbage).

I really 'lucked out' and found this entire package for sale locally. It had only been run for a couple seasons and was removed because the increased speed caused the hull to 'porpoise' more than the owner felt comfortable running with. The seller even included several pieces of optional equipment; Char-Lynn helm pump and engine-driven power steering pump.

After I removed the old boot, I performed some minor corrosion control and sprayed the exterior of the drive housing with clear lacquer.

Next, I tapped the threads in the forward end of the housing to ensure re-assembly goes smoothly.

I stopped by the local Marine Store and picked up some new packing. It was like stepping back in time about 75 years. They've got boat loads of old marine parts and supplies from yesteryear (both new and used).

Here's my new boot that just came in from Pacific Surface Drives

The new boot gets slipped over the end of the drive tube (actually I had the wrestle it on there).

Here's the ASD8 ball. After only a couple seasons of use, it showed no signs of wear and cleaned up real nice.

Slip the ring nut on then the ball gets bolted back onto the drive tube.

The notches in the back of the ball line up at the top and bottom (to allow lubricant to flow through into the tail housing).

Be sure to properly torque the bolts.

The boot is pulled back to allow access to work the ring nut.

I cleaned all traces of the old gear lube out of the socket and inspected it. The double cardan universal joint also showed no signs of wear.

These four nylon rings go between the nut and the ball.

I supported the drive tube with my hoist and assembled it vertically. After inserting a ring of packing and the O-ring, I carefully lowered the ball into the socket. Here I'm putting the outer ring of packing in place. Next the four nylon rings get put in place and the spanner wrench will be used to tighten the ring nut.

Now we have a new Surface Drive. After it gets mounted on the transom, I'll re-torque the ring nut,
plumb the reservoir, and service it with 80-90W gear lube.

Here's my ASD8 steering cylinder after I 'went through it'. All the corrosion was removed, seals checked, the brass fittings were replaced with stainless, and the rubber hydraulic hoses were replaced with stainless steel braided aircraft lines. Clear lacquer will help keep it looking good.

The last of my stainless fittings finally arrived, so I was able to get my ASD8 trim cylinder assembled also.

Now all the rubber hoses have been replaced with high-pressure stainless steel braided aircraft line to ensure long life and high reliability.

My Arneson Drive came with an Osborne 22 x 28 prop that had been well taken care of (and cleaned up pretty nice). This prop is the correct pitch for my boat and is a little larger diameter than the experts think I'll need. It's perfect for testing, then I'll have some real data to work with. I hope to be testing on the water early next summer.

I'm told I'll need a Rolla 16 X 28, 5-bladed surface piercing prop, but I want to gather some 'hard data' by completing my on the water testing before I invest the money. Howard Arneson gets 120+ mph out of his T58 powered Skater 32' and I estimate my Cobra will be just about 1,000 lbs. lighter. Based on his results, I believe 125 mph is within reach (after I get everything dialed in with the correct prop). Only time will tell.

I began the process of 'dry fitting' my Surface drive.

My transom turned out so nice I I really hated to drill into it.

Now my Arneson ASD8 surface drive is mounted.

Next, I'll set the gas turbine in place and measure the drive line

Once I get hydraulics hooked up, the trim cylinder will hold the drive up.

After the drive line is fabricated, I'll locate the engine and design motor mounts.