I attended the Performance Racing Industry (PRI) show in December and enjoyed walking the floor and hanging out with Mesa, builder of the first SL-C, and Hill McCarty, owner of Agile Automotive. I spent a lot of time looking at, photographing and actuating the sliding pedal box in the AP Racing booth to figure out how it worked. It was a nice design, but it would raise the pedals too high so I wasn’t able to apply their approach to my design for the SL-C. I think the sales guy was convinced that I was going to pay the booth a late-night visit and steal it.
I was tempted to purchase one of the CNC mills in Machinery Row, but NFW would something that big go unnoticed by my better half! I resisted all major purchases until the afternoon of the final day… and WHAM-O a bodacious booth babe caught my eye… slender, curved in all of the right places and lots of billet!
The bodacious booth babe… slender, curved in all of the right places and lots of billet!
The Albins ST6-M was one of those things that I couldn’t unsee. I called Hill to ask him about it and he agreed to meet me at the booth. Apparently he’s had great success running them in several endurance SL-Cs.
After purchasing a ST6-M from Agile, Hill moved to the top of my wife’s shit list and she’s trying to introduce me to some new friends who aren’t into building cars. I sent the deposit just as Covid was beginning to spike outside of China, so I don’t have a good idea as to when mine is going to arrive.
You don’t see sequential transaxles in many street cars because the straight-cut gears whine, they’re not cheap and they often only shift well when aggressively driven, something only an idiot would do on the street with a high-powered SL-C. Hill indicated that, if properly tuned, shifts can be smooth even on the street.
I was concerned about how loud the gear whine would be so I flew down to Maryland to listen to Raver Motorsports’ SL-C running on the dyno. It has a loud race exhaust which would make it difficult to judge how noticeable the gear whine would be on a street car. To address that issue I brought a couple of street mufflers and Hill used V-band clamps to attach them to the tips of the race exhaust. Guess what, the exhaust was still pretty loud ;-)
Smartphone videos never seem to capture the sound properly…
I invited Pnut to the audition and his opinion was that the sound wasn’t nearly as loud as he thought it would be and that it would be “fine” on a street, but that ear plugs might be a good idea for a long drive. He thought we were doing some automotive-buddy-bonding, which we were, but I had a second, unspoken, and nefarious motive which I can summarize in two words — plausible deniability. When my wife goes for the first ride and asks WTF that noise is I will tell her “Pnut suggested that I go to PRI, thought that the Albins would be a good idea and certified that it wouldn’t be too loud”… I think that might move Pnut from #2 on her list to #1.
The Albins has a bunch of benefits:
Lightweight — it only weighs 180 pounds which to my understanding is 27 pounds lighter than a Graziano, 87 pounds lighter than a Ricardo and 161 pounds lighter than the C8’s transaxle. Reducing weight in this area helps balance the car. The only worst place to have excess weight would be to bolt something to the duck tail.
Lightning fast gear shifts, particularly when actuated by a pneumatic shift servo. The Raver Motorsports SL-C is tuned to shift in 40ms. I’ll have a more mild tune for the street and a similar aggressive tune for the track.
Roller Barrel Selector Mechanism which is pretty much the gold standard for motorsport gearbox change mechanisms.
Drop gears can be easily changed in less than 10 minutes. Simply jack the rear of the car up to prevent the oil from draining out, remove the 10 nuts on the rear cover plate and swap the gear out. The plate is sealed with an O-ring so there is no messing around with sealants or gaskets.
Robust: Albins keeps upping the torque specs, but their current rating is 1,100NM of continuous torque in off-road racing (i.e., extended WOT runs, jumping, etc.). I’m also aware of several 2,000+ HP twin turbo cars in the works, so I don’t expect any issues.
Eight large inspection ports enable monitoring of the shifting gears, ring gear, differential and pinion. Each inspection port is held in place with a single screw and is sealed with an O-ring.
It can be rebuilt while installed in the car. Everything is splined and easy to remove/install without a press, puller or any special tools. The only exception is the pinion bearing which is an interference fit and requires heating of the housing to remove, but it’s not part of a standard rebuild.
The drive flanges align well with the SL-Cs wheel hubs. This, combined with the narrow case, results in long axles which reduce the angle of the CV joint. The puts less stress on the CV joints compared to the Ricardo and the Graziano, especially the asymmetric right side which is shorter to accommodate the front-wheel driveshaft which isn’t used in the SL-C.
Integrated oil pump.
The billet bell housing mounts directly to an LS engine obviating the need for an adapter plate.
Albins stocks a range of drop gears, but I’ll start with two, one for the street and one for the track.
Hill had a damaged front case left over from a 130 MPH crash — the SL-C did it’s job and the driver walked away. He sent it to me for fitment purposes and it’s downright skinny compared to the Ricardo. Note that the starter flange is inboard of the hole in the stock adapter plate bracket. This provides a lot more space for the exhaust. While not apparent in the picture, the ST6-M sits further above the bottom of the car than most transaxles which, with proper heat shielding, provides enough clearance for a 3” round X-pipe between the bellhousing and the rear billet cross member. If I were racing the car the combination of the Daily Engineering dry sump pan and the Albins would allow the engine to be dropped about an inch.
It is a bit long and I estimate that it will project about 1/4” past the “SL-C” logo molded into the street tail (I only have the front half of the transaxle, so I won’t know for sure until I get it). This isn’t a big deal for me because I’m completely reshaping that section of the tail.
I’m going with paddle shifters and a pneumatic shift servo. More about that later.