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January 1st, 2022 forum post:
This build diary is the continuation of the thread “Sum's Salt Bullet....Lakester....” I purchased the project from Sumner and picked it up September 2022. Years ago I remember seeing his build thread and thinking it was the perfect layout for fast and stable lakester and I'm excited to continue it. I like the lakester class for the open construction rules and relative safety compared to other classes. Specifically, I like the wider track width than streamliners; yet purpose built aerodynamics and suspension not constrained by obstacles baked into the original vehicle as it had to be built by the manufacturer. Lakesters can also run big tires and do “testing” and other activities over here on the east coast on shorter courses.
My only land speed credit to date is a 103mph electric record at the Ohio mile back in 2013; though I've rebuilt several other cars and boats from piles of parts and had the good fortune to crew on several 200mph+ LSR teams. My priorities with the lakester are to get it moving under it's own power with the simplest means possible that won't drastically compromise the general design. Sumner had a few iterations for the powertrain throughout the years. As the car was purchased, it was configured for chain drive like a motorcycle powerplant to a Datsun differential and with independent rear suspension.
I think that the clearest path forward is cutting the rear suspension off, lengthening the rear of the car 18+” to accommodate the car style drivetrain, and converting to a solid axle mounted rigidly to the chassis. The front TTB style suspension will remain intact, but will be moved 12” rearward. I will use coilovers to save space from the separate spring/shock design as originally built which will make room for the fire suppression bottles up front. Moving the front “axle” rearward should help to move the center of gravity relatively forward which should help CP/CG. Additionally it should delete several sq. ft of surface area contributing to skin friction.
One of the unique things about this car is the side pods taking space between the axles. I originally thought that I would scrap the side pods and just fair the axles shorter. After more consideration of packaging and the potential of the shape with a rigid rear axle, I think the side pods are worth keeping. There will have to be modifications to the aluminum tanks to keep an orderly profile and stay within the track of the wheels.
The car is only 23” at the widest behind the shoulders. Using a Small Block Chevrolet or 90*V engine would be a tight fit and packaging of accessories and exhaust within the body present many challenges. I have a few lower performance SBC's I can use as a base, but all are considerably off the power and investment required for a record. After a lot of consideration the GM atlas engine family Sumner had started accumulating parts for fits the design envelope for this vehicle too well to ignore. Unlike Sumner I'm going straight for the 4.2l E/ motor at first. Trailblazer 4.2 liters are also plentiful with over 40 to pick from in local junkyards.
Since deciding on this path I bought a 2004 trailblazer for parts for $250, pulled the engine, harness, starter, accessories, and good battery, and then scrapped the remainder for $221. The early hurdles to overcome are fabricating an intake manifold that will fit and installing a drysump oil system with a custom pan. The factory oil pans are front sump and the engines are notorious for trapping oil in the head so a head scavenge port will be necessary for any high rpm pulls longer than a ¼ mile pass.
The transmission adapter was easily sourced from emtech. The car can be started on the stock exhaust manifold and driven to it's first test, but will need a custom manifold built before the first race. Cams, valve train, and engine internals are not order-able from a catalog, but are available largely thanks to a handful of dedicated enthusiasts. The 2002-2005 engines make 275hp stock and 2006-2008 make 291hp. The bore/stroke ratio isn't great for top end power potential, though a few built N/A motors have been spun 10,500 rpm and have made good power on gasoline. I think stock worn out 275hp and a disrespectful amount nitrous oxide is a more likely outcome early in this program.
The transmission will be the G-force G101a that Sumner bought for this project. It comes with a V-Gate shifter and I believe it can be left hand shifted manually in the cockpit, but I need to options before I rule it out. It's tight in the drivers compartment which is good, but I'll need to mock up a shifter to see if it's possible to get in/get out of the car and shift within the required range safely.
The axle will be a winters 10” Quick Change rear end. I bought this axle from a dirt racer. It's a 4.86 ring gear with an aluminum 31 spline spool. This is not a great starting point as far as ratios go, but even the 4.86 is capable of the target speed I have in mind for an ECTA meet, testing on a dyno, and testing at local 1/8 and ¼ mile drag strips. A 4.12 ring&pinion gear is available that will help or I can swap the entire housing for an extremeliner later. I'll need to order axles, tubes, and ends from Strange before I can mock up the driveline in the chassis spring 2023.
Transmission and axle yoke to flange adapters are from Nerat Demo and I'll need to machine a register inside the the axle side. I had to order parts for a TH400 on the trans side and a Dana 60 10-spline on the axle side; neither of which I'm using. The Muncie part sold is 27 spline, unlike the 32 spline output shaft of the G101a. One concern I have is that the splines on the TH400 shaft do not engage as deep as a forged nascar yoke. On the limited power levels I plan to run at first I think this will be acceptable, but will need to be addressed before trying to make more power. On the axle side the Dana 60 and Winters quick change both share a 1.250” spline OD and 10 splines and the same seal diameter. Denny's Driveshaft showed the exact same seal diameter and spline engagement for those pinion yokes. Upon initial assembly I discovered I will need to shim the engagement of the splines a couple thousands of an inch, but the splines and seals fit great otherwise.
I just moved homes and shops and am still unpacking. The goal is to get the drivetrain in the car this spring, get the engine started this summer, and make a pass somewhere without body work in fall 2023.
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