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asphalt_gundam
asphalt_gundam
6/15/20 4:31 p.m.

Hello everyone,

This is my 1985 Oldsmobile Cutlass that I've been building to track and street drive for the last 2 years. I'm a little over a year since my first autocross and track day shortly after that. This car has come from a prep'd engine and rear disc brakes on stock suspension to chassis stiffening, roll cage, big brakes, wide tires and overall about less than 5% original.  It has been a struggle finding the right direction to go with chassis setup and picking parts that work at a reasonable price. Since there is really a chasm between drag racing a circle track that road racing falls into for this chassis I'm posting what I have done in hopes of helping out others who want to be unconventional at the track and love these cars as much as I do.

The cars current setup is a budget build....of sorts. Utilizing circle track parts over Pro Touring type parts.

Quick run down:

Stock chassis that has been: Boxed, second "inner" frame tube added, suspension pickup points doubled and gusseted, rear frame notch (for future, wider tires), cross braces at front, rear shocks, and rear of frame. 6 pt roll cage setup for easy in and out street use.

Suspension: Bilstien shocks, AFCO springs, poly front lower control arm bushings, Speedway low friction ball joints +1" lower - +1/2" upper, AFCO upper control arms (both right side 8"), RideTech rear control arms (full spherical bearing), QA1 sway bars, custom adjustable mount holes for rear lower and front upper, bump steer kit, fast ratio steering box

Brakes: Front - Stoptech cryo treated Corvette rotors, Outlaw disc brake staggered 4 piston calipers, Wilwood BP-20 pads, modified stock spindle and custom brackets. Rear - generic rear disc conversion with late 70's Cadillac metric caliper with parking brake on 11.75 rotor and Wilwood BP-10 pads. Wilwood 1-1/8" master cylinder with brake bias adjuster

Wheels/Tires: Forgeline GA3 18x10 with BFG Sport Comp 2 275/35/18

Engine: Built up 350 Oldsmobile punched to 362. Made to be reliable and take track abuse

Transmission: Tremec 3650 from an '01 mustang. I built my own adapter plate and spacers. Modified Ford Ranger pedals and Mustang cable.

Rear end: Stock 7.5 housing, 28 spline Moser Axles, Quick performance LSD and bearings, 3.73 gears, Aluminum diff cover and cap support

 

Key notes for making this chassis handle: 

1. Fix the camber curve: Tall ball joints are a must! The dirt track springs will drop the car A LOT so keep bump steer in mind. 

2. Tire: I've just switched to 275 square and it fits the front with a removed/cut inner fender, rolled outer fender and steering stop to keep it off the sway bar. Rear only "needs" a fender roll but the stock frame will be very tight without a notch

3. Geometry: Once the car is lowered this much the front gets better...rear gets bad! In the stock locations I could easily burn all of 2nd gear and had zero drive off corner till almost strait. Dropping the rear of the lower control arm by 2.25" has made a massive difference. At Gingerman Raceway with GridLife last weekend I could be on throttle just about from turn in (might have been my mistake of braking too much...but way way WAY more traction). Front end seems to want about 3-4 degrees of camber as a happy place (both on last years 225 tire and this years 275). I haven't gotten crazy with caster testing but I've been around 7 degrees. Toe is 1/16 in, again haven't played with it a whole lot but it feels great! The rear end is by far the more difficult to work with and requires significant changes. I am nowhere near optimized yet and its so much better than how I ran all last year.

4. Stiffness: Is your body attached? Mine had 5 body mounts either rusted or ripped out of the frame by last fall from tracking it...that on top of a wet noodle frame doesn't make for a good foundation to mount suspension parts to. That's why I did all the boxing, bracing, and gusseting to mine. The roll cage help too, though it's primary reason was safety.

Most of the build process and the car's evolution over last summer and winter can be found on my Instagram: Asphalt_Gundam 

I'm happy to answer questions and will try to keep this post up-to-date with changes and pros/cons of how they work out.

I love that you went with an Oldsmobile 350. GM experimented with a G-Body Cutlass back in the 80s, but I can't remember what they called it. I believe it was powered by a heavily worked over 307. 

asphalt_gundam
asphalt_gundam New Reader
6/15/20 5:22 p.m.

In reply to Jordan Rimpela (Forum Unterstützer) :

That would be FEX3 projects. Engine was actually pretty stock considering the tricks they did with the rest of it.

I'm an Oldsmobile guy and the number one compliment my cars always got at shows was "it's still an Oldsmobile under the hood".

Javelin (Forum Supporter)
Javelin (Forum Supporter) MegaDork
6/15/20 8:54 p.m.

That's awesome

asphalt_gundam
asphalt_gundam New Reader
6/16/20 9:52 a.m.

Here's some pictures of the more involved chassis modifications.

Cutting then adding thickness and a 3/4" lowered, upper control arm mount location. Haven't tried it out yet but will soon since I need more camber gain.

Did mention the whole car was body off Thanksgiving weekend and back ready to race mid April. You can see the "inner" frame rails I constructed. Way at the back it the two cross braces. One between shock mounts and one all the way at the back.

Here is the factory diagonal braces for the front with an added cross support. And my trans crossmember with added driveshaft hoop.

For the rear and to get traction I made these drop brackets for the lower control arm. Huge difference is an understatement.

The forward offset of the lower 4 is to correct wheelbase/ get the wheel centered in the opening. It also helped fix the pinion angle. Holes are also on a curve to maintain wheel position and pinion regardless of which hole the control arm is in.

Steve
Steve New Reader
6/16/20 10:11 a.m.

This is awesome!

OjaiM5
OjaiM5 Reader
6/16/20 10:27 a.m.

This build is killer. Nice G bodies are becoming harder to find. Such a cool body style.

Young_olds
Young_olds New Reader
6/16/20 10:49 a.m.

Cool to see an olds powered olds, I immediately loose interest when I see engines other then an olds installed. And cool to see a gbody built to turn. I have not owned a gbody but I built a 66 f85 in a similar pro touring fashion. I even have that holley intake and a very close "gold" paint. 

Matt B (Forum Supporter)
Matt B (Forum Supporter) UltraDork
6/16/20 11:14 a.m.

Yeah, incredibly cool is an understatement.  Looks like you addressed the major shortcomings of that chassis (to my admittedly limited knowledge).  I bet you're a bit of a surprise to some at track days.

Purple Frog (Forum Supporter)
Purple Frog (Forum Supporter) Reader
6/16/20 11:19 a.m.

I love it.  Another guy that doesn't start a build thread until he finishes.  

Great job!

asphalt_gundam
asphalt_gundam New Reader
6/16/20 11:38 a.m.
Purple Frog (Forum Supporter) said:

I love it.  Another guy that doesn't start a build thread until he finishes.  

Great job!

What is this "finished" you speak of?

asphalt_gundam
asphalt_gundam New Reader
6/16/20 11:43 a.m.
Matt B (Forum Supporter) said:

Yeah, incredibly cool is an understatement.  Looks like you addressed the major shortcomings of that chassis (to my admittedly limited knowledge).  I bet you're a bit of a surprise to some at track days.

I was honestly nervous taking it to the first few track days. Worried I wouldn't be welcomed for being way outside the box of the normal Imports and newer Domestics. It was unwarranted. GridLife has been hands down the most welcoming. Its getting to the point where people are getting excited to see what I've changed and how the car does when they find out I'm going to an event.

asphalt_gundam
asphalt_gundam New Reader
6/16/20 12:27 p.m.

This is my "on the cheap" big brake kit. Last year's setup was big bore circle track calipers and good pads. They worked well but started giving up around lap 3 at Road America. Plus I couldn't run a performance pad on the rear without locking up. Even with the boss all the way down. Just isn't enough for this car anyway so on to big brakes.

Cryo treated Stoptech rotors for a C5/6 at 12.81 dia vs the stock 10.5

I had picked up some used calipers at a swap meet the spring before. 4 for $50 and in there was a matching left/right Outlaw Disc Brakes staggered 4 piston caliper pair. $56 rebuild kit and $40 powder coat had them like new.

 I then modified the stock spindles and hubs in the same way most other big brake kits require. Remove stock caliper bracket, drill out and tap dust shield holes followed by making my own brackets to bolt on the calipers.

The hubs were chucked up in the lathe and had the rotors removed and were cut down to fit inside the Corvette rotors. 

Pads are "universal" type Wilwood BP-20

cmcgregor (Forum Supporter)
cmcgregor (Forum Supporter) SuperDork
6/16/20 1:07 p.m.

Love it. This thing is so cool.

Matt B (Forum Supporter)
Matt B (Forum Supporter) UltraDork
6/16/20 2:29 p.m.
asphalt_gundam said:
Matt B (Forum Supporter) said:

Yeah, incredibly cool is an understatement.  Looks like you addressed the major shortcomings of that chassis (to my admittedly limited knowledge).  I bet you're a bit of a surprise to some at track days.

I was honestly nervous taking it to the first few track days. Worried I wouldn't be welcomed for being way outside the box of the normal Imports and newer Domestics. It was unwarranted. GridLife has been hands down the most welcoming. Its getting to the point where people are getting excited to see what I've changed and how the car does when they find out I'm going to an event.

Yeah I'd be surprised if you encountered any real snobbery.  On-track safety etiquette matters a lot more than whatever you brought anyway, but I'm probably preaching to the choir here.

asphalt_gundam
asphalt_gundam New Reader
6/16/20 2:32 p.m.

Current track setup:

Camber Left 2.6/2.3 Right 

Caster is 7 degrees both sides

Toe is at 1/16th in

Tires at 30psi hot

Rear lower arms at 2.25" drop from stock

Ride height in front puts the lowers level with the ground. Rear height has upper control arms with 11-12 degrees down towards front and lowers at 2-3 degrees up to front

Notes from Gingerman Raceway: tires wearing outer half more. Left side needs more camber added than right side. 30psi hot has significantly more grip than 35psi. ( I tested last year down to 28 front 26 rear. Got greasy on last year's 225/245 tires but did have more grip up until the delamination). Larger rear spoiler added planted feel to high speed corners over the shorter spoiler. Not sure how strait away speed was affected but it felt down. (I was down on power all weekend so that's more observation than hard knowledge)

Changes before Autobahn to be done:

Move front upper A arms to lower hole for camber gain. 

Realign closer to 3 degrees of camber on Right and 3.5 on Left

If back at full power and drive off corner suffers then I'll drop the rear lower control arm more... testing is needed

wawazat
wawazat Dork
6/16/20 2:40 p.m.

Very cool! 

Way back in the day I had a 1981 Pontiac Grand Prix in that same color.  It was a diesel and when that failed, I swapped in a 327 Chevy/TH400 and a 12 bolt.  It was fun but nowhere near the handling machine your car is!  Of course hot set-up then was 15" Pontiac Rally wheels and Firestone something or other fat 15" tires.

asphalt_gundam
asphalt_gundam New Reader
6/16/20 3:10 p.m.
wawazat said:

Very cool! 

Way back in the day I had a 1981 Pontiac Grand Prix in that same color.  It was a diesel and when that failed, I swapped in a 327 Chevy/TH400 and a 12 bolt.  It was fun but nowhere near the handling machine your car is!  Of course hot set-up then was 15" Pontiac Rally wheels and Firestone something or other fat 15" tires.

Speaking of  wheels and tires. They're 18x10 Forgeline GA3 with 5" backspace. Tires are BFG SportTSport Comp 2 in a 275/35/18 size. I really like them because they let you know when you're getting to the limit, break away and come back smooth as silk. No rubs thanks to frender rolling, frame notch (Incase of wider later), cut/remove front inner fender (steel one, not the plastic), and a homemade steering stop from a bolt and two nuts.

asphalt_gundam said:

In reply to Jordan Rimpela (Forum Unterstützer) :

That would be FEX3 projects. Engine was actually pretty stock considering the tricks they did with the rest of it.

I'm an Oldsmobile guy and the number one compliment my cars always got at shows was "it's still an Oldsmobile under the hood".

Yes, that's it, FEX3. Maybe it was the 307 HO? I'll have to look it up. Between the FEX3 Oldsmobiles and Buick tinkering with all manner of unicorns from a RWD turbo Reatta to a GNX-powered Electra Estate, GM sure did tease us with things they'd never build. Don't get me started on the BMW V12-powered Caprice. 

Racebrick
Racebrick New Reader
6/16/20 8:18 p.m.

When will you be at Autobahn? I would like to see this thing on track.

asphalt_gundam
asphalt_gundam New Reader
6/16/20 8:38 p.m.
Racebrick said:

When will you be at Autobahn? I would like to see this thing on track.

End of the month June 26-28th with GridLife

Daylan C (Forum Supporter)
Daylan C (Forum Supporter) PowerDork
6/16/20 9:21 p.m.

Cool to see you here. Saw your car scrolling through Gridlife posts. Lots of respect on being stubborn with the Olds motor.

NOT A TA
NOT A TA SuperDork
6/16/20 10:13 p.m.

Great thread! I like that you've kept it Olds powered.

I had an '88 Cutlass Supreme 307 4V 4 speed auto. Car guy friend of mine ordered it for his mom late in her life. Went to bank, grocery, Dr's, and church in good weather and stayed inside otherwise. Had 42,000 miles on it but nooo power haha. I had a bunch of cars and some had to go so it got sold and became a donk. I've still got another G body though, '81 Malibu.

Justjim75
Justjim75 Dork
6/16/20 10:26 p.m.

I really like this car, thanks for posting

mjrj (Forum Supporter)
mjrj (Forum Supporter) New Reader
6/16/20 11:13 p.m.

Really cool!  Your car is what I had in mind when I started working on my Delta 88 back in the mid 2000s.  And super cool to see you use the 350 rocket as well.  Hope to see more of it!

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