Monte Makeover (Part 7): Selecting and Sourcing Parts for the Transmission Swap

Editor’s Note: Perhaps the only things Travis Jones loves more than his 1986 Monte Carlo SS are autocross courses and a good challenge. That’s why Travis is on a mission to transform his Monte Carlo from an underpowered, ill-handling daily driver to an Autocross hero. A self-described “GM guy through-and-through,” Travis is a regular on the site OppositeLock, has documented his project on his Instagram page (@sslow6.0), and will give us a first-person account of his build here as a guest writer.

Travis has owned the Monte Carlo since high school. Although he’s thought about selling it from time-to-time, Travis has held on to it for sentimental reasons, even though the car has often sat idle. After his girlfriend inspired him to try Autocross for the first time, Travis started to look at the Monte in a whole different way.

“I became obsessed with taking a 1980s boat and making it handle,” Travis said.

In part 7 of his Monte Makeover series, Jones walks us through the parts he selected, and why as he continues to remake his Monte Carlo.

In the last entry I had turned my fastest time yet at the dragstrip but ran into some transmission issues on the way home. It turned out that the throttle valve had gotten stuck inside the transmission . Before I decided to tear the transmission down, I figured I’d try to let car heal itself. I opened and closed the throttle manually a few times, letting it spring closed. And what do you know…that seemed to fix the issue.

Still, it was clear that the 200-4R was not liking the influx of LS power, and the stall converter was clearly not matched to the power curve. So what to do about this? 

Sure, it’s possible to build a 200-4R auto to handle just about as much power as you want to throw at it. Automatics definitely have their place–in many cases a well built automatic is faster down the dragstrip and even around a road course.

But I decided to finally take my dad’s advice from when I was in high school and swap in a manual.

There are a plethora of possible manual boxes to put behind an LS engine. The TKO600 is a strong, simple 5-speed, but it’s pricey and can require lots of aftermarket parts to function behind an LS V8. There’s also your older 4-speed boxes, like the Muncie M21/M22 and the Saginaw T10; however, overdrive is a nice thing to have if you’re going to be road tripping your car.

I decided on the ubiquitous T-56 or T-56 Magnum transmission from Tremec. These are some of the most positive shifting, durable, and properly geared transmissions out there. Unfortunately, they are also pretty expensive. Despite the fact that a new T-56 Magnum is more than $3,000, I had decided I would just have to bite the bullet — until I saw a Facebook ad for a company called FABbot Fabrication.

FABbot offers an adapter plate to mate an LS motor with the Aisin-made AR5 manual transmission from a 2004-2012 Chevy Colorado or 2006-2010 Pontiac Solstice/Saturn Sky.

You might be thinking: “Neither of those vehicles are making the kind of power that you’re making, and it’s probably going to turn this transmission into a pile of aluminum, steel, and gear oil the first time you drop the clutch in anger.”

That was my thought until I researched the topic.

Generally, the torque rating of a transmission is qualified only up to the highest amount of torque that the transmission would see in its most powerful OEM configuration — 260 foot-pounds in the case of the AR5. However, the actual strength of a manual transmission is based on a few things.

First, you should look the centerline distance between the main shaft of the transmission and the cluster gear shaft. This dictates how big and beefy the gears can be. On the T-56, the centerline distance between them is 85mm, and on the TKO600 it’s 83mm. On the AR5? Just 1 millimeter less than the TKO600 at 82mm.

Next, you should look to the input and output shafts. The TKO600 uses a beefy 26-spline input shaft and a 31-spline output shaft. The T-56 Magnum uses a 26-spline input and a 31-spline output, but the F-body T-56 uses a 26-spline input shaft and a 27-spline output shaft — the same spline count and diameter as the AR5.

It turns out that Aisin, the manufacturer of the AR5, also made the R154 transmission (for the Toyota Supra), which can handle quite a bit of power. The AR5 is very similar in function and design and can be thought of as an upgraded and improved Toyota Supra transmission. After looking up the price of an AR5 from a Chevy Colorado at my local LKQ, I thought it might be a very real possibility.

I also researched real-world examples of the AR5 taking some abuse. The first thing that I sought was the insight of Matt Grunwald, the owner and operator of FABbot. He said that he had swapped an AR5 into an LS-powered RX7, and was making high 11-second passes with 1.6-second 60-foot times on slicks until the stub axle broke.

In efforts to find the limit of the AR5, the team at FABbot have built a turbo LS, AR5-equipped Colorado with the goal of nine-second quarter-mile passes. So far traction issues have been his biggest issue in making that goal. The AR5 held up to 800-plus horsepower dyno tests, but broke third gear on slicks at the track.

Grunwald was confident that an AR5 would be just fine in my application given my power level and goals. Based off this (and other) research, I pulled the trigger on one of FABbot’s AR5 to LS conversion kits.

Don’t get me wrong — I’m not saying that the AR5 is as capable as a T-56 Magnum or TKO 600, but for my power level and build goals (and budget!), I think it will work perfectly. So I went to my Local LKQ and picked up two AR5 transmissions for less than $350.

The AR5 has an interesting gear spread: 3.75 first, 2.26 second, 1.37 third, 1:1 fourth, and a .73 overdriven fifth gear. If you have a 3.73 or 4.10 rear end gear, first gear is probably going to be a useless tire smoke generator.

When it comes to rear gearing with the AR5 and an LS, something in the 3.08 to 3.55 range is probably ideal for most 25-27 inch tire cars.

The shifter sits about 24 inches back from the edge of the bellhousing.

Comparing this to the TKO 600 and T-56, the TKO 600 has multiple shifter distances depending on configuration: 19, 23, or 25.8 inches. The T-56 Magnum also has multiple shifter distances: 18, 23, or 26.6.

The AR5 shifter distance is between the two optional shifter distances and should work okay for most older muscle car applications. The major downside to the AR5 is that there are no commercially available short-throw shifter kits, but I hear that FABbot is working on one.

With all of the dimensions and specs checked, I then had to source the supporting parts necessary to hook up the transmission to a hydraulic clutch.

For a clutch and flywheel, I chose the LUK LFW-191 flywheel, which is the same as the C7 Corvette Z06 factory unit, and the LUK 04-216 clutch kit. This kit includes a hydraulic slave cylinder, but we won’t be using it. Instead we will use a factory Colorado/Canyon slave cylinder (LUK-LSC374) with the FABbot concentric slave cylinder spacer. I’ll use a Russell fitting I got from FABbot to run a -4 AN line to feed the clutch.

Seeing as I wouldn’t be the first to install a manual transmission into a G-body with a hydraulic clutch, I looked to the G-body community for suggestions. The overwhelming response was to use the SickspeedMonte.com pedal set. This pedal set is the brainchild of Bernie Duplan, an enthusiast and engineer who has spent the better part of two decades modifying his own Monte Carlo SS and is an invaluable resource for information in the G-body community.

He offers two versions of the kit: one that uses a factory F-body master cylinder and another that works with a Tilton universal master cylinder which can be adapted to virtually any hydraulic setup. I’ll be going the second route. The additional parts that you will need are the:

• Tilton 75-Series Universal Master Cylinder Kit (TIL-75-875U)
• -4 AN line to feed the slave cylinder (ALL46402-36 or similar)
• Two pedal covers (RNB-20734)
• Pushrod boot (OER-3973089)
• Stainless -4AN/-3AN fitting to adapt the Tilton master to the hose (EAR-SS991902ERL). It’s also possible to use a brake light switch plumbed into the clutch hydraulics to use as a clutch safety switch, preventing starter engagement without the clutch being depressed.

Last but not least, if you want to use your factory speedometer, you’ll need Performance Automatic’s Conversion Box (PMA-PA99122).

We got most of these parts from Summit Racing.