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My son and I started our frame off 1966 GTO restomod when he was 16. It has a low mileage 2006 6.0 LQ9 and a 2000 Camaro T56. We got the car together enough for him to take it to college for his last three years. In any event, he graduated last May and took an accounting job with a firm in downtown DC. When he left, the GTO stayed in Memphis. We did the Power Tour long haul last June, and my wife and I went out west to the Tetons and Yellowstone (and other parts in Idaho and Montana) last September. We logged over 5600 miles in 12 days and the car ran flawlessly. Since the car will be living with me for the next couple of years, I plan to upgrade some things and finish this project. Here is what we are starting with:
The car has a vibration in 6th gear around 100 mph that I attributed to the known 5/6 gear cluster wear issue. I was working in Dallas last week, so I pulled the tranny before I left and took it to Texas Drivetrain in Weatherford, Texas to rebuild/upgrade. They pulled the tranny apart while I waited and found a couple of issues, but overall the tranny was in excellent shape for 80,000 miles. There was no issue with the 5/6 cluster. They upgraded the forks and replaced 5th gear and some other wear items, and told me the vibration issue was not coming from the tranny.
I planned to reinstall the tranny today, but since the car is already partially dismantled, I decided to pull the engine and paint it and install a camshaft I have from a 2001 ZO6 corvette. When we tuned the car, it was tuned for regular gas (for a broke college student). With the cam upgrade and tuned for premium, the car should be even more fun to drive. Here is the car after I pulled the tranny. Next weekend I will pull the motor.
Gotta love being able to drive old muscle cars anywhere!
Don't try this with a carburetor!
I suspect that your vibration is related to improper driveline angles. This is a common problem with LS swaps into A-bodies, especially if they are lowered.
Great looking car, I would love to do a trip like that in my ls swapped monte carlo.
Both my son and I have had fun with this car. We currently have almost 30,000 miles since the rebuild.
Originally Posted by groundczero
I love the color, what is it?
It is a chevrolet car blue from 2004. The name/code is on the can in the garage.
I suspect that your vibration is related to improper driveline angles. This is a common problem with LS swaps into A-bodies, especially if they are lowered.
Andrew
I am just starting to research this issue. I used an electronic angle finder when I set it up, and I think it was 3.5 degrees down on the tranny and 3.5 up on the rear, with the rear end being below the tranny at ride height. One potential problem is the length of the driveshaft. It is steel, 53.5 inches long and 3 inches in diameter. One big driveshaft shop does not recommend anything over 52 inches in 3 inch steel. I'm thinking about a 3.5 inch aluminum shaft (rated to 500 HP), but I still am researching.
Where were your pictures shot? On the way to Yellowstone my wife and I went through Estes Park and through Rocky Mountain National Park - it sure looks like the same territory. And yes, once you have one of these cars set up, they cannot be beat!
Ricky
shot from the top of the world in Rocky Mountain National Park
Great looking car, I would love to do a trip like that in my ls swapped monte carlo.
Your car is super clean and I bet would be a great ride for long trips. I saw you used a GTO based LS engine. Did you ever switch the GTO valve covers? If so , if you still have them would you consider selling them? I would like to mod a set of GTO covers to go under the hood of our GTO (using the truck type manifold).
Your car is super clean and I bet would be a great ride for long trips. I saw you used a GTO based LS engine. Did you ever switch the GTO valve covers? If so , if you still have them would you consider selling them? I would like to mod a set of GTO covers to go under the hood of our GTO (using the truck type manifold).
Good eye! That was on the way from Estes Park to Grand Lake. I was staying with a buddy that lives in Laramie, so we made a giant loop in one day. Laramie to Estest Park, to Grand Lake, then north to WI, and up over Mountain Pass and back to Laramie.
I also used to live in Memphis, in Midtown, around Union and McLean...LOL
Chasing driveline issues takes a long time. Before you go swapping parts, you need to spend a lot of time with a dial indicator and determine how much run-out you have at the trans, front and rear of the driveshaft and at the pinion yoke. Obviously the u-joints need to be in good shape. Once all that is verified, you can start working with angles.
A 3" mild steel shaft of 54 inches has a critical speed of 5856 RPM (http://www.markwilliams.com/driveshafttech.aspx). So it's not a concern on the highway, but I would be worried if you went faster.
We are wrapping up a conversion of an LS 3 into my 1967 GTO Convertible with a T56 Magnum six speed. Really interested in seeing how you resolve the vibration issue. Please keep posting your efforts.
We are wrapping up a conversion of an LS 3 into my 1967 GTO Convertible with a T56 Magnum six speed. Really interested in seeing how you resolve the vibration issue. Please keep posting your efforts.
The driveline vibrations are a common occurrence in A-bodies that are lowered in the rear and with LS swaps. I fixed it with a CV joint driveshaft from The DriveShaft Shop.
I have been driving the car most days (over 12,000 miles in the last 12 months). The driveshaft vibration is still there from 85 mph on - so I just keep it under that limit. I swapped in the ZO6 camshaft, and then had the car retuned for premium gas. On the dyno it ran out of breath (and the injectors were at their limit) around 6,000 but put down 378 hp at the rear wheels.
My wife and I have rooms in West Yellowstone, MT for Labor day weekend - I am driving the GTO to Bozeman, MT and picking her up at the airport. We will spend several days in Yellowstone and then we are headed up to Glacier and on in to Canada (Calgary) after that. I will have the driveline issues corrected before then, and some other upgrades. I will post pictures as I do the upgrades.
The car has 245/45/17 all the way around (so we could rotate the tires). It is not nearly enough rubber on the back, so I would like to go with a 275 , or even a 295 on the back when these wear down. The rear gear is 3:76 GM 12 bolt. With the .5 sixth gear, the car is doing approximately 78 MPH at 2000 rpm.
you may want to check out April 2017 Hot Rod Magazine and see the article "Hot Rod To the Rescue" starting on page 88. This article deals with Constant vibration issues in the driveline.
In their April issue, Hot Rod Magazine used a CV joint as part of their attack on driveline vibration issues as well as addressed the driveline angle issues. Check out the Hot Rod to the Rescue article. Hope it helps.
Calculating speeds - looks like you should be something closer to 81-82 mph at 2000 in 6th, so speedo or tach (or both) may be a bit off -- just food for thought.
The Wallace Racing data that Andrew referenced above for critical speed makes an assumption about wall thickness --- you don't happen to know what wall thickness tubing was actually used on your DS do you? In any event, if my brain/calc didn't let me down, you're spinning the DS at about 4920 rpm at 100 mph, and that's not very far from getting into the 5856 rpm critical speed referenced above.
All that to say -- yup, I think a move to a 3.5" aluminum unit (minimum) and a check of the driveline angles are in order. As for a CV joint on one end of the DS, I think Andrew can tell you all about that... Good luck!
01-31-2016, 08:34 PM
1966 GTO Refresh 
