RicOtt

I previously used the calculator that Andrew referenced and could see that I was over the 80% mark around 90 mph. I need to raise and slightly enlarge the rear part of the driveshaft tunnel to run a larger aluminum driveshaft. I hope to make this modification later this spring, and address the vibration issues then. I read your build on the Volvo - and the problem you had with vibration issues. Are you still vibration free?

Michael Yount

iTrader: (1)

Still smooth as a gravy sandwich....but lusting after AL shaft - space limited as well.

dublingto

Did you update you interior with newer GTO seats? You had another post to this site of someone with a silver and dark blue GTO convertible with the newer GTO seats. I cannot locate the pictures of his car now and would love to see more. How big of a hassle is it to fit those seats into the old body? I am sure the comfort level is much better. Is it worth doing?

RicOtt

The seats in my car came from a 2000 Caddie Eldorado. They are six way/heated seats and very comfortable - we have put over 45,000 miles on them and some very long trips. I fabbed up the mounts - it really wasn't that hard. The silver/blue GTO used GTO seats as I recall. I am thinking about "upgrading" to GTO or Camaro seats when I complete the interior this summer.

dublingto

I am running the T-56 magnum 6 speed transmission to a 3.89 Ford 9 inch. My drive shaft is 57 inches long and we are getting the vibration from 70 mph up. The angles are set at 3.5 degrees at each end and had the drive shaft balanced and still get the vibration. Have you had any success with this issue? I wonder what Andrew has to say about the CV joint. Aside from cost, is there a downside to adding the CV joint? To which end did he add the CV joint?

Toddoky

The engineered maximum operating angle of U-joints is 3 degrees and that is RPM dependent; the faster you spin them, the less tolerant they are of angularity.

Michael Yount

iTrader: (1)

Andrew should weigh in -- CV joints MUCH more tolerant of more acute angles (think FWD halfshafts....). I believe he runs his at the front. Designed properly -- no downside that I can think of perhaps, except, more rotational weight than a u-joint.

Project GatTagO

iTrader: (7)

According to the DSS the CV that they use will handle up to 9 degrees of misalignment (aka. operating angle). The downside is that as the angle increases so does heat and power robbing, and the extra weigh. While the weight adds mass, the actual MOI increase is not too bad given the relatively small diameter of the CVs. Using a CF or an aluminum tube also offsets the weight.

The front operating angle in my GTO is 6 degrees. I think that if I was to swap to the Holley mounts and 302-2 pan, this can be decreased. Todd can maybe speak to this, although I know that ride height plays a factor.

Andrew

Project GatTagO

iTrader: (7)

Mark Williams has a nice graph of this. The driveshaft in my Cougar spins at 4400 @ 75 mph. I believe at that speed the max operating angle is closer to 2.5 degrees.

Here is the tech bulletin.

http://www.markwilliams.com/servicebull/sb0049.pdf

Andrew

dublingto

Hey, any progress on the interior change out to the newer GTO seating? What all has to be changed to put the newer seats into your car? I have put over a thousand miles on my car. Seems I forgot how uncomfortable the old seats are, even with new upholstery. Got a fine drive shaft now, but the vibration, though way less than before, is still noticeable over 75. Kind of upsetting with all that horsepower!

RicOtt

Congrats for getting it going. No, I am still using the caddie seats - they are very comfortable and we have been in a never ending remodel of my son and daughter in law's Master bedroom/master Bath/master closet & laundry room.

I have upgraded the front spindles to C5 corvette, upgraded the rear upper control arms and am about to install the new 3.5 aluminum driveshaft. The car has been in "rehab" since early July and I want it back on the road this weekend. We leave for our big trip in the GTO on August 29. Memphis to Glacier NP via Mt. Rushmore and Yellowstone, then down through the mountains to Vegas, then heading east to Dallas before arriving back in Memphis about September 15. Time is SHORT. I will post pictures of the upgrades this weekend when I figure out how to do pictures in the post Photobucket world.

Ricky

dublingto

Thanks for the follow up post! Got our drive shaft from Mark Williams. One fine impressive piece of work! Wish we could sort out the vibration. Much less vibration with the new drive shaft, but some still there. We lowered the car, so I am questioning that as a possible cause. Running a Ford 9 inch from Johns 9 inch with 3.89 gears. Hope that is not the issue.

Toddoky

I didn't read anywhere where you mentioned what engine mounts and transmission crossmember you are using, but you may want to perform a plumb bob/string line layout on your car to confirm there is no horizontal plane misalignment between your engine/trans and your rear end pinion that could be adding compound angular disparity to your U-joint operating angles.

LS2 67GTO

iTrader: (8)

Hopefully see you in Yellowstone over Labor Day, would like to look at your car. Will be there with the wife in our 49 Chevy 5 window. Safe travels!

dublingto

We removed the Pontiac Chassis mounts and substituted the Chevy small block mounts. We used the Hooker Headers 12611 LS Engine Swap mount Plates on the engine. We used the Prothane 7-1901-BL motor and transmission mounts from Jegs. We used the stock manual transmission cross member, but relocated the frame mounting tabs towards the rear to match up with the transmission attachment point. We had to cut the transmission tunnel to get the T-56 magnum transmission to fit. The driveshaft alignment angles are less than 3.5 degrees.

Toddoky

If your actual U-joint working angles are around 3.5" then they exceed the designed maximum operating angle that U-joints can actually cancel out; 3 degrees of operating angle is the maximum design limit and it's highly RPM dependent...the faster you spin them, the less angle they will tolerate before vibration begins to be noticeable.

The Hooker 12611HKR swap plates are a universal design and don't allow a low enough installed engine height in an A-body to be able to achieve optimized U-joint working angles without performing major surgery on the trans tunnel to be able to get the rear of the transmission up to a proper height.

The Hooker A-body specific engine brackets and transmission crossmembers (and the Holley 302-2 oil pan) were designed to eliminate this issue without having to cut the transmission tunnel in most cases and without the usual inner tie-rod interference with the oil pan.

dublingto

I used the Holley 302-2 oil pan and cut the trans tunnel for the trans to fit. We used the stock manual trans cross member, but relocated the mounting tabs rearward to fit the T-56 trans. Car was lowered about 2inches. I may try raising the rear to see if it helps.