I recently did a t5 swap on my cougar. Car has a 351w and has the clutch cable system installed from modern driveline. Right now I’m dealing with vibration and certain speeds and I believe it has to do with my pinion angles. The motor, measuring from the crank pulley, measures 3.5 pointing down. The drive shaft is at .6 and the pinion is at 1.5 pointing down. I shimmed the transmission at the crossmember as high as I could and got the 3.5 pointing down angle. The rear end I have is the stock 8 in and I still have the factory shims in the rear end underneath the perches. The vibration kicks in around 55mph . Anyone ever done this swap to a 67 or 68 ? I’ve seen a lot of post on 65-68 mustangs but I’m looking for someone who has done this successfully to thier cougar… all info/ input is appreciated! Thanks fellas !
Basically the engine needs to be down, in your case 3 degrees or less. The rear axle needs to point up at basically the same amount, i.e. 3 degrees or less. You never want them pointing directly at one another.
Link to more on the subject:
https://www.motortrend.com/how-to/pinion-angle-change/
Your car came with cast iron wedges between the axle housing and the springs to make this work right. With a transmission swap you may have to adjust the crossmember mounting pad to get that part right.
Key to success is this image:
https://www.motortrend.com/how-to/pinion-angle-change?slide=2
Royce is spot on the money.
Instead of the T5 I have the 6R80 in my 68. Similar situation in that the engine & transmission are pointed down something like 3 degrees. As high as it can go though. So I had to turn the rear end up in the direction of axle wrap. I have the exact angles written down somewhere. I’m using Caltracs so the rear end can’t “wrap” much more the what it’s set at.
Another important thing to remember is that you need at least 1 degree of angle at each u joint. This allows the needle bearings to rotate within there cups. I.e. avoids a static load on the needles.
Thank you ! I have been looking for something like this. I did shim the transmission at the crossmember as high as I could. I have only about an 1/8 of an inch of room or maybe a little more untill the transmission hits the tunnel. So u don’t think I can shim up more on that side. As far as the axel goes , cab I remove the wedges and install shims in its place to achieve the 3 degrees pointing up ?
Thanks for your response. So I have 3.4 point down at the engine and transmission while the rear pinion angle is pointed down at 1.5. Do I need to shim the axle a different way to get the 3 degrees pointed up ?
The engine needs to be around or less than 3 degrees. If you have the cast iron shims for the rear axle it should fix the problem there. Ideally you want around 2.8 degrees or thereabouts on each. It would work say in a range of +/- .5 degrees as long as you don’t exceed 3 degrees.
Any discrepancy will cause premature U joint failure.
Have not done that swap specifically but the math is the same regardless of engine, transmission, axle, car or truck.
As of now, I only have the factory cast iron wedges in the back with the bigger side of the wedge facing toward the front of the car to prop the axle up. Doing this put the rear angle at .5 down angle. I don’t think I have anymore room for the transmission to be shimmed up further . This stuff can be so damn confusing !
The transmission needs to be lowered to 3 degrees or less. The wedges can be shimmed with more wedges so the spring and trans angles match in opposite directions.
I will try to achieve the 3.0 down angle on the transmission however I can and shim the axel up to 3.0 upward angle. I’ll report back. Thanks for your help !
As you discovered, equal but opposite angles is what will cancel or offset the driveshaft vibrations. Driving the car at 3.4 down and 1.5 down for any long distance is probably a lot rougher than you think. You’ll be amazed at how much better it feels when set correctly.
Here’s what it looks like to shim the rear end down. You need to go the other way. I.e. Up. The stock shim and a two degree shim are both rotating the rear end down. In your case you’d want to rotate the 2 degree shim to tilt the other way. I also had to open up the hole in the aftermarket aluminum shim for it to fit flat on the shackle. These are cast aluminum and not good for anything but stock HP. Use billet aluminum for anything hot rodded. Oh, another thing to contend with is that the shims will lower the ride height unless you compensate for it somewhere else.
Nice ! Any part number on those shims ?
I got mine from SummitRacing.com
Pro Comp Suspension Systems
EXP-99-200 - Pro Comp Pinion Shims
I good stepped drill bit helps make nice holes.
Sorry some of the pictures are not in the correct rotation .
So I installed the 2 degree shims to help point the rear end up and I still have a vibration around 45 mph. I’m so pissed ! I have the T5 Transmission lifted and shimmed as high as I can and it still seems to have a bad angle ! The front end of my car is lowered with lowering springs (installed by previous owner ) and sits low in front . I have no idea if this has anything to do with it. I do have a stock set of springs I can swap on . Also, the angle finder I have sucks. Maybe I’m not measuring from the correct location or not o don’t know but I’m ready to sell my car! For reals… no jk but I am pissed. All help is appreciated
Is it just me or does the driveshaft appear to be too short? If the yolk is just barely engaging the output shaft, it could be a source of vibration.
It is a stock c4 yoke on an aluminum drive shaft. The aluminum drive shaft I have is out of a Mustang that I believe is shorter as it measures shorter than the stock cougar two-piece drive shaft that I have.
if I were needing to get a custom driveshaft, I wouldn’t even know where to begin. Damn, I always feel like there’s a problem. And for some reason the vibration starts at about 45 mph with the clutch engaged. With the clutch disengaged I can feel little to no vibration