#41  
Old 03-28-2021, 09:22 PM
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Originally Posted by Guido View Post
This is all good information for me: I hope to hear an update after your test drive today!
well took it out and hammered on it today up to about 90 mph on what I will call a closed course..... Vibration was much better. Tomorrow I'm going to fine tune it some. I came up with -4 at the trans and finished with -3 at the pinion, Today I remeasured with a better digital protractor and it's more like -4.3 and the pinion -2.4 so still room for improvement.

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65 LeMANS , SD performance 462ci Engine, Tremec TKX 5 speed with a 3.73 geared 8.5" 10 bolt
  #42  
Old 04-15-2021, 08:19 PM
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well took it out and hammered on it today up to about 90 mph on what I will call a closed course..... Vibration was much better. Tomorrow I'm going to fine tune it some. I came up with -4 at the trans and finished with -3 at the pinion, Today I remeasured with a better digital protractor and it's more like -4.3 and the pinion -2.4 so still room for improvement.
Bit of an update after checking and adjusting the pinion angle and using the Tremec app I had the the driveline angles dialed in, took the car for another drive on the hwy at 70+ mph same issue bad vibration so then I started looking into critical speed of shafts (my Engineering back ground got the better of me) and I totally over looked this possibility when getting the car back on the road, I had the drive shaft shortened a couple summers ago when I installed an 8.5" rear and the factory tube had to much runout to be used so they used 2.75" dia DOM tubing with the factory weld in yokes to save me the cost of a totally new shaft. This was perfect with the 4 speed as I never really went much above 60-65mph as the engine was around 3000 rpm and you couldn't carry on a conversation in the car. After some searching I found that the true 1/2 critical speed of a 2.75" .dia shaft at the length in my car was right about 2800 driveshaft rpm and with my car at 70 mph the engine was turning 2000 rpm but the DS was actually spinning at 2000x1.32= 2640 rpm too close felt like it was trying to form a pretzel. I went back to the local driveshaft shop and talked to the owner and he build me a shaft/ 3.5" dia .065"wall thickness with 1330 yokes at the rear I used a 1330 to 3R conversion joint as I didn't change the pinion yoke. I was able to test drive the car today up to about 80 MPH and its as smooth as a 56 year old car gets. over all very happy with the outcome.

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  #43  
Old 04-18-2021, 02:40 PM
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geeteeohguy geeteeohguy is offline
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Bit of an update after checking and adjusting the pinion angle and using the Tremec app I had the the driveline angles dialed in, took the car for another drive on the hwy at 70+ mph same issue bad vibration so then I started looking into critical speed of shafts (my Engineering back ground got the better of me) and I totally over looked this possibility when getting the car back on the road, I had the drive shaft shortened a couple summers ago when I installed an 8.5" rear and the factory tube had to much runout to be used so they used 2.75" dia DOM tubing with the factory weld in yokes to save me the cost of a totally new shaft. This was perfect with the 4 speed as I never really went much above 60-65mph as the engine was around 3000 rpm and you couldn't carry on a conversation in the car. After some searching I found that the true 1/2 critical speed of a 2.75" .dia shaft at the length in my car was right about 2800 driveshaft rpm and with my car at 70 mph the engine was turning 2000 rpm but the DS was actually spinning at 2000x1.32= 2640 rpm too close felt like it was trying to form a pretzel. I went back to the local driveshaft shop and talked to the owner and he build me a shaft/ 3.5" dia .065"wall thickness with 1330 yokes at the rear I used a 1330 to 3R conversion joint as I didn't change the pinion yoke. I was able to test drive the car today up to about 80 MPH and its as smooth as a 56 year old car gets. over all very happy with the outcome.
I'm a bit confused on the limited speeds/vibrations. I've been driving 4 speed first gen GTO's since the '70's, and have experienced vibrations on some cars that usually had bent or out of phase driveshafts. All of these cars were stock GM, not modified. I could run these cars up to 120+ mph without vibration with the stock stuff....smooth as glass. When I had the 3.55's in my '65, the 'sweet spot' was 90mph at over 4,000 rpm. Not sure of the need to do extensive re-engineering unless the aftermarket stuff is way out of the ballpark.

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  #44  
Old 04-18-2021, 03:43 PM
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Originally Posted by geeteeohguy View Post
I'm a bit confused on the limited speeds/vibrations. I've been driving 4 speed first gen GTO's since the '70's, and have experienced vibrations on some cars that usually had bent or out of phase driveshafts. All of these cars were stock GM, not modified. I could run these cars up to 120+ mph without vibration with the stock stuff....smooth as glass. When I had the 3.55's in my '65, the 'sweet spot' was 90mph at over 4,000 rpm. Not sure of the need to do extensive re-engineering unless the aftermarket stuff is way out of the ballpark.
I didn't really have to do extensive re engineering, the 2.75" driveshaft tube dia was undersized for what was required of it, this was my fault as I forgot to take into account the increased driveshaft speed with the overdrive trans in the rush to get the car back on the road. I went with 3.5" dia tube for 2 reasons, (1) the factory sized 3.25 " dia tube was not readily available and the cost of the yokes were more. the 3.5 dia tube seems to be the go to size. (2) 3" dia was border line in that at a cruising speed of between 70-80+ it was near the true half critical speed of that dia and length of tubing required to fit in my car. Above or below the critical speed is fine to a point but to operate at this speed continually will result in failure this is true for any reciprocating engine or shaft.
The only way to increase the critical speed of a shaft is to make it shorter or increase the dia of the shaft/tube and in the case of our cars we need to increase dia as the length is fixed. as I said above the shaft was spinning right near the true half critical speed for the dia and size I had installed

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  #45  
Old 01-31-2022, 09:14 PM
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Just a bit of an update on the car and some winter projects I have been working on. I bought an Apex drivetrain crossmember which is basically the same as American powertrain but in steel(not sure who was first to market). They make a bunch of parts. https://apexdrivetrain.com/ This mounts to the stock holes and is modular to fit multiple transmissions. Secondly I finished up my console and installed it. The shifter works great doesn’t look totally stock but at a quick glance…. Had I not been in such a hurry initially the patch panel would not of been required most likely
.







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  #46  
Old 01-31-2022, 09:30 PM
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66beaumont 66beaumont is offline
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Once the bellhousing was dialed in I installed an 11" McLeod dual friction clutch kit and got right at installing the trans. No cutting to the tunnel is required it fits nice. But its not a direct bolt in Due to the shifter I used the shift porch needs to be cut as well as a small piece at the back left side of the tunnel this is only required to clear the shifter.

Shifter offset from above:


Shifter position in the car


Shifter porch laying in place ( i cut to much out needs some welding)



Carpet laid in place to see how it would all fit.

If you had purchased from SST you wouldn’t have had to cut the floor at all probably. I just had to make a little clearance in one corner with hammer in my 69. You’ll love that tkx

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69 gto ,all#match,467,th400,3:55 Easton posi,resto completed may 2016. 427 hp/530tq. Stump puller with stock#62 , stock intake and qjet
Th400 gone. Tkx close ratio with .64 of
66 Pontiac Beaumont sport deluxe,BB 5sp tko 3:08 auburn 450hp 550 torque wife sold it
  #47  
Old 01-31-2022, 09:47 PM
70GS455 70GS455 is offline
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Originally Posted by 66beaumont View Post
If you had purchased from SST you wouldn’t have had to cut the floor at all probably. I just had to make a little clearance in one corner with hammer in my 69. You’ll love that tkx
Or MDL

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  #48  
Old 01-31-2022, 10:03 PM
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Or MDL

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Living in Canada I purchased from a local supplier, This was to cut out the excessive shipping and if I had any problems down the road easy to deal with warranty etc. The shifter installed is the same one Modern drivetrain sells with there kits its made by https://redrobertsinc.com/ I would consider what I had to do a bolt in, But If I had to do it over again I would get the shifter mentioned below just to save a step or two. The trans was installed January 2021 and has about 2000 trouble free miles so far and I love it.

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