[TB1]

Little bit of an update, I have the car on the road and driven it about 50 miles so far and I'm impressed with the way it shifts the gear spread seems to be great with my 3.23 rear gears. Only down side so far is I have a pretty good vibration at 70MPH and above, jacked the car up on some chalks to load the suspension today and had a better look at the pinion angle which didn't seem to be an issue with the Muncie but I was pretty hard pressed to go over 60 mph for the most part due to traffic etc. I found the trans output is -4° and the pinion yoke was basically 0° so I have adjusted the rear upper control arms to get the pinion angle at +3 and will test drive it tomorrow and see how it is. I'm thinking my lower profile energy suspension trans mount may be part of the reason for the -4° but I was unable to shim the trans any higher as it was close to hitting the shifter porch.

I mentioned below also about the cross member. I mistakenly said that the rear bolt hole for the rubber insulator will become the front hole for the new trans this is not correct. I had a factory hole just aft of the original front mount location this was used as the new front mount hole and the rear hole needed to be drilled on each side.

[Formulajones]

You're going to have a lot of happy cruising this summer.

[Holeshot71]

Originally Posted by TB1

I found the trans output is -4° and the pinion yoke was basically 0° so I have adjusted the rear upper control arms to get the pinion angle at +3 and will test drive it tomorrow and see how it is.

Are you saying you lowered the front of the pinion down to get the +3*?

I think if you are down -4* at the trans you will want the front of the pinion UP the same amount (-4*) minus a couple degrees to compensate for the pinion rotating up during acceleration.
So if you are down -4* at the trans you want the front of the pinion UP roughly -2*

Hope this makes sense, this topic can get pretty confusing lol

[TB1]

Originally Posted by Holeshot71

Are you saying you lowered the front of the pinion down to get the +3*?

I think if you are down -4* at the trans you will want the front of the pinion UP the same amount (-4*) minus a couple degrees to compensate for the pinion rotating up during acceleration.
So if you are down -4* at the trans you want the front of the pinion UP roughly -2*

Hope this makes sense, this topic can get pretty confusing lol

The trans is down 4° and I moved the pinion up 3° degrees towards the floor it was at zero when I started. I figured moving it up would be positive and down from zero would be negative? . I'll take it for a drive today and see how it is now, but murphy's law will show at 3° it will be to much and I'll have to drop it back to 2°!

[Holeshot71]

Originally Posted by TB1

The trans is down 4° and I moved the pinion up 3° degrees towards the floor it was at zero when I started. I figured moving it up would be positive and down from zero would be negative? . I'll take it for a drive today and see how it is now, but murphy's law will show at 3° it will be to much and I'll have to drop it back to 2°!

You moved the pinion up in the front towards the floor which is correct but that is actually -3° looking at your angle gauge, which is why I asked.. 😎

[Guido]

This is all good information for me: I hope to hear an update after your test drive today!

[TB1]

Originally Posted by Guido

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.

[TB1]

Originally Posted by TB1

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.

[Vid]

Originally Posted by TB1

Little bit of an update, I have the car on the road and driven it about 50 miles so far and I'm impressed with the way it shifts the gear spread seems to be great with my 3.23 rear gears. Only down side so far is I have a pretty good vibration at 70MPH and above, jacked the car up on some chalks to load the suspension today and had a better look at the pinion angle which didn't seem to be an issue with the Muncie but I was pretty hard pressed to go over 60 mph for the most part due to traffic etc. I found the trans output is -4° and the pinion yoke was basically 0° so I have adjusted the rear upper control arms to get the pinion angle at +3 and will test drive it tomorrow and see how it is. I'm thinking my lower profile energy suspension trans mount may be part of the reason for the -4° but I was unable to shim the trans any higher as it was close to hitting the shifter porch.

I mentioned below also about the cross member. I mistakenly said that the rear bolt hole for the rubber insulator will become the front hole for the new trans this is not correct. I had a factory hole just aft of the original front mount location this was used as the new front mount hole and the rear hole needed to be drilled on each side.

Another thought about the vibration, if you haven’t already, maybe consider having the driveshaft balanced? I had a similar vibration in my’67 wagon and that cleared it up.


Sent from my iPhone using Tapatalk

[TB1]

Originally Posted by Vid

Another thought about the vibration, if you haven’t already, maybe consider having the driveshaft balanced? I had a similar vibration in my’67 wagon and that cleared it up.


Sent from my iPhone using Tapatalk

The driveshaft was shortened and balanced with the new yoke after I measured once the trans was installed. weights are all still intact. Going to test drive later today and see how it goes.