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Driveshaft Vibration

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Nghtshd88

Nghtshd88

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Did you ever get this fixed? The flanges on the differential for the GT350 and GT manual transmission seem to be the same part number.
They are 100% different at least for 16'. I know for a fact as the holes will not line up. Maybe different for other years.
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exhausting1

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Greetings everyone, Newbie here to your forum. I do not own a Mustang, however I do own a 6R80 transmission out of a 2016 Mustang Ecoboost car. I have a 1937 Ford. A complete Fatman Chassis with coilover suspension, adjustable shocks, Disc brakes etc. The engine is a 2.0Ecoboost from Ford Performance that has the turned up factory tuned computer that is not available anymore. I see 23-24lbs of boost and it is rated at 350ftlbs of torque. The 6R80 is controlled by a Quick6 controler, works great. The first gearbox had about 15000 miles on it when I got it. On first driving of the car there was a "minor" vibration at about 65mph and would lessen as speed got higher! Changed the final gear in the 9inch rear end .25 points higher and kicked the vibration up to about 73-78 mph, so the issue was definitely from the tranny back, eh?
I have both a two piece driveshaft and a one piece. I have worked every angle on engine, (as I can vary that), the differential (using angled shims) and intermediate angles on the two piece shaft. Nothing I do will change it except make it worse.
I have machined the output flange to make sure it runs true to the output shaft. the shafts have been balanced a couple times each.
When the original tranny I had started dropping into 3rd gear while on the highway, uugghh! and after changing out the Ford redesigned plastic wire connection piece( I forget the name of it) which also houses the output shaft rpm counter which was the main issue, I realized the problem with the driveshaft is related to the output rpm sensor gettng trashed also.
The 6R80 as configured for the Mustangs (at least the Ecoboost) utilizes a output shaft "bushing" which is part of the housing. I believe it is a steel sleeve that is pressed into the housing itself. The entire output shaft is relatively short and while held in the front by a bearing captured into a dear drum, the distance between them is very short which means the shaft is not supported well enough for the loads it sees from the driveshaft. It is a known issue among transmission re-builders as there exists a aftermarket sleeve, apparently made from a "better" material for the job. I have also found out that even a rebuilt or re-manufactured transmission will not necessarily have this issue addressed.
Make a long story shorter, it was possible to grab the front of the driveshaft and move the output shaft up and down maybe as much as .25"! I purchased a "remanufactured" tranny from Jasper,(not cheap) . The output shaft was probably half as much "slop" in the new tranny. I figured they did not address the output bushing, but it was a lot better, ok? Driveshaft vibration was reduced by a noticeable amount. Ok, so my hunches are probably correct. The bearings or bushings holding the output shaft are not good enough, the shaft is too short and not supported properly for the job. The busings will wear out prematurely which is why some folks get the vibration with more miles verses a box which is bad from the factory or wears out faster than another.

Want further proof? I also have noticed that if I get to the highway in like less than 5 minutes there is no vibration. Okay, after driving for maybe another 10 minutes and the vibration returns.... so the issue is as the transmission warms up and gets hotter the "bushing" holding the back of the output shaft grows bigger (not good) with the expanding aluminum case and allows the driveshaft to whip around.

I understand a few Pickup trucks have this issue also.

It is not hard for me to see why Ford will not address this issue as it "is" a design flaw, (IMO) and the real fix is to refit a better bushing at the rear of the case but the problem is the wnitre transmission has to come apart. Not cheap, right? There ya go.

I will be playing with the hose clamp fix to see if I can counter balance the "whipping". I am keeping my fingers crossed.

Link to article in "FrontStreet" mag. https://frontstreet.media/2019/10/18/this-1937-ford-ecoboost-tudor-humpback-breaks-all-the-rules/
Calvin
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Cobra Jet

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Greetings everyone, Newbie here to your forum. I do not own a Mustang, however I do own a 6R80 transmission out of a 2016 Mustang Ecoboost car. I have a 1937 Ford. A complete Fatman Chassis with coilover suspension, adjustable shocks, Disc brakes etc. The engine is a 2.0Ecoboost from Ford Performance that has the turned up factory tuned computer that is not available anymore. I see 23-24lbs of boost and it is rated at 350ftlbs of torque. The 6R80 is controlled by a Quick6 controler, works great. The first gearbox had about 15000 miles on it when I got it. On first driving of the car there was a "minor" vibration at about 65mph and would lessen as speed got higher! Changed the final gear in the 9inch rear end .25 points higher and kicked the vibration up to about 73-78 mph, so the issue was definitely from the tranny back, eh?
I have both a two piece driveshaft and a one piece. I have worked every angle on engine, (as I can vary that), the differential (using angled shims) and intermediate angles on the two piece shaft. Nothing I do will change it except make it worse.
I have machined the output flange to make sure it runs true to the output shaft. the shafts have been balanced a couple times each.
When the original tranny I had started dropping into 3rd gear while on the highway, uugghh! and after changing out the Ford redesigned plastic wire connection piece( I forget the name of it) which also houses the output shaft rpm counter which was the main issue, I realized the problem with the driveshaft is related to the output rpm sensor gettng trashed also.
The 6R80 as configured for the Mustangs (at least the Ecoboost) utilizes a output shaft "bushing" which is part of the housing. I believe it is a steel sleeve that is pressed into the housing itself. The entire output shaft is relatively short and while held in the front by a bearing captured into a dear drum, the distance between them is very short which means the shaft is not supported well enough for the loads it sees from the driveshaft. It is a known issue among transmission re-builders as there exists a aftermarket sleeve, apparently made from a "better" material for the job. I have also found out that even a rebuilt or re-manufactured transmission will not necessarily have this issue addressed.
Make a long story shorter, it was possible to grab the front of the driveshaft and move the output shaft up and down maybe as much as .25"! I purchased a "remanufactured" tranny from Jasper,(not cheap) . The output shaft was probably half as much "slop" in the new tranny. I figured they did not address the output bushing, but it was a lot better, ok? Driveshaft vibration was reduced by a noticeable amount. Ok, so my hunches are probably correct. The bearings or bushings holding the output shaft are not good enough, the shaft is too short and not supported properly for the job. The busings will wear out prematurely which is why some folks get the vibration with more miles verses a box which is bad from the factory or wears out faster than another.

Want further proof? I also have noticed that if I get to the highway in like less than 5 minutes there is no vibration. Okay, after driving for maybe another 10 minutes and the vibration returns.... so the issue is as the transmission warms up and gets hotter the "bushing" holding the back of the output shaft grows bigger (not good) with the expanding aluminum case and allows the driveshaft to whip around.

I understand a few Pickup trucks have this issue also.

It is not hard for me to see why Ford will not address this issue as it "is" a design flaw, (IMO) and the real fix is to refit a better bushing at the rear of the case but the problem is the wnitre transmission has to come apart. Not cheap, right? There ya go.

I will be playing with the hose clamp fix to see if I can counter balance the "whipping". I am keeping my fingers crossed.

Link to article in "FrontStreet" mag. https://frontstreet.media/2019/10/18/this-1937-ford-ecoboost-tudor-humpback-breaks-all-the-rules/
Calvin
0E2A5655_edit_edit_header.jpg
@exhausting1 (Calvin):

First, welcome to the forum and that’s one really sweet looking 37!!

You have to check out this thread, it has a lot of tech regarding the S550 driveline vibes; and you should add your post there - what you have posted about your findings and possible solution will definitely help MANY!!!! https://www.mustang6g.com/forums/threads/vibration-between-50-70-mph.15990/
 

exhausting1

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Finally got to work with the Hose clamps on the driveshaft. Marked the front of the shaft in quarters numbered 1,2,3 and 4. Started with 2 clamps with the screw part at # 1. Drove car at speed and thought it might be a little better. Moved the clamps to position # 2, drove again and the vibration is gone. Made a coouple more minor movements of the clamps to no difference so I am very happy at this point.

Let me be clear here. I have been at this for over a year. This shaft in particular has been balanced twice just to be sure. Understand that to balance a driveshaft both ends are held fixed in a fixture that is concentric and does not "run out" at all. The angles are perfect on both the trans and differential. Tires are perfectly balanced and run up on a high speed balancer also. There is nothing to point to but the tail-shaft on the 6R80 running out, ie, not held strong enough to overcome the forces working in the driveshaft and car...
Adding weights in the proper place on the driveshaft has balanced out the entire system which is impossible to do at a driveshaft shop.
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