Featured Technical T5 Swap Vibration Woes

Thank you Ebbsspeed. Good video, my understanding was that the angle should be equal or near equal never thought about the w configuration, I definitely prefer the z configuration. If there is no offset as in the first example in my post then the u joints will wear at a higher rate since there is no movement on the needle bearings.
Dan

 

Zero angle only poses a wear issue when both the transmission and the differential are fixed-mount, such as with independent suspension.

Suspension movement will move the needle bearing just fine.

 

Hey, k_b;
"Any idea on how to reduce working angle without raising ride height?".

Actually, it's more about changing the degree/angles, vs ride height, as I don't know which way you gotta go here, so's it'a sorta guessing & tossing out ideas. So, after getting some of the other "known-done-rights" outta the way, let's verify & correct the driveline angles, so's they're "known-done-right", or, at least acceptable.

But, a couple ideas.

For the rear axle, leaf-sprung, you can use tapered shims. They go twixt the axle pad & spring. I guessing spring-under here? If so, put the fat part facing front to raise the pinion-nose up, & the fat part facing rear to lower the pinion nose down. The shims are usually sold as a "# of degrees change"(& it's fairly small, btw. & look like a wedge.), look at 4x4 shops. Unless you get crazy w/them - & don't stack them - the change in rear ride height will be very small, 1/8->1/2" maybe?
As for the mill & trans, you can do both or just one.
The mill is usually the easiest, but returns less degree change. Simply use shims under the motor mount, in the same shape as the motor mount, please. Like round washers for biscuits, rectangle for well, rectangle-shaped mounts. Things to watch for, are clearance(s) at the bellhousing->firewall/trans-hump, then rocker-box->firewall, & air cleaner->hood underside. Also might need to move/lengthen fuel-line->pump line abit. You won't get a lot in the front, due to height restrictions/available-room. The change in degrees at thetrans output will be fairly small. Might be enough, or have to be combined w/other changes. Kindaof a PITA...
The trans is the hardest, but should get you the most change. IDK what you have for trans mount there, but if it's a sorta-thin rectangle-box piece of rubber, look for a thinner one, & use same-shaped shims of different thickness to adjust height of trans output & get some degree of change. Depending on trans vibration-absorbing-device, iffen there's no bolts sticking out thru the top, you *could* trim off some of the top, thinning it that way, & back to the shims for adjustment. Either way, you'll probably need some different length studs &/or bolts. Third way is to modify the metal frame-mounted trans crossmember or find a lower one so's you can use shims for adjustment(s). Again... .
If there is no rear trans mount, & you have a pair of bellhousing mounts at the bellhousing(like a lot of 40's->50's cars - I don't remember what the falcon has), then the ideas are the same, but you have to modify each one on each side so's the engine & bellhousing sit level, side to side. FWIW, I used to have a ford caboverpu econoline that someone swapped a Sprint260 into. & got it crooked, a # of ways. Oddly enough, never had vibration/drivability issues. But the way the engine leaned sorta gave me fits, but it was too solid to change, so I left it. Worked ok.

HTH.
Marcus...

 

On this car the engine mounts both have bases on a horizontal plane, and side bolts on a vertical plane.

The inclination of the engine and transmission can be increased by shimming between the rubber mount and the frame mount.

The inclination can be decreased by slotting the side holes in the rubber mounts, to the extent that the center link and under-engine crossmember will allow.

Shimming the engine mounts up, and the axle such as it raises the pinion tip by the same amount will decrease the working angles.

A Falcon has three-point drivetrain mounting. One mount on each side of the engine, about 2/3rds forward of the back of the block, and one pad under the tail of the transmission.

 

Just watch your fan clearance if you are running a 3-core radiator.

 

Thanks, Gimpy;
I couldn't remember.
So here, the only problem would be if he needs to lower the trans tail, & can't delete any factory shims, so's that means finding a thinner other-oem or aftermarket trans-mount, or metal modification. It might just be easier to modify the crossmember to lower the actual trans-mount area in the crossmember itself. ??? Then shims could be added/subtracted as needed, using factory stuff.
Hope the guy gets this done, it can be quite frustrating at times.
Marcus...

 

The point is that in your final configuration the u-joint angles should be the same number of degrees, positive or negative, at each end.

Your scenario where you simply change the angle of one centerline (6º in your example) could result in a lot of different u-joint angles, depending on driveshaft length, the distance between centerlines of the pinion shaft and transmission output shaft, whether the pinion shaft centerline is above or below the transmission output shaft centerline, etc.

 

sure you have checked that the pilot bushing is the right size. Are you sure you have the right slip yolk some are longer & have splines deeper. The hardest vibration I ever had to find was a worn tail shaft bushing

 

I only agree with half of what you are saying. For best results in our automotive scenario (where the trans is typically higher than the rear end/pinion), positive OR negative isn't best, only one is. Three down and three up IS the best. Three down and three down may technically cancel each other out but, in this scenario, three down and three down is absolutely NOT the best option. That being said, we have no idea which method the OP chose. I doubt it's down and down but who knows? ... We also don't know how the OP views his installation ... does he actually have three down, three up but is simply referring to it (in his mind because I haven't seen him state either) differently as I found on another thread that some people do.

Exactly ...

So how exactly did the OP do it? And by "how" I mean "draw me a picture" because what is down to some is up to others and vice-versa

 

That’s why I posted the pictures, to me down means the transmission tail shaft or pinion is pointed toward the pavement up means pointed towards the cars floor. IMO
Dan

 

This is some excellent insight! I hadn’t heard of the “W” configuration being used before. I’ll take a look at this tonight and see if that’s feasible for my application.

Yesterday I managed to plumb-Bob the centerline of the engine/trans against the unibody centerline and found the engine and trans was running at an angle, driven by the engine being moved 1/2” towards the driver side. I managed to correct the transmission and centered it in the car and raised it slightly but I’ll need to drill out the engine mounts on the frame to correct the engine. Right now, the engine and trans is nearly parallel to the chassis.

I also swapped the rear axle shims out from 4 degree (3 degrees pinion up) to 2 degree (1 degree pinion up). However your comments on the W configuration have me curious to try removing the shims all together and measure working angles to see if this helps.

FWIW none of the changes I made impacted the vibration I’m experiencing yet.

 

did them 60's falcons have rubber isolators from the leaf springs to the axle, I only say it as i have a 68 ranchero 8'' and it has the rubber doofers that enwrap the leaf springs, also what spigots or locates or concentrically positions the input shaft bearing housing/retainer into that mdl adaptor and then that to the bell housing? i only ask as there are two sizes of spoigot or register or whatjamicallits for them, i.e. a chevy camaro t5 post 1994 will have a small register AND still be a ford pattern case, if the mdl adaptor is milled to accept a larger ford input shaft bearing retainer doofer, then where is the spigotting registering concentricity. i think i have seen them before, as an adaptor ring or something, you know - especially if the only thing really holding the bell to the trans is 4 countersunk locations. plus
IF you have a 10 spline 1 1/6 input shaft - world class fitted to your trans to run the 8.5'' 216mm friction disc
have you had fitted the jeep 10 spline input shaft over a ford 4-6 or 8 cylinder variety, and do their tips have a different girth.
I only say this as I forgot to fit the needle roller bearing input shaft into my motor just now, going from auto to manual there isnt one at all
plus my pal done forgot to fit one whe he swapped in a brand new motor, and the clutch turned to dust, the flywheel which was billet and ££££ over heated and the whole gear train suffered.

saying that even the 4 cylinder pinto? v6 ford cologne and the v8 windsor engines are different if you like, does one simply assume that they all share a similar input shaft bearing outer dimension - come input shaft tip od,

oh, did you paint the rear axle pinion yoke where the driveshaft u/j seats into it?

did you have to reweld the axle saddles on the 8'' do the saddles on the 8'' if stock have the 1'' locating holes in the flat part that locate into a rubber than steps down into the 3/8ths pin on the spring?

 

I’ve never seen a W alignment in operation on a production car or truck driveshaft. I would not use it. Take my advice for what it’s worth, but realize that I know that many guys smarter than me have engineered cars to work properly. Who am I to break the laws of physics?

 

Might be ok for low speed applications like a steering shaft.

 

A few models of Range Rover use the W configuration. It works fine.

 

No rubber isolators. The leaf springs sit on pads welded to the axle.

 

Here are my suggestions:

1: Simple check..........are the ends on the driveshaft clocked correctly ?

2: I'd put the car on a 2 post lift and have someone inside to run the engine up to speed while the wheels are turning and physically look at the components while up to speed. This requires a lot of care for personal safety but you may be able to see something thats not working or where the vibration originates. Again, this requires lots of concern when near the vehicle.

3. If you don't want to do 2, think about mounting a camera or phone with a camera under the car and taking it for a drive. Remember if the front of the driveshaft breaks, it could pogo the vehicle.

Since you only get the vibration when the driveshaft is in place, the lift would eliminate any possibilty of the front tires contributing to the problem. (Don't laugh, years ago my son's friend had a severe vibration in his car when driving, yet the steering wheel felt fine. Then we saw that the front tire had a big knot in it. New tire and prob solved.)

I have to believe its still caused from something in the driveshaft or possibly rear tires. I know you said you had the driveshaft done 3 times, but did they use the same tube? Could it have a slight bow in the middle? Did you swap your existing tires around or use completely different known good tires ? One more thought...what is the OD of the driveshaft you are using?

 

If you are after decreased working angles, you will need to increase the angle of inclination of both the engine/transmission and the pinion.

When I ran a T5 in my 1960 Falcon, the engine and transmission were set at 5º sloping down towards the rear of the car, and the pinion was also set at 5º. I forget what the driveshaft slope was, but it was only a few degrees off of the powertrain angle. It had no vibration even as fast as it would go.

I think people get too caught up on what are referential angles, and not the working angles.

The tilt of the engine/transmission and the pinion are angles that reference the ground. That is not the critical measurement.

The critical angles are the working angles of the u-joints.

Those are a combination of the object angles, ride height, and length of the driveshaft.

Just about every vehicle has a driveshaft that is on a slope. Classically, but not always, that is such that it is lower at the pinion than it is at the output shaft on the transmission.

In that case, lowering the tip of the output shaft in relation to the front of the crank, and raising the tip of the pinion, in both cases increasing their angles away from level, will decrease the u-joint working angles.

Put an angle finder on the driveshaft and measure the slope (chassis level). Post that number.

 

Your tail shaft and pinion center lines not only need to be parallel, they also need to be as close to the driveshaft slope angle as practical.

The driveshaft slope is largely a factor of how long the driveshaft is, and the difference in height between the tail shaft and pinion.

If you had a 4-inch difference in height, and a 48" driveshaft, with a level tail shaft and pinion, you would have working angles of 4.78°.

Now, if you tip the engine/transmission by 3°, and the pinion to match, your working angles change to 1.78°.*

If you tip the engine/transmission by 4°, and the pinion to match, your working angles change to 0.78°.*



Working angles need to match.

The hypothesis that you need to de-angle the pinion on a street vehicle, to compensate for spring wrap under load doesn't prove out.

It may even cause vibration, and premature wear.

Just making them match, and get them as close to the driveshaft slope as possible.

The only time that a u-joint has uniform rotational force is when it is at a 0º operation angle.

The farther from 0º it is moved, the more uneven the movement becomes.

This uneven movement is largely cancelled out by the opposite-end u-joint being at a complimentary opposite angle.

The less uneven movement that needs to be cancelled-out the better.

*Yes, I am aware that moving the u-joint pivots also changes the slope, and driveshaft length requirement, but that is too complicated to graph in a simple post.

 

The whole referential angle issue is largely misunderstood.

Powertrain components are not "tilted" for a mechanical function reason. It is not "for" the u-joints, or carburetor, or any other functional reason.

Transmissions were lowered in the tail to reduce the intrusion into the passenger compartment by both the ever enlarging transmission cases, and the driveshaft.

The angle itself is arbitrary. Some common numbers have become de-facto standards. The 3º/3º arrangement is common, but again, that is what one set of engineers needed to run in order to not prevent installing a bench seat. It could just as easily been 2.97º/2.97º, 4º/4º, or 5º/5º.

In reality, the only things that matter are parallelism, and minimized complimentary working angles.

 

Amen.

 

Yep.
Go measure some leaf spring trucks. The 3* rule isn’t inforced on many of them.
I put drive shafts at zero and no issues.

 

One of our suppliers reps was putting on a seminar and demonstrated drive line angles with one of those machines; was pretty interesting see in "real life" how U-joint angles affected the shaft. Guy was going to get into it further; but when we took a break Desert Storm was blasting out on the TVs in lobby and bar and nobody went back to class.

 

I had a long winded reply typed out but after re-reading this whole thread I think everything I could think of has already been mentioned . Is it possible that your rear axle is rotating under power, not talking about spring wrap but perhaps loose u bolts? Never heard of that happening but it seems like maybe it's the only thing left that could be contributing to some monkey motion that hasn't been mentioned. Since we're throwing out opinions I'll give the driveshaft guys the benefit of the doubt that they did their job right, especially after several times, and I'm assuming you are checking/replacing your output shaft bushing after each of these destruction sessions. Almost has to be something internal to the trans, a wildly unequal u-joint angle set up or some axle housing rotation. I doubt you would see this type of rapid destruction if your u-joints were only off from each other by a couple degrees

 

Lots and lots of u-joint angle and vibration threads have been on boards all over the internet, but none that I recall ever had damage done to the yoke.

I am sure the driveline shops have checked, but is the driveshaft clocked right?

U-joint working angles ( tail shaft to driveshaft, and driveshaft to pinion ) are the only numbers that really matter. The frame or roadway angles are of no importance.

Dead straight from engine to pinion will wear out u-joints, you may only get 90K miles instead of 100K but with no vibration. It's only straight setting still.

We had four, 5 ton electric trucks at work, all four broke the output shaft of the gear reduction box because the four piece driveline was out of phase. The constant speeding up and down of the driveshaft during regenerative braking was to much for the shaft and the heavy ( 200 + lb ) electric motor. Once phased right, all the weird vibrations went away.

 

I agree with both of the above but ... although yoke damage and pinion angle aren't typically (if ever) mentioned together, "we" need to check off all the possible wrongs in order to determine what exactly we started with in the first place. Pinion angle may be only one of this guys problems IF it's a problem.

I too agree that the driveshaft should be pictured so "we" can see if it's clocked "correctly". Again, he has supposedly had three different shafts made by three different shops so it might be safe to assume they were built correctly but "we" still don't truly know that/what exactly he is working with. That being said, a friend has a '67 Camaro that he swapped an aftermarket 5 speed into. He had a new driveshaft made. Interestingly, the original Camaro shaft was not clocked "correctly" as we know it. Apparently GM did this intentionally in order to combat some sort of vibration (or so the story goes). Seriously though, clocked "wrong" as we know it now has been done by GM.

I am not claiming the pinion angle is at fault for the damage/wear but it would be nice to know that he set it up correctly so we can rule that out as a possible factor (in conjunction with flaws in the install).

 

The " standard" for driveline angles forever

 

I am assuming this is a Mustang T5. If So do you know anything about it's prior life? My reason for asking is (and I admit I have not read every post in this thread) but when I build a T5 Transmission especially a Mustang V8 Trans that has the 3.35 first I always check the mainshaft for straightness. A lot of builders overlook a bent mainshaft. If they have been driven hard and raced 2 out of 5 mainshafts will be bent behind 5th gear. You had mentioned your builder replaced 2nd gear. What did he find wrong with 2nd gear? was it just the engagement teeth from poor shifting? or was the main teeth damaged as if the main teeth had damage I can almost guarantee you the cluster shaft should have been replaced also. I am leaning towards you have a bent Mainshaft since you have been through 3 driveshafts already

 

I know you said T5 was rebuilt with trans output bushing. My T5 had a vibration at 70ish mph and I replaced the output bushing and then vibration is gone. There is a tool to pull and replace the bushing with the trans in the car. Many onnthe Mustang forums have done it.

https://www.amazon.com/Extension-Housing-Installer-Transmission-Borg-Warner

 

Tell me you've never worked on a Ford, by not telling me you've never worked on a Ford.

The uncommon Fox/SN95 chassis used the 'U' configuration. More commonly known as a Mustang, Fairmont, Thunderbird, Mark VII/Continental...

Being the trans is a T5, gears are more likely to strip than a shaft is to bend. The output shaft might get twisted under drag launches. This would cause the splines to twist and prevent plunging of the slip joint. This would bind and lock up the rear suspension, but I would suspect this would be noted at lower speeds.
Unless its a very minute twist that only becomes noticeable at higher tailshaft speeds, with possibly some aerodynamics that pushes the rear down and into this bad spot. Where in slower speeds the driveshaft doesnt stay at that given depth of plunge, or not long enough to be noticeable.