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Front Drive Shaft (4406) question

I had vibrations over 55 MPH in my explorer after the 4406 swap. After I moved out to AZ I took the driveshafts to a shop out here. They installed new U-Joints, and balanced both. Now the only thing limiting my speed is me. It is smooth clear up to as fast as I'm brave enough to take it with the bigger MT tires on it.

I have had both a double cardan on the rear and a single. Currently the single is in as that is the one I had balanced.
 



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That's a positive vote for it working out well.
 






My front driveshaft findings: the 97 and 98 4.6 F150/Expedition front driveshaft is about an inch longer than the 99-03 front driveshaft when fully compressed. Figured it out after crawling under half a dozen of these at the junkyard. I also noticed the later model driveshaft has a boot/bellows seal which covers the slip shaft, while the earlier model has an integral dust seal that rides on the exposed slip shaft, so I guess that is another way you could identify the two different shafts. I came home with a driveshaft from a 99 Expedition on this trip, and I was able to get in installed on my explorer, but even this shorter shaft would just barely squeeze in there.

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I took it for a short test drive, and an annoying vibration started by 40 mph. Sidenote: after I got my rear shaft balanced my rig runs very smooth up to at least 80 mph without the front driveshaft. Anyway, once I got back home I measured the front driveshaft angles using the Tremec app on my phone. After measuring I’d be surprised if anyone has gotten a single cardan front shaft to run smoothly in this setup...

The TC output flange and the front pinion flange are somewhere between 5 to 7 degrees out of parallel – you want to be within a degree or two of parallel for a single cardan setup. I removed the rear mounting bolt for the front diff to see if I could get them closer to parallel. Even pulling the rear mounting point down by an inch or so (which is an excessive amount) got me no more than 2 or 3 degrees closer to parallel, so that is not going to be a viable option.

On the bright side, the operating angle between the shaft and the pinion were pretty close to zero (in the vertical dimension anyway), which would be ideal for a double cardan or CV setup – no wonder they came this way stock. The fact that the TC output is an inch further outward on the 4406 compared to the 4404 puts the horizontal operating angle between the shaft and the pinion close to 2 degrees, which is not ideal, but the double cardan setup is still looking way better on paper. Looks like I’m headed back to the junkyard again. I’m going to end up spending more time and money on the front driveshaft than I did on the rest of the swap.
 






98GreenLimited, you have discovered the very same thing I did. I personally think the biggest reason we are have having issues is just what you pointed out, the 4406 front output shaft is at least 1" closer to the left side frame rail causing the angles in the horizontal plane to be greater. I have personally tried both the stock 91-96 front drive shaft with the flange conversion and the F150 single u-joint drive shaft you just tried. In my experience the F150 drive shaft is far worse than the double carden drive shaft.

I am still running the stock 96 double carden front drive shaft with the conversion flange, but I still get a vibration that starts to become noticeable between 65 and 70mph, and then increases with speed. I think the only true solution to eliminate the high speed vibration is to go with a true CV style joint (ball and socket) at the transfer case and the front diff like the newer F150's have. Even all of the newer mustangs have CV style joints at both ends of the rear driveshaft. The issue with this is obviously finding someone to make a special shaft like that. From my research, the front yoke and the adaptor at the transfer case would have to be custom machined.

I hate that you are re-living my hard lessons, but it does make me feel better that I'm not the only one. Keep us posted with what you come up with.

P.S. don't get rid of the stock V8 front drive shaft. One of the combinations I would like to try is to machine an adaptor socket to bolt onto the transfer case to use the stock AWD front drive shaft (I've measured it, this is possible to do with enough time or money). I just don't know if using a CV at the transfer case and a u-joint at the pinion will be enough to eliminate the vibration.
 






glad i have manual hubs
 






What are you doing for manual hubs - the AVM's?
 






Yea i did them in a 99 mountaineer and now have them in my V8 sport , but the 01 sport trac will probably end up with a sas ,
 






Any problem with them to date? I've read so much back and forth that it's been hard to decide, but the front driveshaft concerns are pushing me toward using them.
 






No problems , but its pricey , the hubs are around $125 on ebay and the seals and clips around $100 , then you need the new half shafts and hub bearings for a 99 ranger , i used them alot this year with all the crappy weather , no issues at all
 






Conveniently I already have the 99 Ranger parts on the truck, so the cost isn't quite as high.
 






If you have a complete front end on a ranger id pop the ball joints loose and swap the knuckle with hub bearing intact to save the seal and very carefully remove the clip on the halfshaft so you can reuse it , all you need is the AVMs ,
 






Sorry - to clarify I'm actually working with a '99 Ranger. In the middle of swapping the 5.0 from a '99 Explorer into it. The Ranger has the stock PVH hubs in place.
 






Oh lol ok so yea just a set of AVMs , definitely wanna see a build thread on that
 






I don't really have one good dedicated thread, unfortunately. It's mostly been a collection of individual questions asked as needed and piggy backing off of other's well documented threads. At this point the engine is assembled and I'm now trying to remember how all the external bits fit into place on the 5.0. The original plan was just to pull it out and transfer it over (bought it as a running 2wd donor for $400 that I drove home), but I made the mistake of popping the bearing caps to inspect everything. One thing led to another, and now it's three months and $2,000 later for essentially a full rebuild. I suppose the good news is that I'll be putting in a rebuilt engine with a more aggressive cam, intake spacer, all new belts, hoses, rebuilt injectors, new A/C compressor and condenser, etc... It's just taken a lot more time and money than I'd planned for (and sold the wife on).
 






98GreenLimited, you have discovered the very same thing I did. I personally think the biggest reason we are have having issues is just what you pointed out, the 4406 front output shaft is at least 1" closer to the left side frame rail causing the angles in the horizontal plane to be greater. I have personally tried both the stock 91-96 front drive shaft with the flange conversion and the F150 single u-joint drive shaft you just tried. In my experience the F150 drive shaft is far worse than the double carden drive shaft.

I am still running the stock 96 double carden front drive shaft with the conversion flange, but I still get a vibration that starts to become noticeable between 65 and 70mph, and then increases with speed. I think the only true solution to eliminate the high speed vibration is to go with a true CV style joint (ball and socket) at the transfer case and the front diff like the newer F150's have. Even all of the newer mustangs have CV style joints at both ends of the rear driveshaft. The issue with this is obviously finding someone to make a special shaft like that. From my research, the front yoke and the adaptor at the transfer case would have to be custom machined.

I hate that you are re-living my hard lessons, but it does make me feel better that I'm not the only one. Keep us posted with what you come up with.

P.S. don't get rid of the stock V8 front drive shaft. One of the combinations I would like to try is to machine an adaptor socket to bolt onto the transfer case to use the stock AWD front drive shaft (I've measured it, this is possible to do with enough time or money). I just don't know if using a CV at the transfer case and a u-joint at the pinion will be enough to eliminate the vibration.

Interesting. I had my CV go out right after I bought my Mercury, and the only choice was a new drive shaft or a rare used one, in 2003. I had an adapter made to use a normal u-joint shaft, and installed that, for about $175, including cutting off the old CV and replace with a u-joint.

That adapter was about $60 IIRC, and now you can buy a version of that, shorter than mine was. That's for the reverse of what you are thinking of though, male CV side to a u-joint flange. You want the female CV side, but mine could work possibly, it's just a square profiled round steel piece(drilled out for the needed holes and clearance). You might hunt that aftermarket version of the CV adapter part, it wasn't terribly expensive(10 years ago(maybe $40)).
 






edit: derp, disregard previous post.

Front pinion angle is about 3.0*
Not sure on the angle of a 4406, but the 4404's front output is also angled upward, about 4.5*
Driveshaft angle is about 3.1*
That makes for a huge operating angle @ the t-case. About 7.5*.
Operating angle at the pinion is only around 0.1*.
Difference in operating angle between front and rear should not exceed 1* to run vibration-free.

https://www.waterousco.com/media/wysiwyg/pdfs/content/J3311-1-DSSP.pdf
 






edit: derp, disregard previous post.

Front pinion angle is about 3.0*
Not sure on the angle of a 4406, but the 4404's front output is also angled upward, about 4.5*
Driveshaft angle is about 3.1*
That makes for a huge operating angle @ the t-case. About 7.5*.
Operating angle at the pinion is only around 0.1*.
Difference in operating angle between front and rear should not exceed 1* to run vibration-free.

https://www.waterousco.com/media/wysiwyg/pdfs/content/J3311-1-DSSP.pdf

Did you by chance measure the front to back angles, if the BW4406 is at least parallel to the pinion shaft, that way? That can't be changed at all so hopefully that's fine.
 






I may be way off here, but I have a thought. If I remember right, there isn't a lot holding that heavy TCase up. The transmission mount is all. If the transmission mount is weak, or worn, and the transmission is sagging then the Tcase is also sagging and that could affect the angle. Anyone tried new Transmission mounts? Maybe one of those Poly mounts the Mustang guys use?
 






Did you by chance measure the front to back angles, if the BW4406 is at least parallel to the pinion shaft, that way? That can't be changed at all so hopefully that's fine.

Do you mean the angles @ front and rear outputs of the t-case?
I don't have a 4406, I've just been struggling with a vibration issue for years (literally), and decided to check out the driveline angles, along with checking specs in my factory service manual (no t-case output angle in specs, specs only provide engine angle which is measured on the starter)

I may be way off here, but I have a thought. If I remember right, there isn't a lot holding that heavy TCase up. The transmission mount is all. If the transmission mount is weak, or worn, and the transmission is sagging then the Tcase is also sagging and that could affect the angle. Anyone tried new Transmission mounts? Maybe one of those Poly mounts the Mustang guys use?

This is true. A bad mount will increase the angle of the front output.
Unfortunately there are no better aftermarket bolt-on replacements.
Mustang ones can fit, but require modifying the crossmember (which some have, as I've seen some pics around here)
 



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Do you mean the angles @ front and rear outputs of the t-case?
I don't have a 4406, I've just been struggling with a vibration issue for years (literally), and decided to check out the driveline angles, along with checking specs in my factory service manual (no t-case output angle in specs, specs only provide engine angle which is measured on the starter)



This is true. A bad mount will increase the angle of the front output.
Unfortunately there are no better aftermarket bolt-on replacements.
Mustang ones can fit, but require modifying the crossmember (which some have, as I've seen some pics around here)

I meant the front drive shaft angles, looking down on it. I hope those are parallel at least, for either TC.

The trans mount I think is very important, for strength, and the shaft angles also. It may not change the angles much, but a little may help a lot.
 






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