Front Drive Shaft (4406) question

[SWIGIN]

Ford has had drive lines running down hill for decades. Because of this the front DS can have vibration problems. This is nothing new to us who have been lifting Fords for years.

I've said it multiple times on this site, you NEED a double cardan front DS to have the best chance at no vibration. It splits the crapy front transfer case output angle over 2 u joints. Now, some guys still have a problem when using a double cardan shaft but some don't start with a nice rebuilt DS. You just throw on a junkyard DS and it vibrates well then I guess that means double cardan shafts don't work....not really.

I don't know who but one guy on here who swore that Double cardans don't work later came back and said after he had it checked out and rebuilt with new joints that it works fine. No way!...LOL

I'm just an old school Ford guy but these long math filled threads make me laugh. This is all something that every Ford I ever lifted had to deal with and a Double Cardan is your best bet on being Vibration free.

Sure there are other ways to skin a cat but I always start with the tried and trued methods first.

 

[98GreenLimited]

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.

Just curious after reading the post above, do you have new u-joints in your double cardan shaft? Did you get it balanced? I think the conversion flange might be enough to throw it out of balance.

An adapter similar to this?

 

[98GreenLimited]

glad i have manual hubs

I might have to go that route if I don't get something cheaper to work.

 

[98GreenLimited]

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?

I put a new trans mount in when I did the swap, but we'll see how long it lasts. I wish there was a bolt in poly mount.

 

[98GreenLimited]

Ford has had drive lines running down hill for decades. Because of this the front DS can have vibration problems. This is nothing new to us who have been lifting Fords for years.

I've said it multiple times on this site, you NEED a double cardan front DS to have the best chance at no vibration. It splits the crapy front transfer case output angle over 2 u joints. Now, some guys still have a problem when using a double cardan shaft but some don't start with a nice rebuilt DS. You just throw on a junkyard DS and it vibrates well then I guess that means double cardan shafts don't work....not really.

I don't know who but one guy on here who swore that Double cardans don't work later came back and said after he had it checked out and rebuilt with new joints that it works fine. No way!...LOL

I'm just an old school Ford guy but these long math filled threads make me laugh. This is all something that every Ford I ever lifted had to deal with and a Double Cardan is your best bet on being Vibration free.

Sure there are other ways to skin a cat but I always start with the tried and trued methods first.

I wish I had seen your other posts before spending time and money on single cardan shafts and new u-joints.

 

[gavin]

Ford has had drive lines running down hill for decades. Because of this the front DS can have vibration problems. This is nothing new to us who have been lifting Fords for years.

I've said it multiple times on this site, you NEED a double cardan front DS to have the best chance at no vibration. It splits the crapy front transfer case output angle over 2 u joints. Now, some guys still have a problem when using a double cardan shaft but some don't start with a nice rebuilt DS. You just throw on a junkyard DS and it vibrates well then I guess that means double cardan shafts don't work....not really.

I don't know who but one guy on here who swore that Double cardans don't work later came back and said after he had it checked out and rebuilt with new joints that it works fine. No way!...LOL

I'm just an old school Ford guy but these long math filled threads make me laugh. This is all something that every Ford I ever lifted had to deal with and a Double Cardan is your best bet on being Vibration free.

Sure there are other ways to skin a cat but I always start with the tried and trued methods first.

Double-cardan is not the be-all end-all.
There's a reason Ford moved away from double-cardan to GKN CV joint in the 2nd gen Explorers.
That reason was NVH-related issues.
Hence a TSB on the 1996-1997.5(?) MY to replace the 4404 with a different model which is the one that accepts/uses the GKN CV.

Besides, even the double-cardan still require the proper driveline geometry.
If, as stated above, the output is further away from center than stock, that creates compound angles which makes things trickier.

 

[98GreenLimited]

I’ll try a double cardan 1st gen shaft with new u-joints, as SWIGIN suggests. If that vibrates, I’ll get it professionally balanced. If it still vibrates because of the sideways angle at the diff u-joint I might have found another option besides AVM hubs. 96 – 98 Jeep Grand Cherokees with the NP249 (full time 4WD) have a double cardan at the transfer case and a CV at the diff.

These jeeps have a dana 30 up front which has the same pinion shaft size and spline count as the D35 in the explorer, so the CV pinion yoke should bolt right up - see the example picture below. The only difference is the O.D. of the D30 pinion yoke shaft (seal surface) is smaller than the D35, so a different pinion seal is needed. I found that a D28 pinion seal has the same shaft diameter as the D30 and the same housing diameter as the D35, so that should work perfect.

There are quite a few different lengths for these shafts, but the shortest is 28-1/4” from the center of u-joint on the TC end to the face of the CV on the pinion end. Add maybe 2” for the precision 627 conversion yoke and 1” or 2” for the extra length of the CV pinion flange (it looks longer). This puts it in the ballpark for being the perfect length. The 28-1/4” shaft comes from a 96 with a 5.2, but this same year and engine also had a shaft that is an inch longer - but it might still work. The 4.0 shafts are even longer, so are 97 and 98 shafts - not sure if they are too long.

Here are some links and part numbers for the curious:

Driveshaft (I would get this at the junkyard, along with the matching CV yoke)
D35 u-joint yoke (to compare measurements)
D30 u-jount yoke (to compare measurements)
Pinion seal: Timken or National 4244

Hopefully the 1st gen shaft works out for me, but if it doesn't I might give this a shot.

 

[CDW6212R]

I like that idea too. Hopefully the Explorer shafts will work well, but it's good to find options.

 

[SWIGIN]

Double-cardan is not the be-all end-all.
There's a reason Ford moved away from double-cardan to GKN CV joint in the 2nd gen Explorers.
That reason was NVH-related issues.
Hence a TSB on the 1996-1997.5(?) MY to replace the 4404 with a different model which is the one that accepts/uses the GKN CV.

Besides, even the double-cardan still require the proper driveline geometry.
If, as stated above, the output is further away from center than stock, that creates compound angles which makes things trickier.

Ford did away with the double cardan because the CV is cheaper, end of story. The CV will not put up with 1/2 the abuse that a double cardan will, they are much stronger.

When you have a bad flange angle it is far better to spread that over 2 u joints then one CV.

These are things I have learned over the years, they are not opinion they are facts.

 

[delexploder]

that jeep setup is interesting , keep us posted if you do it

 

[98GreenLimited]

Update:
I got a 1st gen front d.s. last week, put new u-joints & 627 conversion flange, and installed it. I had a vibration starting at about 60 - 65 and getting progressively worse up at higher speeds. I took it out and had it balanced. It was out of balance which made me hopeful that the vibration would be fixed. It still vibrates in the same speed range, though it might be slightly better than before I had it balanced. They just took off the factory weight and didn't put anything else on, so I'm wondering if it is actually well balanced? That would be quite a coincidence if the new conversion flange happened to perfectly balance the shaft.

I feel like it is a balance or runout issue causing my current vibration, rather than the angle at the pinion u-joint for a couple of reasons. The driveshaft guy said that 1-3 degrees operating angle would be fine at the pinion end of a double cardan shaft. Also the vibration is in the same speed range and seems to be the same frequency as the vibration I had from the rear driveshaft, which was fixed with a balance. The u-joint angle related vibration I got from the single cardan F150 front shaft started around 30 mph and was so severe and high frequency that I didn't take it over 45 mph. U-joint angle vibrations occur twice per rotation, while balance and runout issues cause a vibration once per revolution, so it seems more like a balance or runout issue.

I measured about 0.015" runout on the TC end of the shaft and about 0.005" runout on the pinion end. The TC flange itself has about 0.005" runout, so I clocked the driveshaft to match the high spot of the flange with the low spot of the shaft, and got the runout down to about 0.010" on the TC end. No improvement in vibration.

I think my current issue may be with play in the slip shaft splines, especially with how far the shaft is extended. It feels like there is no play when the shaft is nearly fully compressed, but when installed it is extended about 3" (see picture before I replaced the boot). I measured about 0.020" to 0.030" of up and down play at the slip joint with the shaft installed. This seems like it might be excessive and would allow the shaft to spin like a jump rope at 3000 RPM.

Not sure what I am going to do. I've already put a significant amount of money into this front shaft, and I don't want to spend more money on this shaft or the Jeep shaft setup, since neither is guaranteed to fix the vibration. I am leaning toward the manual hub swap, even though it will be a lot more expensive. At least it will certainly solve any vibration issues with the front shaft, and I will get new hubs/bearings and CV shafts out of the deal.

 

[delexploder]

I really think you will be happy with the manual hubs but looking at your pic i think i used a different yoke on mine due to the same issue ( being too short ) i just cant remember what i used , maybe one from a rear shaft

 

[SWIGIN]

Have you tried recently to drive it without the front drive shaft installed?

 

[98GreenLimited]

Have you tried recently to drive it without the front drive shaft installed?

Yeah, I only had it installed for a few hours each time I tested it out. Currently running without the front shaft and there is no vibration.

 

[ahodges]

You are re-living everything I have experienced and tried. I have yet to make the vibration disappear.

 

[MAS Tequila]

I gave up for a while.

Mine has been without the front shaft for all of the time since the swap, 2 years ago, except for a few miles to know that neither the F150 nor the double cardan worked for me.

No one talks about the 1” offset with the manual case.

With my suspension lift and the offset I plan to try one with a dc at both ends.

If that doesn’t work I’ll likely put the awd case back in.

 

[ahodges]

The double carden or CV at both ends will be the fix for the vibration, I'm sure of it. Do you have an idea on how to do that without custom machining work? The time it will take to do the custom machining is the only thing keeping me from doing it. I'm convinced the extra 1" offset of the front output shaft is the cause.

 

[vroomzoomboom]

have you guys thought of notching the holes in the cross member a little bit to slide everything over? i know i have posted in this thread before, and dont know if i mentioned that. as well as when i put the 347 in, i used the front driveshaft from that truck in mine. i can honestly say doing 60 or more now that i dont have a roar or vibration in it. i also launch it in 4x4 on dry pavement and havent had problems.......but now that i have posted this, im sure i will now lol

 

[CDW6212R]

@98GreenLimited brought up a good point, the slip shaft needs to be compressed enough when installed. If the shaft is stretched with less engaged than ideal, that could be a vibration.

I like the idea of moving the TC over a little, I bet 1/2" or so would not hurt anything.

 

[SWIGIN]

Sliding it over would put the face of the flange at a slight angle to the front one.

Worth a try I guess but I don't see it working. Especially since a lot of people had no problems at all.