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Free wheeling hub differences: EMS & DynaTrac

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I purchased and installed the EMS HC-00D-SRW-35 35 spline locking hub kit on my 05 2500. The information I have on the DynaTrac kit is word of mouth from another TDR member. Before I bought the kit I did some searches for the differences between the two, but there was not a lot of information on TDR. DynaTrac did not respond to my product inquiry via their site's email link. EMS did and they cost a lot less (or so I thought) so I went with them.



Turns out I didn't pay close enough attention to the DynaTrac website. I thought the $1895 kit was 30 spline and you'd have to pay even more for the “Stage II” upgrade to get 35 splines. I believe the standard $1895 DynaTrac kit for the 05 comes with 35 spline stub shafts. If DynaTrac gives a TDR discount, then the price difference really is not that much between the two kits. Is the cost savings is worth it? Maybe, if you're ready for some extra work beforehand. You'll have to decide for yourself.



As for the physical differences, EMS uses a five hole Ford spindle that gets re-drilled with the four bolt pattern for our trucks, hence the EMS logo covering the spindle bolt holes in all the EMS advertisement pictures. DynaTrac uses a custom spindle with four threaded holes. There must be something different about the stub shafts or spindles (or both) since the EMS kit moves the ujoint outboard of the stock location, away from the center of the truck, while the DynaTrac kit moves the ujoint slightly inboard. EMS says moving the ujoint outboard is to minimize ujoint bind while turning. It sounds like some of the DynaTrac kits come with the wheel studs and bearing races installed, some don't. The EMS kit came with them loose.



The member who installed a DynaTrac kit said everything fit as designed. I was not so lucky with the EMS kit. EMS customer service was good.



Issues I ran into during the install:

One spindle had been mis-drilled and required replacement.

Both spindles had bearing fitment issues which required polishing parts of the spindle.

Both ABS blocks required grinding due to interference with the hubs.

One stub shaft had minor indentations on the surface where the needle bearing rides. I just polished it up so I could finish the install.

One stub shaft required grinding the yokes to fit through the steering knuckle.

Both lockouts were loose and rattled. Added additional o-rings.



Lessons learned:

1. Inspect everything carefully prior to starting the install.

2. Dry fit everything together before doing the actual install!
Its much easier to deal with issues before parts are bolted to the truck and covered in grease.



All in all the kit was more of a chore to install than I expected. Not really a big deal, just after fighting to get the unit bearings out I was expecting a simple bolt on for the kit. I'm not so sure about moving the ujoint from the stock location, both from the ujoint bind standpoint and because of where the internal axle shaft seal at the differential rides on the shaft. I am also somewhat concerned that the spindles fit into the steering knuckles loosely. All the other spindles I've worked on, Dana 60, GM 10 bolt and Jeeps, had all fit tightly in the knuckle. Maybe once all the rust from the unit bearings was removed, the hole in the knuckle was slightly oversized? So far everything works.





Feel free to post up your install issues, good or bad, with either kit. Hopefully this thread will help others to make a more informed purchase.







PS if anybody has the DynaTrac kit and hasn't installed it yet, please measure the spindle OD where it fits into the steering knuckle. I'll be pulling mine to do ball joints soon and will measure it to see if there is any size difference compared to the DynaTrac spindle.
 
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Fre-spin kit.

Coincidentally,this morning I spoke to a guy with an '03 with the Dynatrac kit. He installed it himself and everything went well. His mileage has increased maybe 1mpg. on the highway,with handling identical to before. He did it for piece of mind. That axle shaft sure does stick out a lot with stock tires and wheels though. Don't know if EMS' does the same. No rockcrawling,that's obvious.
 
A friend and I each installed the Dynatrac kit on our '03's in March of this year. The bearings were installed in the hubs, and there were no machining or tolerance issues on the spindles. The kit does not include new U-joints, so Precision 464's were installed during the conversion, and I drilled the upper ball joints for grease fittings. The supplied wheel studs are too long for steel wheels, so rather than cut them, I purchased the correct studs from Dorman, as I was told the DC studs were $11. 00 each. I don't believe re-using old studs is a recommended practice. Also, Dynatrac uses two types of bearing retaining nuts, so you'll have to get the appropriate socket. The only thing I would have liked is some other finish on the hubs than black paint.

As far as results go, I feel the conversion is worthwhile, not so much for the

1-2 MPG increase, but for the fact that the truck drives and steers so much more freely. And if you have to go into the front end for any other repair such as U-joints or ball joints, this is almost a no-brainer.
 
I also just installed an EMS kit. I also ground alittle off each yoke although I could of pushed them through the knuckle. I also had to file a taper on the ABS blocks and a little clean up on one spindle, otherwise the kit was fine and they do have good customer service. I do have one ongoing problem with the hub on the driver side. It comes out of free and tries to turn into the lock postion. Anyone else have this problem ? I have been bending the wave spring to put more tension on the cap, this has slowed it down but I guess I need to bend it more to keep it in the detent. They did tell me that they would send me new lock outs if this does not work so, I have no complaints at this point. Doug
 
Update

Out of the blue EMS sent me a replacement stub shaft, I guess they read this post. That was nice of them and all, but this is getting ridiculous! There is another issue with the hub kit.



Even though the lockouts are installed correctly and tightened up, they are loose and rattle when driving down dirt roads. As a temporary fix the lockouts are duct taped to the hub. :rolleyes:

I have emailed EMS and they have not responded. Warn (the manufacturer of the lockouts) responded and I spoke with a customer service rep on the phone. Rather than try to explain the issue I have attached a rough sketch of the problem.



/webdata/photopost/data/506/medium/hub.JPG#ad




The lockout is too far away from the hub, far enough that the o-ring doesn’t even touch. According to Warn the lockout should bottom out on inside gear assembly, not the hub body. Obviously the lockout should still be close enough to the hub for the o-ring to be under compression, which will seal out dirt and to keep things snug. The Warn rep mentioned that sometimes Ford hubs have a similar issue and that using two spiral lock rings in the hub may solve the problem. Since the lock rings are about . 0625” thick and the gaps on my hubs are only about . 0515”, using two spiral lock rings would be too thick.



Anyhow, just a heads up on what to watch out for. I’ll post the fix for this latest issue when the root cause of the problem is determined.
 
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Uhhhhhh... its been a while since I installed mine, but did you try reindexing the lockout inside the hub?? I thought there was only one way they went together?



steved
 
I installed the Dynatrac kit on my '03 with NO problems (thank you rbattelle for having me prepared for the unitized hub removal!) and have been very pleased with the results. 1. 5 mpg improvement and the comfort in knowing that the front end is not revolving needlessly!
 
... . I thought there was only one way they went together?



steved
Yeah, its a no brainer... only one way to go together. Most likely its either the hub has the retainer ring groove in the wrong spot (or too wide), the oring groove in the lockout is too deep or the three standoffs on the lockout are too tall or maybe a tolerance stackup of all three. Right now I'm leaning toward just taking about 1/32 off the lockout standoffs, but I am waiting to hear back from Warn to see what the recommended fix is.
 
I know you indicated that stacking retainers would theoretically be too thick, but would the compression of the oring provide the additional clearance needed?



And even if the lockout body is pulled back into the hub a bit more than usual, wouldn't the cap still engage the lockout and tighten down on the oring? Isn't that the point of having the screws on the cap, to tighten the cap to the hub (and sealing via the oring)???



I thought I remembered mine doing this too and it was installation error on my part... something wasn't quite seated inside the hub? I just can't remember, its been over 1. 5 years since I had them apart. I wish I could be more help...



steved
 
Two retaining rings would be about 0. 011" too much and make the lockout hit the hub face (if the o-ring allows it to get that far) before the standoffs on the lockout touch the internal gear.
Warn said:
In most cases the hub assembly when installed will allow some movement (roughly 1/16 or so), the locking hub should not be “bound” up tight when installed. You should be able to grab the cap assembly and be able to slightly move it side to side.
LOL, 1/16" (0. 0625") is too much in and out movement since the o-ring will loose contact with the hub face by 0. 050", even less once the o-ring takes a set.



I did get an email back from the Warn rep and he said he could not get me the dimensions for the lockout! Huh??? No way to tell if its the hub or the lockouts without knowing the proper dimensions#@$%!



This is going nowhere, so a little reverse engineering. The o-ring cord is about 0. 140" diameter and the o-ring groove is about 0. 090" deep. Now iirc a face o-ring should have like 20% crush, so that would be 0. 112"

0. 112" minus the o-ring groove depth of 0. 090" = 0. 022"



I am just going to assume the ideal gap between the lockout and hub face should be no more than 0. 020" and grind down the standoffs on the lockouts until its right. Right now the gap is 0. 0515" so its only 0. 0315" or about 1/32 of an inch to grind down.



So much for a bolt on kit. I think somebody needs a QC inspection program before allowing parts out the door:rolleyes:
 
Grinding the standoffs is not going to work. I am surprised that Warn would suggest 2 retaining rings because as you can see in the following sketches there is not enough clearance between the internal gear and the lockout for two rings! Sorry for the crappy drawings, switching from AutoCad to jpeg messes them up. Anyhow, it looks like a fat #342 o-ring may be the easiest solution to get out of this mess.



#ad




#ad
 
Really worth the money?

So do you think this Dynatrac kit is even worth the money? How long is one mpg going to take to break even and start saving money?



I would like to gain some mpg and eliminate moving parts that don't need to be moving, and having the option of going to low and still being in 2wd might be nice. If it's only going to pick up one mpg give or take, I have a hard time forking out that kinda money. Especially when I would debate doing the install myself to save more money, but possibly mess something up in the process? I've never been in the front end of a truck before, rear ends a few times on trucks and cars only. Someone mentioned a TDR discount with dynatrac, is that hypothetical or an actual discount. It would have to be pretty hefty to make me decide to go ahead with it. And the hubs stick out farther, and are just black, not chrome?



Is there no cheaper way to make it a free wheel kit? I know on a Ford work truck the shop guys just swapped in a set of warn manual hubs. Same with a buddies '89 Suburban, a lot cheaper I would think.
 
Going from 19mpg to 20mpg pays back appx $789 per hundred thousand miles at $3. 00 per gallon. Think what it will pay back three years from now when fuel is $6. 00 per gallon!!
 
Going from 19mpg to 20mpg pays back appx $789 per hundred thousand miles at $3. 00 per gallon. Think what it will pay back three years from now when fuel is $6. 00 per gallon!!



Agreed, IIRC, several of us "calculated" the cost/benefit and figured that the hubs would pay for themselves in around 140k... not to mention the added benefit of decreased wear, lower cost of bearings, lower cost of maintenance (no need to frequently change the front diff if its not doing anything), improved tracking, etc...



And if you think about it, with a factory bearing at $400, replacing two of them is half the price of the DT kit, which would benefit you by never needing to change the unit bearings again.



And further, for some of us, it was a matter of driveability, than cost savings. I for one have a truck that suffers from the 3rd gen 70mph vibes... getting rid of those vibrations at highway speeds = priceless.



steved
 
Discount?

Yeah I did the math and came up with approx 144,000 mi to pay for it. I don't have the vibes and didn't know that the factory bearings were so much to replace. So back to the other part, was there some sort of TDR discount or not?



Turns out I didn't pay close enough attention to the DynaTrac website. I thought the $1895 kit was 30 spline and you’d have to pay even more for the “Stage II” upgrade to get 35 splines. I believe the standard $1895 DynaTrac kit for the 05 comes with 35 spline stub shafts. If DynaTrac gives a TDR discount, then the price difference really is not that much between the two kits.
 
... And if you think about it, with a factory bearing at $400, replacing two of them is half the price of the DT kit...



And that cost is if you do it yourself! And if the original only lasted you 50-60K miles and you have to do it again and again, it pays for itself quicker.



I plan on putting one of these kits on as soon as my wheel bearings go (the stockers will probably last me 300k miles). :D
 
I did the dyna trac kit just so I cold use low 4 without going into 4wD. Use it all the time. Nice with a loaded trailer on a steep paved hill.....
 
I kinda thought the 2wd low was about the only other reason to get the kit, along with the mpg increase. If my stock wheel bearings last 300k mi, or even 150k mi I'd be happy. With the big tires I might need them sooner than some other people.
A loaded 28ft flatbed would be a lot easier to back with the 2wd low though...
 
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