Eritex Inc's HRD 3.1 setup and tip thread

[HiloDB1]

Originally Posted by Narly1

2.5 mm ones are easy to come by..... 2 mm thick ones are another story.....

Narly1

And why would you want 2mm thick ones? The bushing is 2.5mm thick.

[gunnar]

The 2mm thick bearing post(#27) might have been in error. When I first mocked up the dig, I did have some slop between the hex that mounts on the tranny output, and the hex/rear output piece, which was cause for concern. When I measured the depth of the bearing pocket on the front hex piece, it was closer to 2.5mm, so that is what I bought. After installing the bearing, and using grease, the slop disappeared. Also it is important to polish the guide pin that the slider piece rides on, I used some rubbing compound with a felt wheel on the dremel, and when lubed it works very smooth. Also be very careful when threading into the delrin slider, it can strip if tightened too much. Unfortunately, I have partially stripped mine, but using some thread locker, it seems to be holding okay for now, but will most likely order a new piece.

[Narly1]

Originally Posted by HiloDB1

And why would you want 2mm thick ones? The bushing is 2.5mm thick.

Just as Gunnar surmised, I thought 2 mm was the correct width based on previous posts. Thanks guys for all the good info, I can hardly wait for my two digs to arrive!

Narly1

[cruzer971]

So why would we get a bushing instead of a bearing in the kit.
Gerame, is there something we should know?
I had a bearing from my revo parts, so I put it in because everyone else was doing it. Is there a benefit to the bushing?

[gunnar]

In this case, there is no huge benefit, because most of the time the two hexes will be locked together(4WD) In freewheel or dig mode, as long as the bushing is properly lubed, the dig should(and does) function fine. The bearing might tighten things up some, in my unit, it seemed the bushing was slightly loose(and I mean very slightly) and the bearing helped it some. Also it goes back to the old days when car kits came with bushings stock, and bearing kits made the cars better.

[CreepyCrawl]

Originally Posted by Offroader5

Nah...the plate would still be on the opposite side of the trans.



Well, I know that :-P

I was talking about using it with a mirrored trans.

I've been looking at that as well, but I just don't see how it could work on a mirrored tranny.

[Duuuuuuuude]

Anybody else have trouble getting the transmission outdrive to fit properly on a CDW output? I'm lacking 1.5-2mm from it sitting where it should...:-(

I'm thinking its going to need a nice bevel to match the output and sit nice.

[TSK]

Originally Posted by Duuuuuuuude

Anybody else have trouble getting the transmission outdrive to fit properly on a CDW output? I'm lacking 1.5-2mm from it sitting where it should...:-(

I'm thinking its going to need a nice bevel to match the output and sit nice.

Duuuuuuuuude, I think that the dig is made to work with the original output. You would definitely have to bevel the inside of the drive hex for fir over the CDW's taper output shaft, but I don't think youd be able to match the bevelexactly and you'll probably run into a ton of problems relating to proper seating and plavcement of the drive hex. I would just run the stock rear output and run the risk of having to replace that instead of messing with the drive hex. Maybe mod the stock one for a second flat spot though.

[Duuuuuuuude]

Originally Posted by TheSCorpionKing

Duuuuuuuuude, I think that the dig is made to work with the original output. You would definitely have to bevel the inside of the drive hex for fir over the CDW's taper output shaft, but I don't think youd be able to match the bevelexactly and you'll probably run into a ton of problems relating to proper seating and plavcement of the drive hex. I would just run the stock rear output and run the risk of having to replace that instead of messing with the drive hex. Maybe mod the stock one for a second flat spot though.

We'll see. I went ahead and put a bevel on the inside, and it put it down where it needed to be. There turned out to be another issue as well. The CDW output is a tad too long too. I peeled off about 1mm on the grinder and it seemed to go together pretty well. I may take a touch more off just because.

I should have it up and running tonight!

btw: whatever happened to the break-in procedure that was going to be posted up?

[TIMZKRAWLER]

Originally Posted by Duuuuuuuude

We'll see. I went ahead and put a bevel on the inside, and it put it down where it needed to be. There turned out to be another issue as well. The CDW output is a tad too long too. I peeled off about 1mm on the grinder and it seemed to go together pretty well. I may take a touch more off just because.

I should have it up and running tonight!

btw: whatever happened to the break-in procedure that was going to be posted up?

yeah,i was wondering about the break in also and the set up vid

[Duuuuuuuude]

Finally got it in and rolling. Had to move alot of stuff around to get it all stuffed in there.

Works great...only I'm having trouble getting it to lock into dig. You'd think a 645 would have enough oomph. Seems to be getting better though...might just need a little more use to get it wore in.

[Mic]

I received mine yesterday and put in in today. I polished the shift bar with semicrome and a drill to a mirror finish. Greased everything as shown in this thread. I was missing one bolt but was able to find one in my collection. I am running it with a JR Z270 servo(was sitting in my box for a while) only puts out 43 oz but shifting is a non issue. I have to admit even with the longer than promised wait I am pretty satisfied with this thing. Nice job

[CreepyCrawl]

Originally Posted by Duuuuuuuude

Finally got it in and rolling. Had to move alot of stuff around to get it all stuffed in there.

Works great...only I'm having trouble getting it to lock into dig. You'd think a 645 would have enough oomph. Seems to be getting better though...might just need a little more use to get it wore in.

You may want to check everything again...the HRD doesn't function on a pressure plate set up, so the servo only engages/disengages the collar over the hex. The torque rating doesn't need to be high.

Gerame's vid:

http://s15.photobucket.com/albums/a3...=Digvid002.flv


And from Gerame's original HRD post...

Being a mechanical system, there is movement needed to align 2 components. The difference is, the HRD 3.1 can engage 4WD or Dig every 60 degrees of drive shaft movement. If the drive shaft moves 60 degrees and the axle ratio is 2.92 to 1, then the tire needs to rotate 20.5 degrees at most to engage 4WD or dig.

60/2.92=20.5

Now, if the tire had a diameter of 5", and Pi is 3.1415, then 360 degrees of rotation of the tire would cover 15.7075".

5x3.1415=15.7075

Divide 15.7075 by 360 (degrees on a circle)= .04363

.04363 is the distance traveled for 1 degree of rotation on a 5" tall tire. Multiply that times the maximum degrees need to engage the HRD 3.1 (20.5) and you get .8944"

This dig, with 5 inch tires, will need about 7/8 of an inch (maximum) of tire rotation to align.

60/2.92=20.5
5x3.1415=15.7075
15.7075/360=.04363
20.5x.04363=.8944

Also, because the collar captures the drive components, slippage is not possible.

Sorry, I am rambling, think of a drive shaft dig bolted to the back of an Axial trans. I will try to get a vid of the dig in action without the case on it
__________________

[Duuuuuuuude]

Originally Posted by CreepyCrawl

You may want to check everything again...the HRD doesn't function on a pressure plate set up, so the servo only engages/disengages the collar over the hex. The torque rating doesn't need to be high.

I used the 645 'cause thats what I had laying in front of me. I've got a lighter duty servo that I dug up that will find its way in.

I think I'm going to have to pull it apart and repolish the rod and probably the inside of the case where the shuttle runs. It just won't make that last little bit to lock it down.

[gunnar]

Yes, but you do need some servo force to line up the hexes with the collar. Once they engage, then no real pressure is needed to hold them in. I did have some minor hesitation with a 225 servo, but I do have some resistance with my cable setup, but not alot. Now I'm using a 7955, so it works everytime now! The dig is getting smoother engagement with more use.

[CreepyCrawl]

Originally Posted by Duuuuuuuude

I used the 645 'cause thats what I had laying in front of me. I've got a lighter duty servo that I dug up that will find its way in.

I think I'm going to have to pull it apart and repolish the rod and probably the inside of the case where the shuttle runs. It just won't make that last little bit to lock it down.

Cool...I certainly wasn't trying to say that you didn't know what you were doing

I chucked the shift rod into my Dremel and hit it with some 280 grit at 6000 RPM, then did the same thing with some Mothers polish, and it's silky smooth.

I was thinking the same thing that you are about polishing all the engagement components as well...it certainly couldn't hurt.

And Gunnar, that cable set up is slick dude...nice work!

[gunnar]

Thanks Creepy. Be careful when polishing the aluminum. Smooth is nice, but take off too much and the slider might get sloppy. I think just getting the pin smooth helps the most, possibly smoothing the edges/corners of the hex pieces will make it better also. Might want to leave the rear locking hex on the back piece alone, wish it was a little thicker back there, but it should be ok. I think a small steel insert back there would be nice(kinda like what S3R did).

[CreepyCrawl]

Originally Posted by gunnar

Thanks Creepy. Be careful when polishing the aluminum. Smooth is nice, but take off too much and the slider might get sloppy. I think just getting the pin smooth helps the most, possibly smoothing the edges/corners of the hex pieces will make it better also. Might want to leave the rear locking hex on the back piece alone, wish it was a little thicker back there, but it should be ok. I think a small steel insert back there would be nice(kinda like what S3R did).

I was thinking the same thing, so I went real easy with everything...each component seats very well so far.

I also sanded off some minor burring on the chamfered ends of the the shift pin before I polished it.

Gerame had mentioned posting a break in vid...anyone know what the official Eritex procedure is?

[Mad4Rnr]

Love the dig, smooth as butter.

I realy didn't do anything special during the install but I did change the assembly procedure a bit:

AX10 from stock to comp

Mainly I mounted the trans drive output hex first and then just the dig plate to the housing. I wanted to make sure the drive hex was properly aligned with the inner diameter of the dig plate. Because the guts are alligned perfectly it shifts super smooth and I believe wear should be minimized too.

[gunnar]

Yes, I did the same procedure too. It helps when everything is lined up. Nice pics on your install also