Project Hellraiser 4

Page 17

   
 
 

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I thought I was done with Project Hellraiser 4 but after a roll in Mammoth the other weekend I find the buggy is in need of a new rear end.

After first glance it didn't look too bad.  The spindles that were butt welded to the Dana 60 center section both broke at the welds (and it was the welds, not the material in the HAZ zone).  Initially I thought with a little quality time on an axle jig I could resurrect the old axle assembly.

But as time wore on it was becoming clear it would be cheaper to just start from scratch.  The above picture is the short side axle which we had to pound back out thru the spindle to make trail repairs.  As you can imagine this had some repercussions with the spindle, namely it went from being round to something closer to an egg shape.  On later inspection I found the long side axle was also tweaked along with some nasty bends in the axle tubes themselves.  It wasn't looking good.

I then held out hope that the center section was ok and useable but upon opening the diff cover I discovered that was not the case.  The pinion gear had shredded itself.  Before I even got to this point I was 90% sure I was just going to install a new rear end but these findings just confirmed my line of reasoning was correct.  The only good parts remaining, the spool and 1410 pinion yoke would become spares for the front axle.

Since I am still paying off the 4 seater buildup I had a pretty tight budget which would become the driving force in my choice of replacement axle. However, to be fair I made a spreadsheet and compared a few options: building a Spider 9, building another 35 spline D60, building a D70u and building a 14 bolt. I gave up on the Spider 9 idea after reaching over 4k in parts, it was just too much money for a little extra bit of ground clearance and a potentially weaker gear set. The D60 and D70 fell by the wayside when I found the perfect 14 bolt axle which happened to be sitting in Jack's back yard. 

One of our former members started to build another rig but then canceled the project. He had already installed a mini spool into the 14 bolt, installed a new beefy differential cover, some new bearings and seals in the hubs along with some fresh rotors and wheel studs.

I also got the weld on disc brake brackets and a pair of spare axle shafts.....

.... and a set of single rear wheel (SRW) hubs.  Total cost was $400.  For reference, that's about the cost of a bare Spider 9 axle housing (with no ends).

Here's a comparison shot of the dual rear wheel hubs (DRW) vs. the SRW hubs, the SRW hubs will narrow the axle by 4 inches overall which puts me within .75" of the front axle width.  I just had to swap the new bearings from the DRW hubs to the SRW hubs.

Since this axle still had stock gears (4.10's) I ordered a 5.13 gear set to match the front axle, an install kit and new ring gear bolts from Randy's Ring and Pinion at a cost of nearly $300.  This puts my total for a new rear axle (with spare shafts) at $700.   

Now the downside: this axle is commonly referred to as "the rock plow".  While the 14 bolt ring and pinion is a big upgrade over the D60 setup, that same plus becomes a negative when you factor in the center section which houses it. I measured the ground clearance to be just over 2 inches less than my shaved 60 housing. I am hoping between the sticky tires I run and some better driving I can overcome the clearance deficit. I suspect the hardest thing to overcome will be getting used to a centered rear differential since my previous setup was offset to the passenger side.

It is possible to cut 2" off the bottom of the 14 bolt housing, plate it for a net gain of 1.75" of ground clearance.  The only problem with this plan is it requires you to shave the ring gear down as well which I just don't have time for.  so I am going to try a different approach, I want to see if I smooth out the bottom of the 14 bolt housing eliminating any hang up points if I will notice much of a difference from my old shaved 60 housing with more ground clearance.  The picture above shows the bottom of the 14 bolt housing and the large rock catching lip it has in stock form.

I used a sawsall to cut the lip into smaller sections.

Then I cut the small pieces off one by one.

I then switched over to a grinder and started smoothing all the edges out.  the dark indent in the lower left hand corner of the first picture still looks like an edge but it is actually a smooth transition.

 

Here's a before/after comparison.  After roughly 2 hours of work I had an extra .50" of ground clearance and a smooth bottom ;)  If you don't want to keep the lower two bolt holes you can actually gain another 1" of clearance by wiping them out but you'd have to modify the diff cover and plate the bottom of the diff.  I really wanted to keep all the diff cover bolts this time so I ground the housing down to within .375 of the lowest bolt hole.  I may actually go back and take a little more off with the grinder right at the peak after seeing how much meat was still left when I installed the new gear set.

I went with another Ballistic Fabrication rear axle truss this time around.  The original on my D60 was a little too long for use on the 14 bolt axle (the D60 was offset so I had that truss made about 8" longer than the default).  The one problem I realized after installing the truss was I no longer had a good target for the rear air bumps so for now they are removed.  I am not sure if I am going to add them back into the mix as I wasn't utilizing them in the previous setup (there were no signs of me ever bottoming them out).

Even though this is a stock 14 bolt with a centered differential, the actual differential housing is not really centered.  The pinion itself is the centerline so the truss is actually offset to the driver side a bit which makes the swaybar look like it is offset to the passenger side.

For future reference here are what the link angles look like from the side view.  I also thru a tape measure under the differential and discovered I had only lost an inch of ground clearance VS. the shaved D60 I had in there previously, I had 11" under the lowest point on the differential with the tires at trail pressure.  After 4 days of trail riding I couldn't tell I had lost the clearance and the rig performed as if it never had extensive surgery, not bad for a grand total of $700 into the rear axle and another $140 or so for the tabs and truss.

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