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Discussion Starter #1
I found a deal on a set of 39” tires…spent some money on rims and what not. Took the Cruiser out and have broken two pinions in the rear end since. I’ve heard there’s a fine spline pinion out there, but I just don’t think I trust it based on how I broke the others. I think price is pushing me toward a 14 bolt, but I have a few questions.

1. I’d like to keep the front for a while (at least until it breaks). Can I run a 14 bolt with 4.10s and a stock Cruiser front without problems in the T-case? Are the gears the same? Anybody done it?
2. The 14 bolt will be 8 lug. Should I sell the rims and get new/used ones or try and change to 6-lug outers? Any idea what the conversion would cost? I’m going to cut them down anyway, is this something easy to tack on? Will my 15” rims fit with new 6 lug outers? Is the conversion a good idea in general?

Bottom line, I want to do it right, but can’t afford to do it all at once.

Thanks in advance!
 

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Sounds like you're stepping into a domino effect with modifications. Get the fine spline unit and get a wrap bar of some sort. If you put a 14 bolt in it will be about 10 inches wider than the front. I think I've seen 6 lug hubs for a 14 bolt but why throw the money at it and not do the front as well.
 

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There's another thread that discussed the merits of FJ fine spline pinions and few reported breaking them with SUAs or with SOAs and an anti-wrap bar. Bobby Long also treats pinions and ring gears (cryo?) to make them even stronger. So fine spline pinions have possibilities for seriously enhancing strength, assuming you have an anti-wrap bar. :grinpimp:
 

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sounds like you don't have any wrap bar. Try the fine spline pinnions!

Otherwise, semi floating 14 bolts are available and more than overkill for 39s. And yeah, it'll be a little wide.
 

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I'm putting a D70 in the rear of my 40. Cutting down one side and using 9" outers. Have to have new axel shafts made but thats the game right. Over all I it is like $500 more to get it finished. It will be 4" wider than stock too and I will still be able to use 6 lug and my transfer. The front can wait till money can acomidate it.
 

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Discussion Starter #6
I don't have an axle wrap bar. Would it really make that much difference. It would seem to limit flex alot. The last one snapped while going up a steep hill. No romping on the gas, no hopping.

Is a GM with 4.10s close enough to a stock LC with 4.11s that I'm not going to break something in the T-case?
 

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Bender said:
Is a GM with 4.10s close enough to a stock LC with 4.11s that I'm not going to break something in the T-case?
They'll be fine. Tire wear probably causes more difference than the .01 ratio that'll be present.
 

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The wrap bar makes that much difference and so does the fine spline. If you want the ring and pinion cryoed to get a little more strength out of them...contact 66CJdean form the board...he is very easy to deal with, prompt, and knows his stuff. He sent out a cheapie disposable razor when he cryoed my stuff for me....and I have been using every day for over 2 months now..still cuts just like it was new.
 

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Here is my Rec:

Get the 14 bolt. You can get a semi-float rear that is already set up for 6 lug, but I would get the 8 lug setup witha full float rear. Save some money and get yourself a 60 front. The stock cruiser stuff will NOT hold up to 39" tires. Save yourself the headache of doing the work 2 times, and do it right the first time.

dima
 

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Depends on what engine you have. The FF 14 bolt is supposedly one of the toughest axles out there (but they have been broken). Drawbacks of the FF is the big-ass dif that hangs down, 8 lug only, and only locker is really a Detriot. SF 14 bolt is still super strong, can come in 6 lug same pattern as Toy, smaller diff (still big though, but you can shave these too) and there is an ARB and some others (Eaton e-locker, etc). Personally I am a fan of the SF. If you find a mid 90's you can find them with disks and ebrake too but they are usually about $500 for that setup. You will be fine if you run that in the rear for now. But the fine spline diff and wrap bar could and probably would stop most breakage if that's all you've broken so far IMO...

(My $.02 from someone who's never even broken a birf though...)

Andre
 

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Bender, man you almost win the award for lurker of the year. 2002 <50 posts!

The Cascade Cruisers has a member Ed, that runs 39’s on all stock running gear. He is SOA with a track bar. To date he has only killed one coarse spline pinion and a few mini birfs. He now runs a FS pinion and Longs, ran all this summer hard with his new 350TPI and no issues. (Yes he is on barrowed time on the front end IMO) Just info on the power of a track bar and FS pinions.

Mark

Moab 04' shot of Ed in action:

EDIT: Ok no photo the POR bord is having issues right now.
 

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Kinda off the subject. Does Interco have 39.5 in the SX Swampers??? It seems everything I've found they just go to 38.5.

SD
 

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Off topic............but I really like that winch mount. It keeps the winch out of the grill. I put mine through the bumper, but I kind of like that FJ with it below the bumper.
 
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