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D60 low vs hi front axle and ratios - the same old topic - sorta

white-rhino

Older than dirt
Joined
May 19, 2020
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154
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Michigan but not in Detroit
Full tube buggy. LS/350/203/205 with GM 60/14b combo. Running both 43 SX stickies and reds. Currently 5.13 ratio.
The old story - a low pinion is not as strong as a hi pinion. I know it, understand it but I have never been able to find an actual percentage difference. I have a buddy who thinks the low pinion is 30% weaker. Has anyone ever found an actual number. AGAIN - I understand the "why". I'm just looking for the difference. Lots of searching without a definitive answer. (feel free to flame me if you can show me how poor my search skills are)

Next up, 5.13 was the lowest gearset available for a long time for the 14 bolt, now 5.38 is available. So back to the front LP60, going to 5.38 would be weaker. My gut feeling is this is not a wise move.

So, I am looking for success / failure stories about running this big of a tire on the LP and any experience with going to the deeper ratio.
 
Specs on 350?

edit: Nevermind, I see LS. I have no clue on the % so can't help you there but I have been around a lot of busted 60 front R&Ps both HP and LP. The common denominator is always LS and 43 stickies. 43 stickies break a lot of shit. You will not be happy with that setup unless you are adept at changing R&Ps fairly often. And with what you can get a Super Duty 60 for these days, what's the point of running an old chevy LP front anymore?
 
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I wheeled for years in a toyota, chevy dana 60 with 5.38s and 42s, low power, no issues. I have replaced one set of 5.38s in a chevy 60 missing a few ring gear teeth. His setup was a CJ7 with a 350 and 43" non-sticky TSL SXs, when I setup the new gears I ended up replacing the carrier, the lash was 30 on one side and 10 on the other, not sure if it was the cause or the effect of the gear breaking.
 
Sounds like you already have the LP 60? I have one in the front of my buggy and yeah it's weaker going forward which is usually up hill with a lot of weight transferred to the rear so no big deal. I like to look at it that when I'm backing up hill with the weight transferred to the front, it's stronger than a HP. If I was starting from scratch, I'd build a 14 bolt front not a HP 60. Nothing really wrong with HP 60s though either. I run 5.13s fyi...
 
Sounds like you already have the LP 60? I have one in the front of my buggy and yeah it's weaker going forward which is usually up hill with a lot of weight transferred to the rear so no big deal. I like to look at it that when I'm backing up hill with the weight transferred to the front, it's stronger than a HP. If I was starting from scratch, I'd build a 14 bolt front not a HP 60. Nothing really wrong with HP 60s though either. I run 5.13s fyi...

I was going to say the same thing.

Good thing about 5.13 is you can do a Jana 76 kit and probably never have issues.
 
Yes, the 350 is the TH350 trans. Sorry. Yes, the driveline was already in the buggy when I bought it. My last crawler had a Ford HP60 on 39 Reds with no problem and honestly I never gave the LP much thought when I bought the rig. Dumb yes - but it is what it is. This axle has Yukon shafts, joints and lockouts. I consider the Yukon shafts marginal and figured to go to Branik eventually.

The last time I was out last fall I got a bit out of control in some rocks and stabbed the throttle. I did a WOT in the rocks for about 15 ft and broke a link bolt. Limped it back to the trailer and tore it down for winter mods. I finally finished it up and took it for a test run Sunday and had a clunk. Turns out I have a couple broken teeth. So it's leading me down the path of looking for options.

I know several guys running LP's without much problem but there is no question a 42-43" stickie is pushing the limits. I had never heard of the Jana76 kit but it sounds like it might be the ticket for me. Thanks for the heads up! 👍 At least it has tangible numbers vs "a low pinion is weaker than a high pinion". LOL

I've also considered starting to gather parts for a front 14bolt.
 
Basic pic

5EBC5CBE-1FCE-4444-9157-35FF46862EF8.jpeg
 
Yes, the 350 is the TH350 trans. Sorry. Yes, the driveline was already in the buggy when I bought it. My last crawler had a Ford HP60 on 39 Reds with no problem and honestly I never gave the LP much thought when I bought the rig. Dumb yes - but it is what it is. This axle has Yukon shafts, joints and lockouts. I consider the Yukon shafts marginal and figured to go to Branik eventually.

The last time I was out last fall I got a bit out of control in some rocks and stabbed the throttle. I did a WOT in the rocks for about 15 ft and broke a link bolt. Limped it back to the trailer and tore it down for winter mods. I finally finished it up and took it for a test run Sunday and had a clunk. Turns out I have a couple broken teeth. So it's leading me down the path of looking for options.

I know several guys running LP's without much problem but there is no question a 42-43" stickie is pushing the limits. I had never heard of the Jana76 kit but it sounds like it might be the ticket for me. Thanks for the heads up! 👍 At least it has tangible numbers vs "a low pinion is weaker than a high pinion". LOL

I've also considered starting to gather parts for a front 14bolt.

Jana kit is probably your best bang for your buck and I would think would be pretty damn strong.

Pass drop 14b can be hard to package since the pinion is very offset of the large casting.
 
Jana kit is probably your best bang for your buck and I would think would be pretty damn strong.

Pass drop 14b can be hard to package since the pinion is very offset of the large casting.

Yep, I started going down that path of options and none are easy or cheap. I appreciate your input. It's nice to actually see some tech responses on a forum these days. I remember posting on the other site a year ago an axle shaft question and never got a reply. Especially for someone like me who is not a household name. Thanks much!'

After a ton of reading and talking with Carl twice yesterday I ordered up a kit. It sounds like a fairly detailed mod and install. He says it takes him about 12 hours so I'm guessing 30 or more for me. LOL
 
Try to find bobby longs old posts or site with breakage info. He did torque failure analysis on shafts, maybe he had gear sets and such too.
 
How much are you gaining in crawl 5.13 to 5.38? seems not much.
 
Yep, I started going down that path of options and none are easy or cheap. I appreciate your input. It's nice to actually see some tech responses on a forum these days. I remember posting on the other site a year ago an axle shaft question and never got a reply. Especially for someone like me who is not a household name. Thanks much!'

After a ton of reading and talking with Carl twice yesterday I ordered up a kit. It sounds like a fairly detailed mod and install. He says it takes him about 12 hours so I'm guessing 30 or more for me. LOL

It would be great if you could post up the install for the rest of us. The Jana kits are something that get discussed a lot, but it seems like very few people are actually running them. I've seen Carl's own write up he did on Pirate about it, but I would be curious how the install goes for someone that isn't trying to sell the kits.
 
How much are you gaining in crawl 5.13 to 5.38? seems not much.

About 5%, but since he is doing the Jana 76 conversion, he won't be going to 5.38s since 5.38 Dana 70 gear sets don't exist (Low pinion anyway, Currie has a high pinion Dana 70 5.38 set).
 
It would be great if you could post up the install for the rest of us. The Jana kits are something that get discussed a lot, but it seems like very few people are actually running them. I've seen Carl's own write up he did on Pirate about it, but I would be curious how the install goes for someone that isn't trying to sell the kits.

I can do that. If you have ever talked to Carl, he's a trip and a little hard to follow. LOL. I talked to him back 14-15 years ago when I bought my first set of Jantz Joints before he sold out to Yukon. He was fun then - still is. The kit is a couple weeks away so it will be a mid-late March project. Perfect since my first wheeling plans are April.

Yes on the 5.13 vs 5.38. No options there and that's OK. Saves me spending money on rear gears.
 
I can do that. If you have ever talked to Carl, he's a trip and a little hard to follow. LOL. I talked to him back 14-15 years ago when I bought my first set of Jantz Joints before he sold out to Yukon. He was fun then - still is. The kit is a couple weeks away so it will be a mid-late March project. Perfect since my first wheeling plans are April.

Yes on the 5.13 vs 5.38. No options there and that's OK. Saves me spending money on rear gears.

That would be great, it is always nice to see some actual tech get posted :smokin:
 
Carl is great and he's nothing but helpful but here's my experience with the Jana kits. They're cheaper than building a new housing but still expensive, the install really sucks, it's more difficult to get a good pattern, and you're not gaining much strength if anything. I did one in the rear of my buggy, maybe I helped the ring gear strength so then I immediately twisted a pinion to smithereens (still 19 spline baby junk). My buddy did it in the front of his buggy with a lp60, even added the load bolt option, and he was still tearing up R&Ps with a stock 6.0. Eventually he built a big knuckle 14 bolt and the problems went away.
 
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Carl is great and he's nothing but helpful but here's my experience with the Jana kits. They're cheaper than building a new housing but still expensive, the install really sucks, it's more difficult to get a good pattern, and you're not gaining much strength if anything. I did one in the rear of my buggy, maybe I helped the ring gear strength so then I immediately twisted a pinion to smithereens (still 19 spline baby junk). My buddy did it in the front of his buggy with a lp60, even added the load bolt option, and he was still tearing up R&Ps with a stock 6.0. Eventually he built a big knuckle 14 bolt and the problems went away.

We all know big tires break things. I'm hoping this mitigates my risk. Bulletproof? Probably not.
Honest question - what driving style do you and your buddy do? I've had stuff last a long time till I got into a WOT or bound up a tire. Then it breaks surprisingly quick.

oh, and JohnnyJ - you really don't want to go there do you? 🖕
 
The LP60 Jana 76 kit has worked well for me with 5.13 gears, 6.0 LS and 43 stickies. I have the load bolt and my front cover has the bolts that preload the bearing caps. No failure since I installed the kit in 2012. I don't do a lot of full throttle assaults and try not to bind it up. The engine was a stock van motor until a couple of years ago. The current engine dynoed 315 at the rear wheels with the 43s on it at the time.

I think that the reason I have never snapped the splines off of the pinion is I have a 1 piece front drive shaft that doesn't have the steep u-joint angle at the axle like some 2 piece shafts have. If I had it to do over, I would have built the buggy around a drivers drop 14 bolt front axle though.
 
There was a guy on the old board who was running Jana 76 f&r with 7.17s, iirc it was a yellow buggy that had a 22re and then went SC v6. Maybe racing 4800 or 4500?
 
The LP60 Jana 76 kit has worked well for me with 5.13 gears, 6.0 LS and 43 stickies. I have the load bolt and my front cover has the bolts that preload the bearing caps. No failure since I installed the kit in 2012.

this is how its done, along with an arb :smokin:

its unfortunate that the gear manufacturers dont step up their game and start offering all the different types of d60 gears with a 35 spline pinion

edit obviously a 14b/d80/hpd60/ford 10" would be a better choice but if youre sticking with the lpd60 thats a the way to build it
 
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The LP60 will stay in as long as it survives with the Jana 76 kit. Time will tell. If it doesn't survive, who knows..............
Currently I would consider a 14b or a Superduty center section. Although it would be awesome to do a Spidertrax housing with 10" Gearworks, it's simply not in my budget. I'm leaving for Florida tomorrow. The parts should be here when I get back and then the upgrade begins. :)

And yes, I ordered the load bolt option.
 
I know there are HP70 gears with a 35sp pinion (made by Currie).
Do they also exist for a LP70 ?
 
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