axle flip, pros and cons.

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axle flip, pros and cons.

Postby flatbottom mudslinger » Mon Jun 14, 2010 9:14 am

I just aquired another project. A duck boat tow rig/ hunting/trapping/ canoe hauler, or just an all around off road toy. Its a 1970 Toyota FJ40 Land Cruiser. I bought it from its original owner and was last registered in 1978. Its been in a barn since then. Anyway I want to lift it, now should I spend the money on lift springs or keep the stock springs and do an axle flip? Is there anything wrong about doing an axle flip? What are the pros and cons? Heres one pro, Itll be free (unless I replace the "U" bolts, which I will) I am a fabricator and it is something I can do in my own garage.
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Re: axle flip, pros and cons.

Postby ajmorell » Mon Jun 14, 2010 9:40 am

By axle flip do you mean going from an SUA (spring under axle) to an SOA (spring over axle) setup? I can't guarantee this is the case on the FJ, but I know on many other leaf-sprunf vehicles when doing an SUA->SOA there is a bit more to worry about than just the spring mounts, things like steering geometry, etc. That being said, an SOA setup is a good way to gain a few inches of lift and SOA suspension setups have their advantages over SUA setups.
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Re: axle flip, pros and cons.

Postby flatbottom mudslinger » Mon Jun 14, 2010 7:27 pm

SOA is exactly what I mean. I came up with just under 9 degrees on the crossover link as opposed to the factory dead level. Thats at a 6" lift and assuming the link bar is 40" (I didnt measure it yet) The nice thing is that the spherical joint at the end of the link bar bolts straight in from the front so any type of lift will rotate the link bar around the circumference of the ball and wont put any additional torque on it from an odd angle. As it would if I moved the axle forward or back.
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Re: axle flip, pros and cons.

Postby waterfowlhunter » Wed Jun 16, 2010 8:37 pm

This is common practice with older cj5's and 7's. Done a few and it works out fine. When welding on the new spring perches you can adjust drive shaft angles slightly to compensate for the aproximately 6" of axle drop. new U bolts and nuts are a MUST in my case as I just pop the old ones off with the gas wrench (torch). :beer:

pros, it is basically free

Cons, Sometimes the old springs are rotted where they are clamped down and should be replaced anyway.
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Re: axle flip, pros and cons.

Postby flatbottom mudslinger » Thu Jun 17, 2010 9:24 am

I too thought about rotating the spring mounts to take some stress off of the driveshaft. Good tip. You clued me in on a couple things I hadnt thought about.....yet. I wasnt even thinking about getting new spring perches, I was just going to clean up the old ones and weld them back on. However, now that you mention it, I have access at work to a CNC plasma cutter and a press break, I can make new ones. I never thought either about the springs being rotten, Ill check em out when I get there, Im still in the process of removing the body. Another thing that I did think about was replacing the U bolts for sure. Im also going to convert to disc brakes all the way around and what do you guys think of Teraflex Revolver shackles? Ive heard that theyll unwrap at steep angles but they may have redesigned them. I saw some on a website yesterday that had a bend in them similar to an anti inversion shackle and an added tab to stop the rotation at, or just past center. At $250 a pair they may be a later bolt on, after the project is reassembled, painted, licensed, and insured.
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Re: axle flip, pros and cons.

Postby waterfowlhunter » Thu Jun 17, 2010 6:48 pm

I personally do not like any kind of Long / extended shackles even if they do have a stablizer in the middle. I actually rate them right there with lift blocks. That extra leverage they put on things just does not give me a feeling of safety or reliability with hard use. I can not say anything bad from personal experience but have seen more than enough blocks that poped out or broke springs and several long shackles that twisted or broke on hard trails. There are NUMEROUS places that will bend springs for you or even make custom packs for you at a very resonable cost. I am in the process of gathering parts for the solid front axle conversion on my Silverado HD. So far it looks like I can run 35" tires with bushwacker cut-out fender flares and no rear lift. I figure by the time I buy a new truck I will have everything to convert the old truck into a toy. :yes:

take your time and do it right the first time even if it takes a bit longer and a bit more $$$ or you will wish you had. The excitement of getting your project on the road sometimes gets in the way of doing it right.
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Re: axle flip, pros and cons.

Postby ajmorell » Thu Jun 17, 2010 8:02 pm

waterfowlhunter wrote:take your time and do it right the first time even if it takes a bit longer and a bit more $$$ or you will wish you had. The excitement of getting your project on the road sometimes gets in the way of doing it right.


I can't emphasize that enough. I see so many posts on other forums about shortcuts or the cheapest way to do things, it's like people don't realize you are typically sacrificing something by doing the job cheaply....
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Re: axle flip, pros and cons.

Postby flatbottom mudslinger » Sun Jun 20, 2010 3:29 pm

waterfowlhunter wrote:I personally do not like any kind of Long / extended shackles even if they do have a stablizer in the middle. I actually rate them right there with lift blocks. That extra leverage they put on things just does not give me a feeling of safety or reliability with hard use. I can not say anything bad from personal experience but have seen more than enough blocks that poped out or broke springs and several long shackles that twisted or broke on hard trails.
Im not talking about a lift shackle. Im talking about a revolver. I dont think they add anything to the height or stance of the truck, theyre just for articulation. They can fold and twist on me all day long because thats what theyre designed to do. Its the best way I know how to get articulation without going to a coil and link. If I was a hardcore off roader I probably would but Im not, Im a hunter, trapper, and fisherman. I just want go anywhere I need to and not get stuck. Dont get me wrong Ill definitly try to find my limits and have some fun with it but the reason I bought it is 1: theyre cool as hell and Ive wanted one for almost ten years 2: a daily driver 3: a short wheelbase SUV to tow my 15' boat and haul my traps.
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Re: axle flip, pros and cons.

Postby ajmorell » Sun Jun 20, 2010 7:37 pm

flatbottom mudslinger wrote:Im not talking about a lift shackle. Im talking about a revolver. I dont think they add anything to the height or stance of the truck, theyre just for articulation. They can fold and twist on me all day long because thats what theyre designed to do. Its the best way I know how to get articulation without going to a coil and link. If I was a hardcore off roader I probably would but Im not, Im a hunter, trapper, and fisherman. I just want go anywhere I need to and not get stuck. Dont get me wrong Ill definitly try to find my limits and have some fun with it but the reason I bought it is 1: theyre cool as hell and Ive wanted one for almost ten years 2: a daily driver 3: a short wheelbase SUV to tow my 15' boat and haul my traps.


I'd say skip the revolvers for now. In terms of overall capability they probably wouldn't gain you much. The money would be better spent or saved and put towards locking the axles, or a winch IMO.
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Re: axle flip, pros and cons.

Postby flatbottom mudslinger » Mon Jun 21, 2010 6:24 am

yeah the revolvers are an easy bolt on later. I have most of the body off, all thats left is the windshield and tub. Then I can pull the drivetrain and start on the frame, preassure washing and sandblasting. When I reassemble the frame would it be a better idea or not to put the shackles at the back of the springs instead of in front? They came from the factory in front but Ive seen the, both ways. Which is better?
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Re: axle flip, pros and cons.

Postby waterfowlhunter » Mon Jun 21, 2010 6:36 am

The reason to move the shackles to the rear of the front springs is ride quality. But you have to consider the driveshaft when doing this. When they are in the front the axle moves slightly forward when articulating. when they are in the rear the axle moves back and can cause driveshaft binding if the slipjoint if not the correct length and even transfer case damage.
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Re: axle flip, pros and cons.

Postby OrangeLake » Mon Jun 21, 2010 7:37 am

ajmorell wrote:
waterfowlhunter wrote:take your time and do it right the first time even if it takes a bit longer and a bit more $$$ or you will wish you had. The excitement of getting your project on the road sometimes gets in the way of doing it right.


I can't emphasize that enough. I see so many posts on other forums about shortcuts or the cheapest way to do things, it's like people don't realize you are typically sacrificing something by doing the job cheaply....


:ditto: My brother in law has a 72 FJ40 that he just axled-over. He rushed a bit, skimped on getting actual Fj parts, tried to fab his own (which is fine for a pro), and didn't rotate or line up the axles just right and now it shakes once you get to 40 and above. It's a pain to ride in. Don't be afraid to take it by a shop for help. It's worth getting help or paying someone for some work and not having to tear down the build to fix your mistake.
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Re: axle flip, pros and cons.

Postby flatbottom mudslinger » Tue Jun 22, 2010 3:20 pm

waterfowlhunter wrote:The reason to move the shackles to the rear of the front springs is ride quality. But you have to consider the driveshaft when doing this. When they are in the front the axle moves slightly forward when articulating. when they are in the rear the axle moves back and can cause driveshaft binding if the slipjoint if not the correct length and even transfer case damage.
I didnt think moving the shackle to the rear had anything to do with ride quality, I thought it was for a better approach on obstacles, either way, check this out..... If I lift the truck the driveshaft will pull slightly forward to accomodate the longer reach to the lower differential. Now if I move the shackles to the rear the driveshaft will have that extra room needed to go back upon suspension compression. Am I thinking about this right? I mean if I lift the truck and keep the shackles in the front I will need a longer driveshaft, but because Im lifting the truck AND moving the shackles they kind of equal each other out so I can run the factory driveshaft......I think.
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Re: axle flip, pros and cons.

Postby waterfowlhunter » Tue Jun 22, 2010 5:47 pm

flatbottom mudslinger wrote:
waterfowlhunter wrote:The reason to move the shackles to the rear of the front springs is ride quality. But you have to consider the driveshaft when doing this. When they are in the front the axle moves slightly forward when articulating. when they are in the rear the axle moves back and can cause driveshaft binding if the slipjoint if not the correct length and even transfer case damage.
I didnt think moving the shackle to the rear had anything to do with ride quality, I thought it was for a better approach on obstacles, either way, check this out..... If I lift the truck the driveshaft will pull slightly forward to accomodate the longer reach to the lower differential. Now if I move the shackles to the rear the driveshaft will have that extra room needed to go back upon suspension compression. Am I thinking about this right? I mean if I lift the truck and keep the shackles in the front I will need a longer driveshaft, but because Im lifting the truck AND moving the shackles they kind of equal each other out so I can run the factory driveshaft......I think.



Not really correct. the lift will dictate the driveshaft length not moving the shackles. The shackles only come into play under spring compression, you need the driveshaft to be the correct length in a static condition but still have enough slip spline to not pull apart or compress too far under full spring droop or compression. on the ride situation, with the shackles in the front your front wheels have to actually try to push forward when they compress. with them in the rear the front wheels actually give a bit rearward and then ride up over the obsticle. I have done several of these and it does make a difference in ride both on and off road.

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‘For those who would give up essential liberty to purchase a little temporary safety, deserve neither Liberty nor safety.’ —Ben Franklin.”
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Re: axle flip, pros and cons.

Postby flatbottom mudslinger » Wed Jun 23, 2010 4:55 pm

Ok thinking back to the actuall SOA conversion if I rotate the spring pads (which I will) what is an acceptable angle for the differential to sit at? Im sure theyre level from the factory for a reason. If I rotate the axle forward to put less stress on the universal joint what happens to the lube? Does everything stay lubricated as well as it did from the factory? Do I need to add more than the recommended amount? From the looks of things as it sits in stock form I would need to rotate the axle approximately 15 degrees to perfectly line the yoke with the driveshaft. When I lift it, it may require rotating the axle more like 30 degrees or even 40. If I only rotate it enough to get back to the factory 15 degrees, which, apparently is acceptable or they wouldnt have built them like that, I would still have to rotate it about 15 to 25 degrees. So my question is how much can you get away with without starving the gears of lube or binding on your steering components. Obviously every vehicle is different but with a short wheelbased SUV, GENERALY how much are MOST people rotating their axles with a spring over axle conversion?
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Re: axle flip, pros and cons.

Postby ajmorell » Wed Jun 23, 2010 7:27 pm

It depends on the output type on the transfer case and the driveshaft style. For a fixed rear output on the t-case / CV style driveshaft the angle should be something along these lines:
http://www.myjeepxj.com/uploads/images/ ... _angle.gif

For a slip-yoke output on the t-case something like this:
http://www.hotrodders.com/gallery/data/ ... angles.jpg
http://www.cadvision.com/blanchas/Range ... nAngle.jpg
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Re: axle flip, pros and cons.

Postby waterfowlhunter » Wed Jun 23, 2010 7:51 pm

The diagrams above are nice for most cases. CV joints do help and there are now the roller ball type available that will allow even more severe angles. Jeeps / short wheelbases are a pain for Angles anyway, I did a spring over (and slight shackle lift :no: ) on a CJ-5 with 40" Ground Hawgs and it worked fine with stock driveshafts. it was a v8 3 speed and was driven easy and never at Highway speeds. these had weak axles and drive shafts anyway but we never broke it. it all depends on knowing the limits of your equipment.

There is NO issue at all with the gear lube when rotating the axles as the gears pick up the lube and sling it around the housing anyway. there can be an issue with steering geometry as the angle which the ball joints pivot on will change and you will have to have it aligned anyway so the effects are minor. You would need a driveshaft angle gauge to do it properly. if you are running a lot of power go with non greasable U-Joints as they are generally stronger than the hollowed out ones that are greasable. If you are not running 400+ HP then greasable units are fine IMO.

Hoping to get in the 500hp range with an 8.1L rebuild for my truck and a solid axle conversion if I do not trade it on a diesel before I gather up all the parts. :yes:
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