The Arctic Drive

Gear Grinder
Sep 2, 2019
6
Tromsø, Norway
First Name
Kjetil
Willys Model
  1. Other
Willys Year:
  1. 1958
Hi friends,

I`v been reading about spring over axle conversions and read a lot "don`t do it"..

Now I'm a little curious as I wonder if I have a different control arm than normal in my 58 Willys Truck? With my thinking I will be able to move the axle under the springs and just move the steering arm from the underside of the knuckle to the top without any major change in the geometries of the steering and it is bolt on... I think it will work, what do you know / think?

Best

Kjetil
 

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You will flip the pivot ball from the top side to the bottom side so the drag link will need to be cut and turn 180 and re welded, and your brake hoses will be to short. Drive lines will be to short. Far better to re arch the springs or replace them....WA7OPY
 
When you raise the body, which is essentially what you are doing, the angle of the driveshafts change. To correct this change, you have to tilt the axle towards the transfer case, or transmission to compensate. When you do that, you loose the caster angle. When you loose caster, you no longer have a return to center after turning, and it doesn't handle correctly. The best way of doing it is to cut off the inner "c's" on the front axle, and turn and re weld them.
 
FYI..When I took mine apart I tried moving the steering arm to the top to see if it would work. It won’t work stock as a bolt on.
 
Finally... something that I actually know about: spring wrap, caster and steering linkage flips...

Hi friends,

I`v been reading about spring over axle conversions and read a lot "don`t do it"..

Now I'm a little curious as I wonder if I have a different control arm than normal in my 58 Willys Truck? With my thinking I will be able to move the axle under the springs and just move the steering arm from the underside of the knuckle to the top without any major change in the geometries of the steering and it is bolt on... I think it will work, what do you know / think?

Kjetil

The biggest issue you will have with a spring-over is the increased likelihood of the springs in the rear wrapping - literally bending into a sideways S-shape - under acceleration. The over-simplified reason for this is that as you move the spring eyes further away from the axle centerline without increasing the arch or strength of the leaf spring, you give the axle more ability to twist; it's basically triangulation that's working against you though increased leverage. This is especially prevalent off-road when the rear of the vehicle is loaded (as in, pointed uphill), but it can happen on pavement as well if you have enough power under the hood. The reason this is the worse of the issues is because it's inherent to the design: every other issue that comes from a spring-over - driveline angles, TREs, steering - can be adjusted, but the relationship of the spring eyes to the axle center is geometric, fixed, and not adjustable. If you aren't particularly worried about off-roading or hard acceleration, you may not need to be concerned about this... particularly if you're only looking for clearance.

The "control arm" that you mentioned/showed isn't a control arm; it's a Pitman arm. Likewise, your tie rod and drag/intermediate links are called such...and what you're talking about doing is basically a simple spring-over with a tie-rod flip. In the YJ/TJ world, we do them all the time, but it's not quite as simple, here...

You will flip the pivot ball from the top side to the bottom side so the drag link will need to be cut and turn 180 and re welded, and your brake hoses will be to short. Drive lines will be to short. Far better to re arch the springs or replace them....WA7OPY

That bend in the intermediate linkage is a real bitch to work around; from the photos - and this is my unfamiliarity with the specific platform coming into play - it doesn't look like a 180° cut-and-weld will put it back into the correct alignment. I would guess that a custom piece or something from another vehicle that's relatively straight would end up being correct, if he does a simple spring-over with no added craziness...but that's just a guess. The tie-rod flip (which might actually be optional) should be straightforward: remove it, alter the TRE hole in the steering arm of the knuckle by reaming it (bushing/welding may be needed), and then set the link on top of the knuckle. I'll go look at my '51 here in a minute and see if it looks as easy as I remember it looking.

The brake line and driveshaft changes will be equivalent, regardless of the method he uses to change the suspension height: that's a cost of doing business, and a wash.

When you raise the body, which is essentially what you are doing, the angle of the driveshafts change. To correct this change, you have to tilt the axle towards the transfer case, or transmission to compensate. When you do that, you loose the caster angle. When you loose caster, you no longer have a return to center after turning, and it doesn't handle correctly. The best way of doing it is to cut off the inner "c's" on the front axle, and turn and re weld them.

A couple of small corrections:

1) He's raising the entire chassis, not the body: if he was only raising the body no adjustment of the axle would be necessary because the relationship between the transfer case outputs and the axles - connected by the driveshafts that you mention - would be unchanged. Stupid technicality, I know, but still one that needs to be said, because:

2) With an effective 5" lift, the driveshafts may or may not be a problem...but the problem is more in the universal joints than the shaft. Yes, the shaft may need to lengthen, but what we're really concerned about right here are the u-joint operating angles; if they aren't synched up, they'll eat themselves. With that in mind:

3) A rotated inner-C is a lovely way to go to fix caster angles if you want to build a flawless front suspension, but it's also unnecessary in most cases...and that's because a double-cardan front shaft can usually solve the u-joint problem just as effectively, and it can do so while allowing the stock axle geometry to remain mostly unchanged. The more important question at this point is "do we actually want to change the stock geometry and caster angle?" Without knowing his final tire size and desired track width, the calculations that show ideal caster and scrub radius can't be made...so he may not need to rotate those C's after all. Regardless, it's a sexy way to point the front axle at the t-case.

4) I know you know this, but it bears saying for those that don't: the rear is simpler because there's no real alignment to deal with. Just center the housing, align the rear axle pinion with the output of the transmission or t-case, tack the perches, cycle it, adjust as needed, and then burn it all in. Everything else is handled by the leaf springs themselves.

FYI..When I took mine apart I tried moving the steering arm to the top to see if it would work. It won’t work stock as a bolt on.

I'm a bit confused: are you talking about the intermediate link between the pitman and the knuckle, the drag link, or what? I can't see where anything else could be flipped from top to bottom.

I'll go look at my '51 here in a few minutes and see what it'll really take to do a correct spring-over. That said: I still don't like them, but that's because I've seen one too many wrapped sets of rear springs in my time. I agree that a more heavily-arched set is a better idea, across the board.
 
Wow...I just got EDGE YOU ME CATED! Some crazy knowledge on this forum.
 
Looking at my front knuckle, driver's side: can the actual steering arm - the piece that connects to the intermediate link - be flipped? The bolt pattern is very similar, top-to-bottom. If not, there seems to be enough room for a high-steer arm off the top. Either way, a flipped tie rod looks like it'll hit the springs. Hmm.
 
Looking at my front knuckle, driver's side: can the actual steering arm - the piece that connects to the intermediate link - be flipped? The bolt pattern is very similar, top-to-bottom. If not, there seems to be enough room for a high-steer arm off the top. Either way, a flipped tie rod looks like it'll hit the springs. Hmm.
Bolt pattern is the same but it won’t work on top.
 
Hmm. Since the intermediate link rests on rop of the steering arm in the stock configuration, it seems very possible to use a "flipped" intermediate in a spring-over, which would be both well-protected and possibly simple to build. Even if the stock arm couldn't be flipped, knowing that it will bolt up makes the fabrication of a custom high-steer arm infinitely simpler. In that eventually, it's just a matter of reaming the arm to accept the tapered shank of whatever TRE you choose that has a thread pitch/diameter than will play well with a customized intermediate link...and that may be simpler than I realize. I should go take mine apart to see what TREs might work.
 
Finally... something that I actually know about: spring wrap, caster and steering linkage flips...



The biggest issue you will have with a spring-over is the increased likelihood of the springs in the rear wrapping - literally bending into a sideways S-shape - under acceleration. The over-simplified reason for this is that as you move the spring eyes further away from the axle centerline without increasing the arch or strength of the leaf spring, you give the axle more ability to twist; it's basically triangulation that's working against you though increased leverage. This is especially prevalent off-road when the rear of the vehicle is loaded (as in, pointed uphill), but it can happen on pavement as well if you have enough power under the hood. The reason this is the worse of the issues is because it's inherent to the design: every other issue that comes from a spring-over - driveline angles, TREs, steering - can be adjusted, but the relationship of the spring eyes to the axle center is geometric, fixed, and not adjustable. If you aren't particularly worried about off-roading or hard acceleration, you may not need to be concerned about this... particularly if you're only looking for clearance.

The "control arm" that you mentioned/showed isn't a control arm; it's a Pitman arm. Likewise, your tie rod and drag/intermediate links are called such...and what you're talking about doing is basically a simple spring-over with a tie-rod flip. In the YJ/TJ world, we do them all the time, but it's not quite as simple, here...



That bend in the intermediate linkage is a real bitch to work around; from the photos - and this is my unfamiliarity with the specific platform coming into play - it doesn't look like a 180° cut-and-weld will put it back into the correct alignment. I would guess that a custom piece or something from another vehicle that's relatively straight would end up being correct, if he does a simple spring-over with no added craziness...but that's just a guess. The tie-rod flip (which might actually be optional) should be straightforward: remove it, alter the TRE hole in the steering arm of the knuckle by reaming it (bushing/welding may be needed), and then set the link on top of the knuckle. I'll go look at my '51 here in a minute and see if it looks as easy as I remember it looking.

The brake line and driveshaft changes will be equivalent, regardless of the method he uses to change the suspension height: that's a cost of doing business, and a wash.



A couple of small corrections:

1) He's raising the entire chassis, not the body: if he was only raising the body no adjustment of the axle would be necessary because the relationship between the transfer case outputs and the axles - connected by the driveshafts that you mention - would be unchanged. Stupid technicality, I know, but still one that needs to be said, because:

2) With an effective 5" lift, the driveshafts may or may not be a problem...but the problem is more in the universal joints than the shaft. Yes, the shaft may need to lengthen, but what we're really concerned about right here are the u-joint operating angles; if they aren't synched up, they'll eat themselves. With that in mind:

3) A rotated inner-C is a lovely way to go to fix caster angles if you want to build a flawless front suspension, but it's also unnecessary in most cases...and that's because a double-cardan front shaft can usually solve the u-joint problem just as effectively, and it can do so while allowing the stock axle geometry to remain mostly unchanged. The more important question at this point is "do we actually want to change the stock geometry and caster angle?" Without knowing his final tire size and desired track width, the calculations that show ideal caster and scrub radius can't be made...so he may not need to rotate those C's after all. Regardless, it's a sexy way to point the front axle at the t-case.

4) I know you know this, but it bears saying for those that don't: the rear is simpler because there's no real alignment to deal with. Just center the housing, align the rear axle pinion with the output of the transmission or t-case, tack the perches, cycle it, adjust as needed, and then burn it all in. Everything else is handled by the leaf springs themselves.



I'm a bit confused: are you talking about the intermediate link between the pitman and the knuckle, the drag link, or what? I can't see where anything else could be flipped from top to bottom.

I'll go look at my '51 here in a few minutes and see what it'll really take to do a correct spring-over. That said: I still don't like them, but that's because I've seen one too many wrapped sets of rear springs in my time. I agree that a more heavily-arched set is a better idea, across the board.
I don't agree with #3. Changing the driveshaft will have zero effect on castor angle. A stock geometry is for the stock vehicle it came from and, doesn't necessarily mean it will work on other vehicles.
 
I don't agree with #3. Changing the driveshaft will have zero effect on castor angle. A stock geometry is for the stock vehicle it came from and, doesn't necessarily mean it will work on other vehicles.

I didn't suggest that the driveshaft would impact caster angle; thinking that it does is preposterous, because it has nothing to do with caster. What I said was that the double cardan shaft can help u-joint angles. So, let me clarify something: the severely-increased universal joint angles that occur when one lifts a suspension are what we're really worried about with a spring-over...but because double cardan shafts exist, we can solve that problem rather easily. We do not, as you suggested, need to rotate the front housing in order to help the angle of the shaft; the only reason that we need to rotate a front axle is to intentionally adjust caster...but we can't make a determination on what caster angle is actually needed because we do not know the final tire size. At this point then - as we have both now said - it may or may not be a situation where the stock axle orientation remains viable; more information is needed in order to make that call.
 
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