Brian_D
1/2 ton status
Love that green color, i use that color a lot when doing paintings. good job!
CK5
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'72 K5 - Greg's @MightAsWellK5 Build
- Thread starter Greg72
- Start date
This is the build description. I will improve this later. (GB)
MNorby,
Do you happen to know what the recommended stickout is for the 14" strut?
The 16" ones I have are 6.5", from what I was told if you run them with too little shaft exposed you end up into the 2nd stage of valving (or something like that) and lose out on the nice initial soft rate that give ORIs such a good ride quality.
I'll keep messing with this.... Basically the challenge up front is to fit 3 major items:
Links
Driveshaft
Steering linkages
Sounds easy on paper, but as MiniWally as preached..... "cycle the suspension 50 times.... Then cycle it another 50 just to be sure". Turning the tires full-lock adds a whole extra dimension to getting everything packaged and working properly.
This is going to cost me some brain cells before its all said and done.
-G
Do you happen to know what the recommended stickout is for the 14" strut?
The 16" ones I have are 6.5", from what I was told if you run them with too little shaft exposed you end up into the 2nd stage of valving (or something like that) and lose out on the nice initial soft rate that give ORIs such a good ride quality.
I'll keep messing with this.... Basically the challenge up front is to fit 3 major items:
Links
Driveshaft
Steering linkages
Sounds easy on paper, but as MiniWally as preached..... "cycle the suspension 50 times.... Then cycle it another 50 just to be sure". Turning the tires full-lock adds a whole extra dimension to getting everything packaged and working properly.
This is going to cost me some brain cells before its all said and done.
-G
From what I understand the newer STX ORIs don't have as much of a set ride height spot like the older STs. They still recommend at least 5-6" up for any of their shocks just so you aren't sitting right on the bump portion.
http://www.pirate4x4.com/forum/15051052-post24.html
http://www.pirate4x4.com/forum/15051052-post24.html
I would agree with the get rid of the long tube header idea. Block huggers or shorty rear dumps would work great. Unless you plan on spinning this thing at a bunch of high RPM's not sure you need them.
Long tube headers are good for low end torque as well as hp, they are worth it in my opinion. Heck, even on a mild ~400 hp small block my brothers car picked up 40 hp going from shortys with a Y pipe to long tubes. Shortys and y pipes are good for stock engines and are better than manifolds, but won't be good for your big block. With that said, going the extra step for large race tubes and equal length doesn't really make a significant difference, it will make a tiny difference, but nothnig you will feel. I think small/medium tube long tubes like you have are a good compromise.
As for your suspension, I think you are making it a lot more complicated than you need to. With 16" of travel it's not really worth having a super complicated multi-link steering system. I can say that 14" is about the limit for stock type tie rod ends for the steering. Obviously that will vary with ride height, droop, arm length etc, but I would not have been able to get another inch of down travel or it would bind my tie rod. 2 more inches of travel would require it all to go up in compression, which could be possible if engines and crossmembers were moved.
But I say just build a 3 link, radius arm (Wristed if you want), or a parallel 4 link up the front. There is really no point in building a triangulated 4 link with mechanical steering because the little gain in roll steer, etc is not worth the stuff you have to give up everywhere else like space constraints and extra cost, joints, maintenance, etc.
The only way I would go triangulated 4 link up front would be to use hydraulic steering on an offroad rig only. Also, then you would really need to move your engine way back to be out of the way of the uptravel for the links, etc. You'll end up spending triple the time and money on the steering system for something you probably won't even notice the difference with 16" of travel. If you were going 22 - 28" of travel or something, then it would be necessary to go with a more complicated steering system.
The steering system for 16" of travel could be a simple draglink with a vertical rod end or spherical joint on the tie rod at the axle end and a horizontal unit at the pitman arm. Make sure its as equal in length and angle to your panhard bar as you can and you are good to go.
As for your suspension, I think you are making it a lot more complicated than you need to. With 16" of travel it's not really worth having a super complicated multi-link steering system. I can say that 14" is about the limit for stock type tie rod ends for the steering. Obviously that will vary with ride height, droop, arm length etc, but I would not have been able to get another inch of down travel or it would bind my tie rod. 2 more inches of travel would require it all to go up in compression, which could be possible if engines and crossmembers were moved.
But I say just build a 3 link, radius arm (Wristed if you want), or a parallel 4 link up the front. There is really no point in building a triangulated 4 link with mechanical steering because the little gain in roll steer, etc is not worth the stuff you have to give up everywhere else like space constraints and extra cost, joints, maintenance, etc.
The only way I would go triangulated 4 link up front would be to use hydraulic steering on an offroad rig only. Also, then you would really need to move your engine way back to be out of the way of the uptravel for the links, etc. You'll end up spending triple the time and money on the steering system for something you probably won't even notice the difference with 16" of travel. If you were going 22 - 28" of travel or something, then it would be necessary to go with a more complicated steering system.
The steering system for 16" of travel could be a simple draglink with a vertical rod end or spherical joint on the tie rod at the axle end and a horizontal unit at the pitman arm. Make sure its as equal in length and angle to your panhard bar as you can and you are good to go.
Heath,
Yeah, I think 16" up front is unrealistic. Miniwally recently commented that having a little less wheel travel up front (vs. rear) is actually a good thing, since it keeps the truck more stable at speed.... something about having a little extra "margin" out back to absorb bumps to keep it from trying to swap ends.
At my current belly height (26") the best I'm going to do up front is 6" of uptravel before the axletube crushes the oilpan. Realistically, I need to leave myself some room for error so maybe 4-5" is my TRUE maximum for bump.
The main reason for the effort with the 4-link is to keep the axle nice and centered under the truck under compression / articulation. Every panhard bar design I've seen and tried mocking-up myself ends up spitting the axle out one side of the truck by a few inches under droop. It seemed like a bad tradeoff, but perhaps the amount of "error" at reasonable wheel travel numbers is so slight that it's not worth worrying about?
From all the suffering I've already done trying to package the 4-link, I can totally appreciate why almost everyone does a 3-link instead. It feels like I could get one of those roughed-in if given 8-hours or so of uninterrupted time in the shop!
Got a link to any good "wristed" radius arm setups? I know theres a lot of torsion in the axletube with the solid mounted radius arm setups, but I haven't really spend much time looking at that type of solution in several years.
-G
Yeah, I think 16" up front is unrealistic. Miniwally recently commented that having a little less wheel travel up front (vs. rear) is actually a good thing, since it keeps the truck more stable at speed.... something about having a little extra "margin" out back to absorb bumps to keep it from trying to swap ends.
At my current belly height (26") the best I'm going to do up front is 6" of uptravel before the axletube crushes the oilpan. Realistically, I need to leave myself some room for error so maybe 4-5" is my TRUE maximum for bump.
The main reason for the effort with the 4-link is to keep the axle nice and centered under the truck under compression / articulation. Every panhard bar design I've seen and tried mocking-up myself ends up spitting the axle out one side of the truck by a few inches under droop. It seemed like a bad tradeoff, but perhaps the amount of "error" at reasonable wheel travel numbers is so slight that it's not worth worrying about?
From all the suffering I've already done trying to package the 4-link, I can totally appreciate why almost everyone does a 3-link instead. It feels like I could get one of those roughed-in if given 8-hours or so of uninterrupted time in the shop!
Got a link to any good "wristed" radius arm setups? I know theres a lot of torsion in the axletube with the solid mounted radius arm setups, but I haven't really spend much time looking at that type of solution in several years.
-G
Just got a PM from Kelly (blacksheep10) with the following recc's:
16" ORI STX = 6.5" shaft stickout
14" ORI STX = 5.75 -> 6" shaft stickout
12" ORI STX = 5.5" shaft stickout
Any idea if ORI still does "custom configs" for the STXs the way they used to for the STs?
I think in the old days it was accomplished with different length internal tubes and a bit less shock oil.... not sure that all of that is still necessary... maybe just remove a bit of oil?I'd kind of like to be running at 5" stickout on maybe a 14" strut, that seems like it might be a good complement to the 16" / 6.5" stickout I'm already doing for the rear.
-G
I think from that one post is they got away from the custom length tubes with the STX shocks. Your 16s you have for your front, are they STX or just STs?
I bought the new 16" STXs for the rear... haven't bought anything yet for up front.
Wanted to wait to see what sort of room I'd have to work with. I just PM'ed Kelly to see if a custom 14" STX with 5" stickout is possible. I just don't see any way to comfortably get more than 5" of travel up front without increasing the overall height of the truck (and I'm NOT going to do that).
-G
Wanted to wait to see what sort of room I'd have to work with. I just PM'ed Kelly to see if a custom 14" STX with 5" stickout is possible. I just don't see any way to comfortably get more than 5" of travel up front without increasing the overall height of the truck (and I'm NOT going to do that).
-G
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I think ssyork dropped his 16" STs in his front down to 5" bump without any ill effect. If you need to go to 12" or 14" ORIs let me know and I'll see what kind of deal Kyle will do on the ones he bought before buying my Sonoma and are too short for its setup. He will probably make ya a good deal so he can buy the correct length ones.
Greg;
Honestly, Ditch the 4 link go three link with a track bar, get the trackbar mounted up so that the frame end is at the same elevation as the axle end. This is easy to do if you raise the axle end up. The stick out, due to the track bar, from side to side is minimized then and you can "guide" the drive shaft somewhat that way as well. Steering and everything else is "normal" then.
Don't be afraid to look at drivers drop front axle, I know you have the atlas but it's unused and could be sold for most of it's value OR maybe swapped for a drivers drop. I think they just change the way the case is put together, all the same parts just assembled backwards?
Is the high pinion needed for the portals, dumb question from me but if it isn't why high pinion. Low pinion will help with your driveshaft issues. BUT remember that most of the time solving one problem creates another down the line so make sure of everything. I would buy a bunch of header primary bends and build a header for that side that drops the exhaust in front of the oil pan, around the drivers side and tie it all into one larger pipe and only have one muffler etc.
14" of front travel is quite a bit. We only run 16" of front travel in the race car and while a it more would be nice it is hard to keep driveshafts happy etc. with more. Keep in mind that I ran 14" of travel when the race car was my rec rig and never had issues with it, nor did I think I needed more.
I know what your trying to get at, and build but from the outside looking in I think you need to remember that this is a full bodied early blazer that you are going to be hesitant to dent up when it's done. With that said, why make it to where it's got more abilities in the suspension that the body will allow it to use? Does that make sense?
Got to go to work and then fix my boiler so I have heat at home but maybe this will help.
Honestly, Ditch the 4 link go three link with a track bar, get the trackbar mounted up so that the frame end is at the same elevation as the axle end. This is easy to do if you raise the axle end up. The stick out, due to the track bar, from side to side is minimized then and you can "guide" the drive shaft somewhat that way as well. Steering and everything else is "normal" then.
Don't be afraid to look at drivers drop front axle, I know you have the atlas but it's unused and could be sold for most of it's value OR maybe swapped for a drivers drop. I think they just change the way the case is put together, all the same parts just assembled backwards?
Is the high pinion needed for the portals, dumb question from me but if it isn't why high pinion. Low pinion will help with your driveshaft issues. BUT remember that most of the time solving one problem creates another down the line so make sure of everything. I would buy a bunch of header primary bends and build a header for that side that drops the exhaust in front of the oil pan, around the drivers side and tie it all into one larger pipe and only have one muffler etc.
14" of front travel is quite a bit. We only run 16" of front travel in the race car and while a it more would be nice it is hard to keep driveshafts happy etc. with more. Keep in mind that I ran 14" of travel when the race car was my rec rig and never had issues with it, nor did I think I needed more.
I know what your trying to get at, and build but from the outside looking in I think you need to remember that this is a full bodied early blazer that you are going to be hesitant to dent up when it's done. With that said, why make it to where it's got more abilities in the suspension that the body will allow it to use? Does that make sense?
Got to go to work and then fix my boiler so I have heat at home but maybe this will help.
wilpetty
1/2 ton status
I'm really late, but what an awesome build Subscribed
Heath,
Yeah, I think 16" up front is unrealistic. Miniwally recently commented that having a little less wheel travel up front (vs. rear) is actually a good thing, since it keeps the truck more stable at speed.... something about having a little extra "margin" out back to absorb bumps to keep it from trying to swap ends.
At my current belly height (26") the best I'm going to do up front is 6" of uptravel before the axletube crushes the oilpan. Realistically, I need to leave myself some room for error so maybe 4-5" is my TRUE maximum for bump.
The main reason for the effort with the 4-link is to keep the axle nice and centered under the truck under compression / articulation. Every panhard bar design I've seen and tried mocking-up myself ends up spitting the axle out one side of the truck by a few inches under droop. It seemed like a bad tradeoff, but perhaps the amount of "error" at reasonable wheel travel numbers is so slight that it's not worth worrying about?
From all the suffering I've already done trying to package the 4-link, I can totally appreciate why almost everyone does a 3-link instead. It feels like I could get one of those roughed-in if given 8-hours or so of uninterrupted time in the shop!
Got a link to any good "wristed" radius arm setups? I know theres a lot of torsion in the axletube with the solid mounted radius arm setups, but I haven't really spend much time looking at that type of solution in several years.
-G
I can vouch for the more travel in the rear setup, mine tried to swap ends vertically and it wasn't fun. Whoops at 50 MPH with only 10" travel in the rear is not a good idea, 14" up front worked fine though.
As far as side travel, let me give you an example, I measured this quick using CAD in less than 5 minutes with a 2D sketch. In this example you have a 40" long track bar, set at about 8.7 degrees up at ride height(it rises 6" at the frame end).
During normal driving, even moving up and down 3", it will move .34" to the right on the way up, and .43" to the left on the droop.
If you compress the axle up 5" it will move to the right .44". Droop it down 5" and it will move to the left 1.1".
If you have 7" of downtravel )12" total, it will move 1.7".
If you have 14" of travel and 5" compression, then it can droop 9", quite a bit, at that droop the axle would move 2.4" to the left, but keep in mind that is full 9" of droop which would mean the front end of your truck is in the air or near it, and if your track bar is correct that will be 9" of droop with no bumpsteer. So even after a jump if the axle moves over as it compressed the tires should stay straight ahead. My track bar is shorter than 40", I don't remember the exact length, but I do not notice any bumpsteer at all with my 14", it always goes where I point it even when I feel weightless at the end of a race going over a slight dip at speed. In fact, even when I almost flipped it because the back was bouncing, it kept going straight over the whoops, steering worked great actually. The rear suspension needs more travel though.
Yes, your axle can move side to side, but during normal driving within the middle 6" of travel, that's only ~3/8" either way. Now, during more extreme maneuvers it can be more, but you won't notice it while driving I bet. If you have a longer track bar it will be less movement. Of you have a more parallel track bar at ride height then movement will be more even with less movement under droop, but the frame mount may be pretty weird, and your draglink may get funky too.
As for wristed radius arms, mine is wristed if I take one of the bolts out of small upper tubes. I've done it once and it didn't make much difference, so I never do it anymore. I guess the bushings flex enough the spings restricted it before the bind did. If i had really soft springs that my not be the case. I prefer the bolt over the pin because I am afraid the pin will rattle and eventually wollow out the hole. Keep in mind with radius arms, the longer the arm, the more inward at the rear, the less bind their will be because the same articulation will results in less angle delta in the arms.
Also, bushnig seperation at the axle is a tradeoff between axle control and less bind.
With your portal axles, I would probably do a parallel 4 link, or maybe 3 link.(when I say parallel I mean laterally, you could still tune the arm angle for anti-dive, etc) I just say parallel laterally to avoid the bind with the panhard bar. It would allow solid heims or spherical joints for more axle control. Radius arms will require at least half bushings or more, and bushings may result in wheel hop with portals, so I don't think radius arms are optimal for portals. Parallel 4 link or 3 link with panhard bar is the way to go for no bind.
I would say 3 link for sure, but I am worried about the torque on the single link with those portals. So I may lean towards the parallel 4 link with the portals, then you would have maximum axle control and the 4 link wouldn't bind with the track bar.
Brandon,
Thanks for the suggestions.
I'm a little confused by your comment about going to a DS drop Atlas though.... what is the benefit of doing that?
The flipping of the 3rd members (standard low-pinion units become high pinion in this configuration) is due to the portals. Unimogs are a 2-gear unit so the output gear turns opposite from the axleshafts. Flipping the pinion gets everything moving "forward" again (pun intended)
A high-pinion in this case should make the angles BETTER, not worse though.... right? I can still clock the Atlas down a little further before it's below the framerails to improve the angularity even more. If I set up the axle housing to aim the pinion straight at the Atlas (with a CV on the other end) I can probably keep the total pinion change to within 5* - 7*. (IIRC, my current rear suspension only has about 10* slope on the rear driveshaft) Depends a lot of the final design, but my spreadsheet keeps track of how much angularity I have on both bump and droop so it keeps me honest when I try to choose link positions that are impossible. Pinion change is also basically going to reflect the amount of caster change as the suspension cycles too, and although I'm not building a desert runner... I know that massive changes in caster can be pretty miserable too.
Now for my dumb question(s):
If I was to build a 3-link based on the configuration I've got now (PS drop Atlas) would I put the 2 links on the passenger side, with the single on the driver's side? Presumably this would leave me room on the driver's side for the steering linkages.
In that configuration, which side does the panhard frame-side mount go to? Drivers side or passenger side? Or is it just a function of keeping it aligned with whatever steering draglink I end up with (parallel)??
It should be obvious by now, I haven't spent any time thinking about 3-link front at all.... but I promise to give it some serious thought, and try a few mock-ups to see if I can come up with something that helps move this build forward.
Funny thing: Stephen Watson said to me MANY years ago "Don't end up building yourself a buggy inside a Blazer body"
His point back then was the same as yours... don't put a super-capable suspension under a rig that isn't ever going to take advantage of it. I tried to take those words to heart, and that was at least the impetus for the "transformer" idea. I can pull all the exterior sheetmetal for wheeling and that will allow me to worry less about damage. Ultimately, I still intend to drive this thing a lot on the street and just enjoy it that way as well... so a true buggy-style rig isn't going to make me happy. I'm trying to "thread the needle" with a true dual-purpose rig, and that is a difficult thing to do.
I guess the "Might As Wells" took me quite a bit deeper into this build than was PROBABLY necessary, but as I've mentioned before I'm learning a LOT along the way and enjoying the problem-solving and creative design process as much as I'll enjoy the end result. I'm sure it's got to be hard to watch how slowly I work at times, but eventually I will "peel the F out" in this thing!
-G
Thanks for the suggestions.
I'm a little confused by your comment about going to a DS drop Atlas though.... what is the benefit of doing that?
The flipping of the 3rd members (standard low-pinion units become high pinion in this configuration) is due to the portals. Unimogs are a 2-gear unit so the output gear turns opposite from the axleshafts. Flipping the pinion gets everything moving "forward" again (pun intended)
A high-pinion in this case should make the angles BETTER, not worse though.... right? I can still clock the Atlas down a little further before it's below the framerails to improve the angularity even more. If I set up the axle housing to aim the pinion straight at the Atlas (with a CV on the other end) I can probably keep the total pinion change to within 5* - 7*. (IIRC, my current rear suspension only has about 10* slope on the rear driveshaft) Depends a lot of the final design, but my spreadsheet keeps track of how much angularity I have on both bump and droop so it keeps me honest when I try to choose link positions that are impossible. Pinion change is also basically going to reflect the amount of caster change as the suspension cycles too, and although I'm not building a desert runner... I know that massive changes in caster can be pretty miserable too.
Now for my dumb question(s):
If I was to build a 3-link based on the configuration I've got now (PS drop Atlas) would I put the 2 links on the passenger side, with the single on the driver's side? Presumably this would leave me room on the driver's side for the steering linkages.
In that configuration, which side does the panhard frame-side mount go to? Drivers side or passenger side? Or is it just a function of keeping it aligned with whatever steering draglink I end up with (parallel)??
It should be obvious by now, I haven't spent any time thinking about 3-link front at all.... but I promise to give it some serious thought, and try a few mock-ups to see if I can come up with something that helps move this build forward.
Funny thing: Stephen Watson said to me MANY years ago "Don't end up building yourself a buggy inside a Blazer body"
His point back then was the same as yours... don't put a super-capable suspension under a rig that isn't ever going to take advantage of it. I tried to take those words to heart, and that was at least the impetus for the "transformer" idea. I can pull all the exterior sheetmetal for wheeling and that will allow me to worry less about damage. Ultimately, I still intend to drive this thing a lot on the street and just enjoy it that way as well... so a true buggy-style rig isn't going to make me happy. I'm trying to "thread the needle" with a true dual-purpose rig, and that is a difficult thing to do.I guess the "Might As Wells" took me quite a bit deeper into this build than was PROBABLY necessary, but as I've mentioned before I'm learning a LOT along the way and enjoying the problem-solving and creative design process as much as I'll enjoy the end result. I'm sure it's got to be hard to watch how slowly I work at times, but eventually I will "peel the F out" in this thing!
-G
Yes I run my 16" non stx oris with 5" showing. Right now they are still at 4.75" from moab in sept. I ordered mine setup for the stage 1 to be from 6-8" instead of the stock 7-9. They put longer bypass tubes and left all the oil. To compensate I only run them with 150 psi in the bottom and around 200 in the top depending on ride height i want. They work great, they don't bottom out harshly at all, but still soak everything I throw at them. I'm no desert truck though. I also put in small poly bumps, due to miniwallys recommendations, that are very solidly mounted that make contact 1/4" before the ori's bump hits. Ori said due to the weight of my truck they wouldn't advise pulling any oil out or changing to a lighter one either. I wouldn't worry about being out of the stage 1 damping, our heavy trucks make up for some of it, just play with the pressure until you find a sweet spot. Changing the rebound screw definitely makes a difference too. I do adjust the upper pressure a little to get different ride heights depending on where we are going, and the ride quality doesn't change. Now I just need them in the rear, so it will stop kicking around!
Greg I have done one of those crazy push pull type steering setups. Its alot more work than you think routing everything and getting it all out of the way.
I also did a 4 link with conventional steering that worked pretty good. But it had several compromises to make it work good.
There is a reason everyone does a 3 link style suspension on their rigs in the front. It is simply the better way to go.
Now if you were planning on racing Brandon across the desert and hoping to beat him I would say carry forth with the 4 link idea and the push pull type steering setup. It will give you allow you to use much longer shocks if you wanted.
Now I am going to reiterate some of what has been said. It is useful to have more travel in the rear for this fact, in the rocks you are usually turning and the rear will need more travel to clear the same rock in the same manner because it will more than likely hit it in a different place. High speed wumping the reason is totally different. If your rear can't take the same hit as the front then you get a pogo effect for the front. Heath knows all about this.
I tend to strive for similar travel results front to rear as has been said biasing a little more travel to the rear.
I realize that alot of folks don't think the KISS principle applies to your truck but overall I still think that once your done all the extra fab work and hours spent actually keeps the KISS principle in mind. Alot of stuff you have done is to make things work very very well together. In my mind that is the epitome of the KISS principle.
So ditch the 4 link. Roll with a 3 link I know the axle shifting due to the inherent flaws of the suspension might be a bit of a annoying point, but all suspensions have inherent flaws. With the amount of room you have the 3 link when its done vs a 4 link will give you no perceptible disadvantage off or on road.
Now you can obsess over how long you can get the panhard bar
I also did a 4 link with conventional steering that worked pretty good. But it had several compromises to make it work good.
There is a reason everyone does a 3 link style suspension on their rigs in the front. It is simply the better way to go.
Now if you were planning on racing Brandon across the desert and hoping to beat him I would say carry forth with the 4 link idea and the push pull type steering setup. It will give you allow you to use much longer shocks if you wanted.
Now I am going to reiterate some of what has been said. It is useful to have more travel in the rear for this fact, in the rocks you are usually turning and the rear will need more travel to clear the same rock in the same manner because it will more than likely hit it in a different place. High speed wumping the reason is totally different. If your rear can't take the same hit as the front then you get a pogo effect for the front. Heath knows all about this
. I tend to strive for similar travel results front to rear as has been said biasing a little more travel to the rear.
I realize that alot of folks don't think the KISS principle applies to your truck but overall I still think that once your done all the extra fab work and hours spent actually keeps the KISS principle in mind. Alot of stuff you have done is to make things work very very well together. In my mind that is the epitome of the KISS principle.
So ditch the 4 link. Roll with a 3 link I know the axle shifting due to the inherent flaws of the suspension might be a bit of a annoying point, but all suspensions have inherent flaws. With the amount of room you have the 3 link when its done vs a 4 link will give you no perceptible disadvantage off or on road.
Now you can obsess over how long you can get the panhard bar
In the front the pinion vs/caster thing is a compromise. Pinion change can be good because it can keep u-joint angle at the pinion low throughout the travel for smoother operation at speed. However, caster change is not good, but as long as you have enough you are probably fine. With only 5" of uptravel, I think I would rather have the pinion stay with the ujoint becase you won't lose much caster even at full compression. You will get more caster at full droop but that is fine.
As for the 3 link configuration, that is up to you, and it will be tough with the portals. You could do the 3rd link on top, at left or right. Or you could put it in the middle on the bottom (it would have to be VERY strong), and put the side links on the top. With long tubes it will be tough to do a 3 link, but without longtubes you will be giving up noticeable power with that 502.
The thing I'm worried about is how much stress the portal axles will put on the odd link. Has anyone done a 3 link with portals?
The panhard bar will always need to be as close ot parallel and length as the draglink. So if you have a drivers side steering box, you need the panhard bar to attach to the drivers side.
The hardest parts with the portals is placing the link mounts on the axle in a way that doesn't create rock anchors, but still gives good vertical separation. I was successful getting 10" of vertical separation at the axle end, and 7" at the frame side for the rear axle. In the Excel calculator, that really seems to help keep the link forces reasonable. Triaged (Dan Barcroft) keeps insisting that a portal axle itself really doesn't require a unique link design, the torque arm originates at the tire contact patch (hope I'm describing that right). If the links are strong enough for the application and have good vertical separation, all should be well.
The single link on a 3-link obviously needs careful attention since the loads are twice as high on the heims. The EVO heims I bought are pretty beefy so I might have enough design margin as long as I use the large ones on both ends for that link.
Longtubes - Well, the original GM502 specifications I found online said this:
For street performance and limited competition applications, the
recommended header configuration is 2" diameter primary pipes, 36 inches long, with 3 1/2" diameter collectors.
recommended header configuration is 2" diameter primary pipes, 36 inches long, with 3 1/2" diameter collectors.
Use 3" diameter tailpipes with a balance tube (“H” pipe) and low restriction mufflers.
I didn't want to skimp out or artificially choke-down the motor with something else. I'll keep working on the passenger side one and with a bit more effort I might be able to make it work... I'll probably have to buy some extra 2" tubing before too much longer.
-G
Greg
My drvers drop comment was a question based on obstacles on the vehicle. Is it easier if you use the axle as a drivers drop? Less in the way, less to modifiy etc.
For the three link, trak/panhard bar goes in the same direction and parallel to the steering linkage. Mount the lowers as close to the knuckles as you can, if they need to be below the axle this will make them less of a rock anchor. Trinagulate them enough to clear the tires in steering. Upper link is up to you, which side is easier? Doesn't matter as far as I know. closer to center is better I think but still doesn't make a lot of difference.
Low pinion vs. high pinion was about making room for the driveshaft to exist without crashing into the header, that's all.
I also would make and or use headers that work for the suspension, not make the suspension work around the headers.
My drvers drop comment was a question based on obstacles on the vehicle. Is it easier if you use the axle as a drivers drop? Less in the way, less to modifiy etc.
For the three link, trak/panhard bar goes in the same direction and parallel to the steering linkage. Mount the lowers as close to the knuckles as you can, if they need to be below the axle this will make them less of a rock anchor. Trinagulate them enough to clear the tires in steering. Upper link is up to you, which side is easier? Doesn't matter as far as I know. closer to center is better I think but still doesn't make a lot of difference.
Low pinion vs. high pinion was about making room for the driveshaft to exist without crashing into the header, that's all.
I also would make and or use headers that work for the suspension, not make the suspension work around the headers.
Can you make a header that would basically like putting a drivers side header on the passenger side so it points forward then bend them to go under front of oil pan and the collector flange under the pan?
