Gen 8/Axe Steering/Suspension flaws, some solutions.

[Timmahh]

Hey hosers and hossettes.

For all you RC Gen 8/Axe owners out there, who notice steering issues, and have found various semi fixes to the steering problems as well as the bump steer issues these rigs see, along with the front axle shift as the suspension compresses (limited improvements here due to layout and geometry which will take more attention to correct or improve) they also have, this thread should help you know whats a required solution, and what only seems like a solution.

For those that know me from days gone past, this won't be much new, but for those that have come since I got out nearly a decade ago, you may find this interesting, lol or not.


So. out of the box the front end works. Not great, but it does what it should, just not HOW it should. lol The bump steer was fairly significant, and some of the 'fixes' offered are good in that they address the correct issue, instead of something that doesn't but tries something to change the setup to work better, in some ways, tackling a minor issue, and in other masking or making the main issue worse.

I had a f-it night, and pulled out the Axe around 1:30 am and finally crashed about 6ish as the Sun was coming up.

First I'll address the axle shift.
If you look, as the front suspension compresses, the axle starts to shift to the right side (passenger). The more compression of the right shock the more shift introduced. However, the left side (Drivers) can compress fully up front, and it induces zero axle shift from what I could see. I studied the front end as it moved through its stages noting what/where/why was going on.

The simple answer is the pan hard setup. Ignoring the plastic axle panhard mount that flexes a bit, and needs to be addressed with an aluminum mount (a few options are out there, RedCats own link mounts, SSD's sets, & Chy-Na specials. I have the SSD in my cart atm), the design/layout/set-up of the pan hard introduces the shift. The reason its only the right side that does it is the pan hard mounts on the right side of the axle. If it was opposite and mounted on the left, then that side would be introducing the shift with the current setup.

Ealier, a month or so back, I posted about this, and to address it I started shortening the pan hard link ends. The problem is as the right side suspension compresses, the pan hard bar starts pushing the axle outward (passenger side) because of its length and position of the mounts.

By shortening the link ends a bit, it shortened the overall length of the panhard so when the left side compresses, the pan hard didn't shift the axle as much as it was a few mm shorter (about 5-6mm total, 3mm from each link end).

This helped, but the amount of shift was still quite long. I went ahead and tried to shorten some link ends further. But it didn't take long before the axle when unsprung started to pull on the left side, shifting the axle again. This is because I made the bar too short with the shortened ends. So there is a Sweet Spot on these rigs, and with its current setup, the best you can hope to improve. I'll get it sorted and post back how long each rod end is. Will also get a few angled rod ends just to see if they'll help any.

I am thinking a well formed S bend pan hard bar, and an angled end on the axle side may help more, but even then, without fully redesigning the mount locations, angles, pan hard bar, link end geometry, the best we are going to end up with is zero axle shift under left side compression, and some (a bit less than 1/4 inch maybe) shift under full right side suspension compression.

I'll grab some pics and detail what I did in the next post to improve the axle shift as best as it can be.

On to the steering issue and bump steer problem.

First the steering issue. This is a bit of a geometry/layout issue but is correctable without the need for spending too much money to fix it.

After a few hours last night, of studying, then fingering everything as it moved, the issues were pretty direct. As others noted, getting the drag link angle matched or as close to matched as the pan hard bar angle is key here.
This wasn't too hard. The generally advertised and accepted method of achieving this is to move the steering cross-link bar to the bottom of the Knuckle arm mounts.

So you are probably saying, wait a minute Tim, isn't the drag link mounted to the cross-link? Yup. it is. You need to remove it from the cross-link, and this is where you will need to drop some pennies because you'll want to get some longer (bent ends preferred) rod ends so you can make the drag link longer so it can reach the knuckle arm mount spot. The bent ends on the drag link will help a lot here as it reduced the angle of the drag link mounts. Once you lower the drag link to the top of the arm, the angle increases and this will start to bind the link ends and the balls. So the bent ends will address the bad angle and eliminate any binding by removing the stress from the greater angle, and get rid of any binding at the link ends and balls.

This opens the top of the knuckle arm area to move the drag link too. When you add longer drag link ends to extend its length to get it to mount on the top of the knuckle area, it makes the drag link angle very close to the pan hard angle. This is a great fix and only requires you to move the links around and a few longer rod ends. Same bolt and nut should work on both sides of the knuckles.
Many are putting the bolts in upside down (from the bottom up) so the pan head of the bolt is on the bottom. This will add clearance and reduce some hangup spots under the axle. I just mounted mine normally for now (nut on the bottom). Depending on rod end length, the end of the drag bar should be pretty close to 90* out from the servo horn gear. The closer to 90* you can get the link mount to the servo arm gear, the better performance you'll achieve here. So pay with some rod end lengths and try to make the drag link the right length, or within a few mm as much as possible.


There is another option for drag-link bars here. Use another brand's link.
I have these SSD kits here and one is a leafer now, so I used the s curved Panhard link, as the steering link was used on the leafer build. So I thought about trying it as a pan hard link on the Axe, but decided to use is as my drag link from the servo to the axle top. The S curve on the SSD introduces a much better link geometry. Added a long end and a short end (straights and stock) to the SSD link and installed it. This allows the steering to move fully from bind point of CVD to bind point of CVD and do it without much issue. Installing a metal Pan Hard mount on the axle will also help keep the front suspension more rigid, which will only add to the steering improvements as they won't flex under stress/tension, which always shows in steering radius as the suspension flexes.

After swapping to the SSD link (which is smaller diameter than the stock Axe link, but is Titanium, opposed to the aluminum, and about 10mm longer than the stock drag link) and getting the right link ends on the correct end of the link (lol say that 4 times fast) so it wasn't too short or too long, it installed on the servo horn where the horn was at almost 90* to the servo gear. This really helped remove any of the remaining bump steer throughout the travel.

You can compress either side of the front suspension, separately, equally, or other, and the only remaining bump steer I see is at full compression of the right side, as the axle shift is introduced, and the servo position doesn't change, they will fight against each other a bit.

So while I was not able to get rid of al the axle shift, it is minimized as much as it can be without a full redesign of the pan hard mounts, link and mounting positions. I'm happy with the end result of minimal axle shift it has now. And after the changes to the steering, getting the drag link angle basically matched with the SSD Link I used, I am very happy with almost no bump steer.


If you notice, the only thing I said you may need to get is a few bent rod ends, not angled, but 2 angled rod ends on the pan hard bar itself may help a little, as using them will add some length and needed end angle to reduce the bind on the link balls. An S curved pan hard with the right Geometry to clear the axle at full compression may really help. I didn't try my SSD Pan hard bar before Using it as the Steering drag link, but i may try it to see how it works out, and if it does improve the axle shift, buy one. Or maybe I'll just take some links that I have or some brake line and try to bend up a properly configured S curved Pan Hard bar if it proves to help reduce/eliminate the Axle shift.

Things of note...
Don't Shorten the Pan Hard ends too much. You'll need to find a happy medium between how much the axle is shifted while the right side is under full compression, and how much it pulls the axle when the suspension is fully unsprung.
I mentioned I originally removed about 3mm per side on the pan hard links.

last night I keep going until I went too far. Which I put on a different end that was slightly longer again, and that is where it is atm. I think I want to add a few mm back, so I need to put another link end on that is just a few mm longer than the one mounted at the axle right now.
BUT, I will wait to do that until I have received and installed the SSD Link Mounts. That flexing pan hard mount on the shock mount doesn't help either the axle shift or the steering issue at all. It probably even has a bit of an effect on the remaining bump steer it has. So once I get them and on, then I'll check it all out again, and see if a longer link end will still be needed.

I think it will, but its 'good enough for this redneck' for now. lol

Again, I'll get pics and take some vid of the changes with in a day or two. May be later this evening yet, but most likely tomorrow after I get back home.


So to fast summerize.
Yes, you can almost eliminate all the bump steer, but there will be some due to the pan hard design.
No you can not get rid of the axle shift without a big redesign. But you can make it livable and remove a fair bit of it, making it much better to drive.

I suspect once I have the SSD link/panhard mount installed, it will be better yet, Not totally gone, but fully livable and not that intrusive on the rocks.

I spent about 45 minutes today on the rocks. It held the lines much better. The nearly gone bump steer didn't get in the way or cause any problems.
The improved steering and turning was great, and will get better with the Solid pan hard mount on the axle.

So for the cost of a few short rod ends, or make your own, you can reduce and make bearable the axle shift. For the cost of a few bent rod ends, you can very much improve the bump steer and some of the overall steering issues by dropping the cross link to the bottom of the knuckle arm, and putting the drag link on the top of the link arm with a few longer link ends.

[Timmahh]

Or you can spend a little money (30ish maybe) and get a SSD S curve Pan Hard bar (sold in a package with their steering s curve link I believe) and use that. Last note. After moving the steering link below the knuckle arm mounts. the link no longer hit the pumpkin cover. Even when at full turn, the cross-link is still a mm or so from hitting the pumpkin cover, so that eliminated 2 issues with that move.

I'll try the SSD ph link as a G8 ph link and see if it clears the axle pumpkin and will work. but just looking at them together, I don't think it will. Think this will need a more custom S curve link to work and reduce as much of the axle shift as possible.

Last Tip. Notice what I didn't talk about using or needing to fix the steering/bump steer issue. Some things are nice, but tackle the wrong issue, which usually induces other problems.


I thought about getting a set of the Aluminum Shock mounts which has the chassis side pan hard mount. But the stock set up seems to be fine atm, and without moving redesigning the pan hard system as a whole, there is no need for one. The chassis side pan hard mount seems to be rigid and fixed from what I can see, to going to aluminum, would only look shiny, but not preform at all.

More later.

[ferp420]

dude you might want to read up on how.a.3.link works

[Timmahh]

Dude, I know how a 3 link works. worked on them on 1:1s. lol

Like I said there are setups that re doable, and then there are setups that are properly designed and implemented.
These are one of those doable units. lol

There is a trade off, however the axles should not be shifting laterally very much if at all as the suspension compresses. Properly designed and installed pan hard systems work flawless.


FWIW, the SSD kit that is built up mostly per the manual except using 130mm shocks in full drop, sees pretty much ZERO axle shift or any movement of either side of the axle until it drops down beyond the limits as the angle of the axle increases past the mechanical lmits. There is also no bump steer that I have noted in that kit until the same angles are there nearly full droop.

Perhaps try some Mechanical Engineering?

[ferp420]

dude shortening the panhard bar incresses the axle.swing bump steer is easily fixed nothing you sead made.any sence if your drag link and panhard bar are.different langths and or diffe4ent angles your gona have bump steer

working on 1:1 is alot different than designing one this is basic stuff

make the links the same lenght same angle put 5he servo in the right spot set your steering links up right and put th3 chassie link mount in the right spot

its not hard

[Flamnpede1]

The bump steer is a simple fix and doesn't require relocation of links or changing lengths etc. I have said this time and time again. Change the freaking servo horn to a low profile horn and it virtually eliminates all the bump steer.

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[Timmahh]

Originally Posted by ferp420

dude shortening the panhard bar incresses the axle.swing bump steer is easily fixed nothing you sead made.any sence if your drag link and panhard bar are.different langths and or diffe4ent angles your gona have bump steer

working on 1:1 is alot different than designing one this is basic stuff

make the links the same lenght same angle put 5he servo in the right spot set your steering links up right and put th3 chassie link mount in the right spot

its not hard

If you Read the entire post you would see I noted pan hard length has little todowit the bump steer, but it can lend to the issue if it is improperly designed or laid out.Which is is under these RCs. Its not Terrible, but there is a lot of room for improvement.

As I noted. Some people like to imagine they fixed a design issue, but changing something else that has little to do with the design flaws, and they are good with that. For me, I am far to anal. lmao

maybe you have not checked the mess that is under these Gen 8s. lol

You assume way to much and read too little it seems.

I guess I never knew Mechanical Engineering was different between designing different mechanical things. lmao DERP

[Timmahh]

Originally Posted by Flamnpede1

The bump steer is a simple fix and doesn't require relocation of links or changing lengths etc. I have said this time and time again. Change the freaking servo horn to a low profile horn and it virtually eliminates all the bump steer.

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A low profile horn only helps a little as it barely moves the drag bar angle. As you said, it VIRTUALLY removes it all, but it doesn't remove it all. lol Slicing hairs? Maybe. But Hairs are where the details hide.

Fixing the bump steer was only one reason for moving the links a bit. Better Steering through both vectors of travel was one of the other reasons for the link move. May not seem like it would make a difference, but it does.


Reducing bump steer was one target. Reducing the amount of shift the axle gets due to the poorly designed pan hard setup was another. And as I noted in my op, with this design, the best you can hope for is a happy medium

It will take a bit of work to redesign the current pan hard under the Gen 8s to get them working as they should.

RC and 1:1s obviously have their 'differences' but properly designed and functioning pan hard setups are not that different. At all.

Try to find someone that will be OK with their pan hard setup moving the axle 6 inches laterally as the suspension compresses.
I'll wait.

There are more ways, and reasons to skin a cat.

[RockCrawlingKid]

So imo the axle shift can only be eliminated if you set the panhard bar parallel to the ground with the truck at ride height so that means body battery and whatever else you run with. The stock link positions are atrocious. Shortening the panhard bar is a terrible idea as it just makes the arc path even shorter and angle more extreme. I have ordered a bunch of parts and I will try and come up with a fix when they arrive. I will post my findings. Parts I’ve ordered

Club 5 aluminum relocation mount
Club5 husky links
SSD front and rear link mounts
Bowhouse rc panhard relocation.
Clamp on aluminum servo horn. It Looks to be of lower profile than the stock one.

I’m really excited about the links and the panhard mount. As it stands the panhard mount on the frame side needs to be dropped and extended. So that’s what the bowhouse rc mount looks like it will do. Honestly once my silver braze flux arrives I’ll get to fabbing my own mount.

I ordered the servo mount purely for the ability to mount the drag link parallel to the tie rod which should help with a lot of terrible geometry coming from the awful stock set up. The drag link must run parallel to the panhard rod and not at a terrible 45° to the tie rod.

Another source of bumpsteer is the distance (measured on the same plane as axle/tie rod) from the panhard mount on the frame to the pivot point of the Servo. That length must equal the distance of the panhard mount on the axle housing to the knuckle/tie rod(knuckle obviously pointing straight forward).

If all these conditions are not met, the panhard bar and drag link will follow two completely different paths when cycled through the full range of motion.

Clear as mud. I also am by no means an expert just my experience. Hopefully I get some good results with the drop in parts. I’ll probably start a separate thread for my rendition of fixes. Side note I’ll probably end up going to a shorter shock as well. I’ll try clipping coils soon enough first.


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[Timmahh]

Originally Posted by RockCrawlingKid

So imo the axle shift can only be eliminated if you set the panhard bar parallel to the ground with the truck at ride height so that means body battery and whatever else you run with. The stock link positions are atrocious. Shortening the panhard bar is a terrible idea as it just makes the arc path even shorter and angle more extreme. I have ordered a bunch of parts and I will try and come up with a fix when they arrive. I will post my findings. Parts I’ve ordered

Club 5 aluminum relocation mount
Club5 husky links
SSD front and rear link mounts
Bowhouse rc panhard relocation.
Clamp on aluminum servo horn. It Looks to be of lower profile than the stock one.

I’m really excited about the links and the panhard mount. As it stands the panhard mount on the frame side needs to be dropped and extended. So that’s what the bowhouse rc mount looks like it will do. Honestly once my silver braze flux arrives I’ll get to fabbing my own mount.

I ordered the servo mount purely for the ability to mount the drag link parallel to the tie rod which should help with a lot of terrible geometry coming from the awful stock set up. The drag link must run parallel to the panhard rod and not at a terrible 45° to the tie rod.

Another source of bumpsteer is the distance (measured on the same plane as axle/tie rod) from the panhard mount on the frame to the pivot point of the Servo. That length must equal the distance of the panhard mount on the axle housing to the knuckle/tie rod(knuckle obviously pointing straight forward).

If all these conditions are not met, the panhard bar and drag link will follow two completely different paths when cycled through the full range of motion.

Clear as mud. I also am by no means an expert just my experience. Hopefully I get some good results with the drop in parts. I’ll probably start a separate thread for my rendition of fixes. Side note I’ll probably end up going to a shorter shock as well. I’ll try clipping coils soon enough first.


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You pretty much detailed the issues I seen as I really took a good look at the current config. more than just a couple simple fixes needed.

Absolutely on the chassis pan hard mount. ITs like they just kind of copied some other stuff that was out, changed enough to say it was their own, but never really dug into the ins and outs of a pan hard setup from a functional and engineering standpoint. lol

The things I detailed are some fixes, and a couple of bandaids, particularly on that pan hard setup.

You are on the right path for real solutions, not more bandaids.

As far as centering the servo, until the rest of it is ordered, this is just money spent that would be better put somewhere else in the front end impo.

[Timmahh]

The stock panhard as setup is too long. as the left side compresses, the axle shits outward. the more compression, the more shift. better than 1/4 inch (about 6 inches in real life. lol). Shortening the rod ends will help reduce the shift and as noted previously, shorten the link ends just a little too much, and the shifting starts to occur at full unsprung height. Thus the happy medium that can be had. Only reason it is a happy medium is without fully redesigning the pan hard setup, its as good as it will get. All your points on the pan hard fixes are on point.

At most, 4 maybe 5mm could be able to be removed from the overall panhard length (4mm will probably work best) just to reduce some of that heavy shift. At 4mm, there is no shift at full unsprung, and the left shift on full compression is reduced a fair but, but still to much for my liking.

I'll head out to the pile tomorrow, need to test out the new and previous lines I had set up anyways, and put it through some paces.
I expect it to preform better than it did before these mods.
Full steering is helpful. especially both ways. lol

[Timmahh]

On a side note that is steering related, I noticed another issue that will need to be fixed. This isn't so much a design issue as it is a not the best plastics issue. The right side link arm on the knuckle is twisted and tweaked a bit. Now that it turns with some force, I think I bent it a bit when I had the wheel pinched up 2 days ago.
I could put on a set of stock portal covers, but the plastic will bend again no doubt under high stress.
May as add some low front end weight and go with brass, so I guess I'll be checking out some brass covers soon. Aluminum would probably work better by adding less stress from the added weight on the plastic housing/chubs. But the added weight of the brass and a solid link mounts on the knuckles would further improve the durability of the steering setup.

[ferp420]

Originally Posted by Timmahh

If you Read the entire post you would see I noted pan hard length has little todowit the bump steer, but it can lend to the issue if it is improperly designed or laid out.Which is is under these RCs. Its not Terrible, but there is a lot of room for improvement.

As I noted. Some people like to imagine they fixed a design issue, but changing something else that has little to do with the design flaws, and they are good with that. For me, I am far to anal. lmao

maybe you have not checked the mess that is under these Gen 8s. lol

You assume way to much and read too little it seems.

I guess I never knew Mechanical Engineering was different between designing different mechanical things. lmao DERP

like i sead its not that hard but you can try to redesign the wheel if you want

[RockCrawlingKid]

Originally Posted by Timmahh

On a side note that is steering related, I noticed another issue that will need to be fixed. This isn't so much a design issue as it is a not the best plastics issue. The right side link arm on the knuckle is twisted and tweaked a bit. Now that it turns with some force, I think I bent it a bit when I had the wheel pinched up 2 days ago.
I could put on a set of stock portal covers, but the plastic will bend again no doubt under high stress.
May as add some low front end weight and go with brass, so I guess I'll be checking out some brass covers soon. Aluminum would probably work better by adding less stress from the added weight on the plastic housing/chubs. But the added weight of the brass and a solid link mounts on the knuckles would further improve the durability of the steering setup.

Yes that’s because of the bad drag link angles. The way it’s set up stock is very inefficient and does not move in the same path as the tie rod. And no doubt will twist the knuckle ear. My run this morning was very challenging for the truck, very steep and large boulders and lots of loose gravel/stones. I bound up steering quite a bit and seen tons of flex coming from panhard mounts on both sides. And then on hill climbs there is a lot of needless steering going on while suspension cycles.


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[Timmahh]

Originally Posted by ferp420

like i sead its not that hard but you can try to redesign the wheel if you want

You may need to take some actual mechanics classes. Maybe some mechanical reasoning classes. Logic classes may help also. SMFH

[ferp420]

Originally Posted by Timmahh

You may need to take some actual mechanics classes. Maybe some mechanical reasoning classes. Logic classes may help also. SMFH

dude your so backwards your headlights are red


you should stick to driving handycabs i here they have vary short panhard bars for a wheel chair

[ferp420]

Originally Posted by Timmahh

.

Try to find someone that will be OK with their pan hard setup moving the axle 6 inches laterally as the suspension compresses.
I'll wait..

whens the last time you jacked up a jeep cheroke or any rig with a 3 link

that front axle moves atleast 6"as it cycles though its suspention traval so i would say almost every jeep owner is ok with the axle shifting side to to side as it moves though its range of suspention traval cause there are alot of heeps out there and people seem to realy like them

[tuxstang]

There is no way to remove the swing of the axle from a Panhard setup, unless you rewrite geometry. And as with most of our trucks, the pivot points are not aligned at ride height, with way larger vertical amplitude than on a 1:1 truck, good luck to minimise it to an unnoticeable level.

[Flamnpede1]

Originally Posted by RockCrawlingKid

So imo the axle shift can only be eliminated if you set the panhard bar parallel to the ground with the truck at ride height so that means body battery and whatever else you run with. The stock link positions are atrocious. Shortening the panhard bar is a terrible idea as it just makes the arc path even shorter and angle more extreme. I have ordered a bunch of parts and I will try and come up with a fix when they arrive. I will post my findings. Parts I’ve ordered

Club 5 aluminum relocation mount
Club5 husky links
SSD front and rear link mounts
Bowhouse rc panhard relocation.
Clamp on aluminum servo horn. It Looks to be of lower profile than the stock one.

I’m really excited about the links and the panhard mount. As it stands the panhard mount on the frame side needs to be dropped and extended. So that’s what the bowhouse rc mount looks like it will do. Honestly once my silver braze flux arrives I’ll get to fabbing my own mount.

I ordered the servo mount purely for the ability to mount the drag link parallel to the tie rod which should help with a lot of terrible geometry coming from the awful stock set up. The drag link must run parallel to the panhard rod and not at a terrible 45° to the tie rod.

Another source of bumpsteer is the distance (measured on the same plane as axle/tie rod) from the panhard mount on the frame to the pivot point of the Servo. That length must equal the distance of the panhard mount on the axle housing to the knuckle/tie rod(knuckle obviously pointing straight forward).

If all these conditions are not met, the panhard bar and drag link will follow two completely different paths when cycled through the full range of motion.

Clear as mud. I also am by no means an expert just my experience. Hopefully I get some good results with the drop in parts. I’ll probably start a separate thread for my rendition of fixes. Side note I’ll probably end up going to a shorter shock as well. I’ll try clipping coils soon enough first.


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I'm sorry to say but the club5 relocation and links are not designed properly. I bought the whole setup and tried many different combinations of above the knuckle below the knuckle etc. and it all ended with me sending the entire setup back because it was so bad. The link that ties the knuckles together sticks so far out I felt is was going to be a hanging point and the way it flops up and down just drove me crazy. I also ordered the suspension links and after the issues with the steering setup I didn't even bother installing them and just sent them back.

Things you did right....SSD Lower link mounts, and the low profile servo horn.

I currently have somewhere around 60 miles on the truck and other then those two items above I really haven't changed much for the steering / suspension geometry. It crawls, it trails and does pretty much everything I could ask for. So for me I'm not going to waste money or time redesigning the suspension because it doesn't match a 1:1 truck exactly or might be a few mm's off during suspension travel. All I can say is it works and people might be overthinking things a bit.

[ferp420]

thats a great video it exsplains the panhard bar set up vary well but what it dosent include in the video is how it relates to the steering
to point out a few things in determining the langth of the panhard bar that they dident go in to the panhard bar mounts upper.and lower are the same distance from the center line of the axle so the mount on the axle is fixed we need a panhard mount thats is the same distance from center as the lower mount thats outside the frame and it needs to drop down aswell so out and down so to make that posable on the gen8 you have to move the panhard bar forward of the shocks that also allows you to brace the back side of lower panhard bar mount off to the upper link mount on top the pumpkin making for a extremely strong lower panhard bar mount add ssd lower link mounts and it bulletproof

theres no way to stop the axle from swinging especialy with a big lift but under normal driving you can make it unoticeable under full flex it dosent matter anyway