Pearl's mod/build LT rear/DK +3.5 LT/Custom Baja Bumper/Thorley Headers/Manual T-case

[Inv4drZm]

That's a bummer, have you thought about the Marlin Crawler kit to see if that would help with some of the bump steer?

I'd be surprised if Marlin Crawler's knuckle geometry fixed the issue.

The kit has you remove the rotor dust shield but that only gains you maybe 1/2" of tie rod length before hitting the rotor.

Moving the mount toward the bumper doesn't extend it that much and changes ackerman.

 

[aemravan]

That's a bummer, have you thought about the Marlin Crawler kit to see if that would help with some of the bump steer?

Correct me if I’m wrong ….but isn’t the marlin kit literally using the lc200 rack..? If so, their added down travel would actual hurt the bump steer numbers.. I’ve heard several folks that were told by marlin that the lc200 won’t work with stock arms “because of excessive bump steer” .. I’m either missing something here, they don’t understand bumpsteer.. or are pushing people to their kit with false advertisement (I really hope not and don’t think so.. but who Knows)

From my very basic understanding of bump steer, the only true way to correct the geometry is to shorten the rack like they do with the tundra rack to get the inner tie rod pivot points more towards the center of the rig. The combination of arms , travel and tie rods only exaggerate the bum steer but are not the cause or solution of it. From the numbers Mason ran, if you’re doing an lc200 rack you’re actually better off with the limited travel stock arms since the most excessive bump steer is at the extreme down travel starting about 40% of full droop and continuing al the way to full droop.


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[aemravan]

I'd be surprised if Marlin Crawler's knuckle geometry fixed the issue.

The kit has you remove the rotor dust shield but that only gains you maybe 1/2" of tie rod length before hitting the rotor.

Moving the mount toward the bumper doesn't extend it that much and changes ackerman.

Should have read all the way through first, now I see where they are making the claim of better bump steer vs stock. I didn’t realize they moved the knuckle geometry some. But I’m with you .. there is only so much room before the rotor.. ask me how I know .. lol. Depending on the size of the heim they are using I’d be hard pressed to think they even gained a half inch.. room to the rotor is highly limited.

Granted my setup is using a 3/4” bolt which I think is overkill.. but this is the stock centerline to rotor..

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[4RunnerAquasport]

Correct me if I’m wrong ….but isn’t the marlin kit literally using the lc200 rack..? If so, their added down travel would actual hurt the bump steer numbers.. I’ve heard several folks that were told by marlin that the lc200 won’t work with stock arms “because of excessive bump steer” .. I’m either missing something here, they don’t understand bumpsteer.. or are pushing people to their kit with false advertisement (I really hope not and don’t think so.. but who Knows)

From my very basic understanding of bump steer, the only true way to correct the geometry is to shorten the rack like they do with the tundra rack to get the inner tie rod pivot points more towards the center of the rig. The combination of arms , travel and tie rods only exaggerate the bum steer but are not the cause or solution of it. From the numbers Mason ran, if you’re doing an lc200 rack you’re actually better off with the limited travel stock arms since the most excessive bump steer is at the extreme down travel starting about 40% of full droop and continuing al the way to full droop.


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One of the subjects discussed in length on the Tacoma World RCLT thread is that the travel numbers aren't quite as good as other high dollar kits. That would alleviate a little bump steer.

I was also think the spindle included with the kit is custom fabbed, isn't it? So maybe the tie rod connection on the spindle is positioned further outboard than oem and closer in line with the arc of the control arms. Which might help w excessive BS.
Edit: He may have found a way to mount the hub further out a small amount to help with rotor clearance.


When Steel City racing broke that heim mount on the spindle at the KOH, I think MC redesigned it a little, and maybe addressing BS was part of that.

 

[Inv4drZm]

One of the subjects discussed in length on the Tacoma World RCLT thread is that the travel numbers aren't quite as good as other high dollar kits. That would alleviate a little bump steer.

I was also think the spindle included with the kit is custom fabbed, isn't it? So maybe the tie rod connection on the spindle is positioned further outboard than oem and closer in line with the arc of the control arms. Which might help w excessive BS.
Edit: He may have found a way to mount the hub further out a small amount to help with rotor clearance.


When Steel City racing broke that heim mount on the spindle at the KOH, I think MC redesigned it a little, and maybe addressing BS was part of that.

I don't see how moving the hub can affect tie rod length. If you placed spacers behind the wheel bearing and bolted it back down it would only make the tie rod effectively shorter. And removing material from the backside of the wheel bearing and bolting it back down would run the rotor into the tie rod mount.

From what I gained looking at pics on that first KOH prototype failure, he had slotted the tie rod mount to adjust ackerman which made it way weaker and snap off during the race. Why he kept what seems to be a prototyping feature on a race truck is unknown to me.

I would pay to see bumpsteer numbers of Marlin's kit vs the competition but it may not matter because most people will just rock crawl with it.

 

[aemravan]

I reamed my knuckles out to accommodate the Tundra OTE taper, which obviously won't work for the 4Runner OTE.

Does anyone know where to source a tapered bushing sleeve like this? I found ball joint bushings and a few others designed for Jeeps or the big 3, tried McMaster and Grainger, but no luck.

Its OD is small end: .70"
Large end: .76".
ID: 62" for a 5/8 bolt
Overall length is: .85"

I need something in this size range, then maybe I can ream it out to match the 4Runner OTE taper.

So I think finding a specific tapered sleeve is going to be pretty darn hard (next to impossible I would say..) but what I would say is...since you have gussets installed it would probably not make financial sense to source used spindles and buy another gusset kit and redo the work... so instead.. would it not make sense to have a shop turn you some custom inserts? Possibly consider straight-drilling the knuckle like I did so that the OD can just be turned down as needed and have the ID machined down to the taper you need? Obviously I don't know what sort of cost you're looking at but just an idea.. Alternatively I think it could be reasonable to just source a used set of spindles and redo the gusset work but you're probably talking $500-ish in parts... surely there's a machine shop that can crank out two little sleeves for less than that..

 

[aemravan]

I don't see how moving the hub can affect tie rod length. If you placed spacers behind the wheel bearing and bolted it back down it would only make the tie rod effectively shorter. And removing material from the backside of the wheel bearing and bolting it back down would run the rotor into the tie rod mount.

From what I gained looking at pics on that first KOH prototype failure, he had slotted the tie rod mount to adjust ackerman which made it way weaker and snap off during the race. Why he kept what seems to be a prototyping feature on a race truck is unknown to me.

I would pay to see bumpsteer numbers of Marlin's kit vs the competition but it may not matter because most people will just rock crawl with it.

I would absolutely love to see the numbers as well.. just to know..

One thing I did notice browsing a few videos/pictures of the kit is that it looks like the steering pickup point on the knuckle appears to be shifted up and forward pretty significantly, or I am crazy? The heim just about clears to the front side of the rotor from what I can tell.

If it does sit significantly higher, this theoretically should aid in when the bump steer start pulling the tire in as it droops out, right? The effective arc-length is the same, sure, but if you moved the knuckle point up, you would potentially give yourself added downtravel before your arc starts transitioning mainly from Vertical travel to horizontal. This also kind of goes back to me looking at my setup that I did with the LC200 and wondering if it was possible to mount the heim from ABOVE instead of from below.. it would get rid of quite a bit of angle, not bind on down travel and I guess possibly make it less prone to bump steer at full droop?

 

[Inv4drZm]

I would absolutely love to see the numbers as well.. just to know..

One thing I did notice browsing a few videos/pictures of the kit is that it looks like the steering pickup point on the knuckle appears to be shifted up and forward pretty significantly, or I am crazy? The heim just about clears to the front side of the rotor from what I can tell.

If it does sit significantly higher, this theoretically should aid in when the bump steer start pulling the tire in as it droops out, right? The effective arc-length is the same, sure, but if you moved the knuckle point up, you would potentially give yourself added downtravel before your arc starts transitioning mainly from Vertical travel to horizontal. This also kind of goes back to me looking at my setup that I did with the LC200 and wondering if it was possible to mount the heim from ABOVE instead of from below.. it would get rid of quite a bit of angle, not bind on down travel and I guess possibly make it less prone to bump steer at full droop?

You really should aim to have the tie rod parallel to the control arms. Moving the outer tie rod up will only make the toe change more at bump instead of droop. I played with the mount up and down in my model and concluded you can't buy much with moving it up, and you just end up with adding some toe in on compression which to me seems worse than toe in at droop.

That said if you are able to raise the steering rack by about as much as you can raise the OTR mount, that will help with bumpsteer. Putting a 1/2" spacer or something like that under the motor and getting the rack spaced up wouldn't make it perfect but would help.

And moving the tie rod forward and backward across the brake rotor will change ackerman which will effect tire scrub and wear through a turn. Not to mention reducing full steering angle. But could potentially help somewhat with reducing bumpsteer.

 

[4RunnerAquasport]

I don't see how moving the hub can affect tie rod length. If you placed spacers behind the wheel bearing and bolted it back down it would only make the tie rod effectively shorter. And removing material from the backside of the wheel bearing and bolting it back down would run the rotor into the tie rod mount.

From what I gained looking at pics on that first KOH prototype failure, he had slotted the tie rod mount to adjust ackerman which made it way weaker and snap off during the race. Why he kept what seems to be a prototyping feature on a race truck is unknown to me.

I would pay to see bumpsteer numbers of Marlin's kit vs the competition but it may not matter because most people will just rock crawl with it.

What I was thinking was if in his custom spindle design, he was able to build out the hub mount, and move the ote mount out a little bit, to match the arc of his control arms, and effectively keeping the same distance between the heim and rotor.
He would have to lengthen the cv axle a little bit, so I dont know. But, yes I would pay to see those BS numbers.

Sherpa doesnt seem have much trouble with BS. They jump that truck a lot. Maybe they found a way to eliminate some of it.

 

[Inv4drZm]

What I was thinking was if in his custom spindle design, he was able to build out the hub mount, and move the ote mount out a little bit, to match the arc of his control arms, and effectively keeping the same distance between the heim and rotor.
He would have to lengthen the cv axle a little bit, so I dont know. But, yes I would pay to see those BS numbers.

Sherpa doesnt seem have much trouble with BS. They jump that truck a lot. Maybe they found a way to eliminate some of it.

The spindle has 4 points (for my visualization); UCA mount, LCA mount, bearing mount, and tie rod mount.

Moving the bearing and tie rod mount outward is effectively the same as moving the UCA and LCA mount inward.

This will shorten the control arms and also increase scrub radius (like adding wheel spacers). And like you said CV axle length wouldn't correspond to arm length, axles would need to be extended +3.25" to fit on +2.75" arms or something like that.

 

[aemravan]

You really should aim to have the tie rod parallel to the control arms. Moving the outer tie rod up will only make the toe change more at bump instead of droop. I played with the mount up and down in my model and concluded you can't buy much with moving it up, and you just end up with adding some toe in on compression which to me seems worse than toe in at droop.

That said if you are able to raise the steering rack by about as much as you can raise the OTR mount, that will help with bumpsteer. Putting a 1/2" spacer or something like that under the motor and getting the rack spaced up wouldn't make it perfect but would help.

And moving the tie rod forward and backward across the brake rotor will change ackerman which will effect tire scrub and wear through a turn. Not to mention reducing full steering angle. But could potentially help somewhat with reducing bumpsteer.

Hate to hijack the thread and have an ongoing discussion on geometry across 3 different threads at this point but yea I certainly see what you're saying.

If I'm understanding the ackerman geometry, it should not be impacted at all by the steering rack/tierod setup, but rather only by the the angle originating from the centerline of the rear axle and being drawn through the balljoints up front, correct? If so, I agree that simply shifting the knuckle mounting point for the outer tie rod closer or further away from its origin would definitely impact the ackerman. But since the front-steering setup would ideally have the pivot for the steering point be forward of the ball joint and towards the centerline of the tire, I imagine that if you were to move this point not only closer to the rotor, but also significantly forward, you would be able to retain close-to-good ackerman?


with regards to toe in/out at droop vs bump, I tend to agree here 100%. Whether you are crawling or high-speed desert running, it certainly seems to reason that you would want the worst case scenario to happen under the least amount of possible loading on your tire. For the angles, interestingly enough.. if you look at my current setup with the lc200 rack, my tie rods seems to be more or less parallel to the lower control arm, but at an offset angle to the CV joint shaft. For the RCLT, their tie rod also seems to be dead inline with the lower arm, but also just about parallel to the CV shaft. I'm certain a lot of this has to do with the high-clearance shape of the lower arm, but just something that jumped out at me that makes it look like there definitely was some thought and experimenting that went into their kit.

From my guestimate of how much the pivot point would need to move up I would say its within .5-.75" from where it sits now. This is purely visual feel as my rig sits now. I feel like that would put me in a sweet spot on the arc length of the tie rod for bump steer both at full droop and full bump.

But the deeper I get into the rabbit hole of suspension geometry the more I realize I don't know and understand it :lookout: lol.

 

[Inv4drZm]

Hate to hijack the thread and have an ongoing discussion on geometry across 3 different threads at this point but yea I certainly see what you're saying.

If I'm understanding the ackerman geometry, it should not be impacted at all by the steering rack/tierod setup, but rather only by the the angle originating from the centerline of the rear axle and being drawn through the balljoints up front, correct? If so, I agree that simply shifting the knuckle mounting point for the outer tie rod closer or further away from its origin would definitely impact the ackerman. But since the front-steering setup would ideally have the pivot for the steering point be forward of the ball joint and towards the centerline of the tire, I imagine that if you were to move this point not only closer to the rotor, but also significantly forward, you would be able to retain close-to-good ackerman?


with regards to toe in/out at droop vs bump, I tend to agree here 100%. Whether you are crawling or high-speed desert running, it certainly seems to reason that you would want the worst case scenario to happen under the least amount of possible loading on your tire. For the angles, interestingly enough.. if you look at my current setup with the lc200 rack, my tie rods seems to be more or less parallel to the lower control arm, but at an offset angle to the CV joint shaft. For the RCLT, their tie rod also seems to be dead inline with the lower arm, but also just about parallel to the CV shaft. I'm certain a lot of this has to do with the high-clearance shape of the lower arm, but just something that jumped out at me that makes it look like there definitely was some thought and experimenting that went into their kit.

From my guestimate of how much the pivot point would need to move up I would say its within .5-.75" from where it sits now. This is purely visual feel as my rig sits now. I feel like that would put me in a sweet spot on the arc length of the tie rod for bump steer both at full droop and full bump.

But the deeper I get into the rabbit hole of suspension geometry the more I realize I don't know and understand it :lookout: lol.

Its been months since I've looked at this stuff but I have a few pages of notes. I haven't quite looked into ackerman yet, was just focusing on bumpsteer with my model. But I think extending the width of the rack and effectively shortening the tie rod does create reverse-ackerman which could explain why my brother's tires chirped on pavement easier and created an unusual slow speed handling.

Ultimately I pretty much decided moving any part of the knuckle away from stock might help bumpsteer, but not eliminate it, at the sacrifice of one thing or another which probably isn't worth it. The shortened Tundra rack seems to fix all the issues and I think the closer to factory geometry the better.

 

[aemravan]

Yea I feel you on that.. I guess all in all it's not ALL that much more expensive.. my lc200 rack swap ended up running me $1100 with having to make the custom tie rods and double-shear plates.. so in the grand scheme of things I guess you're really only looking at roughly $1000 difference between the 2 setups?

 

[Inv4drZm]

Yea I feel you on that.. I guess all in all it's not ALL that much more expensive.. my lc200 rack swap ended up running me $1100 with having to make the custom tie rods and double-shear plates.. so in the grand scheme of things I guess you're really only looking at roughly $1000 difference between the 2 setups?

LC200 Rack using LC200 ITRE: $425

Modified Tundra Rack: $1000
Camburg Heim ITRE: $200
or use your stock inner tie rod but it might be a bit weak not sure.

I was just going off the base racks are about $600 difference but I guess depending on what else you want for tie rods could change the price.

 

[4RunnerAquasport]

surely there's a machine shop that can crank out two little sleeves for less than that..

Since the spindles are reamed to Tundra specs and the inner thread is the same as a the 200, I went with some Tundra specific OTEs w heims.

They helped w the BS, but not enough.
The sleeves pictured above are made in house by the company that makes the OTEs. So you"re right, finding the right size will be almost inpossible. I finally got in touch w them, and said they'd send me two more, but I have no confirmation email from them so I maybe finding a machine shop to turn those out.

I've already reamed the pictured sleeves out to fit our OEM OTEs, so when I get home next week the old rack will get put back in and this ****ing 4 month fiasco will be over, at least for now.

I bought an 07' Tundra rack (under 100k miles) for $170 before I left, so at some point I'm gonna pull both racks apart, do some measuring and maybe see exactly what the limitations are for cutting down the 200.

I spoke to Travis from Taco World, he and his Dad will still do the machine work on the the parts. So that might be an option later on as well. Which saves some money by doing the disassembly/assembly yourself.

I also thought about a one piece CNC ram for the 200, which would be quite spendy. But it would be a solid unit and have machined gears, not stamped.

All I know is I've been studying this damn brain teaser for awhile, trying find a solution. So in learning from my major mistake, I'm conceding the failure for now and putting this truck back together.

 

[aemravan]

LC200 Rack using LC200 ITRE: $425

Modified Tundra Rack: $1000
Camburg Heim ITRE: $200
or use your stock inner tie rod but it might be a bit weak not sure.

I was just going off the base racks are about $600 difference but I guess depending on what else you want for tie rods could change the price.

You’re probably, considering you more than likely still have to do motor mounts, steering shaft , spacer plates, get hardware, etc the difference becomes just the rack.

Is the modified tundra rack really $1000 total?? I guess if the can be found used under 200 bucks and you’re pulling it apart yourself it should be more than doable for $1000.. hell if that’s the case I don’t want to know ! Lol. I spent $150 just on the outer tie rods fabrication.

Maybe I rushed it a bit and could have saved up a bit , sourced a tundra rack and had it machined to have a closely matched to stock geometry. Oh well, that train has certainly left the station haha.

Just out of curiosity though .. is mourning the tundra rack anything remotely similar to the lc200 ? Just thinking way down the road if this thing isn’t working out for me off-road.


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[aemravan]

Since the spindles are reamed to Tundra specs and the inner thread is the same as a the 200, I went with some Tundra specific OTEs w heims.

They helped w the BS, but not enough.
The sleeves pictured above are made in house by the company that makes the OTEs. So you"re right, finding the right size will be almost inpossible. I finally got in touch w them, and said they'd send me two more, but I have no confirmation email from them so I maybe finding a machine shop to turn those out.

I've already reamed the pictured sleeves out to fit our OEM OTEs, so when I get home next week the old rack will get put back in and this ****ing 4 month fiasco will be over, at least for now.

I bought an 07' Tundra rack (under 100k miles) for $170 before I left, so at some point I'm gonna pull both racks apart, do some measuring and maybe see exactly what the limitations are for cutting down the 200.

I spoke to Travis from Taco World, he and his Dad will still do the machine work on the the parts. So that might be an option later on as well. Which saves some money by doing the disassembly/assembly yourself.

I also thought about a one piece CNC ram for the 200, which would be quite spendy. But it would be a solid unit and have machined gears, not stamped.

All I know is I've been studying this damn brain teaser for awhile, trying find a solution. So in learning from my major mistake, I'm conceding the failure for now and putting this truck back together.

If you already have the tundra rack and can pull it apart yourself to send off for machining that may be the way to go.. I was thinking they are significantly more money to get into. A rebuild kit for the rack isn’t bad at all and certainly warrants saving on a used one.


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[y=mx+b]

I would pay to see bumpsteer numbers of Marlin's kit vs the competition but it may not matter because most people will just rock crawl with it.

I'm willing to bet you've already done more suspension simulation than Marlin Crawler has done for the RCLT lol. They're so vague about that stuff that they've either looked into and its poopoo, or they have no idea.

I think they're making a cool product, which is the right direction towards making strong IFS options for our rigs. BUT, every time BigMike talks to the customer base, I cringe at how he stands on his high podium to talk down to the peon question askers.

 

[4RunnerAquasport]

You’re probably, considering you more than likely still have to do motor mounts, steering shaft , spacer plates, get hardware, etc the difference becomes just the rack.

Is the modified tundra rack really $1000 total?? I guess if the can be found used under 200 bucks and you’re pulling it apart yourself it should be more than doable for $1000.. hell if that’s the case I don’t want to know ! Lol. I spent $150 just on the outer tie rods fabrication.

Maybe I rushed it a bit and could have saved up a bit , sourced a tundra rack and had it machined to have a closely matched to stock geometry. Oh well, that train has certainly left the station haha.

Just out of curiosity though .. is mourning the tundra rack anything remotely similar to the lc200 ? Just thinking way down the road if this thing isn’t working out for me off-road.


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I think he's charging more now for the T-rack mod, plus we would be paying for shipping coast to coast. Solo or JD, can't remember which one, gets $1600+ for theirs. This price point is what got me into this mess. McGeorge Toyota was $425 w free shipping on the 200 back in December. So without doing enough research I got bit lol.

Now my failure has me determined to figure this out one day,

Everything I've read about Travis' mod has him tapping the rack @ 14mm for the ITE, which I believe ours is 22mm from the factory. For 37 to 40" tires, 14 mm seems like a weak point to me. But, I don't have the knowledge to back that up.

Camburg has an option in a drop down tab for our 03' - 09' on the inner clevis, if that's the case, can a modded rack be tapped to that 22mm spec safely? And would it clear the outer housing at full lock? If it's the same outer diameter as a Taco inner clevis with just a larger bolt, then it might work.

 

[4RunnerAquasport]

Just out of curiosity though .. is mourning the tundra rack anything remotely similar to the lc200 ? Just thinking way down the road if this thing isn’t working out for me off-road.


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To me it looks like on his 4th gen, Wishbone Runner on Taco World mounted his forward like the MC 200 rack. He initially was going to use a 200, but ended up going w a Tundra.

Travis' pics looks like he mounts the Tundra closer to the OEM Tacoma location.

Does the V8 oil pan restrict this mounting point?

And does moving the rack forward create a difference in Ackerman angle?