Just swapping in coil overs...

[MTKID]

...or the next most simple way to accomplish this.

I know this is a polarizing topic but there are so many knowledgable people on this board that I would like to pick their brains.

A couple reasons this isn't easy is this affects a critical area of the suspension that cannot fail for the safety of the occupants just because someone found something that seems to fit but is not truly engineered to work properly. I understand. No one here holds other people responsible for their ideas for a solution, if they are not selling such a solution. We all must use our own brains to determine if a solution is right for us or not.

Also, many here make a living designing or selling existing tested kits that are engineered from the beginning to work perfectly. I don't intend to offend anyone by proposing that a coil-over could possibly be installed and still function safely with improved performance. Albeit not ultimate performance, but an improvement on a torsion bar.

Get to the point already!

Q 1. Can a coil-over just be swapped in? Many people say the shock attachment points cannot withstand the forces of supporting the vehicle. Others have said they are perfectly sufficient, although this determination seems to be made merely by comparison of other vehicles shock towers. I believe only one fabricator in Russia actually has tried this and I recall it failed. If anyone can link that experience to this post it would be great! Where did it fail? Why did it fail? Were they driving like they were in the baja 1000, possibly jumping the truck?

Q 2. If a coil-over can't be simply bolted up, then where is the likely failure point? Top shock support, bottom shock support, or are both equally too puny? What can be done to reinforce the locations that someone thinks will fail?

Q 3. If the attachment points could be reinforced sufficiently, what coil-over would work best for a starting point? Not ultimate performance here, just improvement over torsion bar and good reliability matching the rest of our great rigs.

I don't mind negative responses, as long as it comes along with some explanation. If you think some thinking is flawed, please explain why. Something productive too would be great, but if you need to get your anger monkeys out, go ahead.

I hope this thread creates ideas that someone, possibly myself, feels comfortable trying and we see the 100 series continue to improve.

Micah

 

[Somebodyelse5]

First pass responses, I’ll probably add more later if I find some time to put pen to paper:

Q1. Coil over cannot be swapped in, strength aside, the top shock mount is pretty narrow where the body of the shock sits, the coilover just won’t fit in the factory upper mount. Size is the first constraint.
Strength we can calc, I can give it a go, might be able to get something reasonable with @CruiseLanderAZ’s help to determine of the lower mount is strong enough. Issue here is that our assumptions may not match toyota engineer’s...without that, tough to say for sure, but some conservative numbers can be had

Q2. To fix the size constraint, you’d need to chop the upper shock mount and fab a new one. Nothing particularly radical here, but it will require welding to the frame, typically outside the realm of a homegamer. If the lower mount needs strengthening, it’s possible to add doublers to beef it up. Again, needing to weld, cut, and bend metal.

Keep in mind that welding brings with it a lot of possible issues that we just can’t know...heat affected zones impacting the base material, we don’t know much about the materials in the lower arms. Would it be fine? Probably. Will it last as long as an OEM arm, used as normal? Doubtful.

 

[MTKID]

First pass responses, I’ll probably add more later if I find some time to put pen to paper:

Q1. Coil over cannot be swapped in, strength aside, the top shock mount is pretty narrow where the body of the shock sits, the coilover just won’t fit in the factory upper mount. Size is the first constraint.
Strength we can calc, I can give it a go, might be able to get something reasonable with @CruiseLanderAZ’s help to determine of the lower mount is strong enough. Issue here is that our assumptions may not match toyota engineer’s...without that, tough to say for sure, but some conservative numbers can be had

Q2. To fix the size constraint, you’d need to chop the upper shock mount and fab a new one. Nothing particularly radical here, but it will require welding to the frame, typically outside the realm of a homegamer. If the lower mount needs strengthening, it’s possible to add doublers to beef it up. Again, needing to weld, cut, and bend metal.

Keep in mind that welding brings with it a lot of possible issues that we just can’t know...heat affected zones impacting the base material, we don’t know much about the materials in the lower arms. Would it be fine? Probably. Will it last as long as an OEM arm, used as normal? Doubtful.

That is a wonderful start and much more than I was expecting!

I'm impressed if you can come up with some real numbers for the strength of the parts in question, even if only estimates.

There are adapters to convert from shock mount to coil-over top mount but I realize this may reduce the overall available length too much. Do you agree?

We have a number of qualified fabricators in my area that I trust to accomplish almost anything we can dream up. If I can afford such a solution is another question but it doesn't hurt to ask. So far, they have been very reasonable and wonderful to work with.

What is a "doubler"?

 

[abuck99]

There’s an active thread on the topic.

100 Series Coil Over Conversion Kit

 

[MTKID]

There’s an active thread on the topic.

100 Series Coil Over Conversion Kit

...well, I felt that was KOR’s thread and I didn’t want to hi-jack it with a thread trying to to find a different solution than their offering. You may also notice I commented on that thread mentioning I’d start this new thread.

There have been a few threads on the topic over the years but I was just trying to push the topic again...

 

[Somebodyelse5]

That is a wonderful start and much more than I was expecting!

I'm impressed if you can come up with some real numbers for the strength of the parts in question, even if only estimates.

There are adapters to convert from shock mount to coil-over top mount but I realize this may reduce the overall available length too much. Do you agree?

We have a number of qualified fabricators in my area that I trust to accomplish almost anything we can dream up. If I can afford such a solution is another question but it doesn't hurt to ask. So far, they have been very reasonable and wonderful to work with.

What is a "doubler"?

I have a final exam tomorrow, so I should be working on that... but after I get that knocked out I will tackle this. My thought would be to determine what loading the factory lugs on the lower control arm shock mount can handle, and then see what loading the coilover would likely apply. Get an approximation for damping force from the factory shock, and see how they compare. That'd at least be a decent starting point, the idea of "equivalent strength" is generally how most aftermarket products are designed... "is it as strong or stronger, than the original?"

Take a look at what the top shock mount looks like (ignore my nasty UBJ), the way the mount hugs the shock, there is no space for a coil to fit. and definitely no space for one of those adapters to fit.

A doubler is an added piece of material, patched onto a structure, to increase the strength locally by spreading the load over a larger area. You can do doublers, tripplers, quadruplers (all still generally just called doublers) to increase strength while gradually increasing stiffness (a jump in stiffness is a stress concentrator). They are really common on aircraft fuselage. My thought would be, weld some plate around the lugs on the LCA shock mount, maybe also on the lugs themselves.

Here's an example of a doubler

and some more reading if you are curious:
Doubler Plates of Ship Structures
Example of doublers repairing cracks on 737 fuselage
737-300 R1 Door hinge crack repairs. : aviation

 

[MTKID]

I agree, there isn’t enough room in the upper shock support to fit a coil. Therefore a new upper shock mount is needed. Is there any reason not to raise its upper position higher? Also, could it be tipped in a little more (toward the center line of the vehicle) to prevent interference with the UCA. Obviously this would need to be tested to make sure it doesn’t then hit anything on the other side but it seems like a way to alleviate one previous issue.

Also, has anyone ever tested if the upper range of travel could be increased a little without binding of the CV? I don’t have any extra clearance with my tires but those running smaller tires may be able to increase a little up travel if this can be done safely. I believe the previous issue would have been damage to the shock which would be eliminated with proper use of a higher upper mount.

 

[Somebodyelse5]

View attachment 1674066

But in all seriousness, I am not sure that the 100 could accept any more up travel without extending axles... look at where the bump stop is, they'd need to do some creative stuff to get around the engine cradle (idk, wtf do you call that bit inboard of the bump?)

I agree, there isn’t enough room in the upper shock support to fit a coil. Therefore a new upper shock mount is needed. Is there any reason not to raise its upper position higher? Also, could it be tipped in a little more (toward the center line of the vehicle) to prevent interference with the UCA. Obviously this would need to be tested to make sure it doesn’t then hit anything on the other side but it seems like a way to alleviate one previous issue.

Also, has anyone ever tested if the upper range of travel could be increased a little without binding of the CV? I don’t have any extra clearance with my tires but those running smaller tires may be able to increase a little up travel if this can be done safely. I believe the previous issue would have been damage to the shock which would be eliminated with proper use of a higher upper mount.

Up travel is not limited by shock, it's limited based on the engine support structure (idk what you call that structure, see pic)

 

[CruiseLanderAZ]

Might ORI struts be easier than trying to accommodate a 2.5" coilover

 

[Newps]

Here you go...it's been done before.....

 

[MTKID]

Here is my initial findings for ORI STX, which in general do sound ideal for this application, although their shortest length is a little longer than we are used to running in a shock...

STX08 8" Travel 15.825" Mounting distance compressed 23.2" Mounting distance extended
1/2" or 5/8" mounting bolt diameter.

Maybe this could be accommodated somehow with new upper mounts. Travel would certainly be beyond what anyone has successfully tried, I think. Would this create approximately 3" more travel range than stock? I know, I know, the need to address the CV's limitations then.

 

[MTKID]

Here you go...it's been done before.....

Sweet! Thank you for sharing that. That is the one that ended up failing, correct? That's what I remember about it, but it's been so long ago, and I didn't think there was very much information available.

 

[CruiseLanderAZ]

Here is my initial findings for their STX, which in general do sound ideal for this application, although their shortest length is a little longer than we are used to running in a shock...

STX08 8" Travel 15.825" Mounting distance compressed 23.2" Mounting distance extended
1/2" or 5/8" mounting bolt diameter.

Maybe this could be accommodated somehow with new upper mounts. Travel would certainly be beyond what anyone has successfully tried, I think. Would this create approximately 3" more travel range than stock? I know, I know, the need to address the CV's limitations then.

Yea I'd imagine you'd need to do limit straps unless you could do custom lengths. Don't need to use all the uptravel either if you tune them right and add air bumps.

 

[MTKID]

It'd be sweet if you could run them upside down to create more UCA clearance but I don't think that is an option since mounting instructions say no more than 45 degrees from vertical.

 

[CruiseLanderAZ]

It'd be sweet if you could run them upside down to create more UCA clearance but I don't think that is an option since mounting instructions say no more than 45 degrees from vertical.

Just drive upside down. It is a Land Cruiser after all

 

[Somebodyelse5]

I just can't resist...

 

[bwell]

I have been thinking about this since before KOR's kit was first learned of.

I like where you guys are going with this.

KOR's kit just uses an adapter at the top of the coilover mount to gain that bit of required space.

I had been looking at a brand of shocks called FOA Shocks, they're smaller, made to order. They have a 2" diameter 6" travel coilover that extended and collapsed measurements are actually perfect for the geometry of the front suspension's range of motion that matches most of our aftermarket shock lengths. It even has the option to go with dual rate hardware.

As @Somebodyelse5 mentioned my concern was primarily with the LCA mount. I was to the point of, well I could always just get some new lower control arms and reinforce them if needed should the current ones fail or bend or anything worse.

I actually emailed KOR shortly after he released his kit and was about to purchase some of his adapters for the upper mount, and he was fine with selling them standalone at the time.

That's when I found the foa shocks.

F-O-A 2.0 Inch ID Coil Over Shock w/ Reservoir, 6 Inch Travel - F-O-A | First Over All Off Road Shocks

I actually had money set aside for this twice last year, but life happens and I was never able to go through with it yet.

Ever since I bought my 100 I loathed for the smoothness of a properly valved coilover setup.

 

[MTKID]

Doing more research, I found the Tacoma group has been using the ORI 8” but only about 5.5”of its travel, so that recommendation is tested. Also, limit straps were recommended by someone associated with ORI posting on the Pirate forum a while back. Not sure if he was a dealer or employee of ORI.

I would prefer to run something that didn’t require a limit strap personally.

ORI-Struts Experience

I like the idea of being able to adjust the majority of settings with pressure rather than replacing springs. They aren’t cheap but quality never is.

And if a design could eventually lead to use of the full 8” I’d be ecstatic. Not sure if that would be called long travel or mid-travel, but both sound great to me.

 

[MTKID]

I have been thinking about this since before KOR's kit was first learned of.

I like where you guys are going with this.

KOR's kit just uses an adapter at the top of the coilover mount to gain that bit of required space.

I had been looking at a brand of shocks called FOA Shocks, they're smaller, made to order. They have a 2" diameter 6" travel coilover that extended and collapsed measurements are actually perfect for the geometry of the front suspension's range of motion that matches most of our aftermarket shock lengths. It even has the option to go with dual rate hardware.

As @Somebodyelse5 mentioned my concern was primarily with the LCA mount. I was to the point of, well I could always just get some new lower control arms and reinforce them if needed should the current ones fail or bend or anything worse.

I actually emailed KOR shortly after he released his kit and was about to purchase some of his adapters for the upper mount, and he was fine with selling them standalone at the time.

That's when I found the foa shocks.

F-O-A 2.0 Inch ID Coil Over Shock w/ Reservoir, 6 Inch Travel - F-O-A | First Over All Off Road Shocks

I actually had money set aside for this twice last year, but life happens and I was never able to go through with it yet.

Ever since I bought my 100 I loathed for the smoothness of a properly valved coilover setup.

I saw those briefly when I was searching today too. They seem like a good starting price but I think they would be add up quickly when you are done. I’m sure we could get close to the correct spring rates to start but it looked like you selected damping rates ahead of time. Lots of options, lots of variables to mess up but if you got it right I bet they would work well.

Glad you are stoked to try this also. Someone will have success with this effort in the U.S. and hopefully share.

 

[bwell]

I saw those briefly when I was searching today too. They seem like a good starting price but I think they would be add up quickly when you are done. I’m sure we could get close to the correct spring rates to start but it looked like you selected damping rates ahead of time. Lots of options, lots of variables to mess up but if you got it right I bet they would work well.

Glad you are stoked to try this also. Someone will have success with this effort in the U.S. and hopefully share.

You are correct, when I almost placed my order last year I emailed him with vehicle description and he responded with what valving I should request when I placed my order along with spring length and rate.

ORI's are definitely another good option and as long as you have access to a shop that will let you use their nitrogen machine the setup with them is infinite. There were two members that used ORI's on their straight axle conversions on here at one point.

Ultimately I think, it's just a matter of someone taking the plunge.