Long Travel AHC (1 Viewer)

[MTKID]

I feel like that is especially important with IFS. I don’t know the dynamics necessarily, but it feels like the solid rear axle can still flex moderately well with stiffer coils like we ran on 80’s, 100’s (rear axle) and this 200 rear axle, but you stick a stiffer coil within IFS and it seems to have a much bigger effect decreasing articulation.

Possibly a separate discussion/benefit from ride harshness issues.

 

[nwfl4runner]

Thinking out loud as @grinchy brought up a topic I've been noodling on for awhile.

Sensor Lift and Harsh Ride​

AHC is supported by two elements: 1) coil spring that is linear rate 2) hydraulic accumulator that is progressive rate. Combined would be overall progressive rate. The reason that some AHC sensor lifts ride harsh is due a few possibilities.

1. Too much load on the hydraulic accumulator pushing the accumulator into a very high rate region (i.e. too much spring rate).
2. Too much load potentially into bottoming out of the accumulator if worn.
3. Too little droop travel and articulation

Counterintuitive, but because of #1, adding pre-load to the linear spring may help actually soften the overall AHC spring rate improving ride.

Long Travel wants Lower Spring Rates​

Adding pre-load to the stock AHC springs, front or rear, is potentially a better solution than increasing spring rate with aftermarket springs to address load. The premise is long travel suspensions work better with lower rates springs to maximize articulation. The focus on spring rates is often to support a load. I think it's intuitively understood that higher spring rates can limit compression. But it's just as important to consider rates and how they effect droop travel. A higher spring rate coil spring gets unloaded far quicker in droop travel which may also limit articulation in that direction.

As an example, assuming stock 105 lb/in rear springs. Let's assume at neutral ride height, a coil is supporting 600lbs. By definition, that would be compressed a bit more than 6". For every 1" travel in droop, the spring will push back with 105 lbs less by definition.. So say 3" droop, and now the spring pushes down with 285lbs at that extended position.

Doing the same math for a higher rate linear spring, let's say something at 150 lbs/in. At neutral ride height, supporting 600lbs. After 3" droop travel * 150 lbs/in, it's only pushing down with 150lbs of force at that extended position.

Trying to convince long travel peeps to stay with soft coils! If there are load concerns, use pre-load rather than higher rate springs.

Building on this, folks should focus on articulation if we’re talking about long travel. Adding a 1/2” of droop but limiting (either bump stop or spring rate) up travel isn’t the solution for long travel. I think the issue we’ll have with AHC up front is the need for a truly longer shock shaft/cylinder and a longer coil to match to avoid coil bind.

The OEM spacer, no sensor lift, removed swaybar, and running in normal will probably give you more useable travel than anything right now unless folks start going full crazy. Here’s 18.5” of travel to keep everyone motivated!

 

[Spinedoc44]

@Killacaviar Do you have a picture or description on how you mounted your rear shock higher on the axle? I know the factory mount is a bolt sleeved inside a tube and I would like to replicate that than rely on only a bolt for the rear lower shock mount.

Also, do mind linking the front Tundra spacer you used?

 

[grinchy]

Two spring rubber observations:
1) had more impact on the front than on the rear. The blue ones in back make only a minor difference.. this matches to the observation above that the rear spring rate is not as critical as the front.
2) took more stiffness/ harder rubber in the front than I thought would be to firm it up satisfactorily.

I am in full agreement with the observation that ahc needs more spring rate to keep the ride compliant when adding weight. My theory is the ahc has a set amount of mass it can manage - call it 3000 lb,(made up number) and the springs do the 3000 left. So if you add a 1000 lb of mods, you need to up the springs to carrry 4000 lb so ahc can carry/control the same 3000 lb. And bias that spring support much more to the front than the back of you hve any front weight.

Final observation is that a rear bumper, bunch of skid plates, heavy sliders, drawer, rear mount tire etc didn’t really ‘break’ the ride. It was always pretty good, maybe a tiny bit wallowy or pitchy in hindsight, but no passenger would have noticed. Added 170lb of winch and bumper and the attitude control was lost. Very pitchy type of ride. Far too soft feeing.
I actually thought going in the front bumper and winch would ‘balance’ the weight out back and improve the situation.

 

[Killacaviar]

@Killacaviar Do you have a picture or description on how you mounted your rear shock higher on the axle? I know the factory mount is a bolt sleeved inside a tube and I would like to replicate that than rely on only a bolt for the rear lower shock mount.

Also, do mind linking the front Tundra spacer you used?

I'll have the truck in the garage tomorrow for a front spacer swap and more cutting. I'll snap some photos for you.

 

[Spinedoc44]

I'll have the truck in the garage tomorrow for a front spacer swap and more cutting. I'll snap some photos for you.

Awesome man, thanks.

 

[Spinedoc44]

I’m just being a nuisance at this point but would this spacer work for the front?

Front Leveling Kit | 1.5" Lift | for 07-21 Toyota Tundra | Coil Block Aluminum | eBay

[ FITMENT ] <br> <br>Compatible with 2007-2021 Toyota Tundra (Will not fit Rock Warrior Edition). <br> <br>Compatible with 2007-2021 Toyota Sequoia (Will not fit models with electronic struts). <br> <br> <br> <br>[ INSTALL NOTE ] <br> <br>You will need to modify/trim your strut's studs and nuts...

www.ebay.com

 

[CanadianRockyCruiser]

Damn it @MTKID! You had to beat me didnt you…
Just waiting for my set of trailing arms to arrive.

Ill end up at 27.5 front shock toppers (using my rubber tema 20mm spacer as a cushion against westcott 7.5, 30mm coil lift in rear, yes @TeCKis300 im looking for extended sway links in front, and drop in rear end link bracket.

Sway links on that forum thread - jomax or bds, still looking for adjustable ones with oem fittings. You know i cant handle noise…

If anyone has a better opyion for front links, do share please.

Also, i need to extend my rear shocks the same roughly.5”, but im not chopping them up like teck did. Is there any fitting we can adapt to the frame rail mount?

I know that space is tight, and the rear lower axle mount im not sure if it should be messed with by welding etc since getting the angles right would be a pain.

I'm loving this thread so far...

A bit late to the game, but I thought I'd bring up the Japan 4x4 spacers that were used on the rear of the 100 series. It will net 2.2" on the rear axle, allowing you to increase (max out) the lift on the rear AHC sensors. Not sure it qualifies as "long travel", but it will save you from having to weld a plate and drill.
It's -20C out today, so I haven't measured the LX 200 series lower shock mount diameter... is it 19mm? If so these should fit by rotating the AHC ram 90 degrees.
Keep in mind that these particular extensions were designed for the lighter 100 series, but a similar beefy setup might make the rear a 1 banana job.

 

[MTKID]

I’m just being a nuisance at this point but would this spacer work for the front?

Front Leveling Kit | 1.5" Lift | for 07-21 Toyota Tundra | Coil Block Aluminum | eBay

[ FITMENT ] <br> <br>Compatible with 2007-2021 Toyota Tundra (Will not fit Rock Warrior Edition). <br> <br>Compatible with 2007-2021 Toyota Sequoia (Will not fit models with electronic struts). <br> <br> <br> <br>[ INSTALL NOTE ] <br> <br>You will need to modify/trim your strut's studs and nuts...

www.ebay.com

While it may be possible to install that on a LC, I think the AHC hose that goes into the top of the shock at a 90 degree angle on an LX would then interfere with the shock bucket. I think the beginning of this thread has the maximum recommended size of spacer and it requires a little grinding for the AHC hose still.

And if someone installed this on a LC, then the CV angles that people are concerned about might likely come into play at full droop.

Plus you’d still need to address your bumpstops around the same amount.

Essentially, this isn’t the best solution for real off-road use.

Edit: above response based on assumption that the spacer was 1.5”, which it is not. It’s only 24mm netting 1.5” lift on a Tundra, so this isn’t actually beyond what at least one person has used successfully with RCV axles, and one person without?

 

[TeCKis300]

I'm loving this thread so far...

A bit late to the game, but I thought I'd bring up the Japan 4x4 spacers that were used on the rear of the 100 series. It will net 2.2" on the rear axle, allowing you to increase (max out) the lift on the rear AHC sensors. Not sure it qualifies as "long travel", but it will save you from having to weld a plate and drill.
It's -20C out today, so I haven't measured the LX 200 series lower shock mount diameter... is it 19mm? If so these should fit by rotating the AHC ram 90 degrees.
Keep in mind that these particular extensions were designed for the lighter 100 series, but a similar beefy setup might make the rear a 1 banana job.

View attachment 3187193

View attachment 3187194

Can confirm the LX570 shock uses a 19mm bolt hole as well. x 45mm long.

I was looking hard into these as I was aware of their use on the 100-series. Wasn't sure about the 2.2" extension which is why I choose to fab 1" of extension. Looks like others are able to make 2.2" work, by also shimming down the stops.

 

[1UZJ80N60]

I’m just being a nuisance at this point but would this spacer work for the front?

Front Leveling Kit | 1.5" Lift | for 07-21 Toyota Tundra | Coil Block Aluminum | eBay

[ FITMENT ] <br> <br>Compatible with 2007-2021 Toyota Tundra (Will not fit Rock Warrior Edition). <br> <br>Compatible with 2007-2021 Toyota Sequoia (Will not fit models with electronic struts). <br> <br> <br> <br>[ INSTALL NOTE ] <br> <br>You will need to modify/trim your strut's studs and nuts...

www.ebay.com

1.25 is the max you can do on the LX... and even at that cv angle is a major problem at full droop... Ii broke the factory joint and since have upgraded to RCV'S

 

[1UZJ80N60]

Building on this, folks should focus on articulation if we’re talking about long travel. Adding a 1/2” of droop but limiting (either bump stop or spring rate) up travel isn’t the solution for long travel. I think the issue we’ll have with AHC up front is the need for a truly longer shock shaft/cylinder and a longer coil to match to avoid coil bind.

The OEM spacer, no sensor lift, removed swaybar, and running in normal will probably give you more useable travel than anything right now unless folks start going full crazy. Here’s 18.5” of travel to keep everyone motivated!

View attachment 3187113

1.25 spacer achieves major droop... but had come at the cost of a broken axle on the 1st trip woth it installed.... I'm now running rcv's woth 2 rock crawling trips and zero issues

 

[Spinedoc44]

While it may be possible to install that on a LC, I think the AHC hose that goes into the top of the shock at a 90 degree angle on an LX would then interfere with the shock bucket. I think the beginning of this thread has the maximum recommended size of spacer and it requires a little grinding for the AHC hose still.

And if someone installed this on a LC, then the CV angles that people are concerned about might likely come into play at full droop.

Plus you’d still need to address your bumpstops around the same amount.

Essentially, this isn’t the best solution for real off-road use.

See that’s where I’m confused. @Killacaviar said on page 3 he used a tundra spacer of 30 mm (which the one I linked is obviously more than that). I’m just curious what he used to not have to disassemble the coil over.

 

[Killacaviar]

I’m just being a nuisance at this point but would this spacer work for the front?

Front Leveling Kit | 1.5" Lift | for 07-21 Toyota Tundra | Coil Block Aluminum | eBay

[ FITMENT ] <br> <br>Compatible with 2007-2021 Toyota Tundra (Will not fit Rock Warrior Edition). <br> <br>Compatible with 2007-2021 Toyota Sequoia (Will not fit models with electronic struts). <br> <br> <br> <br>[ INSTALL NOTE ] <br> <br>You will need to modify/trim your strut's studs and nuts...

www.ebay.com

This is the exact one I have siting in my garage. It’s 24mm total. I have a 30mm on now and was able to modify the ahc line to slide into the bucket. No problem there if your will to make the changes.

As for too much droop with that spacer, stock arms and a sway bar connected with factory links…no way it’s going to be a much of a problem as others have suggested. The oem sway bar is the droop limiter, not the cv. I have ran a 30mm with oem everything and beat the front end more the most (primarily crawling and going extremely fast over rocks) and no issues.

With a tundra swap may be a different story, @1UZJ80N60 front end isn’t comparable, his long arms and lower shock mount mods raise his ratio’s.

I’ll have that space in (it will be a reduction from where I am) tonight and I’ll let you know how it goes. The only concern is UCA interference with the coil spring.

 

[AnyMal]

Everyone wrote up great summaries here while i went to bed i guess lol.

With what I’ve observed taking things apart a couple times already. the droop limiter on ahc seems to really be the shock, with the sway bar as a load bearing safeguard. With the bar link out, and my lower arm bolts loose, I had a good 1-2” of flex at the bottom with my foot pressing down on the hub.

So basically with x lift, and an x by motion ratio shock spacer matched, you should be totally safe.

The CVs will still bind on both platforms probably the same.

And one thing i will add, i believe the ahc shock extends further than the LC traditional shock.

So all that being said, the AHC thesis is now solid. Its extended travel from factory, and with sway modifications we can max travel up to x CV angle with very little cost, and oem ride characteristics returned by preload.

This is a major win in my book. And not only the right way to do it, but also affordable and safe.

Installing probably today and will take some pics.

 

[AnyMal]

I'm loving this thread so far...

A bit late to the game, but I thought I'd bring up the Japan 4x4 spacers that were used on the rear of the 100 series. It will net 2.2" on the rear axle, allowing you to increase (max out) the lift on the rear AHC sensors. Not sure it qualifies as "long travel", but it will save you from having to weld a plate and drill.
It's -20C out today, so I haven't measured the LX 200 series lower shock mount diameter... is it 19mm? If so these should fit by rotating the AHC ram 90 degrees.
Keep in mind that these particular extensions were designed for the lighter 100 series, but a similar beefy setup might make the rear a 1 banana job.

View attachment 3187193

View attachment 3187194

This is kind of perfect actually. Got a link?

I believe they are indeed 19mils back there. And rotating the tube is no biggy.

Thanks! Did not know about these.

 

[grinchy]

I'm loving this thread so far...

A bit late to the game, but I thought I'd bring up the Japan 4x4 spacers that were used on the rear of the 100 series. It will net 2.2" on the rear axle, allowing you to increase (max out) the lift on the rear AHC sensors. Not sure it qualifies as "long travel", but it will save you from having to weld a plate and drill.
It's -20C out today, so I haven't measured the LX 200 series lower shock mount diameter... is it 19mm? If so these should fit by rotating the AHC ram 90 degrees.
Keep in mind that these particular extensions were designed for the lighter 100 series, but a similar beefy setup might make the rear a 1 banana job.

View attachment 3187193

View attachment 3187194

These don't look like they'd be hard to modify shorter . . .

 

[tbisaacs]

Me and my CVs reading this thread

Seriously, well done y'all.

 

[TeCKis300]

See that’s where I’m confused. @Killacaviar said on page 3 he used a tundra spacer of 30 mm (which the one I linked is obviously more than that). I’m just curious what he used to not have to disassemble the coil over.

So we're not talking past each other, the advertised lift of spacers is not the same dimension of the spacer thickness because of the suspension motion ratio.

Too bad most advertisement don't list the real spacer thickness. At least we can confirm the 1.5" lift is a 24mm spacer. So motion ratio for a Tundra is about 2:3.

 

[nwfl4runner]

Everyone wrote up great summaries here while i went to bed i guess lol.

With what I’ve observed taking things apart a couple times already. the droop limiter on ahc seems to really be the shock, with the sway bar as a load bearing safeguard. With the bar link out, and my lower arm bolts loose, I had a good 1-2” of flex at the bottom with my foot pressing down on the hub.

So basically with x lift, and an x by motion ratio shock spacer matched, you should be totally safe.

The CVs will still bind on both platforms probably the same.

And one thing i will add, i believe the ahc shock extends further than the LC traditional shock.

So all that being said, the AHC thesis is now solid. Its extended travel from factory, and with sway modifications we can max travel up to x CV angle with very little cost, and oem ride characteristics returned by preload.

This is a major win in my book. And not only the right way to do it, but also affordable and safe.

Installing probably today and will take some pics.

I think I would just qualify by saying you can max DROOP but not necessarily travel. You are still dealing with shock compression as a factor with the factory bump stop. I believe @TeCKis300 measured the amount of shaft left when adding his additional spacer so as to keep his bump stops in the same place. Going beyond that you're robbing compression for droop. Also, need to consider whether you will be able to articulate fully within the range of your vehicle weight. I just harp on this as we're discussing long (i.e., extended) travel.