Long Travel AHC

[nwfl4runner]

Sorry, going back to this, why do you say the droop is unusable assuming you removed the sawy bar or addressed the links? Everyone in this thread seems to think 18-20mm seems to be about what you can run.

On the link binding, wouldnt an easy solution be to drop the whole bar down 15 or 20mm at the frame mounts so that its still in line with the throw of the suspension?

And the bump stops, I probably need to extend them anyways because when I fully stuff my 315/70's they hit the fender lip when turned. They tuck fine straight.

Absolutely a fair question. You’re right in that modifying the frame brackets or endlinks or removing it eliminates one area of binding to free up travel. I just prefer clean travel (unmodified bump) over “dirty” travel, which may be too strong a word, but droop that gets into the range of ball joint and CV binding.

If you’re thinking of adding a significant spacer like the ones you’ve mentioned above, I would just recommend disassembling the front coil, installing the spacer and then articulating it to see how close the UCA ball joint or CV are to binding at droop, and the trade off with the new bump stop spacer you’ll need to avoid shock bottom or coil bind.

 

[skrypj]

So I decided to pull the front end apart today to see what the control arms would do by releasing the lower shock bolt and loosening the LCA and UCA bolts to let the suspension naturally sag all the way down. The ball joints dont seem to bind, what was happening before anything else was my UCA was contacting the spring. Also, even with the wheel fully turned it seemed like the CV's would still turn no problem at max droop(IE, UCA resting on spring). This seemed to be somewhere between 25-30mm of extension of the shock(measuring from the bolt hole in the lower shock to the bolt hole in the LCA.) UCA contact:

I also used my jacks to specifically set up both sides of the suspension so that the hole in the LCA was sitting 20mm below the hole in the shock to simulate where the LCA would be with a 20mm spacer. I did this with the sway bar connected and the links did not seem to be binding. I could push either side of the suspension down farther than 20mm with my hands while the sway bar was connected.

So I dont really know why the 20mm spacer wouldnt work, even with the stock links.

 

[TeCKis300]

So I dont really know why the 20mm spacer wouldnt work, even with the stock links.

Good stuff and thanks for sharing your findings on the limits of those links.

I don't think it's a matter of 20mm won't work. You can do it, and we've seen some other push it beyond that too.

@nwfl4runner said it best. It's about clean travel and maximizing travel. Once you're into 20mm+ shock spacers, you're trading good uptravel for dirty downtravel. There is limited shock stroke and AHC long travel is about maximizing travel with that stroke, rather than trading good for bad.

What I think he means by dirty travel is that once at the extremes of downtravel, there's a lot of toe steer and compromised alignment. (Things that Tundra long arms may improve). The track width narrows as the control arms are at steeper angles trading handling and stability. CV durability is compromised at steeper angles even as it's not hitting hard internal limits.

 

[skrypj]

Good stuff and thanks for sharing your findings on the limits of those links.

I don't think it's a matter of 20mm won't work. You can do it, and we've seen some other push it beyond that too.

@nwfl4runner said it best. It's about clean travel and maximizing travel. Once you're into 20mm+ shock spacers, you're trading good uptravel for dirty downtravel. There is limited shock stroke and AHC long travel is about maximizing travel with that stroke, rather than trading good for bad.

What I think he means by dirty travel is that once at the extremes of downtravel, there's a lot of toe steer and compromised alignment. (Things that Tundra long arms may improve). The track width narrows as the control arms are at steeper angles trading handling and stability. CV durability is compromised at steeper angles even as it's not hitting hard internal limits.

Right but I’m already rubbing on my current tire and wheel setup on the fender lip when turned and stuffed(I kinda suspect to 2016+ fender might be different). I’m gunna have to extend my bump stops anyways and lose that up travel whether I move the shock 15 or 20mm

I guess my thought process is that I should move the shocks travel range to still get the full range of motion. If 15mm isn’t enough to need to extend the bumps, then I’m just giving up travel once I extend the bumps.

 

[TeCKis300]

Right but I’m already rubbing on my current tire and wheel setup on the fender lip when turned and stuffed(I kinda suspect to 2016+ fender might be different). I’m gunna have to extend my bump stops anyways and lose that up travel whether I move the shock 15 or 20mm

I guess my thought process is that I should move the shocks travel range to still get the full range of motion. If 15mm isn’t enough to need to extend the bumps, then I’m just giving up travel once I extend the bumps.

Sounds like you know what you want. In the chance you might try for more clean travel in the upwards direction, there's things that can be done and would be worth the effort IMO

• Dial in some negative camber
• Tuck your fender liners above the fender tab, remove plastic clips, and fold fender table more
• Roll fender
• Body lift

 

[skrypj]

Sounds like you know what you want. In the chance you might try for more clean travel in the upwards direction, there's things that can be done and would be worth the effort IMO

• Dial in some negative camber
• Tuck your fender liners above the fender tab, remove plastic clips, and fold fender table more
• Roll fender
• Body lift

Cool, thanks.

 

[skrypj]

So I messed around some more with my front suspension with the bump stops fully removed. I appears that the rear bump stop actually has the least clearance of the two, even though it seems like the front bump stop contacts the LCA first. I could fit my pinky finger in the gap of the front stop, but not the rear. The stock configuration bottoms out the shocks with about 8mm of gap between the LCA and the rear bump stop mounting face.

The metal portion of the bumpstop itself is approximately 13mm, or 5mm taller than full bottom out with no stop:

With only the rear bump stop installed(no front so only the single bump stiffness was affecting travel), the clearance to the LCA is ~23mm, the total bump stop thickness is 26mm.

While I was at it I decided to measure the travel from full compression to full droop without the bump stops and got almost exactly 10". I used a level on the hub to allow me to have the tape measure vertical while taking the measurements since the hub sits inside the fender a bit:

Stupidly, I did not measure it with the bump stop in place. But with the increase of 15mm at the bump stop/LCA distance with an without the stop, I am going to guess its a pretty dramatic difference in low speed crawling travel.

As just an FYI, my single PerryParts bump stop in the rear location stops the LCA at around 25mm and the total height of the stop is 40mm, so you get an extra ~12mm of more progressive bump and it doesnt really limit up travel in a static situation.

Anyone know the relative motion ratio at the bump stop vs the shock? in other words, 5mm at the bumps = xx mm at the shock.

 

[Harangatang]

@ skrypj
That's super helpful info on the front bumps. I was looking at that earlier this week with the same question of whether or not both front bumps would contact simultaneously.
Was the 10" of travel you measured with the 20mm tophat spacer installed?

​

 

[poppe]

I read through all 30 pages. Went a little cross eyed. Did anyone ever end up deciding on the Wescott preload stuff, specifically using the spacers they provide? I'd like to gain a little height from the sensor lift, but I'm not rock crawling - I just want a little taller with smooth normal AHC cross country trips. Or is there a better solution?

 

[MTKID]

I read through all 30 pages. Went a little cross eyed. Did anyone ever end up deciding on the Wescott preload stuff, specifically using the spacers they provide? I'd like to gain a little height from the sensor lift, but I'm not rock crawling - I just want a little taller with smooth normal AHC cross country trips. Or is there a better solution?

Not to complicate your decision with another option, but by far the easiest solution to help preload or create a slightly stiffer coil is with the Sumo Coil Spring Helper (or similar) that slides into the coil. I think @tbisaacs has some specific mention for them in his build. I do like and would also prefer to use the Westcott kit just for how finished it looks but it takes much more labor and the spring helpers can be tuned a little more with different options.

 

[poppe]

Not to complicate your decision with another option, but by far the easiest solution to help preload or create a slightly stiffer coil is with the Sumo Coil Spring Helper (or similar) that slides into the coil. I think @tbisaacs has some specific mention for them in his build. I do like and would also prefer to use the Westcott kit just for how finished it looks but it takes much more labor and the spring helpers can be tuned a little more with different options.

Okay thank you. I'll do the research on that too.

And if anyone is in the Ventura County CA area and would like to help me do the full AHC travel part, I'd definitely throw in some cash - just putting it out there haha.

 

[Expoguy]

I have done most of the mods with 20mm spacers, wescott preload, max sensor adjustment, tech stream , rear shock mounts and aftermarket bumps. If I remember correctly the combination of sensor adjustment and techstream equals about 1.75" of lift and the conventional lift I have done should be around 3" +. I have decided to install aftermarket UCA's and increase sensor lift with arm mod to get a AHC lift and pressure more in line with the conventional lift. Any input is appreciated!

 

[Heckraiser]

I have done most of the mods with 20mm spacers, wescott preload, max sensor adjustment, tech stream , rear shock mounts and aftermarket bumps. If I remember correctly the combination of sensor adjustment and techstream equals about 1.75" of lift and the conventional lift I have done should be around 3" +. I have decided to install aftermarket UCA's and increase sensor lift with arm mod to get a AHC lift and pressure more in line with the conventional lift. Any input is appreciated!

View attachment 3807805

Curious what that setup looks like on level ground in AHC normal. Do you have any more pics?

 

[Expoguy]

Curious what that setup looks like on level ground in AHC normal. Do you have any more pics?

Sorry but haven't installed UCA's and modded the sensor arm just yet. With current mods it is this but don't have a good level ground side shot. Try to get one later !

Curious what that setup looks like on level ground in AHC normal. Do you have any more pics?

 

[TeCKis300]

I have done most of the mods with 20mm spacers, wescott preload, max sensor adjustment, tech stream , rear shock mounts and aftermarket bumps. If I remember correctly the combination of sensor adjustment and techstream equals about 1.75" of lift and the conventional lift I have done should be around 3" +. I have decided to install aftermarket UCA's and increase sensor lift with arm mod to get a AHC lift and pressure more in line with the conventional lift. Any input is appreciated!

View attachment 3807805

Hey Guy. Rig is looking good!

Giving your idea some thought, I think there's a good chance it should work. This might be the ticket to get that next level clearance. Putting AHC N at a height more analogous to a conventional lift as you put it. While getting dramatically more height with 5" of total suspension lift in AHC H. It shouldn't have compromise to weight handling as you've already compensated for hydraulic pressure with a combination of the 20mm top hat and Wescott spacer.

You'll have to play around with just how much more sensor lift you want, balancing between making AHC N have more height, while also keep AHC H functioning at a useful level by keeping some down travel. Playing with the numbers, something like sensor lifting 3" front and 2.5" rear might be the ticket as it still keeps 2" droop travel in both front and rear axles.

Yes, you'll likely need a UCA to bring caster in spec with a 3" sensor lift. Note that will bring the front tires closer to the body mount so you might have to chop that more aggressively. At the rear, you'll want to consider adding a panhard bar correction bracket.

AHC Setup	Front Travel Compression / Droop	Rear Travel Compression / Droop	Total Travel Front / Rear
Stock, AHC N	3.5" , 5.5"	4.125" , 5.875"	9" , 10"
Stock, AHC H	5.5", 3.5"	6.5" , 3.5"	9" , 10"
Long Travel, 1.75F/1.5R sensor lift, AHC N	5.25" , 5.25"	5.75" , 5.25"	10.5" , 11"
Long Travel, 1.75F/1.5R sensor lift, AHC H	7.25" , 3.25"	8.125" , 2.875"	10.5" , 11"
Long Travel, 3F, 2.5R extra sensor lift, AHC N	6.5" , 4"	6.625" , 4.375"	10.5" , 11"
Long Travel, 3F, 2.5R extra sensor lift, AHC H	8.5", 2"	9" , 2"	10.5" , 11"

 

[CanadianRockyCruiser]

Sorry but haven't installed UCA's and modded the sensor arm just yet. With current mods it is this but don't have a good level ground side shot. Try to get one later !


View attachment 3807960

LRD Offroad

 

[Expoguy]

Hey Guy. Rig is looking good!

Giving your idea some thought, I think there's a good chance it should work. This might be the ticket to get that next level clearance. Putting AHC N at a height more analogous to a conventional lift as you put it. While getting dramatically more height with 5" of total suspension lift in AHC H. It shouldn't have compromise to weight handling as you've already compensated for hydraulic pressure with a combination of the 20mm top hat and Wescott spacer.

You'll have to play around with just how much more sensor lift you want, balancing between making AHC N have more height, while also keep AHC H functioning at a useful level by keeping some down travel. Playing with the numbers, something like sensor lifting 3" front and 2.5" rear might be the ticket as it still keeps 2" droop travel in both front and rear axles.

Yes, you'll likely need a UCA to bring caster in spec with a 3" sensor lift. Note that will bring the front tires closer to the body mount so you might have to chop that more aggressively. At the rear, you'll want to consider adding a panhard bar correction bracket.

AHC Setup	Front Travel Compression / Droop	Rear Travel Compression / Droop	Total Travel Front / Rear
Stock, AHC N	3.5" , 5.5"	4.125" , 5.875"	9" , 10"
Stock, AHC H	5.5", 3.5"	6.5" , 3.5"	9" , 10"
Long Travel, 1.75F/1.5R sensor lift, AHC N	5.25" , 5.25"	5.75" , 5.25"	10.5" , 11"
Long Travel, 1.75F/1.5R sensor lift, AHC H	7.25" , 3.25"	8.125" , 2.875"	10.5" , 11"
Long Travel, 3F, 2.5R extra sensor lift, AHC N	6.5" , 4"	6.625" , 4.375"	10.5" , 11"
Long Travel, 3F, 2.5R extra sensor lift, AHC H	8.5", 2"	9" , 2"	10.5" , 11"

Thanks for the reply and detailed information. Took some rough measurements yesterday as I was concerned about droop. Looks like I currently have 3" of droop left when in High. Although some don't agree with a diff drop my off road shop felt it was a good idea and installed it previously. I have new axles going in and wanted to see what I should be looking for on max CV angle at full droop ? We would previously race prep/clearance CV's to get higher angles but don't think that will be necessary here. Maybe the only thing to consider would be better boots that won't bind and tear. All input welcomed !

 

[TeCKis300]

Thanks for the reply and detailed information. Took some rough measurements yesterday as I was concerned about droop. Looks like I currently have 3" of droop left when in High. Although some don't agree with a diff drop my off road shop felt it was a good idea and installed it previously. I have new axles going in and wanted to see what I should be looking for on max CV angle at full droop ? We would previously race prep/clearance CV's to get higher angles but don't think that will be necessary here. Maybe the only thing to consider would be better boots that won't bind and tear. All input welcomed !

Not a bad call on the diff drop. The CV can only be stronger with less wear running lower angles. Not sure it's absolutely needed as total droop is the same as previous, but again, it's a good preventative measure.

IIRC, the limits of max CV down angle is something like 26° - 27° before internal binding. But it will already be less strong before those angles. IIRC, the last time I measured with full droop, I was at about 23°? I'll need to check my memory on this.

 

[teejnut]

I have done most of the mods with 20mm spacers, wescott preload, max sensor adjustment, tech stream , rear shock mounts and aftermarket bumps. If I remember correctly the combination of sensor adjustment and techstream equals about 1.75" of lift and the conventional lift I have done should be around 3" +. I have decided to install aftermarket UCA's and increase sensor lift with arm mod to get a AHC lift and pressure more in line with the conventional lift. Any input is appreciated!

View attachment 3807805

For the front 20mm spacer. What did you have to mod (if any) to fit the AHC bracket/line back on? And id you keep the original stock top hat studs?

 

[Expoguy]

For the front 20mm spacer. What did you have to mod (if any) to fit the AHC bracket/line back on? And id you keep the original stock top hat studs?

Different studs and grinding to clearance for hydraulic line. The information is somewhere here on Ih8mud but can't remember where. I provided the information to a shop that did the work for me.