How far to move front axle forward?

[MTKID]

I wanted to open up some discussion on how far forward others think the front axle can be safely moved from alignment adjustments.

This will be stock CV, stock AHC shock (w/ OEM spacer).

I know the CV is a weak point but some have speculated that one cause could be moving it too far forward creating severe CV angles, or possibly significant droop.

I will be doing another alignment next week and want to move it as far as is reasonable.

 

[linuxgod]

@TexAZ spoke to SPC and IIRC the answer was 3/4". Not sure how that translates into degrees of caster, which is how most alignment techs would view it.

 

[MTKID]

@TexAZ spoke to SPC and IIRC the answer was 3/4". Not sure how that translates into degrees of caster, which is how most alignment techs would view it.

Thank you for that feedback @linuxgod I thought I recalled someone that had moved it that far forward and had a break. Not sure if it was related. My alignment tech is happy to do whatever I request. I think I am going to go for 3/8" - 1/2" to leave a little extra safety margin. I'll post what my numbers are after.

 

[Markuson]

Thank you for that feedback @linuxgod I thought I recalled someone that had moved it that far forward and had a break. Not sure if it was related. My alignment tech is happy to do whatever I request. I think I am going to go for 3/8" - 1/2" to leave a little extra safety margin. I'll post what my numbers are after.

If you’re referring to what I think you are…The pronounced forward tweak is specific to SPC UCAs…& not the same on OEM upper control arms. SPC allows this because it is uniquely adjustable.

If you’re referring to the CV break TexAZ suffered about 3 or 4 years ago in Moab, that was with an after-market CV. I’ve run a forward adjusted SPC for about 5 years, all on my original (now 14 year old) CVs at well over 8000lb, lifted, including 2 years on 35’s & very hard wheeling. -Zero CV issues.

 

[MTKID]

If you’re referring to what I think you are…The pronounced forward tweak is specific to SPC UCAs…& not the same on OEM upper control arms. SPC allows this because it is uniquely adjustable.

If you’re referring to the CV break TexAZ suffered about 3 or 4 years ago in Moab, that was with an after-market CV. I’ve run a forward adjusted SPC for about 5 years, all on my original (now 14 year old) CVs at well over 8000lb, lifted, including 2 years on 35’s & very hard wheeling. -Zero CV issues.

I didn’t realize that feature was exclusive to SPC UCA’s. I see that now looking at more photos of them. I ordered Dobinson UCA’s

I’m not sure if I want to order SPC.

Is there any forward movement that can be done with just alignment adjustments?

 

[linuxgod]

The factory alignment cams on the OEM LCA will "move the wheel forward" by adjusting caster - the more positive it is the more the wheel is forward in the wheel well.

So long as you stay within Toyota spec, which is no more than about 3.6 or 3.7 deg of caster, you shouldn't have to worry about breaking a CV due to axle binding.

@Markuson I know that @TexAZ's issue was with Tundra CVs and SPC UCAs so kind of a different set up. I would *assume* since SPC said "don't go more than 3/4" forward" that would apply to any UCA + LCA cam adjustment, not just SPC... however it's probably easier to do with the SPC UCAs.

@MTKID, unless you are trying to run a big lift, any aftermarket UCA which has the caster adjustment baked in should work fine for the 2-3" lifts we generally see. Anecdotally I had my SPC set at +2 deg caster and my alignment guy pushed my caster to ~4.4 deg which is way over spec, and I have not broken a CV on a trail. I've since reduced the SPC caster to +1 deg (which is their recommended starting point and is also what most aftermarket UCAs are pre-set to) and I'm still up around 3.7-3.8 deg of caster with some room to move. The advantage to the SPC UCAs is that if your LCA cam bolts are frozen it is possible to set rough caster and to fine-tune camber via the UCA ball joint, whereas all the other fixed options require turning the LCA cams

 

[Markuson]

The factory alignment cams on the OEM LCA will "move the wheel forward" by adjusting caster - the more positive it is the more the wheel is forward in the wheel well.

So long as you stay within Toyota spec, which is no more than about 3.6 or 3.7 deg of caster, you shouldn't have to worry about breaking a CV due to axle binding.

@Markuson I know that @TexAZ's issue was with Tundra CVs and SPC UCAs so kind of a different set up. I would *assume* since SPC said "don't go more than 3/4" forward" that would apply to any UCA + LCA cam adjustment, not just SPC... however it's probably easier to do with the SPC UCAs.

@MTKID, unless you are trying to run a big lift, any aftermarket UCA which has the caster adjustment baked in should work fine for the 2-3" lifts we generally see. Anecdotally I had my SPC set at +2 deg caster and my alignment guy pushed my caster to ~4.4 deg which is way over spec, and I have not broken a CV on a trail. I've since reduced the SPC caster to +1 deg (which is their recommended starting point and is also what most aftermarket UCAs are pre-set to) and I'm still up around 3.7-3.8 deg of caster with some room to move. The advantage to the SPC UCAs is that if your LCA cam bolts are frozen it is possible to set rough caster and to fine-tune camber via the UCA ball joint, whereas all the other fixed options require turning the LCA cams

The factory alignment cams on the OEM LCA will "move the wheel forward" by adjusting caster - the more positive it is the more the wheel is forward in the wheel well.

So long as you stay within Toyota spec, which is no more than about 3.6 or 3.7 deg of caster, you shouldn't have to worry about breaking a CV due to axle binding.

@Markuson I know that @TexAZ's issue was with Tundra CVs and SPC UCAs so kind of a different set up. I would *assume* since SPC said "don't go more than 3/4" forward" that would apply to any UCA + LCA cam adjustment, not just SPC... however it's probably easier to do with the SPC UCAs.

@MTKID, unless you are trying to run a big lift, any aftermarket UCA which has the caster adjustment baked in should work fine for the 2-3" lifts we generally see. Anecdotally I had my SPC set at +2 deg caster and my alignment guy pushed my caster to ~4.4 deg which is way over spec, and I have not broken a CV on a trail. I've since reduced the SPC caster to +1 deg (which is their recommended starting point and is also what most aftermarket UCAs are pre-set to) and I'm still up around 3.7-3.8 deg of caster with some room to move. The advantage to the SPC UCAs is that if your LCA cam bolts are frozen it is possible to set rough caster and to fine-tune camber via the UCA ball joint, whereas all the other fixed options require turning the LCA cams

What I meant was… I believe his CVs were also not made by Toyota. I believe they were after-market.

 

[TexAZ]

My original CVS were factory Tundra units. I had to install Napa units to get off the trail. Forward adjustment doesn't necessarily cause issues, moving them all the way forward will cause binding. SPC recommends not going more than 3/4" forward. I was a little over an inch forward.

 

[MTKID]

My alignment appointment is tomorrow. I chose to stay with the Dobinson’s UCA’s I had already ordered.
Modified them for AHC yesterday. Installing today.

I doubt I’ll be able to move things even 3/4” w/o the unique feature of the SPC but the alignment tech seemed cooperative so I’ll post my numbers when it’s done.

 

[afgman786]

Don't the dobinsons UCA have a small amount of forward adjustment built in to put a 2" lifted 200 back to factory spec? If so you might be able to get that forward adjustment you're looking for if you haven't gone very high with AHC lift I'd assume.

 

[MTKID]

Don't the dobinsons UCA have a small amount of forward adjustment built in to put a 2" lifted 200 back to factory spec? If so you might be able to get that forward adjustment you're looking for if you haven't gone very high with AHC lift I'd assume.

It does say “works for any lift height of 1.5” or more”. I think I have that much from my sensor adjustments.

 

[CharlieS]

Don't the dobinsons UCA have a small amount of forward adjustment built in to put a 2" lifted 200 back to factory spec? If so you might be able to get that forward adjustment you're looking for if you haven't gone very high with AHC lift I'd assume.

I have the Dobinsons UCAs on my rig. Not sure if this was a question, but they are fixed geometry, not adjustable. The were helpful in getting a good alignment on my lifted 200.

 

[MTKID]

I have the Dobinsons UCAs on my rig. Not sure if this was a question, but they are fixed geometry, not adjustable. The were helpful in getting a good alignment on my lifted 200.

do you recall these bits of hardware when you installed yours?

Not usually fond of leftover parts

 

[CharlieS]

@MTKID

Yes, I had leftover bits, and asked Mike about them. I think he said they are for another application, but they are definitely extra, and not needed.

These were the extra parts I had from one kit, so double it and I think I had the same extras as you.