AHC Delete = Vibration. Revert to stock LX470 spring?

[jonothehut]

As the title says, I have deleted my AHC. Replaced with Ironman suspension. Now I have a vibration under load around 60-75 mph. Vibration is not in the steering wheel. Felt on the pedal. The harder I press the pedal the harder the vibration is felt. Tires have been rotated and balanced a few times to ensure they are not the culprit. Aligned a couple times as well.

Doing a lot of research on here and I believe it may be u joint, drive shaft, pinion angle related.

I’d like to test my theory prior to buying parts to hoping it will be the fix. My thought is to diagnose the issue is to remove the ironman rear coil springs and temporarily replace with the stock LX470 rear spring. (Anyone have some LC100 springs laying around and live in SC? ) If the issue is related to u joint, drive shaft, pinion angle my theory is that the vibration would go away.

Does my logic sound correct?

If this does fix the issue, will I ruin my rear shocks if I ride with the LX coil springs for a couple weeks? While I wait for parts?

thank you advance,
Jono

 

[SWCruiser]

did you maintain stock ride height? vehicle have a different stance? even if you bought oem height springs the new springs may give a slight lift- exacerbating any vibes you may have already had. Grease the u joints. does the vibes only apparent under load ? if your in neutral are they still there ?

 

[jonothehut]

did you maintain stock ride height? vehicle have a different stance? even if you bought oem height springs the new springs may give a slight lift- exacerbating any vibes you may have already had. Grease the u joints. does the vibes only apparent under load ? if your in neutral are they still there ?

My apologies if I wasn't clear earlier. No on maintaining the stock ride height currently. When I installed the Ironman kit I did gain about 2 inches of lift. About 2 in the front and 3 in the rear. Thats why I am curious to drop it back down to stock to see if that eliminates the vibration. Yes the vibration is only under load. When I let go of the gas it goes away.

I have greased the ujoints but that hasn’t appeared to help. They did seem to be pretty dry, took a few pumps for old grease to come out and there was very little old grease.



I haven’t tried moving it into neutral. Is that safe/okay to do while driving 70ish? My concern would be putting it back into D at 70.

 

[TurbodreamZ]

I don’t have experience with a 100 but I can tell you from experience on a Tacoma changing the angle of the driveshafts by lifting the truck can cause this issue. You have to add shims on the Tacoma’s carrier bearing to compensate for the change in driveshaft angle to negate some of the vibration.

 

[GTV]

With the LX coils and no hydraulics it will be sitting lower than stock and you won’t really learn anything from that.

 

[Bisho]

Lifting the front beyond 21” hub to fender (about an inch and a half) is where you start to cause cv axle issues, in my experience, unless you also do a diff drop.

I had my driveshaft balanced last year for $65, so it’s a small investment.

 

[Trunk Monkey]

If you think it's one of the drive shafts, remove them one at a time, lock the center, and go for a drive.

 

[jonothehut]

With the LX coils and no hydraulics it will be sitting lower than stock and you won’t really learn anything from that.

Gotcha. That makes sense. Thank you.

 

[jonothehut]

I don’t have experience with a 100 but I can tell you from experience on a Tacoma changing the angle of the driveshafts by lifting the truck can cause this issue. You have to add shims on the Tacoma’s carrier bearing to compensate for the change in driveshaft angle to negate some of the vibration.

Makes sense. I did some searching and didn't find much information on carrier bearing shims for the 100 but seems rear upper and lower trailing arms would be able to adjust the rear pinion back to the correct angle.