Strange front end shake under throttle (1 Viewer)

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Joined
Aug 17, 2022
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10
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73
Location
Tacoma, WA
I have about 1000 miles on the LX470 since swapping out the dead engine. I have been getting more confident in it but the issues are starting to crop up, this one most concerning. I did some searching and didn't see anything matching exactly, but here is what I have. When the vehicle is cold, or only driven around town there is no symptom. If I get on the freeway and drive 60-65 for about 15 minutes, the front end will develop a wheel-speed vibration or shake only when under throttle. It's almost like a death wobble on a solid axle rig. If I turn left it shows up, and it will also show up if the suspension unloads, like going through a dip.

When I replaced the engine, I put in a new rack, tie rod ends, and then had lowe ball joints done plus an alignment. I Can't detect any play in the wheel. I am thinking since its at wheel speed (if I am going 15-20 and lightly accelerate the steering wheel will pitch back and forth, particularly on a rutted road). I am leaning wheel bearing, but if I make a hard left turn at full lock and give it some gas I can hear a slight clicking like a CV. What say the group?
 
Have you checked the CVs? This forum only recommends OEM axles, aftermarket can cause vibrations, it’s worth checking.
 
If you haven't been into the wheel bearings, I'd look at those next. Check the bearing surfaces, preload, grease, etc. If they are part of the problem, you should see something obvious.
 
I crawled around under the car last night. There's zero play in the wheel bearings, at least cold. The problem doesn't manifest until some highway miles but I have to imagine there would be some play. There's a little play in the front driveshaft but it's rotational, not at the u joints. How much movement in the CV axle is acceptable?
 
I took a better look at the CVs, they're shot. Oozing rusty grease out of the boots and I can move them pretty easily while attached. Ordered some new ones on Amazon that one of the members reported being good quality. I'm not paying $1200 for OEM when aftermarket is 20% the cost.

I started disassembly and noticed the bolts that hold the tie rod bracket to the knuckle have thread locker on them. Is it red or blue on reassembly?
 
I would say isolate further. Remove the L&R CV axles and drive it in the freeway and see if death wobble shows up again. If it doesn’t, you have isolated it down to the CV axles. If it shows up, you can further investigate your wheel bearings and/or steering components.
 
If I remove the CVs isn't the front diff going to puke oil everywhere?
Yep, thats right. But hey, if it gets right of the shake, that’s good right? 😅

You could remove the front driveshaft and drive with CDL but that might not isolate the CV’s impact.

I would bet replacing those CV’s will have you driving smooth again, especially since you did all that work in other parts of the front end. Since you updated all that front end stuff, it tightened up everything which is why maybe you can now feel the CV’s vibration easier. Or it could be just greasing the driveshaft.
 
I'm 99% confident it's not driveshaft, the vibration was wheel speed, not driveshaft speed. Weirder things have happened.

What I've found on disassembly is that the wheel bearings are set up perfect. Zero play, backlash drag is dead on. Left CV axle is messed up. Loose, clanks when I move it by hand. The right side doesn't feel bad, but it has shed it's inner boot ring and is puking grease everywhere.

Additionally, the sway bar links are destroyed. The right one had no rubber remaining. The left one was so oil soaked it felt like it was made of foam. So, 🤞 what I think was happening is the right CV was probably overheating (I had only driven in 20-30 degree weather on the freeway previously) binding, and then the slop in the other one was causing the vibration. I hope.

The perils of buying a non runner. With this much work I could have just bought a Disco 😂.

PXL_20221229_030635067.jpg


PXL_20221229_035014955.jpg
 
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After some delays I got it all back together with the GSC CV axles. All seems improved so far. Replacement was not the easiest job but there weren't any major hiccups. Still need a long freeway trip to verify but I think it's a success.
 
Well just did 150 miles on the freeway and some gravel as well and these new CV have cured the vibration. Front end feels fantastic. The sway bar links have also made a huge difference in cutting down slop up front. I'm feeling much better about this as a road trip rig now.
 

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