Drive line vibration caused by too much positive caster?

Good points on the bushings. But your bumpsteer issue the tie rods would have to be significantly out of wack in lengths. Most bump steer actually comes from where the joints line up with the lower control arm to frame mounts. Also if the tie rods are at an extreme angle compared to the lower control arms. It's all in the suspensions geometry. Toyota did an excellent job in this department and I would not worry with bumpsteer. There are many vehicles right off the assembly floor with more than 1.5 threads difference in sides showing on their inner tie rods that do not have bump steer, I actually went and checked my truck and its roughly 2.5 threads difference and no issues. Now if one were all the way in and one were all the way out then there is an issue and the rack would need to be centered then the outer tie rods re-installed.

 

The reason I mentioned the TREs is I had a bump steer issue on my former truck and it turns out who ever had it was simply adjusting one TRE and not the other. Either due to being lazy or the jam nut was frozen and could not be moved.

 

Because of the problem I was having I followed the way-unequal lengths of the tie rods that were on mine on mine and got it back into specs and solved the problem. It came from this guy DJ in the following post no. 3 here: He is a no slouch and is retired engineer from Hunter Engineering, the major alignment machine company, and also has a 1st gen Tundra, which is very much similar to the Taco.

 

What he said is what I was saying in a nutshell as well I didn't want to get that technical and even still he dumbed it down as well there is a lot to bumpsteer and suspension geometry and design and it isn't always a simple answer. I have in the past as the OP from that article switched the tierod from bottom to top on some vehicles but I have a tappered reamer meant for making tie rod and ball join tapers. Those suspensions were designed differently and when lowered the LCA was parallel with the ground but not the tie rods so switching them brought everything in line and got rid of the bump steer. BTW I used hunter equipment when doing alignments and such IMO they have their stuff well above anyone else on the market. I agree with him 100% we were saying the same thing he just said it more eloquently. Good find and yes he is right if the asymmetry is enough it can induce bump steer. Which is also what i said usually when I have seen issues with that has been when someone replaced the rack.

I was trying to explain a lot of what he is saying in his stuff about dynamic vs static in another thread asking if the alignment he had was good and guys were telling the OP that he needed more of camber toe etc.

I read some of his other posts in that thread and I'd like that guy. When he described doing the alignments the old way and painting the tires and such been there done that got that t-shirt. He is spot on with everything he said in that thread. You are on the right track following and listening to guys like that. They not only have the engineering background but also real world experience that more times than not trumps the engineering side.

 

Yup. The remaining problem is trying to find an alignment tech close to where one lives that is competent. I don't know if you saw my post in another thread about this problem but I took the preferred specs to a place and actually caught them cheating the alignment! Not only did they not put it on the rack but they took it out of sight and did a toe-and-go and then and the nerve to give me a print out showing they achieved the preferred numbers. Criminal. Anyway, that is why I have become immersed in alignments. I don't know if you have seen the book Wheel Alignment by Thomas Vauderwange (2011)?

$58 Wheel Alignment

https://www.amazon.com/Wheel-Alignm...1&keywords=Wheel+Alignment+Thomas+Vauderwange The Amazon preview is worth reading alone.

 

No but I have a lot of books on suspension design and vehicle chassis design. I have built race cars, was the suspension tech on a race team, and built several one off vehicles suspensions so I am well versed in the subject manner.