Long Travel BS Thread

Here @906taco I did it for you. The numbers in brackets are driven numbers, meaning they change according to the other constraints. As I said you can get super close, like close enough that bump steer is practically zero, but not absolutely zero.

This is with the frame side spacing and the spindle side spacing the same. Start changing these numbers and it gets worse. obviously the biggest difference maker is moving one side of the tie rod up or down relative to the other side. That will change the bump steer drastically.

These numbers are super small, but will be amplified when measured out by the edge of the tire or wherever you want to measure from

 

Exactly why I went 2wd truck to begin with lol, figured if I really want I’ll add an FJ case and get a junkyard diff.
So far, I just bought another 4wd vehicle

 

I remember someone building these things that a little bump steer isn’t even bad - like an 1/8” it may have been @Basikbiker

 

I should say though @906taco im not calling you out. I think your swing set is very impressive and I appreciate the time you put into dialling it in and making it awesome. I'm just saying "minimal" could be 1/8", which would not be noticeable in the dirt, or it could be half a tenth of an inch, or it could be half an inch. Regardless, "absolute" zero is impossible haha

 

Well, when we’re talking .0** of an inch I feel as though that’s “0” considering most high end laser racks won’t even pick it up. Just saying, but this was all measured via laser. Computers aren’t always right. Sometimes you actually gotta do the thing.

 

At the end of the day could it have .020” of toe change somewhere in the travel? Yes. It very well could. But if we’re going to sit here and call that bump steer then I’m really not going to get into the topic a whole lot lol.

Considering I had a product on my front end that produced OVER 3”, I’m gonna stand my ground and continue to say the swing set has 0 as it could not be picked up through numerous rounds of measuring.

I can quite literally set my toe at full bump or full droop and it will be perfect at ride height. And I know this, because well. I actually did this exact thing.

Also, under further review. You’re forgetting the equation of caster change through the range of motion. Which is partially why you see me recording spindle angle on my original paper.

 

oh yeah I'd call it zero too. I'm just curious what "minimal" bump steer is according to the other guy you were talking about

 

No idea. All I know is mathematically for sure, 16” isn’t happening with a CV in the mix on an 8” shock and stock towers

 

@tacotunner06 is running stock outer cv and I believe 10" shocks? I think he said he's at 16 in the front. I'm actually not sure how wide his setup is.

 

What fucking tcase is that….

also your engine is on the wrong side of the firewall


Edit: this is the second time I’ve seen an aftermarket tcase and now I’m wondering if my NP261HD isn’t up to the task. I mean they come in trucks that make 1000+ lb-ft of torque, that was my reasoning behind saying it was fine.

 

Makes me happy that I’m at 15.5 bumped and strapped with the BTF kit. Really squeezing everything out of it it seems like.

 

He wants to put a bulkhead there lol. Kind of reminds me of this one

https://m.youtube.com/watch?v=u_sSwb9vaO0

 

Do the cv’s feel ok at full droop? Guys that run 1st Gens strap their travel an inch or two early due to premature rack failure at full droop - is that a 2nd /3rd Gen issue also? Chevys kind of the same thing also.

 

Yeah they feel fine. 454 said he strapped it about an inch before anything started binding, that way when the strap stretches I don’t get into trouble.
I have the JD slide rack with double sheared heims, and everything feels really happy.

 

I’m just shocked there’s enough uniball left in the uca for even 15…. I’m on vertical uniballs so it’s arm to spindle hit before I ever worry about uniball bind. And I could squeeze more out but I run out of plunge in the 934’s need to build a completely different geometry kit if I want to get anymore…

 

Yea very small amounts of bump steer isn't so bad. One of those things where it isn't ideal on paper but irl function it ends up not being as bad as it seems. Reason being is that a small amount of bump steer has similar effects to having a small amount of toe-in or out with your alignment. Ideally, with a fresh alignment, the front wheels should be perfectly straight. In irl function we got a long wheelbase rwd vehicle with big pliable sidewalls and the tires are gonna want to spread at speed ...so you set up the alignment with a small amount of toe-in to account for that, even though someone drawing up the truck in cad without this practical knowledge (average engineer these days lol) would have a fit about it. Same thing at full bump; bump steer shows up as a little bit of toe-in at full bump but a small amount is okay because the tires are going to want to spread anyways with the upward force and camber change the ifs gives when hitting something hard enough to get decent bump travel. The negative effect there would be if you only hit something on one side, then the truck deflects away from that side same as it would with heavy toe-in. At droop the opposite. The bump steer shows as toe-out which makes the truck a little less stable as it would make the tire want to climb outwards over any changes in the surface. But, again, in irl function that's not so bad because the forces on the suspension would have to be inherently minimal for the suspension to reach significant droop so there isn't much friction to pull the tire in any direction during major droop events - the effects end up being negligible

 

At what point do you stop calling it a Toyota still? Not much left of one anymore

 

It's an atlas 4. 3.8 main case and 2.72 doubler. I wish I got the divorced tcase though, would have made life a bit easier.

I'm sure your case will be fine man

No, not much left at this point hahaha. Some regrets... I miss driving!!

 

I still attribute my slide rack failure to the amount of toe in at full bump. It was over 2”. Clevis’s on both sides were caved in. So far the heim smashed the bolts.. I can’t even imagine the pressure that was being applied with the amount of bump steer.

It may be hard to notice and pick out to most. But it’s definitely going to be hard on parts. Just don’t see it any other way. So I don’t fully comprehend so many just shrugging it off.

 

Yea where toyota put the factory steering mount on the spindle is a bit of a head scratcher. Like they went through the effort to make a forged steel spindle so they could get such a huge spread between the upper and lower ball joints but still keep weight and space constraints down, and found a great solution for the 1st gen LBJ issues ...but then they put the steering mount in a shitty spot for bump steer ...and ditched the first gen steering layout for one that's got much shittier Ackerman geometry. I'm not gonna pretend i know better than their engineers but it's a bit of a head scratcher. There must be some benefit i'm missing