A suspension question for engineers

For the record, NO CAR, or truck has 100% Ackerman.

Funny that you think the 3rd gen has a tight turning radius, because the rack is very limiting in that sense. All the SAS crawlers use boxes, while the sand fairies sometimes use a rack. Oh, did I say that out loud?

:humble:

I think the 1st gen uses a steering box right? I should know, since I have an 88. But Its in Wisconsin right now, and Im in Wyoming. Havent owned it for long and haven't done any work on it yet.

So what happens with the tire angles when turning then, if they don't use 100% ackerman? Im assuming most vehicles use that concept, but not to the full angles to be true ackerman?

That's steering arm length.

Ok, so then my idea is to slightly extend the steering arm length without eliminating the ackerman effect too much. Im thinking that the geometry MIGHT allow a small amount of space for modification, to where I could reduce the ease in which the front tires move horizontally, without compromising the necessary ackerman angles.

I know every part of the front end is designed by Toyota with a purpose, but EVERYTHING can be modified or improved. Case and point, Toyota started front mounting the racks on the 4th gen, because its a better design
 
It is very rare for "the internet" to do a better job of re-engineering something on a Toyota than the original design.

I am conflicted on this point. Not that "the internet" can do a better job.
Sometimes I think 'yep, them engineer's really got it right and know whats up!'
And sometimes I see the 'known issues' on vehicles and remember they were 'engineered'.
 
I don't believe any of you are engineers, because no one has said they're an engineer. Engineers, and engineering students, ALWAYS say they're engineers. Repeatedly.
 
4-Ripcord is a suspension engineer for Honda. I'm gonna go ahead and say he knows what he's talking about.

I'm an engineering student, and have no good input towards this, therefore I stayed out of it. Alex is right though, too many engineering students seem to think they are engineers after they finish their freshman year...
 
Anyway, you don't have to believe me. Im just some guy on the internet that answered the call. Give it a shot if you want, just don't say I didn't warn you.

No, I would never just give it a shot and risk my life with a half-baked idea. That's why Im specifically talking to you engineers about it. It would be a whole process for me, figuring out if it would work, figuring out the angles, building a model, and then figuring out a way to test it on a vehicle. I have learned this though, engineers don't like their expertise being questioned. :boxer: My buddy is an engineer in Colorado, and we love to argue haha.

I am conflicted on this point. Not that "the internet" can do a better job.
Sometimes I think 'yep, them engineer's really got it right and know whats up!'
And sometimes I see the 'known issues' on vehicles and remember they were 'engineered'.

The only thing I pulled from the internet was a quote from wiki, which is cited from a book on race car dynamics. And yeah I agree with you, Toyota engineer is excellent. I love my 3rd gen. But obviously things can be tweaked. I mean how many people on this forum DONT have a suspension lift, which changes the geometry. All Im trying to find out is if theres a way to make the 3rd gen front end more stable
 
I'll admit my approach was not the most constructive. Let's pretend we are good little engineers and just look at the root problem and the cause.

This is your main complaint, yes?
And my front end still jumps around horizontally over any decent sized bump. Ive always felt that this is a dangerous condition at highway speeds.

Ill start off by asking how long it has been since you had an alignment. Sure seems like a situation of unbalanced static toe-in.
 
I don't believe any of you are engineers, because no one has said they're an engineer. Engineers, and engineering students, ALWAYS say they're engineers. Repeatedly.

From my experience, credentials aren't a substitute for knowledge and those with knowledge don't use credentials in forums. We know who's who. :)

Need to put this in the 4rth/5th gen forum?
 
I'll admit my approach was not the most constructive. Let's pretend we are good little engineers and just look at the root problem and the cause.

This is your main complaint, yes?


Ill start off by asking how long it has been since you had an alignment. Sure seems like a situation of unbalanced static toe-in.

Less than three months ago. But, its always been an issue with my truck. Ive had many alignments over the past five years with all the front end work Ive done. Have never been able to make the front end feel right. Even with the rear mounted steering rack, with everything being newish and tight the front end should be solid. But it still jumps around. Im now at basically stock suspension in the front, with 99 coils on taco 5100 bilsteins, on the lowest setting. Tires are A/T and one size over stock, so that contributes to a rougher ride. But that doesnt explain the tendency of the tires to move horizontally
 
Less than three months ago. But, its always been an issue with my truck. Ive had many alignments over the past five years with all the front end work Ive done. Have never been able to make the front end feel right. Even with the rear mounted steering rack, with everything being newish and tight the front end should be solid. But it still jumps around. Im now at basically stock suspension in the front, with 99 coils on taco 5100 bilsteins, on the lowest setting. Tires are A/T and one size over stock, so that contributes to a rougher ride. But that doesn't explain the tendency of the tires to move horizontally

If you have the means to do so, I would recommend you take it to an alignment shop and have them measure the toe of both sides at various ride height positions. Both compressed, normal, and lifted up a bit. This will enable you to see which side is the one most impacting the steer condition.
 
If you have the means to do so, I would recommend you take it to an alignment shop and have them measure the toe of both sides at various ride height positions. Both compressed, normal, and lifted up a bit. This will enable you to see which side is the one most impacting the steer condition.

We like to call this Toe curve change, it's the way we diagnose bump steer. If you find a knowledgeable shop that has a John Bean V3400, or V2400 aligner there is a sub routine in the software for doing exactly what Ripcord is asking for. There is no other aligner with that software. It also has a subroutine called ProAckerman which can actually measure the Ackerman conditions. NO OTHER aligner in the world can do that. Heck most manufacturers require extensive Trigonometry to figure it out. Or you can do it the old fashioned way, but then the tech REALLY needs to be knowledgeable. Good luck with THAT. heh heh

:artist:
 
I don't believe any of you are engineers, because no one has said they're an engineer. Engineers, and engineering students, ALWAYS say they're engineers. Repeatedly.

I'm not an engineer, but I play one in my garage. And I do have an IBall, so there is that. And I can engineer, no license required.
Life is fun!

:grouphug:
 
My truck is rock solid on the freeway. Perhaps you could drive another 3rd gen, and compare the experience. I've also driven 4th gens, and the increase in stability was difficult to notice. However, when I hop in my TDI wagon, the stability factor increases about ten fold. I think it's just the nature of a body-on-frame truck, with larger than stock tires, and raised suspension; to be slightly less "precise".

From your posts, you seem to looking for a car-like ride, which I can certainly understand. Have you considered a small, second car to satisfy that itch? These are big, somewhat-crude trucks, and they'll never handle half as well as a car.
 
another thing to consider is the god damn slip joint, a couple tack welds on it, and you will notice a huge difference. my truck used to get blown around by the wind, after welding the slip joint the steering improved massively. that being said if any of your bushings are bad they should be replaced front or rear axles.
 
Also, which way is it wanting to wander after bumps? The trac bar in the rear pushes the rear of the body to the right making the truck feel like it is turning left.
 
The cheapest way to gain stability is, a lowering kit, 17 inch rims, and low profile tires, and a 200 dollar stereo with lots of bass...
 
I don't believe any of you are engineers, because no one has said they're an engineer. Engineers, and engineering students, ALWAYS say they're engineers. Repeatedly.

:rofl: Like Crossfit members.

Less than three months ago. But, its always been an issue with my truck. Ive had many alignments over the past five years with all the front end work Ive done. Have never been able to make the front end feel right. Even with the rear mounted steering rack, with everything being newish and tight the front end should be solid. But it still jumps around. Im now at basically stock suspension in the front, with 99 coils on taco 5100 bilsteins, on the lowest setting. Tires are A/T and one size over stock, so that contributes to a rougher ride. But that doesnt explain the tendency of the tires to move horizontally

My worn out truck with stock shocks and bushings does not feel like this? Maybe it's "too tight" now and any little input has a big reaction?

Also, I think some of the issue may be the high COG and short wheel base. Personally I think you are chasing the wrong problem. I have a Gen 2 Tundra and over rough road I think it jogs around more than the 4R. I would drive a stock 3rd gen 4R and see if you experience the same issue.
 
If you have the means to do so, I would recommend you take it to an alignment shop and have them measure the toe of both sides at various ride height positions. Both compressed, normal, and lifted up a bit. This will enable you to see which side is the one most impacting the steer condition.

I can try this. Though, with my truck as close to stock height, I don't see why there would be any issues with getting a good alignment. I have the printout from the last alignment, and everything is good.

We like to call this Toe curve change, it's the way we diagnose bump steer. If you find a knowledgeable shop that has a John Bean V3400, or V2400 aligner there is a sub routine in the software for doing exactly what Ripcord is asking for. There is no other aligner with that software. It also has a subroutine called ProAckerman which can actually measure the Ackerman conditions. NO OTHER aligner in the world can do that. Heck most manufacturers require extensive Trigonometry to figure it out. Or you can do it the old fashioned way, but then the tech REALLY needs to be knowledgeable. Good luck with THAT. heh heh

:artist:

What kind of voodoo mumbo-jumbo are you talking about?? That's interesting info actually. I can look into the shops in my area, but I doubt Ill find a tech who has a clue about that software. I hate going to shops. Hate haggling with stupid people. Hate trying to get them to care about your vehicle enough to where they will actually attempt to do good work

My truck is rock solid on the freeway. Perhaps you could drive another 3rd gen, and compare the experience. I've also driven 4th gens, and the increase in stability was difficult to notice. However, when I hop in my TDI wagon, the stability factor increases about ten fold. I think it's just the nature of a body-on-frame truck, with larger than stock tires, and raised suspension; to be slightly less "precise".

From your posts, you seem to looking for a car-like ride, which I can certainly understand. Have you considered a small, second car to satisfy that itch? These are big, somewhat-crude trucks, and they'll never handle half as well as a car.

No, Im not comparing to a car. Though, I do eventually need to get a car. But my dad has an 09 Tundra, and my brother has an 11 GMC sierra super duty, and they both feel so much more stable in the front end than my 3rd gen. Total Ive driven 3 3rd gens, 1 4th gen, and my 1st gen, and then a ton of other trucks. And my 3rd gen has the worst front end of any of them. Unfortunately, I think the only cures would be front mounting the steering rack, and then getting a progressive coil matched to a properly valved shock.

another thing to consider is the god damn slip joint, a couple tack welds on it, and you will notice a huge difference. my truck used to get blown around by the wind, after welding the slip joint the steering improved massively. that being said if any of your bushings are bad they should be replaced front or rear axles.

Check out my first post. Ive already done the tack weld, and replaced the intermediate unit. The movement is at the tires. Nothing between the steering wheel and steering rack is loose.

Also, which way is it wanting to wander after bumps? The trac bar in the rear pushes the rear of the body to the right making the truck feel like it is turning left.

Yeah, I know how the panhard bar affects handling. At highway speeds when hitting a big whoop you can feel the rear end shift slightly as the suspension compresses. But my trucks issues are all in the front end. The wheels shift in either direction, consistent with which tire is contacting the bump. The steering wheel shifts as well. Everything between the rack and steering wheel is very tight. The whole system "jitters" (hence the name of my truck) and moves. On a bad road, the front end just feels like its all over the place. And bear in mind this is with a front end with almost everything being newish. And with taco 5100s and 99 coils on the lowest setting (no preload on the coils). Sitting very close to stock height. The only thing I haven't replaced that may be of significance, is the power steering pump.

The cheapest way to gain stability is, a lowering kit, 17 inch rims, and low profile tires, and a 200 dollar stereo with lots of bass...

True that

:rofl: Like Crossfit members.



My worn out truck with stock shocks and bushings does not feel like this? Maybe it's "too tight" now and any little input has a big reaction?

Also, I think some of the issue may be the high COG and short wheel base. Personally I think you are chasing the wrong problem. I have a Gen 2 Tundra and over rough road I think it jogs around more than the 4R. I would drive a stock 3rd gen 4R and see if you experience the same issue.

That's interesting, because my dads 09 Tundra TRD package feels ten times better than my 4runner. His front end is so much more solid and stable on rough roads, theres just no comparing the two. But, you are correct in that my truck seems to be ultra sensitive to any input from the road. And yes, the 3rd gen design certainly contributes to the handling qualities. Even more than the short wheel base is the narrow width and short front control arms.

I'm still unclear exactly what it is you're describing here. What horizontal movement?

I guess horizontal movement isn't the best way to describe it. By horizontal movement I mean the tires and steering wheel move with ease in response to input from the road.
 

Members online

Forum statistics

Threads
278,309
Messages
3,554,074
Members
248,016
Latest member
Advally Service

Trending content

Back
Top