A suspension question for engineers
- Thread starter 1985taylor1925
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1985taylor1925
Senior Member
This is off the main topic, but being a VW guy, have you ever driven a Touareg? Basically identical to the Porsche Cayenne suv. The diesel version gets phenomenal reviews. They don't do well for reliability. But apparently they ride like a dream. And you can get the first gen with a v10 diesel that makes 553 ft/lbs of torque! I would love to test drive one
absalom
New member
That's so funny you say that. I'm actually considering getting a 2011+ Cayenne Turbo or diesel for work, and selling my wagon. My only concern is a VW auto tranny
A.Wilson013
New member
Have you tried tightening down the steering rack guide thing?
I was an engineer for awhile, but the kind that makes things explode. So... Maybe not your target audience.
1985taylor1925
Senior Member
Hmm . . . no in fact, the lca and uca bushings are literally the only things I haven't replaced in my front end. I have often considered they might be the issue. But Ive evaluated them many times while doing front end work, and never been able to find any slop in them. I actually just looked at them two weeks ago. I used a jack to press on each of the 4 lca bushings, one at a time, to see if I could get them to shift in any direction. They were all really tight. Non the less they have 240k miles on them, and could be contributing to the jitters
1985taylor1925
Senior Member
I looked at the Cayenne, but the VW is basically the same thing, made in the same factory, and cheaper since it doesn't have the word Porsche attached to it. Plus parts and repair costs would be cheaper, I think. I would love to test drive a Touareg though. My only aversion is the looks. The lines are a little too rounded and weak. But, when you see a Touareg going down the road they look pretty sharp. But man, I want that diesel!
I think you should start there.
1985taylor1925
Senior Member
Im running a Safari LTD rack that's only a year old. Rack guide is tight.
absalom
New member
I hate to say it, but until you replace those bushings (both upper and lower), this thread is meaningless. I assure you, the difference will be astounding. I mean, its fair to assume these vehicles would've never garnered the reputation that they have, if they were sloppy and unstable beasts from the factory. Bushings are cheap on Amazon, and don't take too long to install. Get on it
This is what you want.
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1985taylor1925
Senior Member
I hate to say it, but until you replace those bushings (both upper and lower), this thread is meaningless. I assure you, the difference will be astounding. I mean, its fair to assume these vehicles would've never garnered the reputation that they have, if they were sloppy and unstable beasts from the factory. Bushings are cheap on Amazon, and don't take too long to install. Get on it
This is what you want.
Well, I went out and looked at the lower a arm bushings again today. Spent about an hour trying to diagnose any movement in them, and it turns out that I can get them to move. Fairly easily actually. So I think you are correct. I will replace them with the poly bushings. I do believe that will eliminate much of the characteristic 'Jitters" in my front end.
I have some hair brained ideas. But hey, it generated some discussion and I learned some new things. And, Im not giving up on this idea just yet! More to come . . .
What Im going for is a better on-road ride, so for me solid axle wouldn't be a good idea. Although it would be solid, and easier to work on
absalom
New member
And based on what you said, I went out and test drove a 2016 TRD pro 5th gen at Toyota Tempe. It drove decent, perhaps even a slight increase in stability over mine. However, it redoubled my suspicions. I'm 100% sure it's your bushings at this point. It also made me really appreciate my truck even more, 99% of the handling and driving comfort for less than 25% of the cost of the 5th gen.
1985taylor1925
Senior Member
I know this is all meaningless without actual measurements and calculations. But this is what I was getting at.
Picture of my 3rd gen, compared with my dads 09 Tundra.
The angle on the Tundra tie rods is less severe than on the 3rd gen as you can see. On the Tundra the tie rod is nearly in line with the steering rack. It makes me wonder if the 3rd gen does have something very close to true ackerman, while the Tundra follows the statement I quoted earlier which said "Modern cars do not use pure Ackermann steering, partly because it ignores important dynamic and compliant effects". And based on this, if I could slightly tweak the design. Again, its all conjecture until I actually apply some numbers to it, which I admit at this point I don't completely know how to do.
I was thinking something like this.
Pushing the tie rod back around an inch. There would still be a forward angle on the tie rods, which should still produce the ackerman effect to an extent
Picture of my 3rd gen, compared with my dads 09 Tundra.
The angle on the Tundra tie rods is less severe than on the 3rd gen as you can see. On the Tundra the tie rod is nearly in line with the steering rack. It makes me wonder if the 3rd gen does have something very close to true ackerman, while the Tundra follows the statement I quoted earlier which said "Modern cars do not use pure Ackermann steering, partly because it ignores important dynamic and compliant effects". And based on this, if I could slightly tweak the design. Again, its all conjecture until I actually apply some numbers to it, which I admit at this point I don't completely know how to do.
I was thinking something like this.
Pushing the tie rod back around an inch. There would still be a forward angle on the tie rods, which should still produce the ackerman effect to an extent
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1985taylor1925
Senior Member
That's interesting. Ive never been in a 5th gen. What about wind noise, and drive line smoothness?
absalom
New member
Wind noise, and nvh in general, is greatly reduced. It's a new vehicle with a metric shitton of sound deadening. You could achieve a similar effect by lining your entire truck with FatMat. However, I achieved a staggering 12.3 mpg for the duration of my test drive. Absolutely horrid if you ask me. I'll stick with my 3rd gen and earn a nice 10% return on the savings by picking up some nice mutual funds.
1985taylor1925
Senior Member
Ive done about 50lbs of Rattle Trap in my truck so far (doors and hatch area). I plan on doing the rest eventually. It does make a big difference.
Eh, I'm loosing faith in stocks and funds. Not just in the U.S., but in all markets. Real estate is the way to go. Even in a severely depressed economy people will always need a place to live. Rental properties and flips. By the way, Scottsdale from what I have read, is a great market for real estate right now.
this thread is a champion of eclecticism and random information
hounddogman
New member
Good read but now I need to go buy control arm bushings .
If you are actually interested in suspension design, look at the Caroll Smith series of books. He gives a really good explanation of a lot of important suspension design topics and explains what changing different parameters does to different ride qualities. I believe the book you want is either perform to win or engineer to win.
I did a little suspension deign in college and you are talking about a world where fractions of a degree or fractions of an inch change characteristics drastically. Attempting to reverse engineer suspension without a means of accurately measuring the vehicle is extremely difficult if not impossible.
Glad you found your bushings are shot, I'm sure it will ride better when they're replaced!
I did a little suspension deign in college and you are talking about a world where fractions of a degree or fractions of an inch change characteristics drastically. Attempting to reverse engineer suspension without a means of accurately measuring the vehicle is extremely difficult if not impossible.
Glad you found your bushings are shot, I'm sure it will ride better when they're replaced!
After this thread I have paid more attention the the "front end" handling of my 4R. I can honestly say it drives just as good as my 2nd gen Tundra. As mentioned, the shorter wheel base and narrower body will tend to exaggerate any bump in comparison to the semi-long truck.
I barely need to hold onto the steering wheel of the 4R and find myself just keeping pressure on it with a finger or 2, despite any differing road conditions. The tundra likes to track around more, but I am attributing it to the wider tires and the larger wind area.
In comparison, I was able to let go of the steering wheel for a good couple blocks on the expressway and it tracked great with no input. My truck would had driven into the guardrail over the same distance.
My two side by side.
2015-09-14_12-51-30 by RoyBelluomini, on Flickr
2015-10-13_11-13-52 by RoyBelluomini, on Flickr
I barely need to hold onto the steering wheel of the 4R and find myself just keeping pressure on it with a finger or 2, despite any differing road conditions. The tundra likes to track around more, but I am attributing it to the wider tires and the larger wind area.
In comparison, I was able to let go of the steering wheel for a good couple blocks on the expressway and it tracked great with no input. My truck would had driven into the guardrail over the same distance.
My two side by side.
2015-09-14_12-51-30 by RoyBelluomini, on Flickr2015-10-13_11-13-52 by RoyBelluomini, on Flickr
