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94 Fleetwood Brougham
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Discussion Starter #1
Well, I finally got enough time to get under my 94 FWB and measure the tie rods. One was 1/2" inch longer than the other. Not good. Just read an article in Circle Track by Sleepy Gomez on intentionally setting tie rods to unequal lengths to change the Ackermann effect in turns.

Well, in a street car, they NEED to be the same, as we don't turn left or right only all the time. Mine were off. I suspected it for a long time. I changed out my drag link a few weeks ago, and it appeared the gorilla mechanic who messed with it last aligned it WITH a bad drag link.

Rules: There MUST be an imaginary line to be able to be drawn from the axis or pivot of the LCA (Lower Control Arm) through the inner tie rod ball. And the lower ball joint must be the same axis as the outer tie rod. Assuming our cars haven't been damaged in an accident, this requires that both tie rods be equal.

Without them being equal, the steering (remember, we have variable ratio as well as some with variable effort) is "0" at true center, and the farther away from center you go, the more the ratio increases. In my case, the ratio had already started to increase in right turns before I even started to turn, and the left, was starting at more ratio, to 0, back to increased ratio, causing my car to be twitchy in right turns and lazy in left. Annoying to say the least.

I measured from the grease fitting on the outer joint to the inner grease fitting, observing the "end" of the rod length from under it visually. This gave me a very close overall length of the tie rod to be 20 1/8.

So according to the results that Sleepy Gomez showed, my Ackermann Effect was also very screwed up also. The variable rate box showed more of an issue to daily driving.

Now steering feels good again, still slightly off, but likely due to me trying to dial in the alignment pull with bad tie rod lengths.

Make sure you find a good shop that will ensure the alignment is perfect and not just dr. it up to get you our the do.
 

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'80 Fleetwood Coupe, 1994 and 1995 Mercedes 140 Coupe
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I've a question. Say you now have 2 equal tierod lengths now but the steering wheel isn't centered. What do you do to center it?
 

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94 Fleetwood Brougham
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Discussion Starter #3
Good question, (mine isn't perfect right now either). My thoughts are that:

1. Caster or camber is off (caster will make it pull, which would lead to non centered wheel)
2. Frame is damaged or control arms are tweaked
3. GM screwed up and didn't design something right.

I don't know how good the factory tolerances are, but I would expect them to be pretty decent. So it ~should~ center with the tie rods at 0 toe, and equal lengths.

Until I read Sleepy's article on the effects of the tie rod length on the car, I didn't realize how muich it affected it. If the mag is still out, worth getting for that article alone. There is often good tech in that one, but all too often it is geared towards a budget race car.

Anyone know what the definition of a "GM Metric Suspension" is? When I think of it I thought it was the 78-88 A/G Body. But I am wondering if it is the GM A/G/B/D bodies from 81-up.
 

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Discussion Starter #4
I have finally got enough time to dial in the pull on my suspension. Yes, I could take it to a shop, but then I wouldn't learn anything now would I??

Now that it is centered, I notice some slight difference in how it turns from center to left and center to right. To the left is tighter feeling. To the right is a bit looser, till it gets more into it the turn. So it makes it a bit annoying.

So, toe is set, caster is set, camber isn't. Left side camber is right around zero. Pass side it is slightly negative. My theory is the suspension camber at closer to zero keeps proper loading on the sidewall, where at a negative camber the outer sidewall is not as loaded, and has a slightly less 'preload', and less response to that direction.

I will be working on dialing in the camber this week to prove out my theory.

This might explain why GM has often kept a 0 to positive camber on cars, to improve steering response.
 

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Discussion Starter #5
General comments on setting caster. Even as small as 1/64" shims makes a significant difference in the car pulling to one direction or the other. If I had to guess, I would say a shim of 1/64" is enough to pull the car 2 feet over in the lane for 100 feet traveled (this is just a guess on what I have driven. If I could get them, I would llike to find 1/100 of a inch shims. I will have to find some metal that is approx that thin to fine tuning.

NAPA has shims, but for the $ they are fairly expensive. The "HELP" packages of parts has a package of shims that has them marked clearly and has a pair of 1/8", 1/16", 1/32" and 1/64" shims. This is very helpful in dialing in the alignment.
 

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The tiny differences you speak of can easily be effected by changing load in the car, and even just the amount of grease in the joints. The slightest amount of wear in any of the jointed components will also have as much effect as the tiny adjustments you're talking about. Personally, I think you're going way overboard on this stuff. As for maintaining exactly equal tierod lengths, I don't see where it matters. In "theory" maybe there's a reason, but in the real world, having one slightly longer or shorter in order to meet proper alignment specs only shows the slight amount of deviation there is in the chassis from the actual factory design specs. This can be for a million different reasons ranging from normal wear to past accident damage, to mistakes during the original build. If you think these steering adjustments are in need of "tweeking", you'd go nuts if you ever saw a semi-high mileage car on a frame rack.
 

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Discussion Starter #7
If we had constant ratio steering boxes, it would make less of an issue, but with variable rates, it matters more. I measured mine to be exact (with everything else in good shape) and the car tracks well now. Previously had a bad drag link that was nearly 1/8" to 3/16" worn. It was sad!

The article I read that started me on this "quest" for perfect alignment showed how little difference in tie rod length really had drastic effects once the wheels started to turn. The idea there is that you make all left turns, you can take some advantages of the unequal lengths. Slightly, yes. The article was noting 3/8" unqueal lenghts were seeing 9/16" and more once fully turned. Ever hear a car in a tar parking lot squeal in corners? Likely unequal length tie rods. There is ackerman angles at work, but this can make it really bad. I was seeing over 1/2" difference from one tie rod to the other in mine. The toe was ok, but the unequal lengths were what was driving me nuts in trying to align the car.

I agree, by the time everything is all worn in and settled you are right, it probably a suspension engineers nightmare. Control Arm bushings are likely next "bad" spot on mine.

I tweaked the camber today to get it back to where both sides are now with a visual appearance of equal (I will check later when I get a level surface that I can make some measurements on) and the vauge steering from center to right when I am at center is gone.

I will keep dialing in more caster to see how much I can make it take, as I feel that a car with the most caster is a much better driving car than one with negative camber and less caster. Better on center steering and more camber gain in corners is the benefits of higher caster.

As a comparisson, the S500 MBenz has 10 degrees caster. Where our B/D bodies have only 3 (factory recommended). Take a look at a MBenz when the wheels are turned full lock. That tire LEANS. Lots of camber gain in the corners while keeping good on center feel and response, and tire wear is kept minimal.

Did you have an alignment rack at the limo shop or did you farm that work out?
 

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A Mercedes is a whole different ball of wax. They vary the camber with toe. Take a Mercedes and do a full lock turn circle on some sand. You will see every tire tread mark in the sand. A Cadillac will scuff and the tracking will be off. I'd still rather have a Cadillac. The only Mercedes I'd trade my old 2 door Fleetwood for would be a mint 560 SEC:cool:
 

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Discussion Starter #9
You mean like this one?
http://www.waukeganautoauction.com/inventory_show.asp?stknum=F641

A friend of mine just picked up a 89 S420 for $1K. Decent shape, but needs a hood. On the way home from the auction the hood wasn't latched and....

Is this a similar suspension? Sounds like I need to crawl around under one.

How exactly is it setup? Not sure how you could vary camber with toe...
 

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I have not researched how Mercedes pulls this off until now. Still cannot find a good explaination. Google is my firend but I have to wade through a lot of sales oriented blather........

Stop posting links to cars like that!!!

That was my dream car 15 years ago.

Drive one if you ever get the chance.
 

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Discussion Starter #11
I thought I was the only one who seemed to really like them!
 

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Discussion Starter #13
I drove a proto 2000 S500 (ours was make in Oct 1998) and it was an absolute blast. $90K automobile though!!!
 

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N0DIH said:
If we had constant ratio steering boxes, it would make less of an issue, but with variable rates, it matters more. I measured mine to be exact (with everything else in good shape) and the car tracks well now. Previously had a bad drag link that was nearly 1/8" to 3/16" worn. It was sad!

The article I read that started me on this "quest" for perfect alignment showed how little difference in tie rod length really had drastic effects once the wheels started to turn. The idea there is that you make all left turns, you can take some advantages of the unequal lengths. Slightly, yes. The article was noting 3/8" unqueal lenghts were seeing 9/16" and more once fully turned. Ever hear a car in a tar parking lot squeal in corners? Likely unequal length tie rods. There is ackerman angles at work, but this can make it really bad. I was seeing over 1/2" difference from one tie rod to the other in mine. The toe was ok, but the unequal lengths were what was driving me nuts in trying to align the car.

I agree, by the time everything is all worn in and settled you are right, it probably a suspension engineers nightmare. Control Arm bushings are likely next "bad" spot on mine.

I tweaked the camber today to get it back to where both sides are now with a visual appearance of equal (I will check later when I get a level surface that I can make some measurements on) and the vauge steering from center to right when I am at center is gone.

I will keep dialing in more caster to see how much I can make it take, as I feel that a car with the most caster is a much better driving car than one with negative camber and less caster. Better on center steering and more camber gain in corners is the benefits of higher caster.

As a comparisson, the S500 MBenz has 10 degrees caster. Where our B/D bodies have only 3 (factory recommended). Take a look at a MBenz when the wheels are turned full lock. That tire LEANS. Lots of camber gain in the corners while keeping good on center feel and response, and tire wear is kept minimal.

Did you have an alignment rack at the limo shop or did you farm that work out?
No I farmed them out. I paid $35 for an alignment. For that kind of money, I couldn't justify giving up a bay in the shop. My original floor plan gave me room for an alignment rack but last minute construction changes forced on us by the township caused me to lose that bay.
Unfortunately, in my business the only reason I worried about alignment was to make sure I got maximum tire life. The tiny intricacies with respect to alignment were never explored, especially since we were driving in the most hazardous area of the country (the north east), and most of our drivers tended to hit every pot-hole and curb they could. Multiply that by 250 vehicles and you get an idea of how many alignment racks and techs I would've needed to try to gnat's-ass the cars alignment.
BTW, You mentioned variable ratio steering. As far as I know, the Fleetwood boxes are NOT variable ratio. I know the Corvette had that back in the 90's but the Fleetwood's didn't.
 

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im pretty sure the fleetwoods did. mine does and its an 1988. not sure why they would change that going into the 90's?
 
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