[The Scifi Guy]

My project car's front suspension was a bit cocked up when I got it. The upper left control arm was bent and one bushing there was coming out. The lower right control arm was also bent.The left upper arm had a collection of different washers, including some SS ones from the hardware store(Not shown in the pic) and one fat washer that measures .36". The right side upper arm just had an assortment of same thickness washers. I don't recall the exact arrangement and it now been months and I forget where everything was, but clearly some monkey business had been going on. Also, the two bolts that hold the left lower control arm's cast iron pivot and the spring saddle to the bottom of the front suspension were both replaced with shiny, lower grade, fine thread bolts. Yup, some sort of monkey business was afoot.

So, tomorrow I start reassembly and I had to get the FSM out. The arrangement of the washers affects the caster of the front suspension. The book says that, from the factory, I should have two .24" spacer washers on the upper control arm bolt, one in the front and one in the rear. I've only got one .36" washer and a bunch of thin and a little bit thicker washers. I don't remember there ever being 2 same size spacer washers, front and rear, on my previous cars' upper a-arms. There was always a thick and a thin one. I would usually put the thick one at the rear position on the a-arm bolt and the thinner one at the front position, in order to have more caster.

I've read the FSM instructions and I pretty much understand what to do. I have basically .48" of space, front and rear combined, to work with and I have one .36" fat washer. So, fat washer at the back, thin washer at the front on one side of the car. On the other side, a thin washer at the front and probably 3 thin washers at the back. Unless, of course, I can find another .36" washer in my hoard or make my own washer out of scrap metal and hole saw.

Okay, fine and dandy. Here's the question that this whole thread is about: What is the "crown" of a washer?

See the pics below from the FSM. Observe what is said in section #7: "Make certain that the crown of the plate washers shows outwards". WTF does that mean? What "crown"? "Shows" outwards? WTF does that mean?

5 of the biggest washers I have are "domed" or caved in, depending on how you want to look at it. I always assumed that "domed" washers on my car were damaged, bent, washers and that they were originally flat. So, now I'm guessing that they were made that way for a reason. I am now assuming that those domed washers are what the FSM says are "plate" washers(see diagram).

Are they calling the "domed" side of these washers the "crown"?

Am I supposed to put the "domed" side of these washers facing OUTwards at each end of the big bolt?

Also, notice on the right side of the diagram that there is a dark area labeled as the "rubber dampening ring". I don't remember every seeing a rubber washer in my front suspensions. Gil had mentioned to me that suspensions that use the oem rubber cartridges need to have the rubber washer to prevent "knock" during hard cornering. Notice that there is only one at the rear, but there isn't one at the front. Gil sent me 3 used rubber ones.

 

[Knorm65]

A trick to improve handling is to put the entire .48” to the rear of the control arm to increase caster.

All of my original washers had a toothed pattern on them in the center. I assumed that was the crown.

 

[The Scifi Guy]

Hmmm....interesting. Yeah, I've got those marks on some of my washers also. But I assumed they came from the serrated ends of the inner tubes of the bushings biting into the washers.

 

[opelmeister]

Sorry I can't tell you which goes where but to the best of my knowledge the serrated and the crowned washer are factory, not distorted or scared. If they're the washers that I sent as spacers, the thickest washer, may be the one used with the bolt to secure the crank pulley. That's if those are the spacers I sent? I seem to recall the serrated washers are from the the control arm.

 

[The Scifi Guy]

I actually haven't opened your box yet. It gets opened today. We'll see what I can cobble together.

 

[The Scifi Guy]

Here's some very useful information that someone posted about why you only want one one-piece spacer washer per location and the purpose of the rubber washer. This info only applies to using the stock rubber cartridge bushings:

<<<
Stephen Vaillancourt
Someone might correct me, but my understanding was that the dome part, convex side of the washer, faces the rubber. Turning them dome side out pinches the rubber, which you don't want to do. In the factory rubber bushing setup no part of the suspension bushing is supposed to rotate; the center of the bushings get tightened up solid with the suspension crossmember and the outer part is solid to the arm so arm movement is entirely a function of rubber flexing. That's why the final tighten on that upper bolt is done with the car on the wheels fully assembled, or with the spring compressor set to normal ride height, so the rubber is tightened in the neutral position and can flex both directions.
My first Kadett was a 1.1l car set up for drag racing. The previous owner had jacked it up, loosened and then re-tightened the suspension bolts, and the bushing preload was good for nearly 2" of front end lift. It dropped as much when I reset the front end. On a heavier 1.9L car it would be less pronounced, but you absolutely can see and feel the difference in handling if the bushings aren't set the same, and the they will wear out at different rates.
That is also why the manual specifies only one washer per location. If you stack up washers you're essentially creating a Torrington bearing, and then the bushings might rotate. The last thing you want is the car set in a curve suddenly shifting because the bushing spun under load and dropped the effective spring rate at the one corner.
This is a situation where I think you need to call Gil or Todd and get some washers.
The rubber damping ring always made more sense to me in terms of braking than cornering. Slam on the brakes and the spindles try to rotate the tops towards the front of the car as the calipers are grabbing the rotors. That flexes the upper bushings to move the upper arms towards the front of the car. Since there's a little slop in the whole works to allow those bushings to flex for arm movement they also flex axially a bit too, and the rubber ring adds just enough to keep all the metal bits from touching. You can't accelerate the front the same way, or get fast enough in reverse for a brake stab there to have the same effect the other direction, so only one ring is necessary.
If you have extras would it hurt to put them front and rear? Probably not, but the rear is the only place I would consider essential. >>>

 

[okieopel]

Okay, fine and dandy. Here's the question that this whole thread is about: What is the "crown" of a washer?

The crown is simply the raised area.
Both a road or a gun barrel can have a crown.
This illustration of a crowned road may help.

 

[opelspyder]

There are three thicknesses of special washers that are used for adjustment of caster. On a GT it is typically the thickest one, and the thinnest one. They equal a certain thickness when used. But you have one per side. A lot of Kadetts I’ve done had two of the middle thickness washers on each side of the control arm. These washers have a serrated set of teeth on both sides. You other cupped washers will have a serrated marking from the spacers inside one part of the washer. That tells you it was for the inside. On the lower control arm washers, different years used slightly different washers. But usually they are nice and flat with teeth marks on one side, and a lock washer marking on the outside. I do not think it is recommended to use both washers on one side Kyler. You are supposed to get the correct thickness if you need to adjust these, but the only way to do that is to have taken a bunch of front ends apart that had the other spacers installed.

 

[Knorm65]

There are three thicknesses of special washers that are used for adjustment of caster. On a GT it is typically the thickest one, and the thinnest one. They equal a certain thickness when used. But you have one per side. A lot of Kadetts I’ve done had two of the middle thickness washers on each side of the control arm. These washers have a serrated set of teeth on both sides. You other cupped washers will have a serrated marking from the spacers inside one part of the washer. That tells you it was for the inside. On the lower control arm washers, different years used slightly different washers. But usually they are nice and flat with teeth marks on one side, and a lock washer marking on the outside. I do not think it is recommended to use both washers on one side Kyler. You are supposed to get the correct thickness if you need to adjust these, but the only way to do that is to have taken a bunch of front ends apart that had the other spacers installed.

Rally Bob and P.J. Have both reccomended it. It improved my handling on track significantly.
See below. I ordered spacers of the correct thickness per recommendation from Rally Bob several years ago. You aren’t changing the overall thickness. If you do, then you have to grind some off of the front to adjust.

Factory setting is 3degrees (+/-1). Unfortunately, lower control arms on the GT are notoriously weak and they bend backwards, changing the caster. It is a good idea to reinforce those control arms and OGTS is selling the kit. Rally Bob thinks that even upper pivot tubes are not always welded in the correct position.

Caster is adjusted with two washers of different thickness. Total width of both washers should be 12 mm (0.48”). They should fill the space between the pivot tube and upper control arm. Factory recommends positioning the thinner one toward the front and wider one toward the rear of car. You can position both washers at the rear for increased caster. If this is not enough, you will still have to grind the tube at the front and add washer at the back of equal thickness.

I have shortened tubes 3 mm and made two more washers (1 mm and 2 mm). Together, they are not exceeding 15 mm thickness (12 mm OEM + 1mm + 2 mm). That gave me more combinations for adjusting and equalizing caster between left and right wheel.

 

[The Scifi Guy]

The TOTAL thickness or gap between the a-arm and the suspension is .48" or 1/2". The various washers you use on each side of the car need to add up to 1/2". The "middle" thickness Keith mentioned is .24" or 1/4" and you would put one of each at the front and the rear of the A-arm bolts. The book says that GT's came with .24" ones, but I've never seen that, they always have a .36" and a .12".

I, too, had heard PJ say that it's okay to put all the spacer washers at the back, but he also had ridiculous wide wheels and you get tracking issues when you're super wide at the front. Hence, PJ and I had to add electric power steering to make the situation more manageable for various reasons. My particular need was because I didn't go super wide and cheated by getting high negative offset wheels. Big steering problems doing that. PJ got the electric PS because he could barely turn his wheel at low or no speed. But, both situations benefited from high castor. If my quote from Steven Villiancourt is true about it being a bad thing to put 2 washers next to each other, that would only apply to the rubber oem bushings, in which, the rubber is bonded to the outer shells and the inner tubes. If you are using poly bushings you can stack up all the washers you want.

I think Okieopel nailed the answer: Crown of the road = crown of the washer. The domed side is the crown. I'm virtually certain that the serrations on the outer plate washers is caused by the center tubes of the bushings biting into the washers. The .12", .24", and .36" spacer washers should also have evidence of serrations on them due to the inner bushing tubes biting into them. I'll check this and take pics.

 

[The Scifi Guy]

Update: I had to make my own .36" spacer washer out of scrap metal. Surprisingly time consuming. I also noticed something about the upper control oem rubber bushing cartridges: The rubber is NOT bonded to the outer shell and inner sleeve, you can slide the parts in and out of each other, just like when using poly bushings. The rubber in the lower control arm bushings IS firmly bonded to the outer shell and inner sleeve. At least, that's the way it is on the newly manufactured cartridges I have. Therefore, only the lower control arm bolts need to be only tightened when the car is fully assembled with the car's full weight on the suspension and in the neutral weight position. AND, theoretically, using multiple spacer washers against each other should have no adverse effect. I did things the right way, but I now realize that I could have just stacked up a bunch of thin washers to make a .36" washer. At least, that's what I have determined based on the observation that the upper control arm bushings are free-floating.

Aarrgghh! I thought I could reuse the spring saddles that came with this car, even though I noticed that one was badly worn down. I figured that I could just put the worn down driver's side on on the passenger side and things would sort of balance out. Upon assembly, I just didn't like how it all looked. I've gone to great trouble, expense, and time to rejuvenate this suspension and it's a PIA to replace the spring saddles with the suspension on the car. So, I'm now forced again to stop working on my front suspension and car in general until I can get some decent spring saddles. Aarrgghh!