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grannyknot

changing camber using the strut insulator

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grannyknot    443

There are a few different aftermarket upper strut mounts available that allow you to change camber but all of the ones I have seen remove the vibration insulator of the stock unit and allow the road vibration to come up straight into the body of the car.  So, what if I burned out the rubber of the stock insulator and reposition the inner cup that holds the bearing and top of the shock so I would get 1.5 degrees of negative camber then filled the cavity where the rubber was with something that would do the job?  The liquid urethane that is used to secure modern windshields is the first thing that comes to mind but I'm sure there are a few things that could work.

I would have to calculate the amount of offset that would result in the camber I want and some way to hold the inner cups in that position while the compound cures,  any other problems that anyone can see that I might run into?

DSCN1864.JPGDSCN1866.JPG

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zKars    261

Not a bad idea. Not sure how much camber you get by just shifting the guts. 

Only one way to find out! Light up torch!  (I got lots of spares if you're worried about experimenting...)

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grannyknot    443
51 minutes ago, zKars said:

Not a bad idea. Not sure how much camber you get by just shifting the guts. 

Only one way to find out! Light up torch!  (I got lots of spares if you're worried about experimenting...)

Jim, this is TTT's, you can see how little they have moved the center hole off of center and that allows 1.5 degrees of camber. What kind of compound would you use to take the place of the rubber?

s30_spm2_large2small.jpg

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zKars    261

1.5 is good. More than I expected.

Energy suspension used to sell Urethane potting material. They don't any more.  You really can't afford anything weak in there, can you?  This isn't my area of expertise. Time for more experimention and torture testing.

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Namerow    118

Chris:  Why not contact Steve at 240Z Rubber Parts?  He's been casting soft and hard 'rubber' parts for a couple of years now and should be able to offer some useful tips on materials and processes.  Use the 'Contact Us' link in his website.

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grannyknot    443
11 hours ago, Namerow said:

Chris:  Why not contact Steve at 240Z Rubber Parts?  He's been casting soft and hard 'rubber' parts for a couple of years now and should be able to offer some useful tips on materials and processes.  Use the 'Contact Us' link in his website.

Excellent idea, will do.

Burn baby burn,

DSCN1874.JPGDSCN1875.JPGDSCN1876.JPGDSCN1877.JPGDSCN1879.JPGSo I think I would be looking at a repositioning the inner cup so it looked something like this,

DSCN1880.JPG

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Namerow    118

Another example of how 'creative destruction' can reveal the inner workings of an assembly that usually just gets taken for granted.:geek:

Does the inner cup make metal-to-metal contact with either the top cap or the spring perch, or does it 'float' 100% within the rubber?  If it floats 100% (and I'm guessing that it does), the thickness of the rubber that separates the top of the inner cup from the underside of the top cap is going to be important.  Do you have any sense, or way of measuring, what that thickness was/is for the original configuration?

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I'm positive there was no metal to metal contact originally. That's the whole point of the rubber isolation.

I think this is a really cool idea, and whether it succeeds or not, I love seeing the internal workings of something that was never intended to ever come apart.

I suspect the largest stumbling block to this project will be finding something that will stick to the metal as well as the original rubber did. I've got no experience in that field and have no input other than asking if you have considered using a rubber like the original? There are lots of people molding and vulcanizing rubber. The processing doesn't look that difficult if you can find suitable raw materials.

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grannyknot    443
11 hours ago, Namerow said:

 If it floats 100% (and I'm guessing that it does), the thickness of the rubber that separates the top of the inner cup from the underside of the top cap is going to be important.  Do you have any sense, or way of measuring, what that thickness was/is for the original configuration?

The inner cup does float completely but there is also an air gap that was molded into the the assembly to allow for movement, I had never noticed it before until I started destroying it.

DSCN1870.JPGIt is a very well engineered piece, also the rubber lip that is used to hold the inner cup in also wraps snuggly around the the horizontal bearing and limits water and grit from getting in.

DSCN1871.JPGI did contact Steve at 240z Rubberparts.com and he very kindly splashed the cold water of reality on me, here's what he had to say,

Chris, you will need a urethane rubber with a high Tensile Strength and a shore hardness between 70-90A. 90A being the hardest and most ridged.
you will need to degas the rubber in a vacuum chamber before pouring into the cup. Then it will have to put into a pressure chamber to cure.
Then cured in a oven for 8-10 hrs. 
If you dont degas and cure in pressure chambers, then you will get tiny bubbles and it will be very weak.
The rubber would also need something to bite into( iE a void or grooves), so it will not come out. If you just pour it into a metal cup it will come out freely.
 
I do not make any type of parts, if they fail they could cause any problems.
 
This seems to be a trial and error type of project. 
 
Steve
Owner
www.240zrubberparts.com
www.Datsun240zrubber.com
 
Well, I'm not prepared to go that far but just as I was about to plow ahead anyway I noticed this, the red pencil is pointing at the upper spring cap, in it's new position it will hit the inner wall of the shock tower sheet metal.
DSCN1883.JPG
So that has stopped me in my tracks for the moment, if I can't find a way to sort that out then I will have to leave the upper mount alone and get the camber from the lower control arm. Now although there are lots of different aftermarket LCA's to choose from all of them have also done away with the vibration control bushings. Got to think about this a bit. There has to be away to have the comfort of a stock setup but the performance of an aftermarket setup.
Edited by grannyknot

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zKars    261

How much can you gain by just slotting the stock mount holes toward the engine bay, and shoving the strut inward until the insulator housing hits the inside of the tower? 

I have also seen pictures of a stock LCA cut in half then an adjustable turnbuckle added to the gap to enable length adjustment.

My experience shows ride harness comes primarily from the T/C rod when it is hard mounted. Dropping the wheels into holes make a hell of crash to hear and feel when the TC rod has no compliance.

 Control arm bushings and upper strut mounts are not the big noise transferring items you might think.

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grannyknot    443
13 minutes ago, zKars said:

How much can you gain by just slotting the stock mount holes toward the engine bay, and shoving the strut inward until the insulator housing hits the inside of the tower? 

I have also seen pictures of a stock LCA cut in half then an adjustable turnbuckle added to the gap to enable length adjustment.

My experience shows ride harness comes primarily from the T/C rod when it is hard mounted. Dropping the wheels into holes make a hell of crash to hear and feel when the TC rod has no compliance.

 Control arm bushings and upper strut mounts are not the big noise transferring items you might think.

I could slot the stock mounting holes but then I would also have to modify or rebuild my strut tower braces, not sure I want to do that just yet.

DSCN0784.JPGAs much as I would like a bit more camber and I'll get it one way or another, more caster is what the car needs the most. I was going to order TTT's  T/C rods,

P1010012_0.jpgbut as you say I'll lose all of the vibration dampening. Maybe I should look at adding a welded in turn buckle to the stock T/C rods.

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