Massive caster variance Side to side
- Thread starter Boduke
- Start date
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Closing thoughts on this:
My main issue of massive caster variance i believe to have been cause by poly bush in the lca
And blown out strutrod bush. Forcing lower arm back and erasing my caster on one side. As andysauto1 pointed out.. my ball joint was 1/2” more rearward on the side with negative caster ..upon further research,
I pulled this info off b body forum:
“ A thicker rear strut rod bushing or thinner front strut rod bushing will move the inner strut rod washer rearward along with the strut rod. This moves everything rearward. Any rearward movement results in a loss of Positive caster. The upper control arm adjustment for camber and caster does not have a huge range. Most cars can get no more than 2 degrees using stiock bush
When viewed from the side, an imaginary line is seen through the top and bottom ball joints. The upper ball joint must always be further to the rear than the lower.”
Than i found this:
Im using 72 strut rods
With moog k7040 rubber strutrod bushings. I plan to mock it all up before i cut any bushing to keep the lower control arm where the factory intended it.
Thanks to everyone for the replies. Im just posting my conclusions for future knowledge seekers. God bless the search function..
My main issue of massive caster variance i believe to have been cause by poly bush in the lca
And blown out strutrod bush. Forcing lower arm back and erasing my caster on one side. As andysauto1 pointed out.. my ball joint was 1/2” more rearward on the side with negative caster ..upon further research,
I pulled this info off b body forum:
“ A thicker rear strut rod bushing or thinner front strut rod bushing will move the inner strut rod washer rearward along with the strut rod. This moves everything rearward. Any rearward movement results in a loss of Positive caster. The upper control arm adjustment for camber and caster does not have a huge range. Most cars can get no more than 2 degrees using stiock bush
When viewed from the side, an imaginary line is seen through the top and bottom ball joints. The upper ball joint must always be further to the rear than the lower.”
Than i found this:
Im using 72 strut rods
With moog k7040 rubber strutrod bushings. I plan to mock it all up before i cut any bushing to keep the lower control arm where the factory intended it.
Thanks to everyone for the replies. Im just posting my conclusions for future knowledge seekers. God bless the search function..
michiganpat
Well-Known Member
interesting about the strut rod bushings, as I replaced mine when I did my suspension rebuild w/energy suspension ones. I noticed once I got it back together I have significantly more clearance to the front lower edge of my front fender that I did before the rebuild, to the point where the original suspension, 195/70R14's were about the biggest I could get on the front without fear of catching the fender, and afterwards, I had 225/70R14 rollers with about the same clearance....
when I got my car aligned, even w/the moog problem solver UCA bushings installed for max caster, they were only able to get about 3.5 degrees.
Is that the offset moog bushings? Or just the standard ones? +3.5 would be awesome for me. After looking at this whole setup for so long, it looks there is room to bring the lca forward im shocked nobody has invented a swivel pin that draws the lower arm 1/4” frontward for increased caster.
I like how you think, but that would be a less desirable solution than using the UCAs with adjustable and/or built in additional caster which already exist in many forms. The load would be moved further out on the pin, increasing the force required by the pin to carry. It's been over 40 years since I took statics and dynamics, so I don't remember how to calculate the additional force, but I'm sure one of our engineers on the forum could. Maybe not a problem, maybe not. I think it might also require adjustable strut rods, or at least a custom bushing. It would also likely cause an issue with the torsion bar seating properly.
michiganpat
Well-Known Member
offset moog bushings
michiganpat
Well-Known Member
force would be the same, but increasing the cantilever increases the moment in the out of axis direction. 1/4" probably isn't that big of a deal, and there's enough play fore-aft in the t-bar socket for it to be OK. bigger issue is there is only so much room for it to go foreward, and it's not ideal if you're pulling the outboard side of the LCA so far forward that it is no longer naturally perpendicular to the pivot pin.
Jeremiah (jd)
Well-Known Member
Strut rod tuning is needed at times to dial in the caster sweep.
I have done hundreds of alignments with a tape measure and a caster/camber gauge (Longacre). We used to take them to the alignment rack and have them double checked to a while. The numbers were always good so we started skipping that step.
One thing that helps with consistency is to make a 3/4"-16 adapter for the gauge. I prefer this to the magnet for both repeatability and consistency measuring side to side.
Adjustable strut rods and tubular UCA's make the alignment process much easier.
Lastly, I have had cars that went through multiple ditches, etc. that aligned quickly with even measurements side to side. On the other hand I have aligned very nice unrestored cars that fought me for a few hours trying to get things in spec and even side to side. As said each car is it's own mission of discovery.
I have done hundreds of alignments with a tape measure and a caster/camber gauge (Longacre). We used to take them to the alignment rack and have them double checked to a while. The numbers were always good so we started skipping that step.
One thing that helps with consistency is to make a 3/4"-16 adapter for the gauge. I prefer this to the magnet for both repeatability and consistency measuring side to side.
Adjustable strut rods and tubular UCA's make the alignment process much easier.
Lastly, I have had cars that went through multiple ditches, etc. that aligned quickly with even measurements side to side. On the other hand I have aligned very nice unrestored cars that fought me for a few hours trying to get things in spec and even side to side. As said each car is it's own mission of discovery.
michiganpat
Well-Known Member
my '76 manual is 70 ft. lbs. YMMV
I have a thread going at FBBO and another member posted up something like this....so I made my own.
Alignment at home and aftermarket UCAS too.
Page 6.
Great read over there at FBBO!!
My topics often get off course and have chatter unrelated to the main project but lots of good information gets passed along from other great members. You just have to sift through it all to find it.
Done!
- 3/4 camber and +3.25 caster both sides with moog offset bush
I had to cheat the pass side by using 1/8 washers to kick the knuckle out at the bottom . for more negative camber. I wouldve liked camber closer to zerzo but the more + camber u give it, the more caster goes negatove. U can rip me if u want for the washers but i see no issues.. drives nice.. have to tweak the toe a bit to get wheel exactly straight but i do that as i drive it. I had pictures but i deleted them accidentally.. oh well. Problem solved..
- 3/4 camber and +3.25 caster both sides with moog offset bush
I had to cheat the pass side by using 1/8 washers to kick the knuckle out at the bottom . for more negative camber. I wouldve liked camber closer to zerzo but the more + camber u give it, the more caster goes negatove. U can rip me if u want for the washers but i see no issues.. drives nice.. have to tweak the toe a bit to get wheel exactly straight but i do that as i drive it. I had pictures but i deleted them accidentally.. oh well. Problem solved..
Negative camber like that is not a problem with radial tires. You will likely have even wear if you do corner a bit.
Glad you got it worked out. The washers/spacers is not a problem....it is fine tuning the car to get to where you want to be.
There is a direct relationship between caster and camber. It is probably impossible to have zero camber and a high level of camber, at least with stock control arms with these cars. You have to take some negative camber to obtain a high caster number. Aftermarket control arms could get you there but why? Zero or positive camber will not handle as well.
Glad you got it worked out. The washers/spacers is not a problem....it is fine tuning the car to get to where you want to be.
There is a direct relationship between caster and camber. It is probably impossible to have zero camber and a high level of camber, at least with stock control arms with these cars. You have to take some negative camber to obtain a high caster number. Aftermarket control arms could get you there but why? Zero or positive camber will not handle as well.
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michiganpat
Well-Known Member
one thing I noticed with my car when I rebuilt the suspension over the winter and replaced the 48 year old strut rod bushings with energy suspension poly strut rod bushings is that it pushed my front wheels back a good 1/2" or so. before rebuild, the biggest tire I could fit was a 195/70R14 front, and there was only about 1/2" clearance to the leading edge of the bottom of the wheelwell when turning the wheel. after, the BBP rallyes I picked up with 225/70R14's fit with similar clearance. if the strut rod is pushing the LCA rearward that will reduce the amount of +caster possible.
And i think thats a huge thing with these cars. Oft overlooked r the strutrod bush r smoked or wrong thickness. Pushing and pulling the LCA all over the place. Componded with poly LCA bushings.
Going through this process this eve.
So, how do you know when your adjustablel strut rod isn't pushing around the lower BJ beyond spec?
I tried to find the loose happy place like the dude in the video. Passenger side was meloncholy the drivers was tight....no real loose feeling.
I feel like taking the bolt out near the LBJ and making it real loose and then re-assemble.......??...Ill sleep on it.
Bergman pins
moog problem solver
So, how do you know when your adjustablel strut rod isn't pushing around the lower BJ beyond spec?
I tried to find the loose happy place like the dude in the video. Passenger side was meloncholy the drivers was tight....no real loose feeling.
I feel like taking the bolt out near the LBJ and making it real loose and then re-assemble.......??...Ill sleep on it.
Bergman pins
moog problem solver
I ended up with 0.75-/4.5+ camber/caster. Test drive mañana.
The washers were between the LBJ and the spindle to affect camber?
Yes to give more - camber. without using the eccentrics, so..set for max caster with back cam all the way in and front cam all way out..
Then.. check camber.. if its + you can shim it rather than adjust the cams whereby losing caster.
michiganpat
Well-Known Member
how thick of washers do you need to get a degree of camber? just curious....
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