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harsh ride

B67FSTB

The NorCal dude from Belgium
My front end floats .
I nearly can't push down the car in the front , when i disconnect the shocks , i have some more suspension travel although I can move the top of the shock with minor force.
I have 245/45/17 tires on 17X8 rims bs = 4.75 Offset is + 8mm ( i have seen a diagramm but can't find it anymore )
I have stock suspension and UCA has a 1" shelby drop and springs are : wire thick is 0.59841
: diameter is 5.11798
: number of coils : 9
http://www.proshocks.com/calcs/coilsprate.htm

I have aligned the car :
camber -0.5
caster +1.0
toe + 1/8 "

I am afraid to drive hard : 70,80 mls/hr
any info please of what I can do are have regarding springs.
The front stance is ok with me and I would like to stay it like this.
 
Those springs don't appear to be all that stiff. Our 560lb springs have a .620 thick wire. With that said, the material the springs are made of could be different and make them stiffer. As a starting point, I would pull the springs and test the movement of the suspension to see if there is any binding. It is possible that the upper control arms and lower control arms are binding. If the bushings on the upper arms are overtightened they will bind. If the lower arms were torqued down while the car was up in the air, that will cause binding. A different set of springs might be needed but I would do some testing first.

My daily driver is a 64 Falcon Sprint and when I push on the front of it, it moves less than 1 inch. It has a firm ride but isn't harsh. Our track cars move very little when you push on them. We do drive them on the street, they have a stiff ride but it's not unpleasant.

For the alignment settings, you could use a bit more caster. We put 2deg. positive caster at a minimum in our street cars. Your stability at speed will improve with more positive caster. The camber and toe angle look fine.
 
My front end does the same thing at speeds, and my caster is about the same as yours. This week is supposed to be rainy, so I'll probably tackle adding about 1 - 1 1/2° more pos caster. I'll post result the next day I drive it to work.
 
John
Thanks for responding!
First , is it normaal when diconnecting the upper side of the shocks , i have more suspension travel when pushing the front of the car?Although I can move the shock with ease when diconnected.
Position of the perches , they both sits the same way left and right.Could it still be wrong?
What about my back spacing of the rims.It should be on 17 X 8 a b.s. of 4.5 but i have 4.75 which means that the wheel sits more to the suspension side and thus no so bad , as too far to the outside.
I believe the center line of a 17X8 rim is at 4.5 b.s so +8mm offset should be that is has now 4.75 b.s .
Is that assumption right?
I know , lots of question but i have time for you to respond !!!!
Thx
B.
 
Oh yes
I put poly bushings in the LCA but i put a washer front and back so the poly bushing didn't scrape in the oval excentric bolt opening during suspension travel.
I did the aligned on a digital bench and the car did rest on his weight when tightening the bolts.
 
First , is it normal when disconnecting the upper side of the shocks , i have more suspension travel when pushing the front of the car?

Yes, even a soft shock will lessen the amount that the suspension will move.


Position of the perches , they both sits the same way left and right.Could it still be wrong?

I don't think that is the issue. The rubber perches do cause bind, the rollers will help with the ride quality.


What about my back spacing of the rims.It should be on 17 X 8 a b.s. of 4.5 but i have 4.75 which means that the wheel sits more to the suspension side and thus no so bad , as too far to the outside.
I believe the center line of a 17X8 rim is at 4.5 b.s so +8mm offset should be that is has now 4.75 b.s .
Is that assumption right?

The backspacing changes the scrub radiouse and that won't affect the ride going straight down the road. The more I think about it, your lack of caster is most likely causing the wondering. Adding more caster will make the car more stable at speed and give a better feel to the car.
 
I'm with John. I would get to at least +3 degrees of caster and start there.

Pushing the car with your hands and compressing your shocks with your body weight is like trying to see how grippy a tire is by licking it with your tounge. Not very accurate!

What shocks are you using?
 
I am using stock shocks , nothing special.

I gonna do the aligning again but with +3° caster and -0.5° camber and Toe in 3/8. OK for you guys ?
 
That's too much toe-in. The front end will rise and squeel the tires with that much toe. I would stay with 1/8".
 
John

Yes , i got confused because 1/8 " is about 3mm so i mixed it up in 3/8. :beat

Thanks for noticing !!

Normal backspacing on a 17X8 rim for a mustang is 4.5 inches but I have 4.75 backspace , doesn't that effect toe-in while on driving ?

Thx.
 
No, your toe angle should stay the same with different wheels. That is a good amount of backspacing, you won't have tire rub issues.
 
Bruno, have you resolved this problem yet? Do I need to fly John over to "get er done"?
 
Craig , no , still have the problem.( In fact I haven't the time lately. To many things to do right now.)
I hope to eliminate this to mount my roller perches and later on I gonna alter the LCA and remove the poly bushing and replace them with spherical type bearings.

But you can always sent John to me. I always can use a pro overhere.
 
I'm with everyone else. More caster should solve the issue. I run +4.2* caster now and my car is very stable at 70mph.
 
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