suspension setting-steering

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tiaf124

suspension setting-steering

Post by tiaf124 »

I've just finished a complete front revision in my 1974 124.New ball joints, rod ends, bushings, idler arm,steering box internals , new shocks, 175/70 toyo tires. I trying for a proper suspension final setting (camber ,caster ,toe in angles tire pressure). The car is mostly daily driven .The next option was a 13 inch steering wheel ( rather smaller diameter than the factory one )
I did some adjustments and my car ended up with a very heavy steering :( .It takes quite a lot of effort to turn the steering wheel.
Right now i 've 3/4 negative camber ,4 deg positive caster.
Do you think that i have overdone it with these angles ?
Do you think that the steering wheel is to small that it makes the steering heavier only by it self? A st wheel with 1 inch or more diameter might change the effort dramaticaly ?
What tyre pressures are the proper ones to improve the situation or what other adjustments should i perform to make steering lighter.
Thanks
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kmead
Posts: 1069
Joined: Sat Aug 02, 2008 9:24 pm
Your car is a: 1969 850 SC 1970 124 SC 85 X19
Location: Grand Rapids, MI

Re: suspension setting-steering

Post by kmead »

The smaller steering wheel has raised your effort considerably. The 124 doesn't have light steering at rest in any case so going down an inch or more didn't help.

The greater negative camber also adds to your problem.

I would start with replacing the original wheel to gauge the change in effort.

I would then start doing push ups and other weight bearing exercise so you don't need to change anything.
Karl

1969 Fiat 850 Sports Coupe
1970 Fiat 124 Sports Coupe
1985 Bertone X1/9
tiaf124

Re: suspension setting-steering

Post by tiaf124 »

kmead wrote:The smaller steering wheel has raised your effort considerably. The 124 doesn't have light steering at rest in any case so going down an inch or more didn't help.

The greater negative camber also adds to your problem.

I would start with replacing the original wheel to gauge the change in effort.

I would then start doing push ups and other weight bearing exercise so you don't need to change anything.

If it was only me who drives the car .... anyway is when doing moneuvres on the spot i litteraly
grab the wheel to turn it.
So in your opinion a larger diam steering wheel 1 inch or more would minimize the effort .
If i decrease the camber to 1/2 instead of 3/4 deg, may improve also without sacrificing handling?
Thank you anyway
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TulsaSpider
Posts: 1547
Joined: Tue Apr 29, 2008 7:33 pm
Your car is a: 1978 Spyder 124 2L
Location: Tulsa, Ok

Re: suspension setting-steering

Post by TulsaSpider »

I agree it's physics . Try the standard steering wheel and see if that does not improve things. If not then go to the next step
1978 Spyder 1800 make that 2L! Finally making real progress!
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kmead
Posts: 1069
Joined: Sat Aug 02, 2008 9:24 pm
Your car is a: 1969 850 SC 1970 124 SC 85 X19
Location: Grand Rapids, MI

Re: suspension setting-steering

Post by kmead »

In regards to the camber and caster change (which will have real benefits to handling), with the factory positive camber it is like turning your foot when balanced on the ball of your foot. Fast and easy. With negative camber, imagine turning your foot from the heel and dragging the ball of your foot around in front of it thus the greater effort.

The OE wheel will be the easiest at 14" as I recall.

I still think the pushups would be beneficial... :D
Karl

1969 Fiat 850 Sports Coupe
1970 Fiat 124 Sports Coupe
1985 Bertone X1/9
User avatar
TulsaSpider
Posts: 1547
Joined: Tue Apr 29, 2008 7:33 pm
Your car is a: 1978 Spyder 124 2L
Location: Tulsa, Ok

Re: suspension setting-steering

Post by TulsaSpider »

I re-read your post and noticed that you had re done your steering box. That could be too tight as well. Is it adjusted properly?
1978 Spyder 1800 make that 2L! Finally making real progress!
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v6spider
Posts: 1035
Joined: Tue Feb 28, 2006 6:57 pm
Your car is a: 4.3L V6 Powered 1972 124 FIAT Spider
Location: Mount Vernon WA

Re: suspension setting-steering

Post by v6spider »

The amount of negative camber you have is minimal it should not effect your steering too much. But your caster is too high. Stock is +3 degrees. Being at +4 will surely feel harder when trying turn. Caster is what forces the wheel back straight when coming out of a turn. Too much caster will cause your tires to wear unevenly in the turns. Also check your idler arm/damper and make sure the fluid inside is not dried up. I have had another stock spider that had that issue. I just found another used idler/dampener that was in good shape and it cured the issue.You did mention that you rebuilt your steering box.. I'd check it too just rule it out. You may find it is a combination of issues.

So here are the settings used on my V6 spider:
  • -1 deg. Camber
    +3 deg. Caster
    .060" toe
    25 Psi tire pressure
I have used these settings on a stock spider and they seemed to work well also...

Cheers!
Rob
http://www.v6spider.com
4.3L V6 Powered 1972 124 FIAT Spider
tiaf124

Re: suspension setting-steering

Post by tiaf124 »

I have already revised my stock idler and my steering box is well adjusted( turning the screw i get more lash wheel play than lighter steering wheel ) .
Most of you agree that is mostly due to small wheel diameter.
I thought that 4 deg degrees caster isn't so much . A copy of my 124 manual gives 3,30 deg +0,30 or -0.30 maybe . Maybe that difference of 0,70 deg caster is crusial for my case too.
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v6spider
Posts: 1035
Joined: Tue Feb 28, 2006 6:57 pm
Your car is a: 4.3L V6 Powered 1972 124 FIAT Spider
Location: Mount Vernon WA

Re: suspension setting-steering

Post by v6spider »

As long as the steering comes back on it own somewhat that is what counts. I found with some experimenting that +3 degrees of Caster is plenty. Just when you are driving take note of how much the wheel wants to straighten out as you are in a turn. If it is pushing back pretty hard your caster could be lowered. I also noticed that when I added wider tires it seemed to accentuate the amount the wheel would want to push back. The numbers are just for reference. I used to keep a log of what I set my alignment to on my first v6 spider. This is where I learned what worked and how the settings effected the way the car handled and what the symptoms were for each different issue.

I also bought some books on suspension theory and studied them. I highly recommend 'Chassis Engineering' by Herb Adams. That book demystified just about everything with regards to suspensions and how they work. BTW this book was recommended to to me by another longtime FS.com member Joe Clemente. It would appear that he quit posting on this forum quite sometime ago, but Joe was quite the knowledgeable cat. I am sure Mark knows and remembers Joe. If your still out there Joe thanks for all your help.... :)

Rob
http://www.v6spider.com
4.3L V6 Powered 1972 124 FIAT Spider
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