Open Discussion on Suspension Options

[Thumperbird]

65 Thunderbird, 445 stroker, ~500hp.
Looking for ideas on tuning the suspension.
Would like to keep the basics in tact, in other words not interested in mustang front end or 5 point rear, etc..
Rear is not too bad, traction issues but some stickier tires will help, very little wheel hop but is fairly easy to crack it loose and keep them spinning from just off idle.  Maxed out on tire width without chassis changes. 

Front is where my concerns mostly lie, floats to a degree when over 70/80, oversprung I suspect.  I pulled 200 lbs off the front in the form of intake, heads, and exhaust changes but stock springs still in there.  Front end does not like being disturbed by the 2/3 shift at high speed, not comfortable taking it over a hundred in a hurry.  I can buy non-A/C springs or have some made but what else?

What things can i consider to calm it down? 

Thanks.

[TomP]

Add more caster, all the 60's cars have very little, some of the alignment specs have a range of + and - with zero in between. Zero caster will make a car hard to hold in a straight line with radial tires.

[Heo]

Lower the front so the air flows over the car and not under
Makes wounders on a mustang

[Towd56]

On my wagon - it was a night and day improvement with a bigger 1” sway bar and a set of GOOD shocks. By good shocks - I mean bilstein,Koni, etc. Pricey but in my opinion made a big difference.

[Falcon67]

Add more caster, all the 60's cars have very little, some of the alignment specs have a range of + and - with zero in between. Zero caster will make a car hard to hold in a straight line with radial tires.

This - on the Falcon and Mustang I use at least 2 1/2 degrees of caster, about 1/8 toe and as close to zero camber.  Really stable on the strip too.  With anything close to stock specks they would be like driving a water bed.

[GerryP]

I suspect the front end is too high.  The easiest and cheapest solution is to remove the front springs and cut a quarter coil and see if that gets your ride height back to spec.  If not, then cut another quarter.  Use a cutoff wheel to cut the springs.  A torch will kill the temper in the spring and the steel is too hard for a hacksaw.  Cutting the spring will add a little stiffness (while it appears the spring just compresses, the coils actually twist -just like a torsion bar- so the shorter the spring, the shorter the "bar" and the stiffer the bar).

More than anything, shocks and tires will make the biggest difference in how the car rides.  If you want to firm up the ride, a stiffer shock will go a long way toward that.  I suggest adjustables.  If you slap on a set of non-adjustable Spax racing shocks and find the ride is too stiff, well you've blown a huge amount of your budget on something which you can't change.  So, get adjustables.  Wheels and tires...what more can be said here.  The wheel and tire are a calculated part of the suspension.  The shorter and stiffer the sidewall, the harder the ride and the quicker the car will turn in.  A lot of the "floaty" ride is in the tires.

This is just my opinion, so take it as nothing more than that.  When it comes to old cars, I like to make modest improvements in the suspension and the ride and handling.  That floaty, "Hey is the steering wheel actually connected to anything?" ride is how these cars were in their day.  They do okay as long as they're not pushed too hard.  I appreciate the distinction and the character of these cars.  I also like going over speed bumps and not really even feeling them. Some things are very worth while to upgrade, like the brakes.  But suspension upgrades are only beneficial if you're going to drive aggressively or track the car.  But it's your car and you can do with it as you please. 

[fryedaddy]

i dont think a head,intake and exhaust swap will take 200 off the front.i put alu heads,intake,water pump,and headers on it and put the battery in the trunk and it didn't take hardly 200 off.before i messed with the springs i would try good shocks,tires first.

[machoneman]

Lots of good recs here already.

Lower the front, cut the springs, eliminate the floaty feel (great word to describe old car steering and overall ride quality) get good 3-way (or more) adjustable front shocks. Add a front chin spoiler to keep air out  (any universal straight line or old Mopar  spoiler would work) and yes, get Cal-Tracs for the rear.

Don't know if they make or you can use the C-T springs but if not, be sure your old springs (or new replacements) are up to snuff. Add poly-graphite no squeak bushings to every sway-bar and suspension point to tighten things up. Pay attention to your steering box too as a worn box has that big steering wheel sawing back and forth with excess play. One trick as well is to get another pulley and slow down the P/S pump speed. You'll thank me later as in many old Fords the steering is way too touchy/sensitive (one light touch and car does a 90 degree turn!). 

[Falcon67]

Beware cutting coils - every cut increases the spring rate, resulting in "less bang for the cut" as you continue to hack on them.  You might get the nose down, then wonder why an elephant can sit on the hood and the nose not move.  Increased rate in the front reduces roll rotation, hurting launch traction.  It also increases understeer.  You can also set up harmonics in the suspension depending on where the front/rear spring rates end up.  Not typical, but can happen.  Using a spring catalog to source a spring with a lighter in/lb rate and maybe less free length, or one with lower compressed height an much is a better path. 

Same with sway bars - they need to be matched to springs and weights.  Increasing stiffness - springs, swab bar, shocks, etc - on one end will increase the weight transfer on that end.  In the front - enhances tendency for understeer.  In the back - oversteer.   

[e philpott]

If the front end isn't sitting sky high I would start with a good alignment and get the Castor as high as you can go without effecting Camber while keeping right and left Castor equal to each other

[machoneman]

Beware cutting coils - every cut increases the spring rate, resulting in "less bang for the cut" as you continue to hack on them.  You might get the nose down, then wonder why an elephant can sit on the hood and the nose not move.  Increased rate in the front reduces roll rotation, hurting launch traction.  It also increases understeer.  You can also set up harmonics in the suspension depending on where the front/rear spring rates end up.  Not typical, but can happen.  Using a spring catalog to source a spring with a lighter in/lb rate and maybe less free length, or one with lower compressed height an much is a better path. 

I agree with Chris yet for any older T-Bird, IIRC trying to buy a direct replacement is likely a non-starter. That's why I said the easy way, maybe not the best way, is cutting. Yes, catalog searching will work but one must a pretty good idea of the factory spring length and tension. Maybe another old Ford (Galaxy? Merc Marauder?) spring would work here.

[frnkeore]

Remember, you have a LOT of torque to control, especially for a street car.

If it's your 2/3 shift that is the major problem, that is caused by the weight transfer from the right rear, to the left front, when the torque lifts the Rt rear. On 4 wheel vehicles, weight is transferred, across  corners. On a road car, stiffer springs, all round, will help. Shocks, all round, too as well as a rear anti roll bar (sway bar), larger front bar, too..

There is also a matter of torque steer. Replace the spring bushings with urethane or metal. Consider a Panard bar, also.

As said above, more caster can help too. A little extra toe in might help. But, always do everything, one step at a time or, you'll never know what cures your problem.

One more thing. Do you have any positive offset on your front wheels? That can cause a car to pull to a side that has a bump or uneven surface. In this case it would be sudden unloading of the Lf front. That issue is called Scrub Radius. It's the distance the center of the tire contact is outside of the center of the king pin inclination.

After all is said and done, if you spend any time in corners, at speed, you'll have to balance the the Ft/rear spring rates to get it to handle. To stiff in the rear over steers, not good.

[TomP]

It's a 65 Tbird .... no spoilers shall be installed even if such a thing was available!

If the lighter weight raised the front end, and it certainly would, then cut the springs. Stiffening the springs up by cutting them is not a bad tradeoff! These cars ride too soft.

[Joe-JDC]

You need to get the ride height established before aligning the front end.  Everything changes with height.  Joe-JDC

[Thumperbird]

Great stuff all, thank you very much!
I like current ride height but may end up dropping front a bit with non-A/C springs.
Will likely do the sway bars, maybe new type of shocks, what's in there is new, as are all steering joints and bushings, etc., but I don't know that they are correct for this thing.

I have adjusted alignment for radials but will look at all items mentioned much more closely this winter after getting new springs in.  Left rear leaf must be a little weak as well, all was nice and flat when car was built but some thrashing has caused driver side to drop about 3/8 to 1/2 inch over two years here.

Made a couple passes last night with a little more timing and let the C6 shift where it wanted - right at red line for 1/2 and slightly before for 2/3 and it seemed to be a bit more stable fro some reason than when I execute manual shifts which were likely slightly after red line.  Not worried about ET just solid strong pulls and a little less flamboyant handling when getting on it while not being rigid as heck for daily.

Thanks.

[My427stang]

I think softer springs are going to compound it.  I would recommend a stiffer spring, lower nose if acceptable, and a more firm shock.  Might be able to just get away with a stout shock and no other changes too, or maybe limiting straps to keep the nose from coming up too high and changing alignment. 

I run my Mustang at 3.0 degrees Driver / 3.5 Passenger for caster, 1/8 toe and 1/2 a degree camber.  However it does have the upper control arms dropped too, it is rock steady to 140.

May want to see what the wheels do when you jack it up.  The nose could be coming up and changing toe and camber so much that you are riding on the edges. 

[frnkeore]

What kind/type of traction bars are you using?

[Thumperbird]

No bars, I launch at idle and just back off a touch when it wants to break loose, this is only maybe a 12 second car remember, though have not timed it.
Going to look into rolling rear fender lip, that with a little more wheel offset and I should be able to increase tire width 1 to 1.5", around 9" tread now.
I do suspect the front wheel geometry goes to heck, need to get a video of the car.
It is a unibody, long but very rigid, will sit on 3 jack stands and 4th corner sags less than .5 inches.

[frnkeore]

Something as simple as these, should help:

https://www.ebay.com/itm/Lakewood-Universal-Traction-Bars-Ford-Chevy-SB-350-454-Mopar-383-400-440-Ford/362649678668?epid=5017018124&hash=item546f9af34c:g:hZMAAOxyVLNTA8Ll

They keep the spring from raping and give you a even weight transfer. You should notice a little rise at the rear, under acceleration, transfering weight from the body to the axle and increasing tract.

[amdscooter]

I'm not for cutting springs. Know to many folks who have done it ( and probably done it wrong to boot) and it made them miserable. Drop spindles and maybe a fatter sway up front?

[fe-starliner]

+1 on not cutting springs.  I needed some new coil springs for my Starliner some years ago.  I called  Eaton Detroit Spring, Inc., talked to them and they made me a custom set based on factors such as weight, how low I wanted the front, etc.  Best way to go as far as I'm concerned. Price was reasonable, shipping very quick.

https://www.eatondetroitspring.com/coil-springs/

[Riderjeff]

I'm a big fan of Bilstein products, and you can buy them for your Bird from Thunderbird Headquarters:
http://www.tbirdhq.com/pc_product_detail.asp?key=BF7F462AF82545E2807F3273795DCCD4

Do all 4 corners and you should be very happy with the difference.  Of course, make sure your springs are within factory spec, some good suggestions previously on custom springs as well. 

I've put Bilsteins on all my cars, they really transformed my old Jeep XJ Cherokee and restored new car ride to my Mercedes.