Suspension recommendations needed - Ford Muscle Forums : Ford Muscle Cars Tech Forum
 
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post #1 of 9 (permalink) Old 02-28-2007, 02:37 PM Thread Starter
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Suspension recommendations needed

I have a 68 Fairlane that will be supporting a 500+HP engine soon. Once this is complete and running, I plan to install a 6 point rollbar.
My suspension is in very good condition but needs few changes to adapt to the HP and assist in my launches. It currently has air shocks and leaf extenders on the rear to allow the tires to clear the fender (I bought it this way). As you can see in my picture within my profile, the car sits pretty even but it’s a little high. It also has slapper bars that are bolted at the U-bolts.
The trans is a C4 with a stock gear ratio, 3600rpm stall, and 4:30 rear gear.

What suspension mods would you recommend for this Sunday cruiser that may see 2 dozen passes at the strip per year?
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post #2 of 9 (permalink) Old 02-28-2007, 02:55 PM
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Suspension recommendations needed

i ll be curious to see some of the answers to this post, i also have air shocks on my truck with HD lakewood slapper bars. i just bought some plans for building cal tracs, and can t wait to get them made and on. i heard they are pretty good. i have more problems than you cause i have a truck! good luck!
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post #3 of 9 (permalink) Old 02-28-2007, 08:31 PM
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Suspension recommendations needed

Note - to be track legal with that convertible, you'll have to have an 8 point bar if you're faster than 8.25 (13.49 1/4) because the Fairlane is a unibody car and your main hoop will be welded to floor plates. If it was a full frame car with the main hoop welded to the frame, you could get by with the 6 point. This is both an NHRA and IHRA stipulation.

I suggest you pitch the air shocks and look at a set of Rancho 9000 that would be used with Caltracks. The Caltracks would be the best suspension for the car, but for a couple dozen passes the slappers will do. If the air shocks are required to keep the body off the tires, you need to weigh the back end and then talk to a spring supplier to get some real springs. Calvert Racing sells some good (not cheap) springs.

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post #4 of 9 (permalink) Old 03-01-2007, 11:29 AM
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Suspension recommendations needed

I had my rear springs done at a local spring shop. Added a leaf and then de-arched. I payed about 125.00 per spring.
Just another option for you.

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post #5 of 9 (permalink) Old 03-02-2007, 01:11 AM
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Suspension recommendations needed

For the best traction you want as soft a rear end as you can get and lots of weight transfer. Air shocks are great for looks but not for ride or traction - get rid of them.
Have a set of springs made for it. You need a very thick main spring to take the shock of your launch and thinner springs to react fast to load changes. If the tires won't fit then get tires that do! You need to locate the rear end from side to side so get asway bar at least and the preferred way to locate the rear end is either Panhard bar or Watts linkage.Loosen the bushings in the front sway bar to let it rise more / faster and a set of good 90 / 10 shocks on the front (for when you race). You can put 10 / 90 shocks on the rear. Ladder bars will keep the rear springs from wrapping up but they don't give at all to help your launch so keep the slapper bars but give them an inch or two gap when sitting . That way they will let the springs take the shock of your launch and then stop the wrap-up before it gets dangerous. Transfer as much weight up and to the rear - the higher your CG is the better weight transfer you will have. Oh and get rid of as much weight as you can - every ten pounds you dump is worth another HP.
Paul
The best way to get what you need in the rear end is to build a quad link suspension back there and use coil springs. Lots of money and in a unibody car - lots of work to do it right.


[ This Message was edited by: PaulS1950 on 3/2/07 4:13pm ]
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post #6 of 9 (permalink) Old 03-02-2007, 05:31 PM
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Suspension recommendations needed

The stall is too tight for it to have many traction issues on the track, unless you are running street tires. If that's the case, you are fighting a losing battle if the motor really makes 500 hp no matter what rear suspension you stick under it.

Just for an FYI, my gf's car runs consistant 1.65-1.66 (best of 1.62) sixty foot times using air shocks and slapper bars with a 4.11 gear and has no where near 500 hp.



This doesnt make any sense...

" You need to locate the rear end from side to side so get asway bar at least and the preferred way to locate the rear end is either Panhard bar or Watts linkage"

...unless the car has a "floated" housing. The leaf spring perches keep the housing centered. And a sway bar has nothing to do with keeping the housing "centered".


And this...

"...help your launch so keep the slapper bars but give them an inch or two gap when sitting."

....is backwards. The more air gap you give, the harder it will shock the tires. It gives the springs that much more of a "run" at the tires before it hits them with the torque.

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post #7 of 9 (permalink) Old 03-02-2007, 06:56 PM
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Suspension recommendations needed

Quote:
On 2007-03-02 17:31, kid vishus wrote:

This doesnt make any sense...

" You need to locate the rear end from side to side so get asway bar at least and the preferred way to locate the rear end is either Panhard bar or Watts linkage"

...unless the car has a "floated" housing. The leaf spring perches keep the housing centered. And a sway bar has nothing to do with keeping the housing "centered".


And this...

"...help your launch so keep the slapper bars but give them an inch or two gap when sitting."

....is backwards. The more air gap you give, the harder it will shock the tires. It gives the springs that much more of a "run" at the tires before it hits them with the torque.

With the car sitting on the ground, walk up to it and push the rear end of the car body from side to side - leaf springs do NOT keep a differential centered worth a darn.
A sway bar is located to the frame and the differential housing. It is a spring but it does help a little.

If you adjust slappers to no clearance the tires have to absorb the entire shock of the launch - they will break loose - not a good thing! If you leave a two inch space then the springs absorb a bit of the shock and the tires absorb some too. When the springs wrap to the limit of their travel the tires have started to turnand the slapper bars can allow the springs to unwrap as the torque load decreases. (the tires start to move before the springs wrap far enough to hit their stops)

You might think it is different but a few years of films at the track have proven otherwise to me. (this with a 427 side oiler in a 57 wagon. No broken axles - no broken springs (after we had the thick main spring made) - The best times at the track were with 1 1/2" play for our setup.
Paul
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post #8 of 9 (permalink) Old 03-03-2007, 04:41 AM
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Suspension recommendations needed

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post #9 of 9 (permalink) Old 03-03-2007, 05:24 AM
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Suspension recommendations needed

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