72 nova and truck arms, spring rate needed

[Hotwhilz]

Hi guys, I'm more and more willing to give the truck arm set up a go on my nova, what would be a good ball park for spring rate? and supplier, ths will be a homemade set up and on a budget.

Thanks in advance.

Ben

[Bryce]

We need to know corner weight and unsprung corner weight, motion ratio and susepension travel in both directions.

[Hotwhilz]

Hi, wish I knew all this, looks like Ineed to do some home work! Unfortunatly no access to a scale, suspension travel should be 4 inch at full compression. Hope this helps.


Ben

[exwestracer]

If you're not lightening the car much, and the engine is in the stock location, I'm guessing around 1100-1200lb of sprung weight on the rear axle. That's a GUESS, remember...

Figure 600lb on each spring...and I'd say you want a minimum of 2" spring compression at ride height. That would put you in the 250-300lb/in range.

I've scaled a lot of Novas over the years, but they were all striiped out and had as much setback as we could get away with...

[Hotwhilz]

Hi Guys! thank for those infos, the nova as about two inches of engine set back, basically what the stock firewall will allow, as far as weight saving, nothing major (empty trunk, racing seat, the most of the lightening is in the front)

Will try to get 600 lb springs and probably screw jacks to adjust ride height.

Thanks guys

Ben

[exwestracer]

Will try to get 600 lb springs and probably screw jacks to adjust ride height.

Thanks guys

Ben

NOOO! 600lb springs are way too stiff. :drive2:
Read again... you want some compression on that spring. My suggestion was in the 250-300lb range.

[John Wright]

NOOO! 600lb springs are way too stiff. :drive2:
Read again... you want some compression on that spring. My suggestion was in the 250-300lb range.

600#' s = Way too stiff for the rear springs.

[UMI Tech]

600 lb rears for Project Drift Nova!

ramey

[Hotwhilz]

Hi, Oups seems that I misread the post, the thing that got my attention is that there aren't so many springs for the rear in the 600# range. I may lean torward an E39 IRS rear that way i can swap the gears really easily by swapping the pumpkins ( they are everywhere here). And LSD to boot.

Thanks again!

[exwestracer]

Hi, Oups seems that I misread the post, the thing that got my attention is that there aren't so many springs for the rear in the 600# range. I may lean torward an E39 IRS rear that way i can swap the gears really easily by swapping the pumpkins ( they are everywhere here). And LSD to boot.

Thanks again!

If that BMW uses a coil over wunit attached to the upright, 300 will still be in the ballpark. Your sprung weight will go up some from the diff and cradle being attached to the frame.

If it has a spring on the lower control arm, you may need to go to a stiffer spring depending on motion ratios...

All that will also depend on how much metal you add/remove converting it to IRS.

[Hotwhilz]

If that BMW uses a coil over wunit attached to the upright, 300 will still be in the ballpark. Your sprung weight will go up some from the diff and cradle being attached to the frame.

If it has a spring on the lower control arm, you may need to go to a stiffer spring depending on motion ratios...

All that will also depend on how much metal you add/remove converting it to IRS.

Thanks for the insights, the E39 uses coil over on the upper CA

51928

I know the unsprung will be a bit heavier, on the other end the sprung weight will be far less than the stock leafs and rear axle, most of the bmw parts are made out of aluminum, and the are a ton of adjustement (toe, camber, etc)

As far as adding material, I don't think that I will add more than 40 pounds for coil over support and craddle to attach to the frame. The nova weighs less than the E39 in the rear at least.

The other reason for the swap is the price of the entire rear end ( 200 USD ), I have most of the tubing to make a frame, I can always go back to stock form and the other thing is I needed to swap the gears in my existing rear end so all in all, I think I can build something different,yet more efficient (still to be proven).

What are your thaughts about IRS in those old muscle cars?

[exwestracer]

Thanks for the insights, the E39 uses coil over on the upper CA

51928

I know the unsprung will be a bit heavier, on the other end the sprung weight will be far less than the stock leafs and rear axle, most of the bmw parts are made out of aluminum, and the are a ton of adjustement (toe, camber, etc)

What are your thaughts about IRS in those old muscle cars?

Actually it should be the other way around... Unsprung is the axle, wheels, tires, etc. That should go down with the IRS swap.

As long as it's thought out, I'm all for it. Looking at that cradle, you should be able to follow Scott's Camaro build pretty closely if you choose to go that same route...

[Hotwhilz]

Thanks Ray, I'm going to measure everything this week end ans start a drawing to begin with, I think you are right with Scott's camaro is fairly close

I'll start a thread once I get all the measurement

Regards