Im doing a motor/trans swap from 350/350 to big block 4spd on my 1969 Cutlass, seemed like the logical time to rebuild the UCA/LCA and sway bar bushing. My old springs measure right at 17.25 tall unsprung. Moog as you know has two offerings that im considering, the 5390 and the 5450. While i believe the 5390's will work im considering the 5450's as well. My car has 18" nittto lo profile tires on the front and im concerned about rubbing with the 5390 since it has a lower unsprung height out of the box (16.63) than my 43 year old springs (17.25). The 5450 is even shorter at 15.63. The 5450 shows loaded height at 12" and the 5350 is 11" loaded. The ride quality is definitely a concern as i dont want my fillings rattled loose over every bump in the road. My sense is the 5450 is the way to go. Any one been in my shoes on this? Thanks

 

I should also add that the 5390 Shows a spring rate of 336# which is more than the stock springs i took out.....

 

I put the 5450s in my driver SBO 350 all stock it rides nice , I also added a 1.25" fr sway bar and 1" rear sw bar at the same time.

future plans call for a BBO and from what ive read the BBO is +50lbs on the SBO...so really not to far apart

 

Nice. No chop to the ride? So the front dosent want to roll over on hard accel/braking in corners? Did the rear sway bar make a noticeable difference performance wise?

 

I dont really hammer on it hard but I do drive it. I put on over 2k in the last year. It rides and handles well compared to a stock 40 yo suspension in good condition.

I really only drove it home unregistered before adding the sw bars so I cant say I was even exceeding the speed limit before

 

Understood, thanks for your info.