I have 620lbs/in front springs and 4 1/2 leaf reverse eye leaf springs on the back with all new bushings all around. The front
also has all new tubular upper/lower arms etc. The suspension is dead stiff. I am wondering if it will loosen up a bit after
a few weeks of driving or did I go with too stiff springs? Mustangs Unlimited staff suggest that for the 390 that setup should
be ok.

Jav

 

how does it handle? sorry i know im not answering your question but im curious, looking at purchasing 80% of the suspension parts soon.

 

I have a 1 1/4" front sway bar and I think a 1/2" sway bar on the rear, so there is little body roll.
As far as handling goes, to be honest I have not driven it enough yet to say. I am still waiting on
some part and should be able to take it out for some testing in about a month.

Jav

 

i think eventually it will loosen up, but i dont think in weeks

 

It will be stiff, you put a very stiff suspension on it.

You don't need the rear bar.

 

While those 620's will give you a harsh ride, that 1.25" sway bar is absolutely killing you. The stiffness of that bar is not only preventing any body roll, it's alsoworking againstthe LCA.

A bar of that size should be on one type of car.... a car that is trailered to the track.

LMAO.... do yourself a favor and take everything a parts salesman (working on commission) tells you with a grain of salt. I've talked to the MU staff and unless they've hired some new "experts", I wouldn't trust any of them to stand near my toolbox, nevermind open it. There experience lies in the mistakes they've made screwing up customers orders and their knowledge is limited to what is written in their catalog.

Dave

 

I agree with the previous posters in that your suspension is really stiff. It won't change either. I just went through deciding what springs to get for my 70 FB with a 351W. The stock springs are 289 pound/inch spring rate. So, the 620's are more than twice as stiff to give a comparison. I ultimately decided to go with Mach I coils which are 428 pound/inch. I really don't understand why all of the suppliers push the 620's because everything I have read indicates that they are too stiff for what most people want in a street car.

 

IMHO the front springs are WAY TO STIFF and the sway bar is WAY TO BIG!!!! Get some softer springs, a 1" front bar, ditch the rear bar.

 

Thanks for all the suggestions and advice. I should have found out the original spring rates and just stepped up a bit from them
like 109jb. Live and learn.

Jav