I need to replace the coil springs on my 67 hardtop and was considering using 620 lb coils. I currently have 5 leaf mid-eye springs on the rear with KYB gas adjust shocks all round. I understand 620 lb coils will give me the 1 inch drop from standard I am looking for, but how hard will the ride become? The car is a 289 with C4 and is street driven.  

Did you think about lowering the attachment point for the upper control arm? This will give you about a 1 inch drop in the front and keeps your spring rate the same. Hey it was good enough for the chicken farmer to use in his cars(65-66 shelby's had this modification). It is well detailed in the HOW TO section of this website. Just a thought. Tom  

I've got a 65 fastback that I too was thinking of putting these springs on but my concern was that the ride would be too harsh.  I had even thought of replacing my stock springs with 1" lowering GT/GT350 springs by opentrackracingproducts.com.

How are your 5 leaf mid-eye springs working out for you?  What are they rated at?  How do they ride?  

I have the 620 pound springs on my 65 fastback and also the 5 leaf standard eye springs in back. I dont have the shelby drop but I have found no harshness in the ride. It handles well and I even cut out about 1/4 turn on the front springs to get the ride height I wanted. I dont think you will have any problem with the heavier springs at all. I dont use a heavier sway bar with this combo, only because I didnt think it needed it.  

Mechanicalguy, were your 620# springs stock height before you cut them?  

Well they advertise them as a 1 inch drop but they didnt seem to be. I wanted it to have a slight forward rake. You have to be careful how much you pull out because it increases the spring rate and lowers it more then you think for even a small amount of spring cut out. I would not cut out more then 1/4 turn on these springs. But I dont feel any harshness, the ride is fine.  

I really don't want to screw this up when I buy the parts and make the modifications so if you don't mind I'd like to ask you a few more questions.  Did you make any other modifications to the front suspension like lowering the upper control arms (Shelby mod)?  I've got P205/R6014 in the front and back on my car. I may eventually like to put on larger wheels like 225/R4517s.  I know alot depends What size tires are you running in the front and back?  Do you experience any tire rubbing or bump steer?  

Actually, the tires on my car are P215/R6014.

Thanks.  

I just saw your posted reply to Wheel Fitment under the Vintage Mustangs. I think that answers most of my questions.

Thanks  

Thanks for the replies.
fordwannabe - Hadn't considered the Shelby drop. As the car is only street driven thought I would go with the easier solution. In any case I can't reuse my existing springs (from Pedders) as the left fron has sagged a bit and the guard rubs on the top of the tyre when turning hard right. It's only done this since I fitted the new wheels and tyres (205/60 x 15 - 112mm offset). The old 14 inch tyres were fine. Must be the different offset.

65gtfstbk - The mid-eyes are working fine. Not sure what they are rated at, but they give me the stance I am looking for and the ride is firm but not harsh. I'm a bit like you and really only want to do the job once, hence my question.  

Just a comment about tire size and wheel combo. I have 225/R60-14 all around on Shelby 10 spoke wheels on my 66 GT-350. Slight rub while backing up turning to the left. Started with 205(looked small), then later jumped to 225(seen another 66 at a meet). I'm pleased with the fit. No ride mods other than what Shelby did.

cushman  

The single most authoritative article I have seen on wheels and tire size is from Mustangs plus. I have talked with people in the wheel business and they also refer to it. So I am trying to post it here. We will see how it works out.?


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If you cant read it let me know.  

Well that didnt work. I guess I have to learn how to post pics here.