Ifs

My 1930 Chevy has an IFS under it that is said to be a Kugel. It rides very stiff so I began looking at the coilovers and determined that they were bottoming out. They were almost collapsed when the car sits on the ground. I removed the coilover and spring and it was labled 11 "s with a 200 lb. spring rate. This spring compressed to 6 3/4 when on the ground. I'm in the process of trying to determine the proper spring for the front as I suspect these have been messed with. Is your experience is that spring to soft?

Also when the coilover is removed, should I be able to move the A-arms up or down any?

 

Ask Kugel.

 

To determine the spring rate you need for your application, you need to weigh the front end of the vehicle. The shocks, if they are adjustable, can also be adjusted to handle your desired ride. It sounds like the springs have been altered or the shocks are bad if your bottoming them out.

 

With the spring/shock unit out, yes, you should be able to move the suspension all the way though it's travel smoothly. If not, something is in a bind and needs to be corrected.
Unfortunately, I have seen several aftermarket IFS systems that have been installed into early parallel leaf cars that were installed too low in the car. If you coil overs are at bottom at ride height that could very easily be the problem. There is the choice at that point of going to slightly shorter coil over as long as the suspension's geometry will support it. Another possibility would be a dropped spindle if it doesn't already have such a thing installed. Lot's of these aftermarket IFS systems use basic Mustang II geometry and components, so you might get lucky there too. I would check with Kugle's myself and find out what you have as a baseline.

 

Thanks, I have a call into Kugel. Does the 200 lb. spring rate sound right to you. Research so far shows in the 300 range.

 

I've got to be honest, I've never run coil overs in a front end situation, so I'm probably not the guy to recomend spring weights to you. There used to be a really good spring calculator in the Speedway catalogs that I have followed for rear applications with good results. A piture of your front end with the weight on it might point out some geometric concerns though.

 

I think 200 lbs sounds soft, but I might be wrong...

My M II IFS on my 34 Ford w/350 Chevy small block and aluminum radiator, rides very well with 450 lbs front springs.

BUT:
What's correct on a Mustang II IFS isn't neccessarily correct on another IFS. The spring rate doesn't depend on the front wheel weight alone. The distance from the lower A arm bolts to the spring Mount - compared to - the distance from the spring Mount and further out to the ball joint is very important.