Front suspension rebuild - rubber or polyurethane ?

I have a Mustang II front suspension (real, 1974 Ford, not aftermarket) that probably has 100K+ miles on it and original 1974 bushings. I’m getting some steering vibration on long sweeping curves at speed, thinking that the 50 year old rubber is probably needing to be replaced.

I can get OEM rubber style bushings from NAPA, Rock Auto, etc.. I can get polyurethane from Energy Suspension and other aftermarket companies.

Since the original parts worked, I’m thinking going with rubber again. But would polyurethane be better somehow?

 

Polyurethane is stiffer and less compliant. This means the suspension will be firmer and tighter, good for aggressive driving and track days. Rubber will be more complaint, which means better ride, less vibration transfer, but will give a "sloppier" feel.

That said, I was the Lead Validation Engineer for a Heavy Duty truck Suspension company for many years. I tested a ton of different bushings, rubber, poly, and other materials, including a bunch of Energy Suspension stuff. Energy always provide some of the least durable bushings for these applications (Class 6 thru 8 heavy truck). I have also removed all of the Energy Suspension bushings out of my personal classic cars, because the durability just is not there.

 

I've used the poly ones in the past and never really had issues on my own stuff, but I've seen some poly failures with cracked or really worn and oblong shaped bushings. I put new leaf spring bushings in my F-100 , the quickest ones I could get shipped to me were polyurethane. I installed them, but I also ordered a set of stock bushings to keep in my cabinet in case the poly bushings shit the bed.

 

ive used both but if you r not racing around a lot the rubber s the way to go imo . and its quiet

 

While this is essentially a correct statement, it is possibly a bit misleading. A better way to put it might be that rubber will give a 'standard' street car type of ride, while polyurethane will stiffen things up to a more 'performance' orientated level.

 

Not racing. It’s a street car. I was leaning toward rubber, this confirms it. Thanks.

 

Polyurethane is fine to run on the street. Virtually any suspension modification that stiffens things up so as to acheive better handling will make for a harsher ride. More of the road irregularities will transfer through the less compliant urethane bushings, and you will feel it through the steering and the seat of your pants. You need to choose the balance that suits you and the way you use your car. It is always a bit of a trade-off.

 

Hey, FM;
Did you ever find anything that was better than oem rubber, in terms of both useful-life, & NVH(reduction if possible, or at least not more than oem)?
Stude used steel for bushings that worked well, gm-type bushings also work well, but are abit compliant, & some aftermarket-urethane-something-or-another bushings on a scout I had were all cracked & "flowed"(= junk) w/very low mileage, I did put E.S. urethane bushings in as replacements, but never used it. Not sure how they fared from just sitting. From some reading in the past, it seems E.S. stuff is high-priced junk, which I wish I knew back then. Hoping I'm wrong, no big deal if I'm not.
Marcus...

 

If you can get oem stuff it will last the life of the rod, or rodder.