There is a company where I live making MII tubular a-arms (macgyvers)... rather than using polyurethane bushings as most others seem to be doing, they are fitting their arms up with O.E.M. style rubber bushings; the type that consists of an outer steel shell and an inner steel sleeve and rubber material bonded between....they are similar to idler arm or rear leaf spring bushings in appearance. would appreciate any opinions on this bushing choice as opposed to urethane....perhaps the rubber type may not be firm enough? or short lived? wondering what are the pros and cons ????? thanks.
Why would Ford make millions of them with rubber instead of poly? Maybe they are softer, but they've GOT to give a better ride.
I can appreciate that, but it leaves me wondering why the aftermarket makers like tci, heidts, etc, etc are all using urethane bushings? as opposed to rubber?
Urethane is actually cheaper and easier to make in small runs than the OE Style. They also have a PERCEIVED value in being better with the general public. Urethane is stiffer and won't flex as much under hard cornering, so it must be better, or so the thinking goes. Urethane is also known to squeak with age, especially if they are dry. It's kind of one of those tweak of the week kind of things that you don't really need for a street driven rod. JMO
Yes, loading them up on photobucket right now. Poly is cheaper in more ways than one. The sleeve to install them is much simpler to produce and the bushings themselves are cheaper. They just make building aftermarket arms easier to manufacture. So I'm going the other way. I have had poly bushings on my truck now some 50K+ miles and I have to replace the upper bushings every 10-15K because they just give up. They deform under load like rubber but does not have the memory that rubber has. If you are trying for an all out cornering machine and have too much bushing compliance in your stock bushings then they are a fantastic solution. However they can be a maintenence pain to grease them on a semi regular basis. I feel you can get a better ride quality with the OEM style bushings. Better road isolation to control NVH and last longer provided you install them correctly.
Yeah, rubber gives a smoother, quieter ride. The rubber bushings were originally added to cars to give a smoother, quieter ride. Rubber bushings need to be vulcanized and the equipment is more expensive. Polyurethane is cheaper to cast in limited quantities. It also might depend on the design of the suspension though how well they work. If you're using a-arms that have the pivot points mounted very close to each other front to back, then you may need the stiffer polyurethane to keep the whole a-arm from slopping too much front to back. But if the pivot points are spread out further apart from each other, then the softer rubber ones might be fine and give you a good ride. When you twist a rubber bushing, it actually twists because the rubber is stretchy enough. Polyurethane twists only a little bit, and then if the travel of the a-arm is beyond the amount that it can twist, the polyurethane has to slide over a steel part -- where it usually squeaks. If it slides that too much, it just wears out and winds up with an egg shaped hole. So how you drive, and what sort of roads you drive on, and how often you drive might make up your mind too.
It looks like they could make those mounts for the strut rods (the rear part of the lower control arms) a lot stronger by putting a rectangular plate across the two ears to stiffen them up and turn them into a U-shape instead of two flexible flat bars. The forged piece with the upper control arm bushings looks pretty much like a stock Mustang II with the stock type bushings, or at least similar to them. They look pretty good. The stock parts are pretty good. If you make a setup like that, you might want to drill a couple of small ~3/8 holes near that mustang II piece so that you can insert a pry bar in there while you do the front end alignment. I remember that it's a bitch sometimes trying to figure out where to pry against when you're trying to align that type of front end without messing the paint all up. When you do the alignment, you have to loosen those two studs that clamp the wavy bar to the top spring hat, and then pry it a little at a time until the caster and camber are right. I don't think the people who design those aftermarket front ends think about that when they design those top hats. A couple of holes in the right places would make life a lot easier and give you a place to pry against.
Thanks for posting those pics!....those are exactly the style of rubber bushings that I was referring to..... Thanks for stepping in to this thread Steve!....an expert opinion is very much appreciated....The designer at macgyvers here told me that the rubber bushings they use will give a very good result v/s urethane....but did not know whether to believe him or not 'cause everyone else seems to use the urethanes...He claimed that using oem rubber style is actually superior to urethane for same reasons you explained.. ps: the bushings on the upper arms in your pics....could you tell us the maker (spicer I take it?) and a part number? what are those bushings actually made for? (vehicle type/application?) and those upper arms in your pics, they look really good....are they of your own manufacture, or whose? my little thames van is not really a cornering machine...pretty much a straight-liner...but want decent ridgidity during hard braking... thanks..Ian
The upper bushings are stock 74-78 Mustang II bushings. These are made by my shop and will be available in a short time. This is the first three pair to come off the new fixturing. Oh, RustyBolts, you think maybe I should weld those rear brackets to the frame too?
Companies like TCI, P&J's, and the Deuce Factory originally used some GM bushings on their 4-bar kits. The reason they quit using them is because GM quit producing them. A few years ago GM made them available again. I don't if that is still true. I have the GM part number if anyone is interested. They do give a better ride than urethane and they last a heck of a lot longer. PM me for the part number.
Read what suspension guru Herb Adams has to say about urethane bushing in his book 'Chassis Engineering': "They look great on the shelf in the parts store". Urethane bushings have no torsional shear built in. Factory type suspension is engineered for rubber bushings with torsional shear. Enough said.
I intend on only making my style of arm. I have never really liked using the other style because of interference with the rack and pinion. Most it seems raise the rack a bit for the rack boots to clear the arms. And they only mount the bushing in single shear. As for replacement of the bushings on my arms, we did install and then replace them just to see if it is possible. And it is done just like removing them from stock arms. Either a cold chisel under the outer ring or a punch from the inside. Because of the way we machine the bushing sleeve the rubber bushing sleeve is held by the same amount of material and press fit as they would have been in a stock control arm.
As for replacement of the bushings on my arms, we did install and then replace them just to see if it is possible. And it is done just like removing them from stock arms. Either a cold chisel under the outer ring or a punch from the inside. Because of the way we machine the bushing sleeve the rubber bushing sleeve is held by the same amount of material and press fit as they would have been in a stock control arm.[/quote] Steve Elpolacko), in the event one wanted to powdercoat control arms wih pressed in OEM style bushings: would that be done first with bushing installation to follow after coating? I don't imagine that the baking oven temp. of 400+ deg. would do the bushings any justice and would likely wreck them? thanks..
Yeah. Sorry, I was just trying to chip in some ideas if it'll help anybody who's planning something similar. I've seen some finished cars with brackets like that with no lateral bracing.
Powdercoat first, then bushings. In fact if you were to have them coated, ask your coater to mask off the inner surface to prevent build up of material that would affect the press fit on installation. For good measure I put a light smear of anti-sieze on the bore before the bushing goes in to slow down rust. RB, a few of the brackets like that we do here don't get boxed. There is no lateral load on that part of the arm as the crossmember controls that pretty well. What tears the rear supports up is braking loads as the car tries to drive through the front wheels. It is pretty hard to see but those brackets almost make it to the outside of the frame on the underside. I learned early on that the braking force will literally rip them from the frame starting at the bottom first then working thier way up. But because of the length of the bracket I am adding an I-beam style gusset in there. Here is annother one we did at the first of the year. Drives excelent, no issues what so ever.
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