Street cars running front tubular arms?
10-05-2007, 09:45 AM
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Street cars running front tubular arms? Are tubular adjustible lower and upper control arms beneficial in street cars?
I suppose installation requires alignments.
What are the advantages and disadvantages?
I suppose installation requires alignments.
What are the advantages and disadvantages?
10-05-2007, 10:48 AM
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The upper arm is exposed to very little stress compared to the lower arm. Notice the diminutive size of the upper arm. It maybe sees 20% of the forces that the lower arm sees. So theres just not a lot to the upper arm. you might see some very marginal benefit from replacing it with aftermarket- maybe a pound of weight reduction, maybe a little bit of increased strength. The upper arm is also straight forward as far as bushings go. Choices are poly or rod. So you'll get a little bit more noise and vibration. if you get a rod end piece you get some added adjustability. Some have a corrected angle for lowering which i'm not sure if its really necessary.
Lower arms have to be very strong. They do a lot more than the upper arm. So you just have to be careful that you get a road racing piece thats focused on strength as opposed to a drag racing piece that is focused on light-weight. There are several makers of both varieties out there. The real problem with the lower arms is bushings. One goes the normal way, one goes vertical. So you'll usually see a rod end at the vertical one. and a poly bushing at the normal one. Again. theres a tiny advantage as far as adjustability goes.
Would the money spent on front arms be worth the improvement? I don't think so. especially not on a car with 275 street tires or less.. but thats just me.
Lower arms have to be very strong. They do a lot more than the upper arm. So you just have to be careful that you get a road racing piece thats focused on strength as opposed to a drag racing piece that is focused on light-weight. There are several makers of both varieties out there. The real problem with the lower arms is bushings. One goes the normal way, one goes vertical. So you'll usually see a rod end at the vertical one. and a poly bushing at the normal one. Again. theres a tiny advantage as far as adjustability goes.
Would the money spent on front arms be worth the improvement? I don't think so. especially not on a car with 275 street tires or less.. but thats just me.
10-05-2007, 02:07 PM
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...how about the rubber bushings that are used in the factory lower arms? Does this cause the factory designed steering and suspension to be a tad sloppy? I'm not a fan of these and every time a change a factory part with a mushy rubber bushing to one with a poly or rod end it seems to improve the way the car feels....
10-05-2007, 03:11 PM
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polyurethane only works well in places where the rotation of the part is square to the bolt through the bushing. whenever the busing is required to rotate in an arc -as in the rear lower control arm- you get suspension bind, poor performance and its just hard on the part as well as the location its bolted to.
The rear bushing of the front lower control arm is required to flex parallel with the bolt going through it and so polyurethane is a very very poor choice for this location. Rubber or rod ends are the only suitable solution at this point. But poly will work OK for both upper bushings and the front bushing on the lower arm. So you'll find that most aftermarket front control arms are either spherical bushings at all 8 points (4 per side) or will have poly bushings at 6 points and rod at the other 2.
Poly in general isnt a perfect solution. In addition to causing bind in many applications it transmits more noise and vibration, it can deteriorate faster than rubber if you dont lube it frequently, it squeaks and it will deform (cold flow). High price to pay for a little reduction in deflection.
yes rubber does flex and tubular components are often stronger than stamped. but the fact of life is that if you put a car with tubular LCA's PHB and tubular front control arms and poly bushings at all 4 corners (everything else stock) up against a car with stock LCA's stock PHB and stock front arms with stiff springs, proper shocks and stiff swaybars... the latter car will rip the former car a new one.
and besides that, the latter car will be as smooth as silk as a daily driver whereas the first car wont.
The rear bushing of the front lower control arm is required to flex parallel with the bolt going through it and so polyurethane is a very very poor choice for this location. Rubber or rod ends are the only suitable solution at this point. But poly will work OK for both upper bushings and the front bushing on the lower arm. So you'll find that most aftermarket front control arms are either spherical bushings at all 8 points (4 per side) or will have poly bushings at 6 points and rod at the other 2.
Poly in general isnt a perfect solution. In addition to causing bind in many applications it transmits more noise and vibration, it can deteriorate faster than rubber if you dont lube it frequently, it squeaks and it will deform (cold flow). High price to pay for a little reduction in deflection.
yes rubber does flex and tubular components are often stronger than stamped. but the fact of life is that if you put a car with tubular LCA's PHB and tubular front control arms and poly bushings at all 4 corners (everything else stock) up against a car with stock LCA's stock PHB and stock front arms with stiff springs, proper shocks and stiff swaybars... the latter car will rip the former car a new one.
and besides that, the latter car will be as smooth as silk as a daily driver whereas the first car wont.
Last edited by OldeSkool; 10-05-2007 at 03:24 PM.
10-08-2007, 01:53 PM
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I just bought UMI front lower control arms to go with my UMI k-member I recently installed. My stock front LCA's needed new ball joints and bushings so I decided to purchase tubular ones. Will let you know the difference as soon as I get everything installed.
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10-08-2007, 03:33 PM
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I wouldn't go so far as to make a simple blanket statement like that.
In a driveline, you typcially work in order of weakest components (if you're smart). If you have a plastic drive shaft, you replace that first, then if you have a wooden clutch, repace that second and then if you have a tin rear, you replace that.
Suspension is a little different in that it isn't so much a linear progression (as in power moving down the driveline). There are a lot of things happening at once.
But the concept of weakest links still holds.
Basically what I'm getting at is... the A-arms are not a weak link.. until you have a set up that really gives them a workout... the stock swaybars and springs (and the obligatory shocks to support those springs) and 275 street tires are not going to put enough strain on the stock arms to make upgrading them worth it.
If your "street" car had sticky 315 tires all around, 500lb/in springs or higher and ~35mm front swaybar... then you might see some loads where a stronger arm might make a difference.
And then there's the question that if its a street car.. even one set up with the goodies I just mention.. will it ever be driven that hard on the street as to overwhelm a stock a-arm? but thats a whole other issue
In a driveline, you typcially work in order of weakest components (if you're smart). If you have a plastic drive shaft, you replace that first, then if you have a wooden clutch, repace that second and then if you have a tin rear, you replace that.
Suspension is a little different in that it isn't so much a linear progression (as in power moving down the driveline). There are a lot of things happening at once.
But the concept of weakest links still holds.
Basically what I'm getting at is... the A-arms are not a weak link.. until you have a set up that really gives them a workout... the stock swaybars and springs (and the obligatory shocks to support those springs) and 275 street tires are not going to put enough strain on the stock arms to make upgrading them worth it.
If your "street" car had sticky 315 tires all around, 500lb/in springs or higher and ~35mm front swaybar... then you might see some loads where a stronger arm might make a difference.
And then there's the question that if its a street car.. even one set up with the goodies I just mention.. will it ever be driven that hard on the street as to overwhelm a stock a-arm? but thats a whole other issue
