Tubular A-Arms

[Atrus]

Anyone knowledgeable on 4th Gen tubular a-arms? I've seen reference to "issues"...the only specific issue I can find is that the shock mounting plates were inadequately designed and cracking/bending, but it seems they've been beefed up (by BMR anyway) and it's no longer an issue.

Reason I ask is I am heavily considering the BMR 1" lowering LCA's to drop the nose of the car down a bit while retaining stock springs and suspension travel. I think the heater hose mod on the rear and the 1" lowering LCA's may give a stance I can be happy with and I'd have absolutely 0 degradation of ride quality.

My biggest fear is that I want something that's robust, reliable, and not going to fail. I don't want these things cracking while I am being an idiot and evading the basic speed limit, nor do I want some issue while I am on the freeway doing 70 with my toddler daughter in the back seat.

[JoeliusZ28]

I personally dont like the idea of getting rid of the spring isolator in favor of some rubber hose thats not meant for that purpose and can dry rot, but thats just me.

One thing you may want to consider is that while retaining stock springs will retain ride qaulity, it also might mean you will bottom out easier, since the setup will want to act the same with less overall travel.

[birdie2000]

Both of those concerns are in the rear only though. The travel won't change in the front since shock/spring assembly isn't changing in anyway. Now, on the koni's with the stock spring in the lower perch, then it is a concern but supposedly not a big deal. I have no comment on the concern of the a-arms failing, although I can't say I've heard much about this in recent years. It was my impression as well that it was fixed.

In the rear, I agree on the hose drying out, although on my car it's only a summer "toy" so inspecting something like that every year or so isn't a big deal to me, and if it needs to be replaced it'll take all of an hour to do. If it did rot and fail somehow I don't think it would have catastrophic results, maybe just a little extra noise until it gets fixed.

As for bottoming out in the rear, are you concerned about the shock bottoming out or hitting the bumpstop? Modifying the bumpstop shouldn't be a huge issue if that's all.

[JoeliusZ28]

Right, travel would be the same in the front, however that would also mean the suspension will compress an inch further than it originally did. Im not sure if that will present any issues or not with wheel / ground clearance.

[Atrus]

I agree with Jim - I am not too concerned about the heater hose in the back. IMHO, I can't see it drying out for several years (heck, the hoses in my car are 13 years old and are fine still). Even if I replace them annually, it's not a big deal to me. And, right - I don't see the hose failure being catastrophic.

My a-arms cracking could be very catastrophic, which is what concerns me.

As far as suspension travel, that was my thought...yes, I'd lose the 1/2" or 3/4" of travel in the back. Hopefully that doesn't cause me an issue. The only reason I am considering the BMR arms (they are pricey) is that they do retain stock front suspension travel. For me, it seems like the compromise....I can choose stock 4x4 with Bilsteins and enjoy the ride but hate the look....I can run Strano/BMR/SLP springs like you did and like the look, but potentially be unhappy with the ride...or I can install these arms with stock springs and Bilsteins and be mostly happy with looks and happy with the ride.

I'm still really interested in Joel's approach, as I am kind of thinking that either this a-arm approach or his approach is what I'll be doing.

[Atrus]

Right, travel would be the same in the front, however that would also mean the suspension will compress an inch further than it originally did. Im not sure if that will present any issues or not with wheel / ground clearance.

Joel, I don't think it does. The arms move the mounting point, it doesn't change the articulation of the suspension in the front. The entire assembly shifts, I believe even the bump stop. I should have the same compression/range of travel as I do stock, shouldn't I?

[JoeliusZ28]

Joel, I don't think it does. The arms move the mounting point, it doesn't change the articulation of the suspension in the front. The entire assembly shifts, I believe even the bump stop. I should have the same compression/range of travel as I do stock, shouldn't I?

Ok, so the shock mount is located further out on the A-arm instead of more shallow into the a-arm? In that case yes you are correct, i didnt understand how the control arms were altered. However, if thats the case you would have reduced travel from the static position (it would be exchanged for more downtravel, total travel would remain the same)

[birdie2000]

Joel, you can see the difference in how they are mounted here.

Normal A-Arms:


Drop A-Arms:


I think you're right Joel, angle of the a-arm for a given shock/spring compression will be a little different, and the a-arm could theoretically travel higher relative to the body than before. I haven't pushed my car since I installed those, but in normal driving I haven't experienced any problems with the tire rubbing or a-arm hitting anything, and that's in conjunction with the fact that the koni's I have dropped it an additional 3/4". Although these probably aren't intended for an autocross/road racing application, I would have to imagine that BMR took some of these concerns into consideration when making such a product.