Thoughts on tall spindle swap

[Clever Idiot]

Ok, folks. I have been planning on doing a tall spindle swap on my Monte for a few years now, due to the gains of the negative camber curve under compression, and bigger brakes - Corvette C5 brakes, specifically.

 

Hit a bump when I looked into it more. Did some Googling, got a little lost, and decided to call BMR Suspension.

 

First, great folks there. Only talked to one guy so far, but he was very helpful and not at all pushy or trying to hurry me off the phone.

 

In case your goals aren't the same as mine, here's what I'm going for. I like to drive 'spirited', as they say. I want a car that will corner and stop, and not behave like a boat on rough seas. Since my daily driver is a lighter, sportier car, the bar's been set fairly high. However, I'm not going to be road-racing. I don't need the absolute best of the best available. I also realize that getting the Monte to handle like my modern driver would be financially impossible, as well as physically impossible. But I've seen enough suspension videos to know that it *is* possible to make an old girl turn and stay fairly flat. That's my goal. Not looking to break any slalom records, but not looking to be thrown out of my seat in a corner, either. We have some fun interstate ramps around me, and I take advantage when I can.

 

So I told Rich at BMR all this. They've tested their tall-spindle A-arms against the AFX spindle now offered by SpeedTech (used to be offered by ATS). Since those spindles have more than I'm looking for (speed sensors, pressed-in bearings) I was asking if BMR's stuff would work with an L&H tall spindle. L&H's is roughly the same price, but a *little* cheaper, and I know the AFX's availability is subject to the output of a forging company that also forges bearings for the military (ie, if a multi-million dollar military contract comes in, the hot rodders get their wait times pushed into months rather than weeks). I haven't contacted SpeedTech at all, so they may have plenty on the shelf at this point. I just know it's been an issue in the past.

 

Anyway, back to the point. I asked about L&H spindle working with BMR's stuff, and Rich said he'd get in touch with R&D and let me know.

 

Here is his response:

 

DJ,

 

I talked to the guys here and it looks like I cant really commit to an answer concerning the compatibility of our tall spindle upper arms with the L&H or others on the market.

 

(R&D) We mapped the camber curve of Tall ball joint vs. Tall spindle & tall ball joint. During our test against the Tall Spindle we assumed a 25" tall tire with a 6" frame height. The tall ball joint was tested against an AFX spindle & the camber curve remained similar until the bump reached 1.5" from static. At that point the curve became a little more aggressive, gaining -.3 at 1.5" compression, -.4 at 2", -.5 at 2.5", and -.6 at 3" over the tall ball joint.

 

(Rich again) These numbers are better & although the tall spindle would be the ideal choice the “bang-for-the-buck” value of the tall ball joints cannot be discounted. In a nutshell it is our opinion that for the average enthusiast the tall ball joint setup improves the camber curve sufficiently for most driving requirements.

 

The tall ball joints will definitely make a vast improvement to your car. It offers a better camber curve, increased positive caster capability, and a lowered CG which is what we are all looking for.

 

Your build recipe will accomplish all of that and at minimal cost. We have also re-designed our A-arms with increased positive caster & they will require less shim stack to achieve proper camber settings on lowered vehicles. We added 2 degrees of caster to the lower A-arm & 2 degrees on the upper.

 

The equal split of caster between the upper & lower arms keeps the wheel properly centered in the wheel well and allows plenty of positive caster without a lot of staggered shims.

 

I have also attached the current 67-69 Camaro A-Arms and the new design so you can get an idea what the A-Body arms will look like soon.

(end email)

 

Oh yeah, BMR is redesigning their A-arms to be available soon. Lighter and/or stronger. Can't remember if stronger, but definitely lighter (and obviously at least *as* strong).

 

Here are the pics:

Old:

 

New:

 

 

So, thought I'd put this out there for anyone else thinking of doing a tall-spindle swap.

 

Cheers.

[Mo's70MCs]

Nice! DJ, good reading, good going on the ground work. What do you think about the frame? Anything in the way of reinforcing, you know with our platform suffering with a bit of sagging, is that something to consider in the way of front end geometry?

[Clever Idiot]

I honestly have no idea. I don't know much about suspension geometry - I dare say I know almost nothing. Camber is about the only thing I know what it means without having to look it up online.

 

I know there are companies out there that have adjustable A-arms, adjustable upper and lower control arms, and that somebody who knows what they're doing can use those adjustments to tune the suspension specifically to their application and driving style. That is all WAY beyond me. When it comes to suspension, you could say I'm a bolt-on kind of guy.

 

But, I will say that the folks at BMR really love the hobby. The guy I talked to on the phone, when I told him I had questions he asked me what I was working on. Told him a 1970 Monte Carlo, and his response was an immediate, "Nice!" and later in the conversation he was saying it'd be great to get me up there once I get it on the road because he likes to see the more unique models. Actually said he'd like to get one at some point. I don't know about other places, just because I've only now started calling around to talk about actually getting parts for the Monte, but most of the time I tell people what I'm working on, I have to explain what it is. So it was cool to talk to someone who was already familiar with it.

 

As for frame reinforcement, I'd give 'em a call. They're stuff is like half the price of Hotchkis, Detroit Speed, etc, and it's not lacking in quality, as far as I can tell. Here's their website. Definitely worth checking out, IMHO.