BMR Releases New Product: A-arms for 67-69 Camaro, Firebird, 68-74 Nova (AAP001)

[BMR Tech]

BMR Suspension
A-arms for 67-69 Camaro, 67-69 Firebird, and 68-74 Nova

Improve handling and front end stability in your 67-69 Camaro, 67-69 Firebird, or 68-74 Nova with an A-arm Package from BMR Suspension. Manufactured from 1.25” and 1.5” DOM tubing and laser cut 3/16” mounting plates, both arms feature low-deflection, internally-fluted polyurethane bushings with easy-to-access grease fittings. Upper A-arms feature offset CNC machined cross-shafts to provide a shorter shim stack for lowered vehicles. These A-arms feature 4 additional degrees of positive caster for increased high speed stability and increased camber gain while turning. The BMR A-arm Package (AAP001) will outperform the OE arms in every aspect – weight, function, strength, and durability. Upper A-arms (AA005) and Lower A-arms (AA006) also sold individually. Available in red and black hammertone powdercoat finishes. Installation time of 4-5 hours.


To preview all of BMR’s high-performance suspension parts, please visit www.bmrsuspension.com, email [email protected], or contact them at BMR Suspension, 12581 US Highway 301 North, Thonotosassa, FL33592, 813-986-9302, Fax: 813-986-8055.

[BMR Tech]

Just wanted to point out that we will also have an upgrade option for the upper arms available in a few weeks that comes equipped with Delrin bushings and Pro-Forged tall ball joints.

[TheBandit]

Hi I'm considering your lower arms for 70 Nova. Do I understand correctly that the lowers have some additional caster built in by moving the lower balljoint forward some? Are these compatible with both stock springs and coil overs?

Thanks,
Clint

[TheBandit]

Hi I'm considering your lower arms for 70 Nova. Do I understand correctly that the lowers have some additional caster built in by moving the lower balljoint forward some? Are these compatible with both stock springs and coil overs?

Called and confirmed the lower ball joint is moved forward to add 2deg built-in caster and the shock mounting is designed to support both stock springs or coil overs.

[Jk918]

Just wish you could get the lowers with the Delrin Bushings as well

[TheBandit]

I bought these lowers for my '70 Nova and installed. Build quality and finish was very nice. The preinstalled ball joints were ProForged. The frame pivot poly bushings are greaseable, but the zerk fittings could not be reached with a standard straight grease gun. I found a 90 degree fitting that slides on from the side of the zerk that works great. I had one major issue, however, which is that the spring pockets are metal-on-metal. My coil springs (600lb/in AFCO 5x9.5 w/ AFCO hidden adjustable adjusters at the frame) rubbed the insides of the pockets and made a horrible, very unacceptable noise. I found a local friend with a set of take-off coil spring rubber isolators from his Hotchkis arms. They did not fit the BMR lowers due to being about 5.5" diameter while the spring pockets are about 5-1/4" ID on the arms, so I cut the outside diameter using a vertical bandsaw and then split them (like a split washer) so they could be installed down into the BMR lower pocket. Once installed the noise was eliminated, however the rubber isolators did lift the car some, so I took it apart again and adjusted my spacers to get ride height back where I wanted it.

Also when combined with Global West uppers (which add all the caster into the top arm while BMR's system is to add some in the lower and some at the top), the least caster I can achieve with shims maxed on one of my cross shaft studs is +8deg with -1.5deg camber. I actually really like how the car drives down the road with this much caster (lots of return to center tendency, extremely hard to steer it without the power steering going), but we'll see once I do my first autocross event. I'm curious to see if there will be noticeable bumpsteer or other ill effects. For what it's worth I also have done the Gouldstrand mod.

Ultimately I think these arms are a good option if you want to use coilovers, but based on my experience you might risk some major noise if you use conventional coil springs.

- - - Updated - - -

Just wish you could get the lowers with the Delrin Bushings as well

To be honest I wanted the poly bushings to keep NVH down, but I'm curious to know how Delrin does in that regard.

[Jk918]

I bought these lowers for my '70 Nova and installed. Build quality and finish was very nice. The preinstalled ball joints were ProForged. The frame pivot poly bushings are greaseable, but the zerk fittings could not be reached with a standard straight grease gun. I found a 90 degree fitting that slides on from the side of the zerk that works great. I had one major issue, however, which is that the spring pockets are metal-on-metal. My coil springs (600lb/in AFCO 5x9.5 w/ AFCO hidden adjustable adjusters at the frame) rubbed the insides of the pockets and made a horrible, very unacceptable noise. I found a local friend with a set of take-off coil spring rubber isolators from his Hotchkis arms. They did not fit the BMR lowers due to being about 5.5" diameter while the spring pockets are about 5-1/4" ID on the arms, so I cut the outside diameter using a vertical bandsaw and then split them (like a split washer) so they could be installed down into the BMR lower pocket. Once installed the noise was eliminated, however the rubber isolators did lift the car some, so I took it apart again and adjusted my spacers to get ride height back where I wanted it.

Also when combined with Global West uppers (which add all the caster into the top arm while BMR's system is to add some in the lower and some at the top), the least caster I can achieve with shims maxed on one of my cross shaft studs is +8deg with -1.5deg camber. I actually really like how the car drives down the road with this much caster (lots of return to center tendency, extremely hard to steer it without the power steering going), but we'll see once I do my first autocross event. I'm curious to see if there will be noticeable bumpsteer or other ill effects. For what it's worth I also have done the Gouldstrand mod.

Ultimately I think these arms are a good option if you want to use coilovers, but based on my experience you might risk some major noise if you use conventional coil springs.

- - - Updated - - -



To be honest I wanted the poly bushings to keep NVH down, but I'm curious to know how Delrin does in that regard.

I hear yea, I've been considering these arms for my 67 F body for a while. I was more concerned about having uppers with Delrin and the lowers with poly. I am not sure what that does for performance by having different bushings between the uppers vs lowers as they have different defections etc.

[TheBandit]

I have not had any problems with poly lowers and delrin uppers - that's what I've been running for the last 7 years with rebushed stock lower arms and Global West uppers. I'm sure delrin would hold the suspension geometry better, but I don't think it's something I would notice at my skill level while NVH is something I do have to live with on a street car.

[Jk918]

I have not had any problems with poly lowers and delrin uppers - that's what I've been running for the last 7 years with rebushed stock lower arms and Global West uppers. I'm sure delrin would hold the suspension geometry better, but I don't think it's something I would notice at my skill level while NVH is something I do have to live with on a street car.

Thanks for the feedback Bandit, mine is mostly a street car as well, and poly is defently aceptable for my skills.. my stock arms have poly bushings, but I've never has delrin bushings or even been in a car that has them. Does delrin exhibit more NVH then poly?

[marolf101x]

I've tested a lot of bushings/bearings/etc.

Does Delrin exhibit more NVH then poly?
Well, that depends on the parts.
If brand new and the poly is properly lubricated, Delrin will exhibit more NVH than poly.
If the Delrin is a self lubricating type and the poly is not properly lubricated the poly may create more NVH.

You are really dealing with two things when it comes to control arm bushings. . .
1-lateral force: energy transfer through the control arm, into the bushing then into the chassis
2-rotational force: how much the bushing resists the control arm moving up and down

Think about hitting a bridge expansion joint that is slightly higher than the road surface (I refer to this as causing "impact harshness"). As the tire hits the joint it is not only forced up (to compress the suspension) it is also forced back (causing a lateral load on the rear control arm bushings.)

Now, lets look at the bushing options and what happens. . .

Rubber:
Lateral-rubber absorbs the lateral load by allowing the control arms to move, thereby "soaking up" and minimizing the force transferred to the chassis.
Rotational-rubber has a progressive rate when twisted. So as the control arm moves up, the force to twist the rubber is low at first and increases the further the control arm moves. This also "soaks up" the force and minimizes transfer into the chassis.
Cons-
Resistance to rotation adds spring rate, which can create poor ride quality if the spring rate becomes high enough.
Allowing the control arms to move about due to bushing deflection changes the alignment, and thereby the tire contact patch, which is not ideal for performance.

Poly:
Lateral-poly absorbs some of the lateral load by allowing the control arms to move a little.
Rotational-poly, when properly lubricated, has very little rotational resistance, so the control arm is more free to move.
Cons-
Decreased bushing deflection transfers more force into the chassis.
Though decreased, the control arms are still moving a bit, thereby still changing alignment, hurting performance.
If the poly is not properly lubricated it "sticks" when the control arm wants to move. This causes a huge increase in spring rate until the sleeve in the bushing "breaks free" and rotates. This can cause huge NVH that can be felt (impact harshness).

Delrin (Acetal, non-lubricated):
Lateral-Delrin does absorb a very small amount of the lateral load. I think of it like hitting a piece of steel or a piece of wood with a hammer. The wood just makes a "thud" sound, while the steel "rings". Delrin gives you the "thud".
Bushing deflection is very low, so alignment is maintained.
Rotational-like poly, Delrin when properly lubricated, has very little rotational resistance, so the control arm is more free to move.
Cons-
Decreased bushing deflection transfers more force into the chassis.
Again, like poly, if the Delrin is not properly lubricated it "sticks" when the control arm wants to move. This causes a huge increase in spring rate until the sleeve in the bushing "breaks free" and rotates. This can cause huge NVH that can be felt (impact harshness).

Delrin (Acetal, lubricated; typically with 13% PTFE/teflon):
Lateral-again, Delrin does absorb a very small amount of the lateral load. It's the same as the non-lubricated Delrin above.
Bushing deflection is very low, so alignment is maintained.
Rotational-self-lubricating Delrin has very little rotational resistance, so the control arm is more free to move.
Self lubricating means very little maintenance is required.
Cons-
Decreased bushing deflection transfers more force into the chassis.

Bearings:
Lateral-bearings absorb nearly no force, it's almost all transferred to the chassis (like the hammer hitting steel "ringing" above)
Bushing deflection is nearly non existent, so alignment is maintained.
Rotational-bearings, in good working order, have very little rotational resistance, so the control arm is more free to move.
Cons-
No bushing deflection transfers nearly all the force into the chassis.
Do require inspection and replacement.


My personal thoughts on rubber, poly, Delrin and bearings:
Rubber-If I were building a street car, and NVH was paramount, I would use large rubber bushings.
poly-I hate poly. It was used in the Street Rod/Hot Rod/Muscle car suspension market as it was inexpensive and not much else existed at the time. (poly can be poured into simple, inexpensive molds) It was good for its time, but that time has gone.
It is useful in other applications, however.
Delrin-Only use self lubricating Delrin. Delrin maintains proper suspension alignment, exhibits nearly the same NVH as poly, but has none of the maintenance requirements.
bearings-only on a full on race car

[dhutton]

I've tested a lot of bushings/bearings/etc.

Does Delrin exhibit more NVH then poly?
Well, that depends on the parts.
If brand new and the poly is properly lubricated, Delrin will exhibit more NVH than poly.
If the Delrin is a self lubricating type and the poly is not properly lubricated the poly may create more NVH.

You are really dealing with two things when it comes to control arm bushings. . .
1-lateral force: energy transfer through the control arm, into the bushing then into the chassis
2-rotational force: how much the bushing resists the control arm moving up and down

Think about hitting a bridge expansion joint that is slightly higher than the road surface (I refer to this as causing "impact harshness"). As the tire hits the joint it is not only forced up (to compress the suspension) it is also forced back (causing a lateral load on the rear control arm bushings.)

Now, lets look at the bushing options and what happens. . .

Rubber:
Lateral-rubber absorbs the lateral load by allowing the control arms to move, thereby "soaking up" and minimizing the force transferred to the chassis.
Rotational-rubber has a progressive rate when twisted. So as the control arm moves up, the force to twist the rubber is low at first and increases the further the control arm moves. This also "soaks up" the force and minimizes transfer into the chassis.
Cons-
Resistance to rotation adds spring rate, which can create poor ride quality if the spring rate becomes high enough.
Allowing the control arms to move about due to bushing deflection changes the alignment, and thereby the tire contact patch, which is not ideal for performance.

Poly:
Lateral-poly absorbs some of the lateral load by allowing the control arms to move a little.
Rotational-poly, when properly lubricated, has very little rotational resistance, so the control arm is more free to move.
Cons-
Decreased bushing deflection transfers more force into the chassis.
Though decreased, the control arms are still moving a bit, thereby still changing alignment, hurting performance.
If the poly is not properly lubricated it "sticks" when the control arm wants to move. This causes a huge increase in spring rate until the sleeve in the bushing "breaks free" and rotates. This can cause huge NVH that can be felt (impact harshness).

Delrin (Acetal, non-lubricated):
Lateral-Delrin does absorb a very small amount of the lateral load. I think of it like hitting a piece of steel or a piece of wood with a hammer. The wood just makes a "thud" sound, while the steel "rings". Delrin gives you the "thud".
Bushing deflection is very low, so alignment is maintained.
Rotational-like poly, Delrin when properly lubricated, has very little rotational resistance, so the control arm is more free to move.
Cons-
Decreased bushing deflection transfers more force into the chassis.
Again, like poly, if the Delrin is not properly lubricated it "sticks" when the control arm wants to move. This causes a huge increase in spring rate until the sleeve in the bushing "breaks free" and rotates. This can cause huge NVH that can be felt (impact harshness).

Delrin (Acetal, lubricated; typically with 13% PTFE/teflon):
Lateral-again, Delrin does absorb a very small amount of the lateral load. It's the same as the non-lubricated Delrin above.
Bushing deflection is very low, so alignment is maintained.
Rotational-self-lubricating Delrin has very little rotational resistance, so the control arm is more free to move.
Self lubricating means very little maintenance is required.
Cons-
Decreased bushing deflection transfers more force into the chassis.

Bearings:
Lateral-bearings absorb nearly no force, it's almost all transferred to the chassis (like the hammer hitting steel "ringing" above)
Bushing deflection is nearly non existent, so alignment is maintained.
Rotational-bearings, in good working order, have very little rotational resistance, so the control arm is more free to move.
Cons-
No bushing deflection transfers nearly all the force into the chassis.
Do require inspection and replacement.


My personal thoughts on rubber, poly, Delrin and bearings:
Rubber-If I were building a street car, and NVH was paramount, I would use large rubber bushings.
poly-I hate poly. It was used in the Street Rod/Hot Rod/Muscle car suspension market as it was inexpensive and not much else existed at the time. (poly can be poured into simple, inexpensive molds) It was good for its time, but that time has gone.
It is useful in other applications, however.
Delrin-Only use self lubricating Delrin. Delrin maintains proper suspension alignment, exhibits nearly the same NVH as poly, but has none of the maintenance requirements.
bearings-only on a full on race car

Great post. Thanks.

[TheBandit]

marolf101x - Thanks for the detailed response. It's great to hear from someone with experience testing this kind of stuff for a living! Poly has been acceptable for me, but it would be interesting to try something else for comparison.

Update on my experience with the BMR lowers
This weekend I drove 100mi each way to an autocross event and had my best outcome yet, placing 3rd in my class among some really cool cars. First I'm happy to report I've resolved the noise issue completely with the coil spring isolators. Second, the tires did not rub at the back of my inner fenders like they used to with stock arms and all the caster coming from my Global West Upper arms. If I was shopping for arms again, I'd definitely look for a set that builds caster into both the upper and lower arms so the wheel remains centered in the wheel well. Reviewing advertising info I found BMR, Speed Tech, Ride Tech, QA1, and Detroit Speed all do it this way, while Global West uses only the upper arm to increase caster and Hotchkis seemed to be unspecified. Third, a major improvement is that the lower-profile bump stop allows more compression travel than what I had on my stock lower arms. This is really noticeable on hard roadway transitions on the freeway where I found myself in the habit of bracing for an impact that no longer happens with these arms. Similarly things feel smoother on the autocross course without the disruptive knock against the bump stops.

My only gripe now with these arms is the lack of steering stops. I would really like adjustable stops so I could keep my tires from rubbing the frame. This is obvious from noise and feel when it happens, so I can back out of the steering a little bit, but the tire acts like a brake against the frame so it was hurting me on a few of the really tight corners where I needed full steering.

[marolf101x]

Possible steering stop idea. . .
Drill and tap the control arm tube, thread in an appropriately sized bolt with a nut already on it. Adjust bolt to stop steering angle, tighten jam nut.
This only works if something attached to the spindle hangs low enough that it will hit the bolt.
Not sure exactly what parts you have, but it might work.

[TheBandit]

Possible steering stop idea. . .
Drill and tap the control arm tube, thread in an appropriately sized bolt with a nut already on it. Adjust bolt to stop steering angle, tighten jam nut.
This only works if something attached to the spindle hangs low enough that it will hit the bolt.
Not sure exactly what parts you have, but it might work.

This is pretty much what I was thinking, although since the arms are 0.120 wall, I might want to weld in a threaded bung so I don't pull it out when tightening a jam nut. The steering arms have a flat area that was used with the factory in-built steering stops - as long as it lines up roughly with the tubing it should work. A bolt and jam nut would make a perfectly acceptable steering stop, but I need to get under there to see how much room I have. A lot of the other aftermarket arms have adjustable stops built this way.

[marolf101x]

That’s how we did it at ridetech, but I put the bolts in flat plate, so didn’t have to worry about material thickness.