Rear LCA Help

[EvoPrecision8]

I'm planning to get coilovers soon. As such, I need a rear camber solution so that I can ensure appropriate, even camber. I always thought that I'd just need to throw on some rear LCA's and I'd be off to the races. However, my recent research makes the matter seem a little more complex than that, and I'm a little confused by a couple of things.

1) I read that adjusting camber via rear LCA also alters toe. Does this mean that toe arms are also required, or is there factory adjustment to bring the toe to the desired spec?

2) Many people (RCE notably) were noting that LCA's put additional stress on other suspension components such as the UCA bushings, and recommend replacing those as well. Is this necessary? I've heard they are a huge pain to install so i would like to avoid it if possible.

If you could help answer these noob questions it would be greatly appreciated.

[Moto-P]

1) If the adjustments you wish to make are beyond the range of adjustments of factory toe links, yes you will need additional aftermarket toe links. Most of the time, however, staying at within 40mm of ride height lowering, and for very minor camber corrections, you can use the factory toe links as long as LCA has a setting near that of the stock arms and are not drastically different to accommodate "Stance hard parking" configurations... For most racing duties, we only need to get 2~3 degrees of static camber.

2) Depending on the RCA of choice, the joints may be urethane, rubber, or hard ball joints. Anything harder than stock bushings will put progressively harder loads and impact on your suspension, and body sub-frame and uni-body structures. While going stiffer will provide a more direct feedback and retention of dynamic alignment on higher loads, simply going harder is not really always the best, and in fact rarely so.

The ideal setup is achieved for many reasons, such as what sort of machine you are looking to build, what your mix of daily driving to racing is, if this is a mixed role car, and finally your driver skill and goals, tastes, and factors of how you drive it. Fully stiffened ball jointed cars will give lightning response, but it usually get VERY tricky for the drivers, and it also reveals more seriously, any flaws in the rest of the car. Ball jointed ends also cause great deal of wear and tear on not just the joint itself, but anything it is attached to as there is no give for alignment pressures of arms in motion, nor constant hits the suspension takes from the road. Only really true dedicated race cars need such level of precision, and even at that, it may be overkill. There are MANY other joints and arms in the suspension too, and if those all are not replaced at the same time, the single hard joint will adversely affect alignment as it moves too. I will not discredit the role of adjustable LCA, and yes for some applications it is necessary to build a race car, and in other times, to increase the durability on things like competition rally cars.
I had a role in designing the RS-R LCA we recently launched, as well as have been a test driver for Cusco versions very early in FRS inception. Both of them work very well for cars that need it, but it isn't frequent on daily driven Sunday racers to need that level of adjustments or durability levels. RSR LCA uses a high quality polyurethane joint for good pairing with stock parts mixed in the toe control as well as racing arms, and do have an optional ball joint you can purchase if the goal is a more hard core race car build strictly for tracks-and sub 200 UTQG tires. Cusco ones are ball-jointed and are proven in hardest of rally racing too, as the unit is also compatible for Subaru WRX's that see a ton of rally action all over. But like I have said, the Stock LCA are also, very good for this car and suffices for most non- high level competition casual track fun.

Best recommendation is to use a rubber or polyurethane bushing equipped LCA, that has some 'give' so that the rest of the suspension can work in unison, and to balance out the design of the rest of that car, that will NOT be seeing equal amounts of bracing, welding, gusseting, pinch-welding, and caging, to even out the rigidity.

Big beefy adjustable LCA isn't really too critical in this sense, as natural camber for FRS suspension statically is nearly 2 degrees at 30mm drop, and it's still within range to be happy on handling with stock LCA. So if you are doing it partly for visual appeal, by all means, but since you will be setting it very close to the stock dimensions for the most part in a daily driven occasional racer with street tires, it really isn't high on priority for most casual Sunday track folks. Best then to save the $500 to spend on better properly designed shocks, and tires that suite the role best, which will do wonders to handling of the FRS.

[EvoPrecision8]

Originally Posted by Moto-P

1) If the adjustments you wish to make are beyond the range of adjustments of factory toe links, yes you will need additional aftermarket toe links. Most of the time, however, staying at within 40mm of ride height lowering, and for very minor camber corrections, you can use the factory toe links as long as LCA has a setting near that of the stock arms and are not drastically different to accommodate "Stance hard parking" configurations... For most racing duties, we only need to get 2~3 degrees of static camber.

2) Depending on the RCA of choice, the joints may be urethane, rubber, or hard ball joints. Anything harder than stock bushings will put progressively harder loads and impact on your suspension, and body sub-frame and uni-body structures. While going stiffer will provide a more direct feedback and retention of dynamic alignment on higher loads, simply going harder is not really always the best, and in fact rarely so.

The ideal setup is achieved for many reasons, such as what sort of machine you are looking to build, what your mix of daily driving to racing is, if this is a mixed role car, and finally your driver skill and goals, tastes, and factors of how you drive it. Fully stiffened ball jointed cars will give lightning response, but it usually get VERY tricky for the drivers, and it also reveals more seriously, any flaws in the rest of the car. Ball jointed ends also cause great deal of wear and tear on not just the joint itself, but anything it is attached to as there is no give for alignment pressures of arms in motion, nor constant hits the suspension takes from the road. Only really true dedicated race cars need such level of precision, and even at that, it may be overkill. There are MANY other joints and arms in the suspension too, and if those all are not replaced at the same time, the single hard joint will adversely affect alignment as it moves too. I will not discredit the role of adjustable LCA, and yes for some applications it is necessary to build a race car, and in other times, to increase the durability on things like competition rally cars.
I had a role in designing the RS-R LCA we recently launched, as well as have been a test driver for Cusco versions very early in FRS inception. Both of them work very well for cars that need it, but it isn't frequent on daily driven Sunday racers to need that level of adjustments or durability levels. RSR LCA uses a high quality polyurethane joint for good pairing with stock parts mixed in the toe control as well as racing arms, and do have an optional ball joint you can purchase if the goal is a more hard core race car build strictly for tracks-and sub 200 UTQG tires. Cusco ones are ball-jointed and are proven in hardest of rally racing too, as the unit is also compatible for Subaru WRX's that see a ton of rally action all over. But like I have said, the Stock LCA are also, very good for this car and suffices for most non- high level competition casual track fun.

Best recommendation is to use a rubber or polyurethane bushing equipped LCA, that has some 'give' so that the rest of the suspension can work in unison, and to balance out the design of the rest of that car, that will NOT be seeing equal amounts of bracing, welding, gusseting, pinch-welding, and caging, to even out the rigidity.

Big beefy adjustable LCA isn't really too critical in this sense, as natural camber for FRS suspension statically is nearly 2 degrees at 30mm drop, and it's still within range to be happy on handling with stock LCA. So if you are doing it partly for visual appeal, by all means, but since you will be setting it very close to the stock dimensions for the most part in a daily driven occasional racer with street tires, it really isn't high on priority for most casual Sunday track folks. Best then to save the $500 to spend on better properly designed shocks, and tires that suite the role best, which will do wonders to handling of the FRS.

That was a fantastic response! Thank you very much! Not including info on car setup and how I plan to use the car in my original post was a huge oversight. My apologies.

I will only be lowering the car by 25-40mm. The LCA's would be primarily to ensure camber symmetry on either side. I do not plan to exceed 2 degrees of negative camber (which will probably be close to where the car naturally sits at that height). I only want to be able to have a very slight bit of toe in as well. The car sees a fair bit of auto x but is also used on the street, and may see a couple track days per year (no tracks around here). The planned suspension setup was going to be coilovers with front camber plates and rear LCA's to start. I also use 200 UTQG rated tires.

Based on this information would you be recommending an adjustable rear LCA with rubber or poly bushings? It seems like I will not require aftermarket toe arms. Are there any other components you feel I should definitely replace?

[mav1178]

Since you are in Canada, things to consider:

- how much servicing do you want/need?
- is rust or road salt an issue?
- what ride quality do you want?

Pillowball-based arms are great but you do have to consider that they are not only harsher than stock, but have more elements to them to potentially fail or get damaged.

If you only want 2 degrees negative camber in the rear, there's no need to invest in a RLCA. Perhaps toe adjustment is necessary if it's excessively lowered, but I lowered my car on Ohlins without rear camber adjustment and it was fine for normal use.

I've moved on to SPC arms and replaced the RLCA bushing w/ a non-pillowball bushing, mostly because 1) trying to keep the car within STX rules if I choose to compete, and 2) needed more rear camber and the SPC arms come with offset front link (toe) bushing inserts that allow for toe correction with additional negative camber.

YMMV.

-alex

[EvoPrecision8]

Originally Posted by mav1178

Since you are in Canada, things to consider:

- how much servicing do you want/need?
- is rust or road salt an issue?
- what ride quality do you want?

Pillowball-based arms are great but you do have to consider that they are not only harsher than stock, but have more elements to them to potentially fail or get damaged.

If you only want 2 degrees negative camber in the rear, there's no need to invest in a RLCA. Perhaps toe adjustment is necessary if it's excessively lowered, but I lowered my car on Ohlins without rear camber adjustment and it was fine for normal use.

I've moved on to SPC arms and replaced the RLCA bushing w/ a non-pillowball bushing, mostly because 1) trying to keep the car within STX rules if I choose to compete, and 2) needed more rear camber and the SPC arms come with offset front link (toe) bushing inserts that allow for toe correction with additional negative camber.

YMMV.

-alex

Thanks for the insight.

The car won't be extensively winter driven, maybe a few ice racing events is all. If I were to winter drive it I would most likely go back to stock suspension for the winter. Road salt isn't a huge issue where I live anyways, because they primarily use gravel.

I mainly want them in order to be able to fine tune the alignment to ensure symmetry, etc. It's possible I may actually need them to reduce camber as well because -2 degrees is sort of the most I want to run. It's not really a question of if I plan to get RLCA's, but more so whether or not I need to get additional components if I do.

[AZP Installs]

We've had great success with the SPC rear arms on both of our track Project BRZ and our road race Spec86. Additionally we use these arms extensively with customer cars to ensure the alignment specs are setup after lowering the cars using springs or coilovers.

Inexpensive and get the job done as well as easily adjusted when needed.

-mike

[wparsons]

40mm drop will put you at more than -2* for sure, you'll have that (or a hair more) from a 25mm drop.