Opinion Rear CA's Modern Motorsports, AZC, Zraceproducts

[Guest CA-350Z]

Question posted in a different thread by Titus RacerX

http://forums.hybridz.org/showthread.php?t=129100

 

I wonder what Jon thinks about the Modern Motorsports parts (rear CA's)

 

I also wonder how Modern Motorsports rear CA are viewed by the experts on this form. Now that AZC is producing Rear control arms for the 240 we have more choices that ever. Wonder what the benefits of Modern Motorsports CA are over AZC, Zraceproducts and others?

 

Thoes with using these products or with opinions please share your experience / thoughts.

 

http://www.modern-motorsports.com/catalog/product_info.php?products_id=68

Modern Motorsports

 

Zraceproducts http://store.zraceproducts.com/suspensionparts.php

 

 

AZC

http://www.arizonazcar.com/lowarms.html

 

[JMortensen]

I'm tired. Someone else go first and I'll do my eval later or tomorrow.

[johnc]

IMHO, they are not really needed. The are nice to have for the ease of toe adjustment, but a good set of 240 or 280Z rear LCAs will do everything these do for a lot less money.

 

But what do I know...

[BRAAP]

Yeeup. I agree with JohnC 100%. The rear OE lower control arms will indeed “locate” the rear wheels laterally and longitudinally in relation the car itself and do a good job of that “locating” under some pretty harsh conditions. The stock rear control arms are fairly light weight, especially for their strength, and the geometry of the S-30 rear suspension isn’t to terrible, i.e. it works fairly well. The major draw backs of the rear suspension is the weight of the struts/hubs and the drum brakes, (the brakes are an easy issue to address). the LCA's perform their intended job pretty well, other than the lack of adjustability which those arms do offer.

 

 

Not trying to thread jack, but I’ve noticed over the past couple years, a trend of people either ignoring or skipping over the front suspension of the S-30 and are eager to alter the rear suspension of the S-30. What is ironic in this is the fact that the front suspension of the S-30 seems to have more faults, needs the most work regarding alterations, yet the rear is where everyone starts their focus?!?

 

... We now return you to our regularly scheduled opines on custom rear LCA’s…

[Titus_RacerX]

Hey, I had to ask! After some PM's with Jon, I have to agree with him, John and Paul. Money better spent elsewhere.

 

But, thanks CA for raising the question.

[buZy]

Let's not jack thread cause we are bored... Instead let us marvel all the efforts of those supporting our 40 year old cars, reguardless of what is better or not.

And never tell another man what he needs and doesn't need lol.

 

I'm using MMS pieces. Street car mostly. No expert. I am only human lol..

 

Pros:

No silly rod ends on the spindle pins.

OEM style end links are very high quality. More compliant than rods ends also lasting longer on the street, aka many more miles, in harsher uncontrolled enviroments.

Adjustment is very infinate and very easy to set.

More than one place to mount the sway bar end links.

Fabricated for MMS by a suspension manufacturer to ISO quality standards.

Oh and...approved by John Coffey (accredited Z race chassis expert/racer and fabricator) in the Summer 2005 issue of Sport Z Magazine.

What more do you need to know? I dont see this guy putting his name endorsing very many products out there. The Z god has given them the blessing lol.

 

Cons:

Heavier than oem. (But a major part of that weight is in the soild inner pivot so the effect on unsprung weight is not a direct comparison.)

 

If I were to do it again I'd still go MMS.

[JMortensen]

OK, I have a beer on my desk, work is all done, wife won't be home for a while, so I'll give you my take.

 

First, John and Paul (not to mention George and Ringo) are correct. For a street car you're much better off putting your money somewhere else. And Paul also makes a very good point about the front suspension. In my years of Z autocrossing, I NEVER got the front end to hook up as good as the rear, I always fought push, and I had all kinds of stuff done to the front to try and get it to hook up better. The front needs more attention than the rear. It's that simple.

 

So why would anyone want new rear control arms?

 

A couple reasons. I think the reason 90% of people buy a set of control arms for their Z is because they look cool. Not my thing, but whatever floats your boat is fine with me. You want bling, control arms offer bling.

 

Another reason is to adjust toe. Toe adjustment is not something that a lot of people need to be doing, to be perfectly honest. If you're in a range of 1/16 toe out to 1/4" toe in and you just commuted in your car, you'd probably never notice that you had an alignment issue. If you're racing, the toe setting can make a big difference, but until you're at the limit it's not really noticeable unless it's bad enough to make the car crab down the road or cause unusual tire wear. Regardless, if you're after an alignment these arms can allow you to align your car.

 

You might want aftermarket control arms to lose weight. As Paul suggested, the stockers aren't very heavy at all. There are better places to lose weight, but if you've exhausted all of those then I suppose this might be a reason.

 

Probably the best reason I can think of to put different control arms on the car is to reduce stiction. Stiction is the initial reluctance to move caused by bushings that are stuck to the shaft. Stiction makes the suspension unresponsive to inputs from the road and is generally to be avoided, but this is especially important for a race car.

 

Strength might be a reason to buy an aftermarket arm. I can't see this really being an issue unless you're rally racing, but I can see people justifying their purchase in this way.

 

The last reason is you're racing. For racing you want the best combination of weight, alignment, precision, and free motion at the lightest weight possible.

 

So let's go down the list:

 

MM-- They use stock style inner bushings as far as I know. buZy suggested that there might be a "solid inner pivot". Not sure what that is, so I won't speculate. It seems clear that a stock inner bushing would work. If you use stock rubber there is too much deflection. If you use poly there is too much stiction. The outer pivots are rubber bushed, so they can also deflect under load. The rod ends are circle track parts, and they have a TON of threads exposed. This is the "threads in bending" thing that you'll occasionally hear engineer types warning against. So the MM arms have threads in bending, and they have by far the most threads in bending of the three arms we're looking at. That said, Ross is an engineer and I am not. It seems to me too that if you do adjust the toe to something other than 0 you're forcing the bushings to misalign which would cause yet more stiction. On the other arms the spherical bearing in the rod end rotates in the housing and doesn't increase stiction.

 

Z Race Products-- These arms are overbuilt to a fault. The outer rod ends are 7/8" where most other arms use 5/8" rod ends. The weight on these as listed on their website is 34 lbs for a pair. That's a lot more than even the heavier 280Z arms. They still use stock inner bushings, so you still have your choice of mushy or sticky. I thought I read that they were going to come up with a toe adjustment that didn't require pulling the spindle pin, but it doesn't look like they've done that. So toe adjustment would be a real pain. Also I'm not sure why all the tubes are bent. A straight tube should be stronger in tension and compression than a bent tube, so it seems like you'd want to avoid bending the tubes wherever possible. It looks like they've gone for style points and even bent the tubes in the middle which didn't need to be bent at all. The outer frame could have been built with straight tubes, but it would have required a different configuration, probably resulting in more pieces and more welding.

 

AZC-- The only good thing I can say about their new rear arm is that it uses rod ends on the inner and outer pivots, so it should reduce stiction a lot more than the other two. Other than that I think its a tremendously bad design, for all the reasons listed on the other thread. His old arms were much better, provided you got the later revised ones that didn't have a 5/8" nut turned down and welded into the end of the arm.

 

When it gets right down to it I think this thread here http://forums.hybridz.org/showthread.php?t=129154 is coming up with some MUCH better solutions to the rear control arm than anything above. Redesigning the arm to be an A arm with a toe link instead of an H arm seems like a HUGE step in the right direction to me. Read that thread to get an idea of why that is.

[260DET]

Yeeup. I agree with JohnC 100%. The rear OE lower control arms will indeed “locate” the rear wheels laterally and longitudinally in relation the car itself and do a good job of that “locating” under some pretty harsh conditions. The stock rear control arms are fairly light weight, especially for their strength, and the geometry of the S-30 rear suspension isn’t to terrible, i.e. it works fairly well. The major draw backs of the rear suspension is the weight of the struts/hubs and the drum brakes, (the brakes are an easy issue to address). the LCA's perform their intended job pretty well, other than the lack of adjustability which those arms do offer.

 

 

Not trying to thread jack, but I’ve noticed over the past couple years, a trend of people either ignoring or skipping over the front suspension of the S-30 and are eager to alter the rear suspension of the S-30. What is ironic in this is the fact that the front suspension of the S-30 seems to have more faults, needs the most work regarding alterations, yet the rear is where everyone starts their focus?!?

 

... We now return you to our regularly scheduled opines on custom rear LCA’s…

 

Agree 100% about a lack of attention to the front end while there is a lot of discussion concerning the rear. Careless I think is looking at adapting the S13 front end which is a lot better than the S30's and has great aftermarket support.

 

On the rear end I made a set of LCA's something like the Modern Motorsports ones but triangulated. This was done simply to get some negative camber and to have the means to adjust toe for circuit racing. They worked very well but agree are not necessary for only road use.

 

EDIT: to answer the question I like the MM design best but for me the box shape part would have to be triangulated.

[johnc]

Oh and...approved by John Coffey (accredited Z race chassis expert/racer and fabricator) in the Summer 2005 issue of Sport Z Magazine.

What more do you need to know? I dont see this guy putting his name endorsing very many products out there. The Z god has given them the blessing lol.

 

I think Ross' rear LCAs are well built and are worth the money for those looking for aftermarket rear LCAs. They make rear toe adjustment easy and reduce that effort (compared to stock arms and offset bushings) by 5 hours. I've installed probably half-a-dozen sets of the MM arms on customer cars over the years and never had a problem.

 

I do have to say that I have not worked with the Z Race Product or AZC rear LCAs so I can't say if the Modern Motorsports LCAs are better or worse then the others. I won't express an opinion on any of these parts until I work with them on a car.

 

Regarding the discussion about where to spend the time and effort on the suspension (front or rear), my reply is: both. What needs to be done to the front is a topic for a completely separate, long, convoluted, and contentious thread.

[Dragonfly]

DISCLAIMER: Since I have the ZRaceProducts LCA's on my car I am going to show some favoratism.

 

Like many others have said the stock LCA's are fine for most people under most circumstances. For anyone who feels the need to use aftermarket LCA's I personaly like the ZRaceProducts the most and YES they are on car adjustable, they have a powder coated exterior and have set screw plugs that allow grease to be added to the adjusting collar for a smoother adjustment. Like Jon said they are over built and they are also heavier than stock. I have only seen in pictures the MM LCA's so I can not make any comments that have value other than the fact that Ross is a man of his word and does good work (I have dealt with him personaly in the past -on the phone- and I know several others who deal with him on a regular basis). The AZC LCA's I am in agreement with others about not liking the latest version, the previous version I personaly felt were underbuilt but I will say that he has been building them for a long time and I personaly have not heard of any failures.

 

John C. maybe I will have to give you a shot at my car so you can get an opinion of the ZRaceProducts LCA's.

 

Dragonfly