JMortensen Posted March 31, 2007 Share Posted March 31, 2007 I hate to see someone bring a product to market and get slammed like this. You guys should be happy that people are making parts for our cars. It's not like there is enough business to even make a living doing rear LCA's for Z cars even if there weren't any competition. This is somebody's side job, and he's apparently had a professional engineering company look over the design and help make the jig that it is produced with. That in and of itself is impressive to me. Have any of you looked at a STOCK arm lately? This thing looks way overbuilt when compared to a stock arm, but I don't see anyone posting about how unsafe the stock arm is or who is going to take Nissan to task when it tears apart and kills them. Quote Link to comment Share on other sites More sharing options...
fastzcars Posted March 31, 2007 Share Posted March 31, 2007 I usually try to stay out of threads like this, but I'm with Jon on this one! Is anyone on this thread a structural engineer? Have you even attempted to make/manufacture such a part from scatch? I sure haven't. I think it's great that SOMEONE has come up with new parts for our 30 plus year old car's! Compared to the stock LCR's that have years of abuse,damage and rust on them, I think I'll trust these over built unit's to the stocker's. Quote Link to comment Share on other sites More sharing options...
buZy Posted March 31, 2007 Share Posted March 31, 2007 I hate to see someone bring a product to market and get slammed like this. You guys should be happy that people are making parts for our cars. It's not like there is enough business to even make a living doing rear LCA's for Z cars even if there weren't any competition. This is somebody's side job, and he's apparently had a professional engineering company look over the design and help make the jig that it is produced with. That in and of itself is impressive to me. Have any of you looked at a STOCK arm lately? This thing looks way overbuilt when compared to a stock arm, but I don't see anyone posting about how unsafe the stock arm is or who is going to take Nissan to task when it tears apart and kills them. Jon you are correct for keeping things in perspective. I am sorry Dragonfly if I was harsh critiquing your work. Didn't really mean it as to shread you. Just having you strive for the best. Quote Link to comment Share on other sites More sharing options...
RB26powered74zcar Posted March 31, 2007 Share Posted March 31, 2007 I have a brand new pair of MM rear CA's, never installed, that I will trade strait up for a pair of these... These are much more appealing to me... Quote Link to comment Share on other sites More sharing options...
mom'sZ Posted March 31, 2007 Share Posted March 31, 2007 Did Fabcon engineer these parts or simply fabricate them? Has there been any engineering done on them? I think this is a valid concern. I thought the same thing when I read that, breaking a lower control arm could be... well... very hairy. We've had this discussion before. It always goes the same way, folks comparing the stock piece's strength. (where's Mike Kelly?) The stock arms are damn strong, flexy maybe, but weak, even after thirty years... no. The last guy who made up some front lower control arms and posted on here, the discussion got so out of hand the thread got deleted. And don't get me wrong, I feel just like Jon, there are far to few folks making parts for our cars and we need to support them. And these things look TRICK! I want them to be good, I want to buy some. (I must use stock arms for my class though) I am just curious to know if an engineer looked at them. Dragonfly, BTW... the underside of your car, the unibody itself, it is very clean.... NICE. Quote Link to comment Share on other sites More sharing options...
Dragonfly Posted April 1, 2007 Author Share Posted April 1, 2007 Did Fabcon engineer these parts or simply fabricate them? Has there been any engineering done on them? I think this is a valid concern. I thought the same thing when I read that, breaking a lower control arm could be... well... very hairy. We've had this discussion before. It always goes the same way, folks comparing the stock piece's strength. (where's Mike Kelly?) The stock arms are damn strong, flexy maybe, but weak, even after thirty years... no. The last guy who made up some front lower control arms and posted on here, the discussion got so out of hand the thread got deleted. And don't get me wrong, I feel just like Jon, there are far to few folks making parts for our cars and we need to support them. And these things look TRICK! I want them to be good, I want to buy some. (I must use stock arms for my class though) I am just curious to know if an engineer looked at them.Dragonfly, BTW... the underside of your car, the unibody itself, it is very clean.... NICE. An engineer by the name of Bruce who works at Fabtec was involved with the building and testing of the first few prototypes as well as the design and building of the jig, these things are way over built. As far as the "if you break it you get a new one free" thing goes it is not a concern of anyone at ZRaceProducts that the LCA will fail and cause an acident, rather the statement is intended to be taken as if you over extend your capabilities at triple digit speeds and slam your car into a concreate abutment (or just total your car for whatever reason) these LCA's will be salvagable parts or in other words they will be some of the very few things on the car not broken. I am not sure if Jerry (owner of ZRaceProducts) will allow me to take pictures of the building and assembly of these parts but if he will I will post them up for you guys. Just to let everyone know I truly do understand the skepticism, as Mike Kelly can tell you if you ask him I actualy purchased a set of Arizona Z's LCA's before Jerry had finished building his and my thoughts were "Arizona Z has a well built and proven LCA why should I buy these others by ZRaceProducts?" then after Jerry finished building several sets and the testing was completed he brought a pair over to my house and let me make a direct comparison to the Arizona Z LCA's... well I imediately put my Arizona Z LCA's up for sale and sold them to Mike so I could by the ZRaceProducts LCA's. At that time I still had several months left of work on my car and Jerry started talking about making his LCA's on car adjustable, we put our heads together and came up with the design in use now, Jerry ran the design past Bruce and got an OK on it and I installed the first prototype on my car which is what the pictures are. I will be putting some track time on these in the very near future and letting everyone know what I feel about them under every situation I can possibly put them into. One last thing for now... I will be at the West Coast Nationals (Motorsport) with the car for both the race school on Saturday and the show on Sunday, anyone who would like to see these in person just look for the green car that says Dragonfly on the side. Dragonfly Quote Link to comment Share on other sites More sharing options...
mark Posted April 1, 2007 Share Posted April 1, 2007 I hope you get to post up pics of the adjustment mechanism. I really want to see that. Quote Link to comment Share on other sites More sharing options...
alexideways Posted April 1, 2007 Share Posted April 1, 2007 I hate to see someone bring a product to market and get slammed like this. You guys should be happy that people are making parts for our cars. It's not like there is enough business to even make a living doing rear LCA's for Z cars even if there weren't any competition. This is somebody's side job, and he's apparently had a professional engineering company look over the design and help make the jig that it is produced with. That in and of itself is impressive to me. Have any of you looked at a STOCK arm lately? This thing looks way overbuilt when compared to a stock arm, but I don't see anyone posting about how unsafe the stock arm is or who is going to take Nissan to task when it tears apart and kills them. Quote Link to comment Share on other sites More sharing options...
katman Posted April 1, 2007 Share Posted April 1, 2007 "Have any of you looked at a STOCK arm lately? This thing looks way overbuilt when compared to a stock arm" Well that just tells me you don't know what you're looking at when you're looking at the stock arm. If these things were "engineered" then I'm sure the builder won't mind posting a link to the stress analysis. I try to stay out of these LCA threads because frankly I can't answer the question why?. I've done a ton of road racing with Z's in various classes and can't figure out why people spend so much time on agonizing over an adjustment that happens once in a blue moon and can be made with a custom inner bushing without putting threads in combined tension and bending. Not to mention the fact that this particular design uses the close coupled end of the control arm which, combined with having to use 1/2 turn increments to the rod end, limits how precisely you can change said toe. Very nice pieces- no doubt about it. But I'll keep my stockers and spend the money somewhere that will actually make me faster. But that's just my opinion. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted April 1, 2007 Share Posted April 1, 2007 Well that just tells me you don't know what you're looking at when you're looking at the stock arm. Careful there Keith! You say this, and then you make some mistaken points to back yourself up. John Coffey was just recently describing how he saw a Z car rear LCA tearing out the spot welds and coming apart on a race car, so they might not be quite so resilient as you might think. I try to stay out of these LCA threads because frankly I can't answer the question why?. I've done a ton of road racing with Z's in various classes and can't figure out why people spend so much time on agonizing over an adjustment that happens once in a blue moon and can be made with a custom inner bushing without putting threads in combined tension and bending. Obviously you have more experience than me. But in my limited experience changing rear toe had a MAJOR effect on the handling of my car, and just as you feel it's "dragging tires" around the track to run toe in out back, I'd prefer to drag the tires if that results in lower lap times (which has definitely been my experience). Two OTHER major reasons would be to reduce friction and reduce deflection. Sure, you can machine bushings out of different materials to accomplish these two goals, but still most people don't have access to machine shops and in my experience paying a machinist to do this work would probably cost about as much as the arms. You're right about the threaded rod in bending and theoretically that is a bad idea, but shouldn't you should also consider the history of this type of part? If we were constantly hearing about broken ArizonaZCar arms then I might be a little wary, but I've never heard of them breaking, and they use a much smaller 5/8" rod end vs the 7/8" rod end used in this design. Not to mention the fact that this particular design uses the close coupled end of the control arm which, combined with having to use 1/2 turn increments to the rod end, limits how precisely you can change said toe. No, it actually doesn't work that way. This design is "on the car adjustable". That means that you don't have to pull the spindle pin to adjust it, which also means that you don't have to rotate the rod ends to make adjustments. My understanding is that there is a threaded tube captured inside the arm which can be rotated to move the rod ends out. This means that fine adjustments can be made. I would agree with you that changing the toe by coarse 1/2 turn adjustments is not a good idea, but that is definitely not what is going on here. Quote Link to comment Share on other sites More sharing options...
katman Posted April 2, 2007 Share Posted April 2, 2007 "You say this, and then you make some mistaken points to back yourself up" I don't recall actually making any points to back myself up. Lets see the analysis comparing the bending moment of inertia at one of the inboard connections of this new design with a stock one for example. I don't think people give the stock one the credit it deserves. If there's an application that "tears out the spot welds" on a stocker then I'd sure want to see some analysis for the aftermarket replacement. "This design is "on the car adjustable". That means that you don't have to pull the spindle pin to adjust it, which also means that you don't have to rotate the rod ends to make adjustments. My understanding is that there is a threaded tube captured inside the arm which can be rotated to move the rod ends out." Ah, I see. I stand corrected. Still rather have the adjustment at the inboard end where the loads are smaller and the resolution would be greater, but clever if it works as you say. Regardless of where you set your toe, it just isn't something that gets changed all the time. We'd check it occasionally but only have to adjust it after wreck rebuilds. Look, I'll say it again, this is a very nice part. But saying "it's way overbuilt" doesn't prove it to me without some supporting analysis. I still don't understand this fascination with adjustable LCA's (especially up front) but to each his own. The stockers ARE ugly, and I'm all in favor of a nicer part, but it seems like every other week another adjustable LCA comes out and I have yet to see somebody say "okay, here's the strength of the stock part, here's the loads we assumed, and here's the strength of our part." What are you running now for rear toe Jon? If it's more than 1/32 in then I gotta keep working on you. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted April 2, 2007 Share Posted April 2, 2007 3/16" total toe in was fastest for me previously. I now have adjustable everything from roll center to bumpsteer to sway bars so I may find that with my more adjustable setup I can tone down the rear toe setting. But previously I was running what I would consider a pretty "standard" suspension for a weekend warrior type car and that toe setting was GREAT! You aren't going to talk me out of faster, so if faster is 1/4" toe in, I'm going to set it so that it goes faster... I agree with you in that I'd like to see someone quantify the strength of their arm. But I'd be REALLY REALLY surprised if the 7/8" rod end was found to be too weak, since AZC has sold their arms for so long and nobody seems to have reported issues with the 5/8" rod ends. Quote Link to comment Share on other sites More sharing options...
Dragonfly Posted April 2, 2007 Author Share Posted April 2, 2007 As far as I know none of these LCA's have been stressed to failure (distructive testing) nor can I myself say exactly what the depth of physical testing was done vs calculation testing. As far as the need for on car adjustagle LCA's go it is a case of what the general populace has been asking for. Katman I am sure you are correct about how often these adjustments will be made, I just had these adjusted and I honestly do not expect them to be adjusted agian untill I manage to smack up my car (crosses fingers and knocks on wood). "Ah, I see. I stand corrected. Still rather have the adjustment at the inboard end where the loads are smaller and the resolution would be greater, but clever if it works as you say." I like the idea of making the adjustment on the inboard side. Clever yes but if I remember correctly Jerry actualy got the idea for how to build the adjustable portion of these LCA's from some friends of his who build trophy trucks and are using this same system. I personaly do not like being the center of a point / counter point especialy when many of those involved have considerably more knowledge than me but I will say that I have absolute full and complete faith in these parts as well as every other part that ZRaceProducts has built. Dragonfly Quote Link to comment Share on other sites More sharing options...
katman Posted April 2, 2007 Share Posted April 2, 2007 'if faster is 1/4" toe in, I'm going to set it so that it goes faster... " Absolutely, but we need to figure out how to make zero handle like 3/16, so yer not "draggin them tires around" . Ultimately that *should* be faster. Anyway, we eventually dialed out the rear toe to zero in the ITS cars with no trailing throttle or on throttle oversteer, the usual symptoms toe in takes care of. Still treating the throttle like a switch- the fastest way around in a 200hp ITS car. With real horsepower a smidge of toe might be necessary. And you have real horsepower. Heck, if somebody gave me the dimensions of the stock control arms I could do the analysis, just haven't got a "Round Tuit". If you look at the MOI of the stock arms about a vertical axis I'd bet it's way bigger than a 7/8 tube. The 1-1/2 .120 wall that these are is much better, but again I'd want to see the numbers. Also, with the 7/8 tubeular AZC arms they're triangulated better than these or stock so the inboard-outboard running structural members aren't in bending, but tension/compression. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted April 2, 2007 Share Posted April 2, 2007 Absolutely, but we need to figure out how to make zero handle like 3/16, so yer not "draggin them tires around" . Ultimately that *should* be faster. Anyway, we eventually dialed out the rear toe to zero in the ITS cars with no trailing throttle or on throttle oversteer, the usual symptoms toe in takes care of. Still treating the throttle like a switch- the fastest way around in a 200hp ITS car. With real horsepower a smidge of toe might be necessary. And you have real horsepower. The fact is I've never aligned ANY racecar (and I've done a few) that had 0 toe in the back. The vast majority have been high hp rear drivers, mostly 911's and 510s and Z's, but a few others including a Pantera and a Ferrari or two. Some were street driven, some were trailer queens. Never had a single one where they called for a 0 toe setting. So that's probably about 0 for 20. Heck, if somebody gave me the dimensions of the stock control arms I could do the analysis, just haven't got a "Round Tuit". If you look at the MOI of the stock arms about a vertical axis I'd bet it's way bigger than a 7/8 tube. The 1-1/2 .120 wall that these are is much better, but again I'd want to see the numbers. Also, with the 7/8 tubeular AZC arms they're triangulated better than these or stock so the inboard-outboard running structural members aren't in bending, but tension/compression. I for one would love to see that happen. Interesting comment about the AZC vs this design. Hope you get a chance to check out the adjustable LCA FAQ I just put together today. I'd like to hear your comments and would appreciate you pointing out any mistakes I might have made. Quote Link to comment Share on other sites More sharing options...
katman Posted April 3, 2007 Share Posted April 3, 2007 "The fact is I've never aligned ANY racecar (and I've done a few) that had 0 toe in the back. " Guess you never aligned a anything with a solid rear axle. Yeah, yeah, anything with a solid axle isn't a real race car.... I'll take a look over the other thread when I get a minute. If it's like most of your work it's proly thorough and accurate. Quote Link to comment Share on other sites More sharing options...
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