Keith Posted November 17, 2005 Share Posted November 17, 2005 I am picking up a complete rear end next week that I plan to swap into my CMC car. Prior to doing this, I plan to put some camber and toe-in into the rear. The more I think about doing this, the more paranoid I get. My reference for doing this is Herb Adam's book called "Chassis Engineering". My plan is to follow the heat method of gaining negative camber where you heat six inches of the top of the axle tube. According to Herb, this should be good for -0.5 degrees negative camber. This seems like a very imprecise approach and since the CMC limit is -0.5 degrees, if you get it wrong, you just hosed the rear end. Since it is safest to do this with the rear off the car, I would think that one would run the risk of a surprise after installation of the rear. Have any of you done this and if so, are you willing to share the safegauards that you took to ensure that you weren't over? I am spending some hard-earned cash on the rear and going all the way to Boston to get it. I would hate to end up with an unusable piece. Quote Link to comment Share on other sites More sharing options...
Richard Pryor1548534703 Posted November 17, 2005 Share Posted November 17, 2005 Does tech ever measure the camber in the rear at the CMC races? Just try to get it close, I doubt anyone is going to bitch about .25 extra degree of camber in the rear...and make sure to toe it in at the same time...rp Quote Link to comment Share on other sites More sharing options...
King Matt1548534716 Posted November 17, 2005 Share Posted November 17, 2005 I think you can only do this with a full-floater type rearend since the camber of the wheel is determined by the straightness of the axle itself on a semi-floater. On a full floater, the bearing end is actually welded to the housing at an angle and beveled splines on the axleshafts are used to compensate for the irregular motion. With a semi-floating axle, a bent housing would have to deflect the axleshaft itself to produce the camber, which would be hell on the outer bearings. But if you want to try it, the best way to alter the angles of the housing ends would be to send the rearend to a shop that has the proper fixtures to straigten the housing (Currie Enterprises would be one). Starting from a known zero camber, you could then heat and measure until you got it right. Or do it with the car on an alignment rack. Quote Link to comment Share on other sites More sharing options...
Richard Pryor1548534703 Posted November 17, 2005 Share Posted November 17, 2005 It works...Herb and Matt Adams have been cambering our Camaro rears since 1990...just perform normal bearing maintence and you'll never have a problem...at least we haven't with over 11 different cars...rp Quote Link to comment Share on other sites More sharing options...
Guest Posted November 17, 2005 Share Posted November 17, 2005 It works...Herb and Matt Adams have been cambering our Camaro rears since 1990...just perform normal bearing maintence and you'll never have a problem...at least we haven't with over 11 different cars...rp Richard, what do you classify as "normal bearing maintenance"? The rearend in my '90 has -.3* from the factory according to a Hunter 4-wheel rack. Just wondering what I should be looking for. Quote Link to comment Share on other sites More sharing options...
Keith Posted November 17, 2005 Author Share Posted November 17, 2005 Does tech ever measure the camber in the rear at the CMC races? Just try to get it close, I doubt anyone is going to bitch about .25 extra degree of camber in the rear...and make sure to toe it in at the same time...rp Nope, but I think that participation in the National race puts a different spin on things. There is nothing stopping someone in tech from checking. Would someone mind if I were a little over? Probably not. Would someone mind if it was a difference between podium or not? Hard to say and I'd prefer to not test people's patience. According to Herb's book, as long as you don't go crazy (say -1.0 deg. camber), this is within the tolerance where you won't cause bind or see excessive problems. ...everything has a tolerance and it appears that -0.5 is well within what people do on a GM 10-bolt. Two f-body guys that I know have done this mod this year. However, they were not building a car constrained by rules so they weren't all that concerned about exactly what camber they got - they just had a target. Is it sensible to expect different camber with the rear off the car versus installed? Quote Link to comment Share on other sites More sharing options...
King Matt1548534716 Posted November 17, 2005 Share Posted November 17, 2005 Keith, if you're going to camber your rearend, now I'm going to have to do it too just to keep up. Where will this end!!?? Quote Link to comment Share on other sites More sharing options...
Richard Pryor1548534703 Posted November 17, 2005 Share Posted November 17, 2005 Matt...it never ends, within the contraints of the rules and one's pocketbook...there are CMC cars that have under $10,000 in them that finish in front of ones that have double that in the build...I've always maintained the quickest way to get quicker isn't the double trick part (once you have a good basic car) but teaching the driver how to get the most out of his equipment....our standard rear end maintenance is to replace rear axle bearings every 15 competition hours...which equates to around a full year or two of CMC racing..ro Quote Link to comment Share on other sites More sharing options...
Keith Posted November 17, 2005 Author Share Posted November 17, 2005 Keith, if you're going to camber your rearend, now I'm going to have to do it too just to keep up. Where will this end!!?? Cool. I think that we both will have worked our way through the rulebook by the end of 2006. That is where it will end. The reality is that I got the spring rates right over last winter. I got the swaybars right for Beaver Run. I will get the gear ratio/LSD and rear camber correct for spring. Then it's just weight and the car is done. That is why I like CMC - the end is in sight. Quote Link to comment Share on other sites More sharing options...
Glenn Posted November 17, 2005 Share Posted November 17, 2005 Does tech ever measure the camber in the rear at the CMC races? Just try to get it close, I doubt anyone is going to bitch about .25 extra degree of camber in the rear...and make sure to toe it in at the same time...rp worst advice i have read in some time. i was just DQ'ed for exceeding my allowable HP by 2% (5hp), and here you are assuming everyone will be ok w/ exceeding an allowable tollerance by 50%. yes, i was DQ'ed for a 2% variance measured on a device that is known for a 3% accuracy. Quote Link to comment Share on other sites More sharing options...
King Matt1548534716 Posted November 17, 2005 Share Posted November 17, 2005 That was a joke, Richard. But I agree with your basic point. My car is finally as close to done as any race car will ever be, so Keith had better come up with something better than a cambered rearend for next season! Quote Link to comment Share on other sites More sharing options...
Keith Posted November 17, 2005 Author Share Posted November 17, 2005 I think that the cambered/toe-ed rear, T2R, 3.42s and 200less lbs is more than enough. Bring it on, baby! Quote Link to comment Share on other sites More sharing options...
Richard Pryor1548534703 Posted November 17, 2005 Share Posted November 17, 2005 Matt...he has...it's called a Camaro...the weather must be driving you guys crazy..as for us..this Saturday is a test day at Laguna Seca with temps around 75 and sunny...it's rough being able to race 11 months out of the year...Glenn...hey, I never said I dispense the best advice, take it as you like it but I doubt a 1/4 degree rear camber is accurately measureable with the devices I've seen at any track I've raced at in the last 40 years....5 hp, now that's a different matter...rp Quote Link to comment Share on other sites More sharing options...
King Matt1548534716 Posted November 18, 2005 Share Posted November 18, 2005 Richard, I'll just direct you over to the Manufacturers Points link, where it should be clear what the correct vehicle is for CMC. Quote Link to comment Share on other sites More sharing options...
Richard Pryor1548534703 Posted November 18, 2005 Share Posted November 18, 2005 Choke!!! There's something wrong with my computer! It's been infected by the dreaded Blue Oval Virus which alters what the standings SHOULD have been...ah, well, maybe in '06...rp. Quote Link to comment Share on other sites More sharing options...
jeffburch Posted November 18, 2005 Share Posted November 18, 2005 I bet the 1/2 degree in the rule is for tolerances in measuring devices and rear end manufacturing. Not to be interpreted as "Go bend it to 1/2 degree"! I crossed the scales at 3153 last time. There isn't any tolerance in weight or HP/TQ. Why would there be with this? And having one year under my belt here, I can offer this to the new newbies; be carefull who you listen to for advise. jb Quote Link to comment Share on other sites More sharing options...
Guest Posted November 18, 2005 Share Posted November 18, 2005 Not sure how they'd measure rear camber accurately and quick enough to make sense @ Nationals. I have a Snap-On magnetic C/C gauge and it's not too accurate vs. a 4-wheel deal. For reference, when the gauge read -1.5* up front it was actually only -0.5* on a "real" alignment rack. Just a thought if someone does want to check at Nationals, I'd be DQ'd on my own gauge. PS- thanks for the wheel bearing maintenance advice, RP. Quote Link to comment Share on other sites More sharing options...
bsim Posted November 18, 2005 Share Posted November 18, 2005 I'm not sure about 'nationals' being the ultimate legality litmus test. I realize this is only going to be my 4th season in CMC, but I don't see this event causing a rampant cheating scandal, or even an SCCA-like protest fest. Or will it be? If so, I don't wanna come. I left that other org because of that - we're all friends on this side of the fence... Quote Link to comment Share on other sites More sharing options...
Lady in Nomex Posted November 18, 2005 Share Posted November 18, 2005 Good point Brad! Quote Link to comment Share on other sites More sharing options...
Keith Posted November 18, 2005 Author Share Posted November 18, 2005 ...anyone willing to share any tech about adding camber to a live axle? Regardless of what the tone of the Nationals will be, showing up with a car that you know is illegal is silly. It is more than sensible to assume that there will be a tech/impound procedure for (at least) the top finishers and I would think it would be a little more than someone popping the hood and sticking their head in the car. What would be truly scandalous (and *very* public) is if many cars showed up and were DQ-ed. On this site over the last 1 1/2 years, I have pointed out things that I felt were unneccessary or difficult/impossible to police and I've been told to sit down, be quiet and follow the rules. So I have. Now I'm seeing an attitude that "gee, if we are going to have to have legal cars for the National event then I don't want to come." Protests are borne out of two things - illegal cars or people who act like weenies. My impression is that very few CMCers fall into either category. If you show up at Nationals, I think you need to assume that your car is going to be checked. If you are uncomfortable with this possibility then you have two choices - don't come or get your car right. I'm still trying to figure some folk out. In case it got lost - the point of this thread is to improve my car in a CMC-legal way and provide a reference for people who may decide to do this themselves in the future. Anyone? Quote Link to comment Share on other sites More sharing options...
Adam Ginsberg Posted November 18, 2005 Share Posted November 18, 2005 I left that other org because of that - we're all friends on this side of the fence... .....ah, naivety is so nice..... Quote Link to comment Share on other sites More sharing options...
bsim Posted November 18, 2005 Share Posted November 18, 2005 Heehee - thanks Adam. Seriously - we all have tech at our race weekends, so why would 'nationals' be any different? OF COURSE there will be tech, OF COURSE there will be inspections. Dyno on site - awsome! BUT, if it's one of these Gestapo-like scenarios, doesn't that kinda ruin the point? On the other hand, we totally agree here:"...showing up with a car that you know is illegal is silly." Quote Link to comment Share on other sites More sharing options...
Keith Posted November 18, 2005 Author Share Posted November 18, 2005 Brad, I guess the only place where we differ then is whether or not we think our car is fair game for anything. Gestapo-like or not, I invite anyone to look at anything on my car and if that it what is necessary to have someone comfortable that everything is legit, so be it. I'm not going to get defensive or annoyed. I just want to get past the "questions" and move on to having a relaxing good time. Remember, this event will be the first time that many people have been on the track together and it is natural to start to wonder about the "other guy" when being out-run. I have no idea whether I will be at the front or the back at this event. That is what makes it so enticing. I actually find it flattering when someone claims my car is illegal. I got that alot in autocross. Quote Link to comment Share on other sites More sharing options...
Richard Pryor1548534703 Posted November 18, 2005 Share Posted November 18, 2005 If the NASA Nationals mimic the SCCA Runoffs in style and quality then it will be an awsome event...if it mimics the normal CMC weekend then it will be an awesome event....you can't lose either way. BUT the difference is that at an SCCA Runoffs, and presumeably a NASA National event, you better meet the letter of the rules in every category. I doubt that any regional NASA event has the capability of accurately measuring the rear camber within 1 degree, let alone less. However, at the NASA National I expect nothing less than pin point accuracy on any measurements taken and the opportunity for competitors to check their cars beforehand to insure compliance. "Regular" CMC events are a bunch of friends getting together for a fun weekend of racing, BSing and comraderie. By its definition the National will crown the "Best in the Country" CMC driver and it's going to get very serious. There will be no additional races that weekend where you have another chance. This is a spend many thousands of dollars to arrive and prep and you darn well better be aware that every, EVERY, little item must conform to the rules...no leeway. The pole sitter in SSC at this year's Runoffs was DQ'ed from his pole qualifying session for a carpet pad 6" too short (a protest filed by a competitor that couldn't beat him on the track)...Ryan CC raced to 2nd in the race, a truly amazing drive, but if he'd started on the pole I have no doubt he would have won the Runoffs. A cautionary tale on two levels. Be prepared for protests from competitors at the Nationals. The "just have fun standard" is not going to work at the Nationals, more's the pity. If you are serious about winning the Runoffs, be prepared. If you're just going to have fun like any other CMC weekend, then you'll have fun. It's going to be two different races and two different attitudes. To each his own. It will be interesting to see what transpires. RP Quote Link to comment Share on other sites More sharing options...
King Matt1548534716 Posted November 18, 2005 Share Posted November 18, 2005 Well put. While it MAY be different, I'd be prepared for it NOT to be different. The issue of tech inspection is just one of the many unanswered questions about how the Nationals will be conducted. Quote Link to comment Share on other sites More sharing options...
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