Mayolives Posted October 30, 2006 Share Posted October 30, 2006 I need input from anyone using 300zxt cv axles with an r200 lsd differential . I'm using Modern Motorsports cv adapters with their axles and I have just destroyed the second cv axle. The first one, on the driver's side, lasted less than 30 minutes on track. The passenger side one had less than two hours of trace time before it disintegrated. Both axles came apart at the inside bearing/race area closest to the differential. Should I have any "play" when the axles are installed? My axles have a snug fit and appear to be fully depressed when installed. These are all new, straight, clean parts installed using Ross's instructions including shortening the cv axles. Quote Link to comment Share on other sites More sharing options...
fentin_fury Posted October 30, 2006 Share Posted October 30, 2006 I have the same setup and just spent sunday autocrossing - no problems. You mentioned you reveresed the outer race as necessary - I take it you are using the proper lubrication etc. and everything worked smoothly once back together. I am using the billet adapters - are you? One thing to check for would be to jack up the car and spin the tires - without the shafts in place. Make sure there is no visible deflections in the adapter - either up or down or in or out. They should run true! If there is visable deflection it is too much - in my opinion. Quote Link to comment Share on other sites More sharing options...
mark Posted October 30, 2006 Share Posted October 30, 2006 Tom, I hate you are having problems. You should have some play in the axels when they are installed. I'm running CV's but no those. If the CV's are like the 280z's one CV end is fixed and one end allows some in and out movement. If you are bottomed out, you need to find more travel. I'm sure you know this. Hope you get is figured out. Quote Link to comment Share on other sites More sharing options...
gearheadstik Posted October 30, 2006 Share Posted October 30, 2006 I have installed this setup in two cars, both were so tight that the covers on the back of the cv kept coming off and had impressions of the axle in them...It might not have been as hard to get them in if we had pulled the spindle pins. I would say they had nearly no play at no squat position.. Both cars are v8 and one runs a 6 flat in the 1/8...no problems yet..Just my .02$ though.. Quote Link to comment Share on other sites More sharing options...
jt1 Posted October 30, 2006 Share Posted October 30, 2006 Tom, I haven't seen one of these taken apart, is there any way to shorten the axles some more? I would think you need about 1/4" additional compression beyond what the axles are when installed. jt Quote Link to comment Share on other sites More sharing options...
Mayolives Posted October 30, 2006 Author Share Posted October 30, 2006 John, The only way to shorten them more than what I already did, ie: reversing the mechanism on one end, would be to somehow cut the shafts size down a bit and weld them back together. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted October 30, 2006 Share Posted October 30, 2006 I think you've got adjustable control arms right? How about lengthening them? Quote Link to comment Share on other sites More sharing options...
240hoke Posted October 30, 2006 Share Posted October 30, 2006 Im pretty sure thats the way the modern motorsports CV's fit on the car. They just BARELY clear with the struts reversed. I have to coax mine in when installing them. However I have checked for binding through travel and put a few hard miles on the car without any issues whatsoever. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted October 30, 2006 Share Posted October 30, 2006 You know, I have another thought on this issue. The passenger side axle should have A LOT of free play in it. It isn't nearly as tight as the driver's side as I recall. So I don't think that this issue you're having necessarily has to do with the CV's bottoming. I'm beginning to think it has to do with the Quaife. Back about 10 years ago I used to autox with a guy who installed a Quaife in his MG Midget autoxer and immediately started breaking axles. The problem is that if one wheel comes off the ground all the power immediately shoots to the axle on that side and it spins it up really fast. Unlike a clutch style LSD or even a VLSD, on the Quaife this happens almost instantaneously. Then when the tire comes down... BANG! Shock loading the axle snaps it. He went back to a CLSD after about 5 axles and never broke another one. When I first heard about the Quaife for a Z, I asked on the IZCC list if anyone had broken a stub axle, and sure enough there were several people that had already broken parts. I think this may be what is happening to you, and I only think this because I'm pretty sure that passenger side CV has a ton of slack compared to the driver's side. If that assumption is wrong and both CV's are basically bottomed, then ignore this post. But if I'm right, then that Quaife may be the problem. John Coffey (who I believe also broke a stub axle with the Quaife in his Z) had his sent to a diff shop where they preloaded the gears inside to prevent it from free spinning like that when one tire comes up, and as a side benefit that allso helps with inside wheel spin on high g turns. On your car with billet stubs, I'm thinking that maybe the weak point in the system is the CV joint. Quote Link to comment Share on other sites More sharing options...
johnc Posted October 30, 2006 Share Posted October 30, 2006 John Coffey (who I believe also broke a stub axle with the Quaife in his Z) had his sent to a diff shop where they preloaded the gears inside to prevent it from free spinning like that when one tire comes up, and as a side benefit that allso helps with inside wheel spin on high g turns. http://www.taylor-race.com That helped but the main solution is to soften the rear suspension enough so that you don't lift an inside rear wheel. Smaller rear ARB, bigger front ARB. And keep the curb hopping to a minimum unless your shock valving has blow offs. Suspension setup with a Quaife is different and is more like what the east coast guys run on their 240Zs, move the roll stiffness forward. Funny how this came up, I'm ordering a Quaife for my 350Z today and I'm thinking about how I want to do the spring rates so I can put power down. Quote Link to comment Share on other sites More sharing options...
Modern Motorsports Ltd Posted October 30, 2006 Share Posted October 30, 2006 What's the available travel on the axles Tom? This was in my prior response your 1st time around but I didn't hear back any followup after 2nd install? Your suspension moves up/down and CV's have to have some travel, was this checked at all? I recall your car was race prepped for track etc and lowered, depending on control arm/suspension mod's the axle may be compressed but from your rocker heights I recall this should be alright. These are on many other track and street prepped Z's without issue so something's unique in your build vs. the others. Specific Z31 setup was actually pioneered by road racers in Ontario on track specific Z's without issue in the shortened position long before we made it available. Alternatively depending on how far your car is lowered perhaps it's putting the CV's into unusual angularity. Typically optimal angularity is not an issue but your setup's created something unique. What's your control arm angles at static rest, pointing down and out about 10-15 degrees for good suspension geometry? Or pointing horizontal or upward? If horizontal or even out and upward then shafts might be being compressed to limits in an angular position. Typical rear geometry on a Z sees rear suspension with control arms angled out and downward and CV's similarly. Then in compression the control arms come near horizontal/similar to CV's and this puts them near their longest position with maximum travel. Lastly, the quaife comment here is excellent and a likely possibility if it's been fully unloaded and lifting your inside tire at high torque. Was a long time ago (ie. 90's) when I'd read of an axle snapped due to rear being unloaded/lifted with a quaife. Not a common discussion point as the racers pull all stops to keep all 4 glued down as best they can I suppose. Quote Link to comment Share on other sites More sharing options...
Mayolives Posted October 31, 2006 Author Share Posted October 31, 2006 JMORTENSEN and Ross C, I don't have a Quaife. I'm using and Nissan 3:70 LSD unit from an 87 turbo car. I really don't know about the rear wheel lift situation but have been know to run over a curb or two. I'm using stock control arms.The car sets about as low as we could get it. The spring rate is very stiff as you remember Ross and I will need to check the control arm angle and get back to you. Thank you for your help and suggestions. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted October 31, 2006 Share Posted October 31, 2006 Hmm... interesting. I thought you had a Quaife and AZC arms. I must be thinking of someone else. If you have the CLSD then I don't know what's up. Check for bind in the CVs through the whole suspension travel, and if they're bound then maybe add some length to the control arms by getting some adjustable control arms. I would think that would be the less expensive alternative to having CV axles machined unless Ross could help you out with that. I wonder if maybe the CV is maxing out its misalignment angle. If that were the case, maybe raising the diff like Terry did might help. This is all pure speculation... Quote Link to comment Share on other sites More sharing options...
Mayolives Posted October 31, 2006 Author Share Posted October 31, 2006 Here is a picture that will give you some idea of the existing angles at full "droop". This is a picture of the car that is on Arizona Z Car' site. Quote Link to comment Share on other sites More sharing options...
Mayolives Posted November 2, 2006 Author Share Posted November 2, 2006 Ross C. (Modern Motorsports), Thank you for your help and support. I have checked the static (resting) angle of the control arm as your suggested. QUOTE: "What's your control arm angles at static rest, pointing down and out about 10-15 degrees for good suspension geometry? Or pointing horizontal or upward? If horizontal or even out and upward then shafts might be being compressed to limits in an angular position. Typical rear geometry on a Z sees rear suspension with control arms" The control arms are pointing up at an estimated 15 degree angle. This is obviously causing the cv axles to bind when compressed and thus leading to failure. JT1 has pointed out that I could install stock 280 axles with the slip joints and although this could work, I believe I would be trading newer, stronger cv technology for a older, weaker setup. My thoughts are to install adjustable lower control arms and adjust them out in order to relieve the stress. I measured the available travel on a cv axle and it is approximately one inch. So I'm guessing that If I adjust the control arm out, and place the axle about in the center of it's available travel, I'll be in good shape. Is my reasoning sound? Any thoughts would be appreciated. Quote Link to comment Share on other sites More sharing options...
jeromio Posted November 2, 2006 Share Posted November 2, 2006 This is kind of strange. My experience is that at full droop, with the car jacked up, that's when the axles are most compressed. I used to have the stock 280ZXt CV shafts and the stock ZXt flanges. These flanges are rather long. With the car jacked up, the driver's side wheel would "hang" when at 3 clock positions when turning the wheel. I was always worried about "catching air" over a riser and blowing up my CV or my diff or both. I switched to the Scottie adapter (sourced from Ross C) which is much shorter. Do you have camber plates in the rear on this car? Maybe you could loosen your coilovers and take measurements of "shaft length" (perhaps with the shaft removed) as the arms move thru their range. Then some others of us could do the same and we could compare? Quote Link to comment Share on other sites More sharing options...
Modern Motorsports Ltd Posted November 2, 2006 Share Posted November 2, 2006 Whew, that's one slammed Z Tom! Your struts must be sectioned notably more than the usual to retain proper piston travel for appropriate bump and compression. (I'd verify that - it's critical!) Did you verify their is no compression available at static rest, or very little? (as engineers we get picky on not assuming) Your info supports that but we don't want to assume. Jeromio - Tom's ~ 15 degree up angle plus any squat due to load which increases this angle further puts his CV's in similar position to full droop compression (similar angle/just upwards instead of hanging down) you experienced with your home brew setup prior to your change to our flanges. So makes sense. It's just not typical for a Z to be this low, quite a camber curve. Tom's got high spring rates and Koni race inserts from ourselves to help control squat/wheel travel for his hardcore track use/desires he indicated, but this doesn't eliminate it's presence and effect on the suspension travel. Angled down and outward as John C's guided us is a preferred camber curve and it puts the CV's into a longer position at squat which is favourable. Tom's is different from this. Ross C. (Modern Motorsports),So I'm guessing that If I adjust the control arm out, and place the axle about in the center of it's available travel, I'll be in good shape. Is my reasoning sound? Your axle will be in fine shape. Just make sure you can achieve a desired camber setting appropriate for your build/tire types at that new wheel location and it's not excessive. Typically lowering increases your camber and your specific very low setup is reason our adjusters on our control arms (shipping info finalized on those/emailed as you requested) have capacity to shorten inwards as some would want to bring lower portion of wheel inward. (particularly autox with small OD wheel/tire combo's lowered notably). In addition, make sure your new proposed wheel/tire location (ie. perhaps 3/8" outward move) does not interfere with inner fenders etc. Quote Link to comment Share on other sites More sharing options...
blueovalz Posted November 2, 2006 Share Posted November 2, 2006 This is kind of strange. My experience is that at full droop, with the car jacked up, that's when the axles are most compressed I agree. In fact, until the lower control arm is perpindicular to the line drawn from the upper strut mount down to the outer bushing pivot point, the strut actually moves outward away from the differential. This is why you have a camber increase with suspension compression. Also, I'd take a good look at your CV operating angles. Yeah, CV joints operate at larger angles than U-jonts, but I think you may be at that limit under high torque applications. I see from the photo that you've got a bit of angle already built in at full droop. I cannot imagine what it is when compressed at normal ride height, and even worst, on hard acceleration or in a turn. My CV-joint axle angle is not this bad (my axles are horizontal at full droop), but this is only because I raised the differential up one inch to reduce some of this angularity. My memory on this is not the greatest, but it seems that these joints are not designed to operate under high torque outside ~26º or so??? Quote Link to comment Share on other sites More sharing options...
Mayolives Posted November 16, 2006 Author Share Posted November 16, 2006 This is an update to my broken cv axles situation. After having some good input from others, I decided that my cv problem had been created by not having enough free travel in my the axles when installed with factory control arms. When the suspension was fully compressed, the axles were stressed beyond their limit and disintegrated. I've installed a set of Modern Motorsports adjustable control arms and have included a few pictures below. You will notice that the axles were not installed when the pictures were taken. I have not determined how much free space to adjust in but plan to put the axles in and then compress the rear suspension and take a better look. The control arms are very well made and the installation was very straight forward. Thank you Ross for the continued support and good products for our cars. Quote Link to comment Share on other sites More sharing options...
Guest Mike Posted November 16, 2006 Share Posted November 16, 2006 Your Z's are nicer than mine:rolleyesg Quote Link to comment Share on other sites More sharing options...
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