Ok guys, Todd Reid pointed it out that something to do with my car setup is making my CVs snap.. I thought back to what I did different to the front suspension since the first race at CMP.. Then it hit me, UPPER CONTROL ARM SWAP!!

Now, what I think maybe happening is that with all the caster I gained, it is now moving the pivoit point on the axles back some more, and creating more of a bind when at close to a full lock.. The reason the left side is braking is because there are simply more right hand corners so the CV wears out quicker. Let me know what you guys think.. By swapping the prelude arms, a lot of caster is gained, so much that the upper ball joint can bearly be mounted into the knuckle without some work..

 

hmmm...is there any sign of ball joints binding up top? In theory, the axle and outer CV really aren't doing anything different than it was before. The axle's passage through the hub and bearing have not changed an ounce. The only thing I can think of is that your upper ball joint was working past it's intended range of motion, putting more load on those areas around the axle?

 

scratch that...I'm wrong. The axle is slightly relocated because of the knuckle being attatched to both uca and lca. So yes, that could very well be the reason you are having those problems. It just seems that that slight change in axle location would be hardly a problem for a constant velocity joint. Doesn't seem like it would be overextended at all.

 

Dunno. Swapping control arms to high caster just isn't that drastic of a change.

$.02

 

Corey, how much of a caster gain do Preludes pick up when you switch the arms? My GS-R picked up about 3 degrees. Significant, but certainly not radical. Just curious.

 

I am not sure how much degress it changed, but it looks to be quite much.. So much that I can bearly fit the ball joint back in the knuckle because of the extreme angle the ball joint is in.. I bet it gained over 5 degrees on the prelude..

 

I think it's nice to have a theory, but 3 degrees of caster on an estimated 12 inch upright length is about 0.6 inches. Displacement at the hub rearward estimated to be 30% of that or 0.2 inches. That's not alot of additional angularity - it's hard to see it causing catastrophic failure very quickly (maybe if you autocrossed alot). I'd have the thing up in the air and run it thru the whole range of motion with the boots off looking for a physical problem. RTR was breaking stuff a couple years ago and King has lost some. Scott says their solution is inspection and repacking every race with particular attention paid to the spline roots. They recently started using Mugens grease instead of Redline in the outer CV. Annual replacement is a given unless imminent failure is detected.

Scott, who wonders if you've just got too much power....

Hmmm - 5 degrees giving approx 0.3 rearward displacement on a halfshaft I'm guessing at 18 inches long would give a lateral displacement of about 0.003. Still not looking like a really good theory yet - gotta find something else. It could be an angularity thing - it's just hiding.


[Modified by RR98ITR, 4:16 PM 8/7/2002]

 

FWIW, I understand that VW racers have discovered that simply by lowering the ride height on the front of GTIs, it is possible to use up the free movement available to the point that CV joints get pounded to junk. I have not had firsthand expereince with this but have heard shortened axles discussed.

Kirk

 

Karl, howmuch caster do you have now that you swapped arms?

 

Corey,
Call Tom Fowler. I don't think they have ever broken a CV on their Prelude, and I think they have about the same power as you.
Find out where they are getting their axels and get some from there.

Oh... 5 degrees caster does seem like alot. I know that Tom DIDN'T do the swap on the Prelude, but I don't remember why (assuming both cars have the same suspension as I know jack **** about Preludes).

 

Ever thought of some cryogenics? I realize that it doesn't solve your problem but it may get you another lap

 

About three degrees. Link to my original findings: https://honda-tech.com/zerothread?id=84781

 

The Civic sees about the same or slightly less with high caster arm placement.

~edit, fixed broken pictures in the other thread~


[Modified by johng, 8:57 PM 8/7/2002]

 

Called OPM on Tuesday, and they have never broken one on their car, but I forgot to ask about control arm swap, and if that would do it... I am going to try to post up a little freehand picture I drew on paint, to visually show what I mean..
OPM uses OEM axles, which is basically what I use...

 

Too much power, I like that one. These are Honda axles?

 

Ok, I know I am NOT an artist, but you can get an Idea with this pic, imagine you took the fender of the car, and are looking at all the control arms from the top
Yellow is Upper ARM
Green is Bottom ARM
Red is Axle
Black is tire

NOT DRAWN TO SCALE!!!
Top picture is of stock configuration
Bottom is with the Swapped arm, look at the "angle" of the axle, and imagine that with the tire/knuckle turning right..

 

Question when you come off tight corners are you gassing it really hard and letting it push out? I can see how swapping the control arms and having a really agressive driving style could cause this.

 

Well, I kinda gas it and let it slide out.. I hit the throttle as soon as I can, but making sure I say on the track and do not spin the tires to bad...

Everyone that races competitively is aggressive...

 

I agree with you 100%. I was just thinking because I do this myself is when I am coming off tight corners sometimes I gas too much and spin tires slightly. I could see myself breaking an axle in that situation if it had extra stress being placed on it. I know this is probably not going to be any help but it kind of seem like the same situation as people that put B16's into crx's and how they have axle problems because of the angle they are at. Just my .02 cents.

 

The only part of this that makes sense is conditional torque at angularity. Remember that in 3rd and up, where we spend most of our road course time, wheel torque is pretty low compared to something like a 1st gear standing start. Then while cornering tightly unless you have a spool your bias ratio is unlikely to exceed 5 to 1 - meaning that the most power you can put thru the outside wheel is 5 times what you can put thru the inside (which still isn't much - it's just better than nothing). So, were not putting down massive power in the higher gears at high angularity - and what of the design safety factor? I'll be really surprised if 1/2 degree additional angularity is the difference between life and death on an assembly all by itself.

Have you already given a detailed description of the exact mode of failure?

Scott, <goes to look>....

 

Hey there.

Read your post about breaking axles. I have been running a 1995 GSR in ITS for almost two years and have experienced all sorts of axles problems over the past couple of years.

I believe that I have most (hopefully all) of my problems figured out. So if I can I will try to let you know what I have figured out.

First what is actually breaking with the axle / CV?

Is it the axle?
Is it the CV joint?
Are you using OEM axles with OEM boots (OEM replacment axles do not count)?

I will tell you that 99% of my failures have been from the non-Honda CV boot actually failing first then the the CV joint overheating after all the gease is gone then the joint actually breaks due to overheating.

Scott Seck
GSR ITS #38

 

Are you running a front splitter? If so, are you getting any air to the joints?

Are the boots vented?

 

Could you just swap the arms back and see if the problem still occurs?

 

Hey Corey, did you try pulling the shock/spring assembly out and working the suspension through its whole range of motion with the wheel turned to full lock? Should be a relatively simple way to check if you're getting bind.

 

Thats my plan for now

Scott Seck - I called OPM and said they don't have any problems with their preludes.. The Axles I use are basically OEM units, boots and CVs and all, same as was OPM using.. I am breaking outer CV joints on the left side..

Other Scott - You must look at how that would create a greater angle in which the CV would opporate.. At a track like CMP which there are three second gear corners in a row, this could really add up to a lot of stress on the joint...

For now, I am swapping the arms back, and see if they live..