Driveshaft coupling question

[Andy S]

We're trying to figure out an issue that came up this past weekend.  We broke a right side motor mount in qualifying and a rear axle (short) the first lap out with a new motor mount.  I suspect. but don't know for sure, that the two are related.  My buddy thought it sounded like a clutch issue and my son was complaining about the car popping out of gear.  I also noticed today that the driveshaft coupling that comes off the motor doesn't seem to align 100% with the tunnel to the rear end...it looks like it's pointing inboard a few degrees.  Is that normal?   It results in the shaft being awfully close to the driver compartment wall.  The offset in the rear looks okay, so the issue isn't the angle at the back.  We haven't been hit, but could the front clip be bent enough to cause the motor to be sitting cock-eyed?

If anyone has advice, or has hada similar issue, please let me know!

Andy
 

[VMS Motorsports]

Seems to be some info missing. Lets start at problem 1:
How did you break the motor mount?
Were you ever hit in the right rear?

[Winterracing]

which side motor mount? could it have broken and bent the coupler which caused it to be off set, or maybe the 2 are unrelated was it a one piece or 2 piece axle?  I've seen the 2 piece break at rough tracks, could have been a rough track that broke the axle and motor mount?

Dan
www.winterracing.net

[VMS Motorsports]

Right side motor mount...

[Hoopy_boy]

 Most Legends Cars have a stripe worn around the driveshaft from rubbing on the driveshaft tunnel support straps... it runs close to the tunnel. The axle twisting had to have been from a previous jolt otherwise you may have a bent axle tube that is stressing that axle with preload from a bent housing. You would have to find someone with a housing jig to check if it is straight. Some chassis guys will pre-bend camber or toe into axle housings to coinside with their set-ups on dirt. Once again, too much rear housing camber or toe manipulation on the rear housing will cause unwanted axle stress and pre-mature axle failure.  To check if your front clip is straight, you have to cross measure from the inside of the left frame rail where it is welded to the firewall across to the inside of the right frame rail behind where the shock tower is welded to it. Then cross measure from the right frame rail inner at the firewall to the rear of the left rear of the shock tower weldment. Tough to do with an engine in as the oil pan is in the way. Only alternative is to tape a string to the corner of the shock tower inside rear where it is welded to the frame with a nut tied to the end of the string on a level surface. Then measure from the firewall inner frame weld points to the string (same distance down on both side strings). If your cross measurements are not the same the clip is bent to one side or the other. Some racers will use an unsquare clip to their advantage to loosen or tighten the chassis beyond front end offset capabilities..... Measurements may be off if one rail is bent up and the other bent down also, which some chassis set-up guru's will use that option also to their advantage under chassis pre-bent stress load reaction characteristics during cornering. Same with the rear offset measurement from backing plate to frame rule. How does a tech man measure your rear offset if the frame rails are bent (take a jig to the track to put your chassis up on after a feature ? haha) Trust me though, if you are going to play with tweaked front or rear clips and their advantages and disadvantages, be prepaired to waste about 3 seasons of trial and error... been there, done that. LOL my set-up note book as nearly as thick as the Yamaha engine manual from playing with these chassis on dirt since 2002 (wife wants me to start charging for set-up advice for these chassis, on dirt )
 The clutch issue may be related to improper bleading procedure. Lots of racers do not know that the master cylinder is blead normally as brakes are blead, the slave cylinder (on the engine) is not blead in that manner. Causes hard shifting issues when the proper slave bleed proceedure is not followed as air gets trapped within it.

~ Gimpster ~

[Andy S]

Thanks for the replies.  The rear end housing is two races old, and there's been no contact either front or rear.   No reason that I can think of that the motor mount would fail.  The axle was a two piece, and broke at the weld.

Are there any threads that outline clutch bleeding procedure?  Maybe I'm doing it wrong.

As always, any advice would be awesome.

[Winterracing]

http://www.legendsracer.com/index.php?topic=1865.0, Just let the clutch gravity bleed, open up the bleed screw and let it go

Dan
www.winterracing.net

[Hoopy_boy]

 In this day and age who puts 2 piece axles in a new rear end housing ? ... and a 2 piece axle busting a new motor mount ??... Now just the clutch needs to be blead ?? Some one is messin around on the computer, or making things up as we go along, cuz nothing adds up. What next.. the clutch was new and shouldn't need to be blead ??

[knoxracing]

I think he feels like the clutch is slipping and causing  a jerk in the engine when the clutch engages. It sounds like he thinks this could cause things to break. The right side mount has been known to break at the bend, the new ones have gussets on the corners.  If the engine was out of align i doubt the bolts would line up with the holes unless it was installed wrong in the beginning or when the mount broke the engine shifted. The engine is bolted down so for the coupler to be angled it would be a mounting issue. I would make sure the coupler is tight. The two piece axles are suspect to brake at the welds, especially if you are on dirt. The way I bleed the clutch is very simple, I fill the bottle and crack the bleeder and let it drip into a pan under the car, gravity bled. When you replace the mount did you have any trouble lining the bolts up?  How close is the steering shaft to the oil pan drain plug? 

[Andy S]

Lots of good info, thanks.

As  for Hoopy_boy's comments:  No, I am not messing around.  I posted the symptoms/issues I as knew them (1. broken motor mount, 2. broken rear axle and 3. driver complaining about the clutch).  I never said how or if they added up, and  really don't appreciate the sarcasm.  This is our first year racing anything more complicated than a quarter midget, and I'm doing the best I can.  As to your other sarcastic comment: the person who puts 2 piece axles in a new housing is the person who HAS two piece axles in his car and couldn't spend and $400-500 on top of a new rear end, after the 3rd member mount broke off.

Andy

[racerrad8]

Andy,
        Don't throw that rearend housing away. If you go to my website I have replacement tabs as well as the double shear kit listed.

www.RPMracingCa.com

If you have any other questions shoot me an email; randy@rpmracingca.com

Randy - RPM

[Hoopy_boy]

 Dude... if you find that sarcastic, you might want to choose another sport because It was said with humor. Ya pissed because I never typed 'LOL" behind it ??
I normally help everybody, and probably have helped more people in Legends since 2002 than you have turned laps in racing.
Turn around and jump my case with implication of sarcasm that YOU read into it... we avoid fellers of your quality around here so I will follow suit ! (people who look for the bad first in what a feller says)

See ya guys 'round somewhere....

~ Gimpster ~

[Andy S]

Hoopy_boy - you sounded sincere to me (I don't know anyone on this forum well enough to know the difference), but if your comments were meant in jest - I apologize (and assume that the same was meant about "fellas of my quality').  I guess what threw me was that your first comment was long and genuinely helpful, so I took your second as your bonafide opinion too.

I guess I'm sensitive because I truly don't know much yet (heck, I didn't know a one piece from a two peice axle until last week), everything seemed to go wrong in such a hurry and I have no idea why.   We bought an older car and have been working on set up all year and it's been coming along nicely, but last week we went from fast time in practice to being unable to complete a hot lap in qualifying or the race in nothing flat.  When he went out for qualifying, the car starting shaking like crazy and he brought it back.  When I started looking, I found the broken motor mount.  Thinking that was the issue, I fixed it and sent him our for the race.  Again, it started shaking like crazyand he parked it after limping around one lap.  This time, I found the broken axle...not sure if it was there when I fixed the motor mount.  As we talked about it, my son said that the car had become hard to shift (and a friend said it sounded like the clutch, but I guess a broken axle might sound similar).

I guess my underlying question was if these things could be related, and if so which is likely to have happened first.  My thought is that the clutch was slipping, which caused the broken mount, which made the  driveshaft shake and ultimately broke the axle.  That's just a guess...and may be 100% wrong, but I was wondering if anyone had any opinions.  The only other bit of info I'd add is that we were running more pinion angle than usual (nearly 3in).  Could that have caused any of the symptoms (regardless of the order)?

Again. sorry if I misunderstood you.  I've read many of your posts and you've helped a lot of folks out, which is admirable.  We race asphalt on the east coast, so it's not likely that we'll see you anytime soon, but if we do I'll buy you the adult beverage of your choice as a peace offering.  Take care.

Andy
   

[Andy S]

Reference my last post:

Pinion angle was 3 DEGREES, not 3 in.

Andy

[Winterracing]

I don't think the pinion angle would have an affect on it, 3 degrees isn't to extreme from what i've seen.  I can't say if the issues are related or not, but sometimes the 2 piece axles just break from wear and tear.  What tracks do you run at?  I also race on the east coast

Dan
www.winterracing.net