Found the weakest link and destroyed it!

racecougar

Registered User
Well, I found the weakest link of my drivetrain a few hours ago in my splitport tbird. I had just pumped in some 93 unleaded and flipped the switch on my flip chip (tuned by Brian Herron of course), and I guess that the tune had more power than the passenger side halfshaft could handle. I stomped on the gas at a stop sign, left about a foot of rubber then heard a loud bang and the car took a leap to the right. I coasted down the side of the road to the nearest driveway and called for my dad to bring a trailer. Left a nice long streak of CV Joint fluid down the street. :D

I just hope that my Trac-Loc didn't get messed up by this. I'm crossing my fingers. I'm going to put a pair of SC halfshafts in tomorrow night, hopefully they'll take a bit more abuse. Are the SC's CV joints stronger though? I know that the halfshaft is thicker, but I'm not worried about breaking the shaft the CV Joint is weaker than it.

Here are some carnage pics. The needle bearings and other pieces that are on that towel were found on the lower control arm.

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-Rod

P.S. - For those of you who know about the Cougar I'm building, imagine what would happen to those halfshafts with that kind of power. At the moment, it has the same size halfshafts in it as this one that I broke tonight. That will most definitely have to change before I even start and move the car though!
 
Bigger is Better

The 1-3/16" normal SC halfshaft and the 1-1/2" halfshaft AKA "Fat shaft" both have larger CV or Tripod joints than the 1" LX halfshaft. Definitely the way to go here.
 
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Damon Slowpoke Baumann said:
Well you actually broke the joint not the shaft..So you can get huge shafts......Wont help the joint

Racecougar said:
Are the SC's CV joints stronger though? I know that the halfshaft is thicker, but I'm not worried about breaking the shaft the CV Joint is weaker than it.

That's exactly what I'm asking here. If the SC shafts don't have stronger CV Joints, then how do people like Chris Wise and David Neibert launch without breaking them?

-Rod
 
Re: Bigger is Better

Jim Cook said:
The 1-3/16" normal SC halfshaft and the 1-1/2" halfshaft AKA "Fat shaft" both have larger CV or Tri-plex joints than the 1" LX halfshaft. Definitely the way to go here.

Thankyou, that's what I wanted to hear.

-Rod
 
Raxles (www.raxles.com) had even stronger shafts and CVs than the SuperCoupes.

Raxle on the left, fatshaft on the right:

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You might want to give Marty a call at Raxles and see if they are still available. I know there were some issues with Ford supplying parts and they stopped making the a while back. I don't know if that has been resolved and whether or not they are available again.
 
First of all, thanks for the suggestions about what halfshafts to use, etc, but unless someone wants to donate a pair of Raxles, they won't be going on this car. THIS IS MY DAILY DRIVER, I'm trying keep costs down.

I installed a pair of SC halfshafts, including a "Fat" shaft (5-speed pass side) on the passenger side. I left the car up on jackstands, started it, and put it into gear to make sure everything was ok. I noticed a "pop" whenever I tapped the brake pedal. I shut the car off and crawled under the car. To my surprise (and horror) this is what I found:

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I can't believe that this practically stock V6 can be so destructive. I think what may have happened is this:

The centersection tried to go "nose up" which the rubber front mounts allowed it to do, thereby stressing the rear cover to the point of breaking. This allowed the whole centersection to move enough for the half shaft to break apart. All in a split second. At least that's the theory. Either way it sucks.

So I pulled the cover off of one of my 90 XR7's today, and went to bolt it onto the FRPP centersection in the splitport tbird, when I noticed that the top of the cover would not sit flush. One of the cap bolts (I guess that may be what they're called) was making contact with the vent. I found out that Ford makes at least two different kind of covers for the 8.8". So I figured it must be an aluminum vs. cast iron thing, and that my 94 Mark 8 would have the right cover since it too has an aluminum centersection. Wrong. Same cover as the 90 XR7. On a chance, I checked my 97 Tbird 4.6L. Bingo, I do have the right cover! So that will be going on tomorrow night after work. That is, unless there are other problems.

Here's another pic of the CV joint:

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-Rod
 
Yes, that's exactly what I thought, too. I really didn't expect it to happen. I'm trying to locate a pair of poly bushings for the front two centersection to subframe mounts. I know Rich makes them at MN12 Performance, but I need a set by tomorrow. If not, I'll have to put the car back together with rubber ones and take it easy for now. The car is scheduled to be dynotuned on Sunday, so I need to get it back together. Anyone know how I can get a pair overnight or locally?

-Rod
 
Got me??

Damn Rod what a crap time for this to happen!!! It took nearly a month for me to get new rubber bushings for the rear upper spindles...I wouldn't have a clue how to get anything overnight.

Hope you can get some help.....


Rick in FL:cool:
 
It looks like I'm going to have to stick it back together with rubber bushings on the front of the diff for now, and just take it easy. I'm positive that a large part of the problem was due to the diff mounts flexing more than they should.

When I went to bolt on the rear diff bracket, I realized that the force of all of these parts breaking actually twisted the centersection in its mounts. I had to loosen the front two mounts and straighten everything out before I could bolt on the rear mount. I can't believe a N/A 3.8L can do this, not to mention that internally the motor is stock. Wow!

-Rod
 
Yikes

Now ya got me all paranoid Rod :confused: I currently run basically a stock motor just freed up the exhaust...but I got this B&M shift kit in and you know how they can hit BAMM!!! Let me know if you can get to the bottom of this cause I never heard of it happening when the engine is basically unmodified..If so I would expect Coy to dump rear end all over the track everytime he goes out:rolleyes:


Rick in FL:cool:
 
Well, I think once I get the poly bushings installed, it will be a relatively strong rear end. The way it is set up now is with the SC 5-speed halfshafts and a FRPP centersection. Here are some of the main engine mods that I can think of off the top of my head:

2000 Splitport 3.8L V6
21lb injectors
DIS ignition
K&N cone
CAI
ASP Underdrive pulley
Ported manifolds - large, free flowing exhaust
Dual Program Diablo Chip, tuned by Brian Herron
FRPP centersection w/ 3.73's and T-Loc


It breaks the 255's loose into second, and can chirp them into third.

-Rod
 
I put the car back together with rubber bushings until the poly ones from MN12performance arrive. The dyno results are posted in the Non-tech forum. 164.9HP and 196.7 FT-LBS.

-Rod
 
Well, I just received the poly diff mounts and installed them. That takes care of the centersection movement, but the car still has a nasty vibration on the highway. It has done this ever since I started driving the car (never drove the car without the 3.73's either). It only occurs when coasting or decelerating with my foot off of the gas pedal. If I even rest my foot on the gas, it stops vibrating. The driveshaft has new U-joints, the centersection now has poly mounts on the front, and I'm running out of ideas. I tried driving the car with only 10 psi in the airbags (vs. 40), but it did not change anything other than the firmness of the rear suspension. By deflating the air bags from 40 psi to 10 psi (or 0 psi for that matter), the car lowers a little over half an inch. I even checked that again today on level ground.

My next plans are to first get a good four wheel alignment. According to Carfax, this car has been in at least one accident, so it’s a possibility that something is not aligned or loose (although I can’t find anything that’s loose). If that doesn't work, then I'll see about getting the driveshaft balanced. I have tried rotating the driveshaft, but it didn’t change anything. I will not be buying a driveshaft for this car, so please don’t suggest that. It’s just a daily driver that I’m not spending much money on.

Anyone see anything that I’m overlooking?

-Rod
 
I wouldn’t be too impressed by your stock V6 breaking the joint. Wheel hop was more than likely the actual cause not the “huge” torque of the V6. There are plenty of guys that break the output shaft on 5sp cars from wheel hop.

Jeff
 
I'm was not impressed when this happened, and I never said that the splitport 3.8L had "huge torque". If you reread the posts, you'll see that the cause of the damage was worn/weak diff mounts. This car doesn't experience much wheel hop, thanks to the airbags and SC springs, and it wasn't hopping at all when this happened.

-Rod
 
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