Surging vibration (this ended very badly) -new pics

hey fastx19.... so I should stop yanking the handbrake and locking up my rears for the powerslide and drift initiation? That just takes all the fun out of it. <Grin> but surely I jest ???

also, I actually think my axles are very slightly in a ascending angle to the outer stub axles (so past horizontal? / bad??) ... but alas, I cant tell now because they are hanging at 45 degrees. <sigh> I will check this once I reassemble. I still have to think that they will cross flat horizontal many times due to cornering and road bumps, so I am at a bit of a loss what this would matter.

Flat horizontal would equal the shortest distance between stubs and tranny (so closest to binding) and I don't think either of the top or bottom angles even come close to the available max deflection available in the CV's - My suspension is also VERY tight -the coil-overs don't allow a lot of jounce so the axles basically stay nearly flat all the time. - even with my 6'6" 275 lbs in the seat ( don't ask me how I fit in there, its like origami)

Help me understand the potential impact of being past "flat / level"
 
That would be lower control arms parallel to the ground, not drive shafts. Fiat designed in plenty of plunge travel into the CV joint system. The suspension can be completely bottomed out at the limits of suspension travel (strut-damper limited) and never have a problem with CV joint or axle angle induced binding.


Bernice


Jefco said:
I think Rapunzell has mentioned before, the minimum height for the rear of the car is when the driveshafts are level to the ground...
Click to expand...
 
5 speed diff carriers carriers can and DO explode under hight torque loads, or why dumping the clutch with sticky tires and high power engine for any gear box is a really bad idea unless it has been specifically designed to support and transmit shock loads of this magnitude. This is a known limit-problem with this gear box. Gear boxes are rated by torque capability and not really HorsePower as it is the twisting forces involved that truly stress out the gear box parts.

The diff carrier is a casting, the rough surface on the casting significantly increases the potential risk of crack propagation. One of the endurance race prep things that can be done (did this to the 5speed when were were running the stock power train in the LeMons car) is to de-burr and completely smooth the rough cast surfaces. This goes a long ways to remove stress risers and reduces the risk of crack prorogation. Removing the outer cast layer tends to stress relieve the part in that smoothing process. Get the diff carrier properly shot peened (not bead blasted which does nothing other than cleaning). This compacts the outer layer making is less prone to cracking and strengthens the part. Cryo treating would be an extra option.


Bernice

GregS said:
I have seen on several forums mentioning the weakness of the 5 speed diff, including this one from SteveC, https://xwebforums.com/forum/index.php?threads/5-speed-strength.23233/#post-191248
Could it have been weakened from some dropped clutch starts, then just decided to let go.
Click to expand...
 
There are many reasons the diff housing may have cracked, you may be able to get a clue by examining the crack(s) themselves. It's a bit difficult to see on most cast surfaces, but cracks will generally tell you a story. It sounds like you had a crack for awhile (reported noise) so you should be able to see where the crack started if you know what you're looking for. It's possible that the casting had an occlusion in a bad place, there was a manufacturing defect (burnt/defective bore), etc, etc. Failure of the diff housing isn't very common, I would think it had nothing to do with the axles.
 
You must log in or register to reply here.
Back
Top