The transmissions in our performance cars are special in that we will rarely ever see their inner working, so long as they continue to operate properly. Usually it’s failure that leads us to open the case of a transmission, or, in many cases, simply replace it altogether.
But there’s a case to be made for staving off those failures altogether …
How do you tell the difference (and deal with) between a scratch and a crack?
fearlesfil said:How do you tell the difference (and deal with) between a scratch and a crack?
a) Experience. A skilled tech can tell how much dye a crack will hold and how it will react to being simply wiped off as compared to a surface imperfection.
b) X ray/MRI. Same way you tell if a bone is broken, you can use imaging technology to find interior structural imprefections in a solid piece.
As for dealing with it, that's going to come down to the individual part. If the scratch is removed during polishing, it's probably nothing to worry about. If the scratch needs major refinishing to remove, it's probably a stress-riser anyway and it's best to just replace the whole part. At some point the thorough investigation is going to cost more than a pre-emptive replacement.
Well it should be noted that this is one of the main methods of industry on may new products going to assembly or out the door! While defects are not common in many forged, machined, heat treated parts, in new parts you almost never get a bad part out of the box with this type of defect that fails the moment you put the part in service or very shortly thereafter.
This is the exact reason to check USED parts! The longer you run them the closer they are to death! In fact they are dying a slow ever present fatigue death with each use!
Transmission parts, gears and shafts epically prone to fatigue failures, ring & pinions, spider gears, CV shafts and just about every other part you can think of is slowly failing sooner or later! Its the best case of pay me now or pay me 10X more later I can think of!
It is one of the most widely used methods for part inspection I can think of and is extremely well used in all Aviation inspections for life cycle inspections and crack detection prior to failure and on THOUSANDS of parts on a single plane! I really like reliability in my racer and not to mention safety!
We are mostly all making big power and power increases fatigue substantially and checking is always better than replacing the entire kit of transmission, rear end, loss of the car as a result of a failure.
Not to be an alarmist just food for thought!
Scott
With either method, how do you tell the difference between a scratch and a crack? Visual only or do they react differently?
You'll need to log in to post.
