What to Magnaflux

[JGB]

After my year of living dangerously (running an older car that had sat for 10 years) Im taking the suspension off and having the parts magnafluxed. Other than all the control arms should things like the uprights be checked as well? The fronts seem to be welded up parts and the rears look to be cast

Fronts


Rears:


Thanks,
Jim

[Fred Michael]

Control arms, axles, hubs, uprights, wheels. Suspension mounts if they are removable. All should be magged or Zygloed as appropriate.

[JGB]

Control arms, axles, hubs, uprights, wheels. Suspension mounts if they are removable. All should be magged or Zygloed as appropriate.

Thanks Fred.

Jim

[Steve Demeter]

If you are taking it all apart and getting stuff magged, I personally would have anything that caries significant load done.

My rule of thumb is that if it breaking can cause loss of control better safe than sorry.

[HayesCages]

I have little regard for magnaflux:

While working on aerial man lifts and digger derricks I saw many times where obvious cracks were not marked for repair on sandblasted parts that were magnaflux inspected in front of my eyes. When I approached the operator and showed him these he flatly denied there being any cracks present.
When parts have been used for years in the field they soak up oils that have leaked. When they are blast cleaned the cracks show pretty well when the oil starts leaching out of them.
The cracks I saw on several occasions, and that were over-looked by the so-called inspector, were thru the steel member and in structural areas.

I'd be very careful who I had inspect your parts. Maybe someplace that inspects airplane parts...

[kevskisps]

Hi, the front uprights on the Elden have internal tubing to the central axle carrier from the pickup points that are then covered in the formed sheet steel that you can see. So I should image as only part of the structure is visible then magnaflux is only going to be able to pick up on the external structure. A simple rattle test to see if there is any internal rusting is a good start and cost nothing

Agree on the comment on sand blasting is another simple way of showing up cracks if the item in question has been carrying oil to penetrate the crack

[provamo]

if you have run the car for a year then i say you have already crack tested it

[JGB]

if you have run the car for a year then i say you have already crack tested it

and think of all the money I'd save

[DanW]

I have little regard for magnaflux:

While working on aerial man lifts and digger derricks I saw many times where obvious cracks were not marked for repair on sandblasted parts that were magnaflux inspected in front of my eyes. When I approached the operator and showed him these he flatly denied there being any cracks present.
When parts have been used for years in the field they soak up oils that have leaked. When they are blast cleaned the cracks show pretty well when the oil starts leaching out of them.
The cracks I saw on several occasions, and that were over-looked by the so-called inspector, were thru the steel member and in structural areas.

I'd be very careful who I had inspect your parts. Maybe someplace that inspects airplane parts...

Wow. I agree. A qualified inspector is needed, not someone who says, "yeah, Joe showed me how to use it." An FAA repair station is ideal. The other alternative would be a ASNT Level II inspector who is trained on wet mag and dry mag particle inspection. The alloy parts require Zyglo or equal. When used correctly mag particle inspection is much more sensitive than dye penetrant.

I have a "quick check" dye penetrant kit that I use at home and take to the track. However, the directions must be followed carefully. I have seen others use dye pen incorrectly and make a mess.

The other thing to inspect are your drive donuts (metalastik couplings). Look for cracking or separation where the bolt inserts are located. Replacements are available through Averill, Pegasus, Dave Bean or JAE Parts. Make sure the bolt grip lengths are long enough that the threads are not loaded in shear. I have had donuts break on my Lotus Elan. It was pretty scary.

Regards,
Dan

[Dmitri]

Wow. I agree. A qualified inspector is needed, not someone who says, "yeah, Joe showed me how to use it." An FAA repair station is ideal. The other alternative would be a ASNT Level II inspector who is trained on wet mag and dry mag particle inspection. The alloy parts require Zyglo or equal. When used correctly mag particle inspection is much more sensitive than dye penetrant.

I have a "quick check" dye penetrant kit that I use at home and take to the track. However, the directions must be followed carefully. I have seen others use dye pen incorrectly and make a mess.

The other thing to inspect are your drive donuts (metalastik couplings). Look for cracking or separation where the bolt inserts are located. Replacements are available through Averill, Pegasus, Dave Bean or JAE Parts. Make sure the bolt grip lengths are long enough that the threads are not loaded in shear. I have had donuts break on my Lotus Elan. It was pretty scary.

Regards,
Dan

ASNT level 2 mt/pt/ut here. Yes, very much agree, make sure whomever does the testing for you is a certified ndt tech.

Dye penetrant is going to have to be used for anything not ferromagnetic. Good results take a lot of prep, and close monitoring of penetrant and developer times. Part needs to cleaned with solvent to remove any oils or contaminants. Blasting is an option but also can cause problems depending on hardness of materials and blasting media. Very fine hairline cracking can be obscured. Same goes for grinding with wire cup wheels etc.

There is different viscosities of penetrant available, fluorescent and visible plus various developers that will help determine how sensitive you want the test to be. Some very fine defects can be found with the proper setup and procedure.

As far as MT goes operator is critical. A componenet needs to be magnatized in a way that every portion is expoaed to a magnetic field perpendicular to the defect. There is various ways of magnatizing including ac yokes, prods, coils etc. Each way has benefits and downsides. Also there is a few forms of mag, dry and wet, visible and fluorescent. Dry mag tends to be quicker and great for doing large areas or say something like every weld on a tubular chassis. You can even use a thin layer of contrast paint to make identifying indications real easy. It is not as sensitive as wet mag.
For race car suspension components i would recommend using fluorescent wet mag. It is extremely sensitive to hairline cracking.

Also, if a tech can't get a positive response on a clearly visible crack in a componenet there's two possibilities, either he has no idea what he's doing or you have no idea what you're looking at. That's why you want certified and experienced people looking at your stuff.

-D. Gurney
AWS CWI, ASNT LVL2 PT/UT/MT

[HayesCages]

ndt tech = non-destructive test(ing) person

[tstrong]

As dmitri above mentions DO NOT BEADBLAST TO CLEAN PARTS BEFORE MAG OR ZYGLO. Especially on the al or mag parts you will cover up fine crack. Cleaning before NDT should be by solvent, detergent, vapor type means. No abrasives. After NDT feel free to go crazy with bead blast wire wheel, etc to make everything pretty. As mentioned don't waste your time and money with anyone not qualified/ certified.

[Ralph Z.]

Has anyone used x-ray? Any opinions on the use of x-ray for identifying cracks?

[S Lathrop]

I can see magnaflux doing an excellent job on things like spindles, things that are solid. It is not going to be very useful on plated parts or parts that are complex fabrications involving sheet metal parts.

Suspension arms and fabricated uprights will have a high probability of internal corrosion. Magnaflux will not give the type of inspection you really need for those parts. For these parts, you might be able to use a bore scope to look inside the parts when the rod ends are removes. Otherwise you may have to drill 1/8 diameter holes in the spots where corrosion is most likely.

There may be other testing processes that can be used. Old race cars are very similar to old airplanes like Piper Cubs where the major construction was welded steel tubing. I would research testing procedures the aircraft guys, especially the vintage aircraft guys use.

[DanW]

Ultrasonic Thickness testing can be performed on suspected thinning or corroded chassis tubes and suspension parts that have had the paint or plating removed.

Again, IT inspection should be performed by an FAA or ASNT qualified person trained in the technology.

[Offcamber1]

The other thing to inspect are your drive donuts (metalastik couplings).

If it is apart, take the time to look at the outer universal joints on the half shafts as well. They may not have had grease for decades.