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Toby Chess

Toby Chess is an I-CAR program instructor, training specialist, and former salvage yard operator. Toby is universally known in the collision industry for his work with first responders and advocacy for body shops and consumers. He can be reached at

Wednesday, 24 February 2016 22:27

Rivets Have Replaced Welding in Many Newer Vehicles — Part 2

Written by Toby Chess

Viewing Fig 11, you will see that the rivet is solid. Like the SPRs, solid rivets need to have access to the backside of the panel. Unlike SPRs, a specific size hole is needed. Solid head shape for solid rivets comes in many forms.

See Fi 12,13 & 14. Diagrams taken from




The counter sunk rivet is designed to sit flush on the panel. It is necessary to counter sink the hole with either a 100 degree or 120 degree counter sinking tool depending on the rivet specified by the OEM. See Fig 15.

Rivets must be matched to the job.

(L) The length of the ‘Body’ is determined by the stack total thickness plus 2mm. Therefore if the stack is 4.5mm then add 2mm so the rivet length will be 6.5mm.

Sizes range from 3.5mm – 8mm in length.

The 2mm is for the correct depth in the stack and it ensures the correct profile (“mushroom”) for the joint

(D) Two main sizes of the ‘Head’

3mm and 5mm in diameter but there are other sizes. In repair Jaguar do use a slightly bigger head.

3mm is used on the Mini quarter panel for example whilst 5mm is used in Audi on certain parts of their repair sections. (Taken from Dave Grusko’s presentation.)

It is extremely important that when installing rivets, that you follow the OEM procedures. If the wrong size rivets are used, it could lead to a huge failure if the vehicle is involved in another collision. To all you shop owners and managers. How many of your techs have a caliper or a micrometer? A side note. I conduct the I-CAR WCS 03 welding test and with the new test standards, the tech has to determine the size of the metal coupons to properly set their welders. Nearly 100 percent of the techs have no idea why it is necessary to know the metal thickness or even how to measure it. I bought this inexpensive gauge from Miller (See Fig. 17) and give it out to the techs that are taking the test. It is amazing to watch the techs after you show them the proper procedures. It may sound corny, but there is a sparkle in their eyes that they have this new and valuable knowledge.

Mike Hubbard is a Tesla, Aston Martin, Jaguar aluminum certified tech from European Motor Car Works in Santa Ana, CA. His first operation when installing a new panel that will be bonded and riveted, is to identify and mark the position of each rivet. See Fig 18.

Still on the subject of installation, here is another tool that is necessary when riveting on aluminum.

When you punch or drill a hole in aluminum, there is a sharp raised edge that needs to removed prior to installing a solid or blind rivet. See Fig 21 for a cross section on a hole in aluminum.

If the lip or the burr is not removed, the head of the rivet will not make full contact with the panels that are to be joined. The rivet could become loose and overtime the adhesive could also loose some of strength due to vibration and movement.

If the vehicle is again in another collision, this area could become a weak point in the distribution of the collision energy. Finally on solid rivets, the same tools for installing SPRs can be used for solid rivets, but you will need to change the madrels.

The same holds true for removal. Moving on to the blind rivets.

The correct blind rivet is paramount in a proper and safe repair. Take a look at the next set of pictures to see what I mean.

You will notice that there is no much difference on the front side.

Now look at Figs 23 &24 which are the back side of the panels.

You don’t have to be a rocket scientist to see the difference. These pictures are self-explanatory. We will look at the Monobolt and Hemlock blind rivets.

It should be noted that a proper hole as specified by the OEM in needed for installation and it is not necessary to have access to the backside. A repair shop called one my contacts who furnish riveting tools. The shop was complaining that his rivet gun did not work on the back panel of the bedside of the F150. It seems that the A-arm on the gun would not reach all of the attachment points for installing the SPRs.

You will notice that the front panel is install with 3 different blind rivets and not with SPR. As I previously stated, you can not repair these new vehicles without the OEM recommend procedures, specific training and correct tools and proper use of those tools. This is a disaster in the making and you better be ready. Enough on my soap box. Lets look at the Monobolt.

A monobolt is a specific type of blind rivet. The mandrel is pulled into the cylinder and expands the cylinder against the backside of the panel. This rivet has high shear and tensile properties and fills the hole. This rivet is excellent for holes that are slightly larger than the recommended hole. See Fig 26.

These are used where there is no access to the inner panel, so the rivet gun must work from one side only. A hole has to be drilled the size of the rivet head, eg for a 6.5 mm rivet, a 6.7 mm hole must be drilled.

The length of the headform must be long enough, 2mm longer than the overall thickness of the stack and be long enough to clamp the panels together. The shape of the headform will be decided by the job required. A countersunk headform will fit into a countersunk hole. The breaking point of the mandrel must be correct. e.g. On the repair of a MB Sill section, rivets with 1.9 ton breaking point must be used. (Recommended RIBE). This is dictated by the car manufacturer. (Taken from Dave Grusko’s presentation.)

Again, you need to look at the OEM repair data to determine the proper blind rivet. In Fig 28, you can see the problems that occur when the wrong blind rivet is used.

The other type of blind rivet that is being used in the collision repair process is the hemlock rivet. Fig 29.

This rivet also need a hole for installation and does not need access the backside of the panel. The mandrel is pulled over the rivet body and the entire rivet is compressed against the rear panel. See Fig 30 for the sequence.

There is a large footprint on the back panel and this rivet has superior tensile and shear strength. Moreover, this rivet is highly recommended for thinner pieces of sheet metal.

The third part of this article will discuss the various types of rivet guns, advantages of FFR rivets, adhesive preparation and a few of the vehicle repair procedures for replacing parts with adhesives and rivets. Did you think this article was a riveting experience?

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