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BOLTS in the Body Assembly -- BD-150

At 10:27 PM 5/2/2009 -0600, Duane Rankin in Glen Carbon, IL, wrote:
"Not sure where the heavy washers, oblong plates, and lock washers go. I am also not sure which size and brand of bolt goes where".

You will may stop worrying about the brand of fasteners if you will read RT-104 first.
Fastener size and quantity may be found in RT-104B.
Translation of BMC standard fastener part numbers may be found in RT-104C.

Most fender bolts are 5/16-24 -UNF (fine thread), although there are a few 1/4-28-UNF in the front fenders and splash panels. All of the original fender bolts had pointed tips for easy installation (call them "body bolts"), so flat tip bolts would be a no-no for concours show. The pointed tips will help immensely for assembly where you find floating cage nuts.

You may notice the number of fender bolts in different lengths is an odd number, meaning left and right sides cannot be symmetrical. One bolt in particular is longer than others. On the RF fender, the second bolt above the air pan in front is longer. This is where the ring lug grounding the wiring harness is attached with a hex nut on the inboard side of the inner fender ahead of the radiator. Many people make the mistake of putting the grounding ring on one of the body to frame bolts in that corner of the nose, but in fact the harness ground was connected to the fender bolt before the body was installed on the chassis.

All fender bolts should have a lockwasher and some form of flat washer. For fender bolts installed from the outboard side, every one should have a large oval flat washer to spread the load over large surface area to minimize distortion of the fender flange. This helps to reduce distortion and bulging of the fender piping when tightening the bolts (although this can still be a bit of a challenge). The only exceptions to this would be where the oval washer does not fit, in which case use a round washer. There may be one spot like this at the extreme rear of the rear fender within the small radius bend area, and maybe one spot at the extreme front of the front fender.

Fender bolts installed from the inboard side should have a round flat washer and lockwasher. The vertical row of 1/4" body bolts inboard of the front fenders ahead of the door post should likewise have round flat washers and lockwashers.

Small bolts along the bottom edge of the front and rear fenders were originally part number AFH2587, referring to an engineering drawing, meaning it was a special part, not a standard fastener. I have not seen the drawing, and I don't recall seeing an original part. My engineering experience tells me this would have to be a #10-32 screw with a special rectangular head, very narrow to fit inside the lower body trim strip. Problem here is that the space inside the narrow flanges of the finisher strip is only about 1/4-inch wide, and the head of a #10 fillister head or cheese head or hex head screw is about 5/16-inch wide. Perhaps modern replacement trim strips are not made the same as original parts. I have never figured out how to make the finisher strip fit over the screw heads, not now nor during past restoration work. Modern replacement screws are commonly listed as 53K126 which is a #10-32x1/2 pointed screw with hex head (likely 5/16-inch hex). I usually put pop rivets there and remove bolts after securing the fender, but that would not be right for concours show.

The lower body trim strip uses special spring loaded T-head studs with #10-32-UNF thread, five each side. The stud heads snap inside the trim strip with threaded studs extending inward. On the inboard side should be small oval flat washers, lockwashers and hex nuts. The narrow oval flat washers are necessary to avoid having the flat washers protruding below the body sill. The trim strip does not cover the last hole or screw at front where the splash panel will attach.

The front valance panel is attached using #10-32-UNF hex head pointed body screws, lock washers and oval flat washers all across. Holes in the valance panel at ends where attaching to fenders will be slotted horizontally for lots of tolerance in alignment. Be careful not to over tighten these screws and strip threads in the floating cage nuts.

Splash panels aft of the front wheels are installed using 1/4-28-UNF x 3/4 hex head pointed body bolts with flat washers and lock washers. There will be one screw in the bottom edge of splash panel to fender being a low profile round head (truss head) #10-32-UNF screw with flat washer, lock washer and hex nut. The rubber seal strip (original style) is secured to the splash panel with split rivets and small close fitting flat washers.

Splash panels ahead of the rear wheels (when used) are installed using 5/16-24-UNF hex head pointed body bolts with flat washers and lock washers. These bolts are installed from inside the body with hex heads hidden behind the rear kick panels, and captive nuts in the splash panel. Note that the SPL calls for 1/4" bolts and shows them oriented as though they would be installed from the outside. So either the SPL is in error, or there may be two different styles of splash panel (not documented). When these panels are retrofit to earlier cars they can be installed using sheet metal screws. There are also two #6 x 1/4" Phillips head sheet metal screws used to secure the bottom end of the panel to the inner body. The rubber seal strip (original style) is secured to the splash panel with split rivets and small close fitting flat washers. The washers are not shown in the SPL, but if you don't use washers the rivet split ends will damage paint on the splash panel.

Splash panels aft of the rear wheels are attached to the inner fender with three 1/4-28-UNF x 5/8 hex head screws with pointed tip, flat washer and lock washer (with screw head inside the boot). Flat tip screw is okay but requires a bit more fiddling with the floating cage nuts that are part of the splash panel. Bottom end of the splash panel is attached to the bottom edge of the fender with a 1/4-28-UNF hex head screw, flat washer and lock washer. The fender has a small welded angle bracket at this point holding a square cage nut. There is no seal strip on the rear splash panel.

Door hinges and striker plates are attached with 1/4-28-UNF flat head screws with Pozidriv slots. Hinge to door screws use flat washer, lock washer and hex nut inside the door shell Hinge to post screws and striker plate screws go into a tapping plate inside the door post.

Shut pillar facing panel (commonly called shut face panel) is installed using #10-32-UNC raised countersunk zinc plated screws (called grommet head screws in the USA). Three in the side screw into floating cage nuts inside the pillar. For the Roadster, two in the front screw into special wedge shape tapping plates that secure the rubber door buffers. The Coupe has only one door buffer for each side. At the bottom forward end of the curved foot will be two RTZ804 screws. These are raised countersunk tapping screws zinc plated. For modern replacement parts all of the shut face plate screws are likely to be chrome or bright nickel plated (highly recommended for corrosion resistance on appearance parts) rather than zinc, and I have never heard of concours points being deducted for this.

Bonnet and deck lid hinges are originally attached using #10-32x3/4 hex head pointed screws with flat washer and lock washer all around. I have my own trick of using a #10-32-UNFx5/8 socket head cap screw with a 5/8-inch diameter thumb screw knob on the end of the hinge attached to the moving panel. This facilitates quick R&R of the bonnet or deck lid, but is definitely not concours.

See also RT-103A - Body Weight and BOLTS Securing Body to Frame, in the Restoration section.

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