Lotus Elan

Alternate fasteners

PostPost by: prezoom » Mon Jul 23, 2018 4:24 pm

At Rohan's suggestion, I'll jump off in to the deep end.

As I have mentioned before, I am a big fan of twelve pointed bolt heads. They use a much smaller socket than an Allen/socket head cap screw headed fastener. In that, you do not need a socket to hold the Allen portion of the wrench. It is also much easier to get the wrench/socket on the fastener in hard to get at situations. They can also be used with a combination wrench (ring one end) that has twelve points, including the newer ratcheting style wrenches. And for me, with the wrench being smaller, the wrench size is the same as the bolt diameter, most bolts/nuts can be used with quarter drive socket. I use them in the following places: exhaust manifold, starter, gearbox to engine, lower cover plate to bell housing, engine mounts both on the block side and to the chassis. A different style of twelve point (AN) are used to connect the drive shaft to the differential flange, along with reduce diameter Jet style nuts, also 12 point. These bolts have variable length unthreaded shanks, so the threads are not in shear. The bolts do require a special chamfered washer under the bolt head. Much easier to fasten and remove without the chance of rounding off the nut, and ring style wrenches can be used on both ends. I also prefer torx headed screws over Phillips screws, less of a chance of rounding out the head. Flame away.
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PostPost by: Chancer » Mon Jul 23, 2018 6:13 pm

Most of my work is on buildings these days and I try to use Torx headed screws wherever possible for the reason you give and also that they stay on the end of the screwdriver when aligning with the hole.

My everyday vehicle uses them extensively but the job i was recently doing, remving trim panels for a CAN BUS wiring fault had PH headed screws located at the bottom of a deep horizontal hole, impossible to reassemble, I will hae to buy one of the self gripping screw starter bits, would have been a cinch with Torx fasteners.

By the way, what is the correct technical or trade name for the spring loaded things that will grip and hold a PZ or PH or slotted screw? I first came across them being used by aircraft fitters, without the correct name its hard to search for them.
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PostPost by: MarkDa » Mon Jul 23, 2018 10:04 pm

I think they're just called screw grippers!
At least that turns up a good selection of images when Googled.

I can't argue with a lot of what you say about bolts/setscrews.
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PostPost by: baileyman » Tue Jul 24, 2018 12:27 am

Phillips head screws should be known as single use fasteners, where removal the first time is uncertain. John
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PostPost by: rgh0 » Tue Jul 24, 2018 12:35 pm

Torx fasteners seem to be common in Europe and on modern European cars but not common in Australia so for most small screws I still use Phillips head despite it one use only tendency

For larger bolts and plugs hex socket versus Torx is also whats commonly available so I use that in the following areas where getting an external socket or ring spanner on to a conventional hex head is challenging. Using a ball headed hex key makes getting into the head at an angle without precise alignment easy

1. Exhaust manifold use socket head bolts rather than studs and nuts but jet nuts as a possible alternative if you really want to keep the studs

2. Radiator mounting bolts for the wide S3 radiator where the head is jammed between the body and radiator

3. Engine mount to chassis bolts where getting at the head to the rear of the chassis bracket is hard as the bracket wraps around it. Same for gear box rear mount to chassis bracket

4. Any other bolt where the head is buried and hard to get a socket or ring on. Such as the top starter motor bolt or rear bumper mounting to body bolts that are hard up against to body. i try to avoid using open ended spanners whenever i can


The other alternative areas is where to use ARP bolts instead of original Ford special bolts as they are generally better (and cheaper) in these high stressed applications

1. Con rods
2. Head bolts / studs
3. Flywheel to crank
4. Main bearing caps ( I have also used Grade 8 socket headed bolts here)
5. Crown wheel gear to diff carrier

cheers
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PostPost by: mbell » Tue Jul 24, 2018 3:10 pm

Any thoughts on a dome head hex/torx for the rear suspension arm to hub carrier bolts?

To replace the half height bolt heads. Main reason would be better clearance with the wheel but might be less likely to get damaged when attempting to remove it.
'73 +2 130/5 RHD, now on the road and very slowly rolling though a "restoration"
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PostPost by: prezoom » Tue Jul 24, 2018 5:15 pm

One other place I use a 12 point, is the 7/16 bolt that fastens the rubber portion of the gearbox mount to the gearbox. I drill a hole in the metal bracket to access the bolt head. A socket head cap screw would work there as well. Makes it much easier to remove the gearbox mounting bracket assembly as a unit.

I realize that 12 pointed bolts and nuts are a bit of a pain to locate. I am fortunate to live near San Diego, CA, where there is a very well equipped hardware store. Marshall's Hardware has, without a doubt, the best selection of hardware that I have ever found. With the advantage that you can buy a single fastener or the whole box. For NAS and AN fasteners, I use Coast Fabrication in Huntington Beach, CA, coastfab.com.
Rob Walker
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1964 Sabra GT
1964 Elva Mk4T Coupe (awaiting restoration)
1965 Ford Falcon Ranchero, 302,AOD,9",rack and pinion,disc,etc,etc,etc
1954 Nash Healey LeMans Coupe

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PostPost by: Lotus14S2 » Wed Jul 25, 2018 12:27 am

I am restoring my S1 Elan, and therefore use standard 6 point fasteners, for the most part. I want the car to look as close to original as possible. The same goes for using Philips screws where they are visible.
The only non spec I use are what are called "reduced dimension high temperature" nuts, which are 6 point, locking, and were used on jet engines. I use them on the exhaust. I have a bunch I got surplus from the old United Airlines maintenance base in San Francisco.
Most of my hardware is AN or MS, also from United, and from the old Boeing surplus store in Seattle. Unfortunately these places are all gone now, due to the new generation of yuppie millennial managers who saw no use for these stores. :D
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