Bolt Thread Patterns and Sources

[jbeach]

This question shows an apparent gaping hole in my mechanical knowledge, but I hope will also be of interest to other forum members:

1) Would someone please explain the thread standard used in our Elans? I keep finding nuts/bolts on my car to which non-metric bolts/nuts of the same apparent size I have on hand, will not fit. I do not believe its a course/fine problem and I'm fairly certain its not a metric/imperial (is that the right term?) problem. So I need a brief tutorial on whatever bolt thread/sizing standard is correct for our cars and how it might differ from other non-metric standards I may come across.

2) I want to amass a good inventory of the various bolts, nuts, and washers I'll need as I continue to restore my Elan. I realize a robust inventory of the many sizes of nuts and bolts used on our cars will be relatively expensive, but, within reason, I'm ready to make that investment.

I live in Columbia South Carolina, so I can't just pop in to my local British Automotive Fastener Shop to purchase my inventory. I believe am limited locally to Lowes, Home Depot, a few locally-owned hardware stores and, of course, several dozen Pep Boys, NADA, O'Reilly's, etc. automotive parts stores.

Can you point me to a source (on-line, or otherwise) from whom I can purchase my inventory?

2a) As part of 2), while poking around at my local auto parts chains, I believe I've noticed different classes or grades of bolts/nuts, and, obviously, stainless steel vs. non-stainless steel. Should I try to purchase and/or avoid any particular class and/or material?

3) On a final point, do you have any suggestions regarding how I should organize/store my inventory? Can you recommend an appropriate multi-bin plastic box, or other system? I'm tired of fishing around in a large plastic tub for a nut, bolt, or washer that "looks about right," only to find it won't fit.

Many thanks!

John

[BullAndrew]

John, the bolts are UNF, which is unified national fine as posed to UNC whichis course.

Yes the metric threads are similar but they will bind and strip.

Google UNF you should not have a problem finding them, I do have a document with the dimensions that I can post if you need it. The work shop manual dose list them and also the torque sayings.

And if you cant find them on ebay then sjsportscars.co.UK as a lotus specialist has them

Andrew

[mbell]

As said the bolts are all almost UNF with the odd UNC, metric and smaller threads for special uses.

As USA is still imperial the bolts are widely available at hardware stores. I'd recommend a visit to a local bolt/fastener store instead of the main stream HW stores (e.g. Homedepot) as the UNF bolts/nut often have to be bought in small bags and are quite expensive.A local bolt store will carry a much better selection at a much better price.

Grade 8 v Grade 5 see:
http://tinelok.com/grade-5-vs-grade-8-fasteners/

[Bud English]

John, here's a handy chart that pretty much explains the fasteners used and converts the Lotus numbers from the parts list (on line copy here: http://rdent.com/manuals/index.html) into numbers that your hardware supplier can handle.

STANDARD HARDWARE PART NUMBER CODING.doc

(31 KiB) Downloaded 772 times

A Lotus part number bolt "XUFB0740" translates into a (X) Hex head, (UF) UNF, (07) 7/16 dia, (40) 2.50" long, bolt. Most all are Grade 5. Any exceptions are likely to have Lotus numbers that don't follow their own system, but have a specific part number and function. Seek help from folks here in that case.
The attachment comes from the introduction to the parts book.

[jbeach]

Thanks everyone.

So, if I understand you all, all bolts that are not metric are either Unified National Fine or Coarse. And Imperial and SAE (bother non-metric) are just other ways of saying UNF or UNC? I ask because I've come across certain fine-threaded nuts in my door (my locks/window frames attach to them) that are clearly not metric, but I've tried every size of non-metric bolt I can find and none seem to fit. Which is why I'm wondering if there's some other standard of non-metric bolt here in the U.S. (SAE?) that is not Unified National.

And mbell, I wish I had a "bolt store" here in Columbia I could visit. The guys at the available Columbia establishments are uniformly clueless.

Many thanks,

John

[prezoom]

One more tidbit in the nut/screw department. You will occasionally find a BA thread. They match nothing but themselves. So, when a 10-32 will not fit.......... An example is the thumb nuts that hold the instruments in place. Those are 2BA. Have not checked other applications on the Plus2, but the door latches on my Sabra GT have some BA screws. You may be able to find some of these at Moss Motors, mossmotors.com, or at Metric and Multi-Standards. At Moss, you need to look at the MGTC catalog, which is on-line and they will send one on request. The have an outlet in Virginia, which is fairly close. Their personnel are a great help and can answer many questions. They also have taps for BA threads, along with Metric and Multi-Standards. Have never purchased from MM-S, and do not know what the quantities are for a minimum purchase. A stiff shot of your favorite adult beverage will probably help about now.

[Chancer]

You will find BA threads amongst electrical items, instruments etc, they may also be used on small rods and clevises like door mechanisms, perhaps the windscreen tension bars.

You will find UNC threads where studs go into castings like the cylinder head, its been d?cades now but I think some of the threads in the engine block are UNC.

You will find BSP threads on fluid connections like o?l lines.

Many reproduction parts will use metric fastenings.

I think you will often find a 1/4" BSF thread on the starter cable terminal.

I dont think its relevant to an Elan with original parts but in the 70's the Ford bellhousings all used metric fasteners whether the threads were in the bellhousing or the engine block but the starter motor threads remained UNC for a long time because Lucas had not changed their tooling and also for interchangeability.

[rgh0]

.......You will find UNC threads where studs go into castings like the cylinder head, its been d?cades now but I think some of the threads in the engine block are UNC.......

.

Yes UNC bolts or studs are generally used into cast iron or cast aluminium components including the body bobbins and the head and block and gearbox and diff.

UNF bolts ( also called SAE) are used generally with nuts or into steel components.

I use the term "generally" as there are some exceptions ( eg flywheel to crank which are both cast iron but use UNF threaded bolts)

regards
Rohan

[dougal9887]

UNF sizes only go down to 1/4" as far as I know. Below that BSF is used. 3/16" is the only small size used I think.
Dougal.

[RogerFrench]

You can get all sorts via the web. Bolt Depot, for example, sell a grade 8 selection that's pretty useful.

[jbeach]

OK, superb. All very helpful.

So, before I take this step, please confirm that if I purchase the following assortment from Bolt Depot (thanks Roger), even though that vendor calls these bolts a "U.S. assortment," they're all UNF. Correct?

https://www.boltdepot.com/Product-Detai ... oduct=7512

Many thanks!

John

[bulfin]

I am pretty sure there is a Fastenal store in Columbia/ I should have most of what you need. Don't expect them to have British Pipe Thread stuff though.

Bob

[Chancer]

OK, superb. All very helpful.

So, before I take this step, please confirm that if I purchase the following assortment from Bolt Depot (thanks Roger), even though that vendor calls these bolts a "U.S. assortment," they're all UNF. Correct?

https://www.boltdepot.com/Product-Detai ... oduct=7512

Many thanks!

John

Being across the pond I cannot say if the price is good or not, what I would say is to find out if they are actually bolts (which have a plain unthreaded section) or setscrews (which are threaded the whole length).

The former will find use on your vehicle, the latter should only be used as a temporary get you home fix.

That said there probably are setscrews used in certain areas of the Elan but not on engine, drivetrain or suspension.

[RogerFrench]

They are all UNF (or SAE over here).
That's a big assortment though - you'll have plenty left over!
Chancer, they are bolts, but the term setscrew here has a very different definition. Like lots of other things, it's taken me years to find out!

John, I doubt you'll need a selection that big, of all grade 8. I bought a much smaller one in 2008 an dhave rebuilt an Elan and TC Europa without using them all up. Some aren't the right size for us anyway.

[Chancer]

So is a setscrew in America what we in the UK would refer to as a grub screw perhaps?

How do you define a fully threaded bolt?

I ask because I will soon be working with French apprentice aircraft engineers on technical English, I used to do so with vehicle technicians and had to be aware of the diff?rences between UK and American English language terms, looks like I have a lot of new ones to learn.