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mrv8q

mrv8q

Luke Skywalker
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So I notice a creaking coming from the front of my new-to-me '74 TR6, and I've determined the noise is a loose front bumper (!). https://i125.photobucket.com/albums/p52/mrv8q/IMG_0525c.jpg shows one of the missing nuts from one of the main support brackets for the bumper. Page 56 of the Bentley shows:"Front bumper support bracket to chassis" as a 3/8 UNF.

Two things: 3/8 seems too small a nut, and is there a standard thread count? These are a nut buster to get to, is anyone familiar w/ these? Thanks!

BTW, I removed the 2 black rubber snubbers from the front bumper, wow are those things heavy!
 
Kevin,

I just looked at my old TRF TR6 Green Book, which shows all front bumper bracket bolts to be 3/8" diameter UNF thread along with matching nuts. There are a couple of different lengths, depending on exactly where they are, either 1 1/4" or 1 1/2". Both nuts and bolts require 9/16" wrench size on heads.

Hope that this helps.

Paul
 
Thanks, Paul, that does help. Dummy me, I didn't realize the 3/8 referred to the BOLT. The nut looked like it would 9/16 to me, is there a common TPI for these ?
 
Nothing common about us at all.

We're British, you know. Sniff, sniff!!

Kev, I really don't know. Every nut and bolt is a mystery it seems.
 
Most of the threads on these things are UNF except if it goes in Aluminum.
 
The size you need is 3/8-24, I never have understood why the manuals don't just spell out the threads per inch specification.

Randy.
 
Kevin,

I had to replace a few bumper connections on
my TR as well. Yupper, they are a pain to
access.

Purchase a 1/4" drive ratchet with a flex joint.
It will make those twisty access turns much easier.

tinster
 
TR4nut said:
The size you need is 3/8-24, I never have understood why the manuals don't just spell out the threads per inch specification.
Click to expand...

Exactly, Randy, I couldn't agree more! Thanks for the info.... After taking my daughter miniature golfing this morning, I'm off to do battle w/ those nuts.
 
Here's a thread pitch chart.

The columns that come up with LBCs are those marked UNC (which is coarse threaded) and UNF (which is fine threaded). There is a column for UNEF, which is extra fine, but I've never seen those on any cars. The other columns to the right of those, you can ignore.

Most of the fasteners on the Triumphs are UNF. Screws, bolts and nuts are measured by the shank diameter of the screw or bolt...not the hex size of the wrench that fits. Once you know this, there are only two possibilites...UNC or UNF. And like I said before, most are UNF.

I have several Thread pitch gauges that make short work of figuring out the pitch of screws. They are inexpensive, and if you do alot of wrench swinging, they are invaluble. Every tool box should have an SAE and metric gauge.

Edit: In that link to the Wikipedia article, there is a link at the bottom that has printable thread matching profiles that can be used in a pinch. Here's one of them that has the most popular sizes that you will see in your LBC.
 
Very helpful, Art, thanks!
 
Hey kevin,

If you find you are running out of K-Mart
brand metric bolts and metric nuts....

I've got a bucket of them (slightly used)
that I'll gladly ship over to you.

tinster
 
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