TR2/3/3A Windscreen Tenax

CJD

Yoda

Offline

• Jun 28, 2017

• #1

I've run into my next "new part" problem. The modern Tenax studs that screw into the top of the windscreen are smaller than the originals. I bought a set from Moss and a set from TRF. The Moss are all too loose to fit in the windscreen holes. The TRF are closer, in that 5 of the 10 will tighten up. I re-tried the originals, and they all fit perfectly. I can hold the originals up against the new ones and actually see there is a difference in the size of the studs, with the original being larger. I would use the original studs, but they are baby tenax and I can find no baby tenax fasteners to match them.

So, has anyone run into this issue and found a fix or work around?

 

T

TexasKnucklehead

Jedi Knight

Offline

• Jun 28, 2017

• #2

I thought all the windscreen top snaps were the baby tenax? I recall taking usable studs off of several other frames for mine -none were as shiny as new. My new top came with snaps that fit the old tenax -much smaller/skinnier than the LTD snaps, and almost require lifting the 'hat' prior to removing or inserting. But if memory serves me, not all the windscreen frames had the same sized threaded holes for the studs. I may still have a few old studs in hiding, but I'm sure they will not look good enough for your car.

Maybe what I'm saying is, perhaps you have the wrong windscreen frame, but the correct studs.

 

OP

CJD

Yoda

Offline

• Jun 28, 2017

• #3

I couldn't tell the difference between baby and standard unless I have both side by side. The babies were only on the first 5500 TR2's. everything after has the standard size tenax on the windscreens. My impression is the babies have some larger whitworth thread or some such difference, but I'm just guessing. All I know for sure is the new tenax have a smaller threaded portion than the original baby studs.

I'm batting about 100 with repro parts the last couple weeks. Of course many of these parts were purchased months/years ago and just waiting patiently on the shelf to frustrate me.

 

T

TexasKnucklehead

Jedi Knight

Offline

• Jun 28, 2017

• #4

I will dig thru my junk. Patience and frustration go hand in hand. I like to remember, there's always time for remorse.

 

T

TexasKnucklehead

Jedi Knight

Offline

• Jun 28, 2017

• #5

So I found 2. They are much longer than I remembered. According to my thread gauge, they are 32TPI. A nut from the regular LTD studs (10-32) spins on it well.

 

D

DavidApp

Yoda

Gold

Offline

• Jun 28, 2017

• #6

Hello John
I seem to remember reading somewhere that the windshield frame fasteners had a shorter thread than the others. If you use the wrong one you may crack the screen. May have been a link to another site that also uses the same Tenax fasteners. Maybe a Ford site.

David

 

OP

CJD

Yoda

Offline

• Jun 28, 2017

• #7

Thanks guys. I have discussed this with the TRF guys, and they are also clueless. I have to assume the baby tenax use a fatter stud than the newer standard tenax. The result is the TR2 windscreen frame has oversize holes to put the newer style tenax into. Some of them will tighten, but only because the hole reduced slightly when I had the frame re-chromed.

I went the wimp way out and used the "Metal Max J B Weld" to anchor them all in the frame. It advertises "5500psi", which is reaching mild steel strength...if it is accurate advertising.

The only other option would be to remove the entire frame, weld the holes up, redrill for the smaller tenax studs, and then re-chrome. Option 2 would be to again remove the frame and silver solder the studs into it in a rather permanent manner. I am not in the mood to remove the glass from the frame right now...so this will have to be a future project. Of course...if the JB holds, I may never get around to it!?!

 

2

2long

Jedi Trainee

Offline

• Jul 1, 2017

• #8

https://www.ebay.com/itm/TENEX-TR2-...ash=item4b1ae51f28:g:IoMAAOSwyWZZVohu&vxp=mtr

FYI - not sure exactly what these are, but may be worth a look.

Dan

 

D

DavidApp

Yoda

Gold

Offline

• Jul 1, 2017

• #9

Looks like an item that could be made if you had a lathe. Going through my old tool box I found 2 Tenex studs but they are the long thread ones. From when I had a TR in 1969 to 1974.
Pack Rat?

David

 

OP

CJD

Yoda

Offline

• Jul 1, 2017

• #10

Thanks, guys. It's one of those things that I could order tenax for months before finding some that fit. I am of the impression that the baby tenax are using a different thread size. From there it is catch 22...if you have the baby tenax studs, you cannot get matching baby fasteners. If you have the standard size tenax, then they will be of the smaller thread size.

I decided to JB weld and delay the problem for now. I'm not happy about it, but I can tell this is one of those old car issues that will take months or years to work through. I don't want to get bogged down right now.

David, I used to have a lathe. I gave it to my uncle who pestered me for decades to get it. I finally gave it to him figuring I could find a better one later. Later has yet to come! I do miss it, for just such situations.

 

OP

CJD

Yoda

Offline

• Jul 2, 2017

• #11

Well, good news and bad.

The good...I got the hood installed on the car. It looks pretty decent. I had Jonathon Skinner sew the seams like the original tops were. I like the look! I am also sure it would leak a bit, but this car will never see rain again...at least on my watch.

The bad news...My lack of faith in any glues was reaffirmed today when the 5500psi JB Weld popped off! I was pretty sure it was going to happen, but I had to try?!?

So, now the windscreen frame will have to come back apart. I have a couple options:

1). Fill in the stud holes with brass, redrill for the proper size, and have the entire frame re-chromed...again.

2). Silver solder the studs permanently to the frame.

I would like option 2, as it doesn't require waiting a couple months for the frame to come back from the chrome shop. It DOES depend on being able to silver solder to chrome and brass. Does anyone have any experience with soldering to chrome??

 

D

DavidApp

Yoda

Gold

Offline

• Jul 3, 2017

• #12

Option 3
Get a machine shop to make them with the correct thread. Would not have to take the screen apart.

David

 

OP

CJD

Yoda

Offline

• Jul 3, 2017

• #13

I cringe thinking about the price tag for machining 10 of them. But...I will check it out because you are correct! Hmmm. Just sitting here I guess there is an option 3.5...silver solder the stud threads and just re-tap them to the larger size. Of course that assumes I could find a tap for whatever odd size the old stud is.

 

Marvin Gruber

Yoda

Offline

• Jul 3, 2017

• #14

John,
I have several w/s frames.
Marv

 

D

DavidApp

Yoda

Gold

Offline

• Jul 3, 2017

• #15

John

Do you have any of the old type Tenex studs that you could measure the thread? What is the ID of the thread in the screen frame?
Seems they may be a German design originally. That could mean a metric thread.
Don't know if you have seen this site.

David
https://www.bresco.com/acatalog/Tenax_Fasteners.html

 

OP

CJD

Yoda

Offline

• Jul 3, 2017

• #16

Interesting! They offer a 2BA thread. The Moss says they use 3/16-14. Anyone know how a 2BA compares?

 

martx-5

Yoda

Offline

• Jul 3, 2017

• #17

Here's a BA thread chart. 2BA threads are very close to 10-32. They measure 0.185" x 31.4 tpi. I've found that just about all of the screws that are smaller than 1/4" on my TR3A (with the exception of some Lucas electrical stuff) is a BA size. The two that I have run across are 2BA and 4BA. The Tenax fasteners on my TS23xxx are 2BA. I just measured a few, and they are between 0.179" and 0.182".

https://www.britishfasteners.com/threads/index.html

 

D

DavidApp

Yoda

Gold

Offline

• Jul 3, 2017

• #18

Hello John

I can send you a 2 BA screw to try in the hole.

David

 

OP

CJD

Yoda

Offline

• Jul 3, 2017

• #19

Thanks, Art. I was hoping the 2BA would be larger than 3/16", but it sounds just a bit smaller. I still ordered the 2BA studs and a 2BA tap. If nothing else, I will be sure the threads and studs absolutely match when I'm done.

Marv, thanks for the frame offer. I actually have a couple spares, but they will need to be re-chromed. I plan to make very close measurements of the spare frame stud locations compared to the one on the car. Since the Hood is now installed, I have complicated the problem a bit, in that I will need the stud locations to match if I swap out the frame. If the holes match, swapping the frame will allow me to send the spare to the chrome shop while I drive the current one.

I'll get there. Thank you all for the tips and suggestions!

 

TR3driver

Great Pumpkin - R.I.P

Offline

• Jul 4, 2017

• #20

Just a thought : my frame had two of the holes stripped. I repaired them both by making what amounts to a custom keen-sert, from a SS 1/4-28 bolt. I did the work in my lathe but there's no reason you couldn't do it by hand. I drilled and tapped the bolt for 2 BA threads, then sliced off a thin section. Took some care to make the holes in the frame (with glass in place and on the car), but I got it done using a bottoming tap.

I was fortunate enough to have room around the glass, but if not, you can grind it away with a Dremel and diamond burr. Go very slowly and use lots of water mist, so you don't put any heat into the glass.

I used a nut with a cut through one corner to hold the insert while working on it.

The flange on the Tenax was large enough to cover the end of the bolt, so nothing shows.

Loctite on the outer insert threads, of course.