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TR4/4A Tr4 Vented gas tank banjo bolt


Senior Member
I'm currently under way on a body off restoration of my '63 TR4 and every nut and bolt has been removed so far with the sxception of one. The gas tank is original to the car and it's vented. The vent pipe needs replacing but the banjo bolt has snapped..partly due to the fact that's it's hollow I guess and can't handle much torque but I see that there is no car specific banjo bolt available for the 4 and the thought occurred to me maybe because it's soldered in and not threaded. I do see a fine bead of solder around the base of the washer..I can't imagine it not being threaded but then stranger things happen to me all the time so I don't panic over surprises..Anyway, before I start drilling with the hopes of retapping, has anyone had one of those bolts out on your TR4 vented tank?
I've had this car for 40 years and a lot of stuff I can work my way around blindfoled but I'm never afraid to ask stupid questions.
I'm new to this forum so I'm sure I will prove that out as I try to get this thing back together..Ha


Jedi Knight
Country flag
There are no stupid questions. Welcome to where some can answer a stupid question with a smart (***) answer.

I think the TR4 tank is similar to the TR3 tank. In any event, I have a TR4 cap on my TR3, but I drilled a small hole in it to allow the cap to vent -and I plugged that vent pipe from the top of the tank. I think you can search this forum and find many others who have had issues with hard cornering and gas flowing out that vent. This forum has proven to me that there is often more than one solution to any problem.

I hope you find your TR4 and this group enjoyable.


Senior Member
I have an original vent tube and banjo bolt from my '62 TR3B I'd sell. I installed a stainless steel tank and set up the vent differently. If interested, send me your email address and send you photos.


Senior Member
Stubborn bolts can be a real nightmare but this one is getting ridiculous..I've used a left handed bit and extractor with no luck and currently using regular bits in increments to slowly eat away at it. I think the solder around the bottom washer seeped under to contact the bolt and has a heck of a grab on the thing. In any case I will probably end up bypassing it using an alternative venting system but in the meantime it's one of those things that after you've spent x amount of time on solving it becomes personal, you know what I mean?! Having said that, if by chance I finally succeed though I would like the option of using it but before I get carried away on the drilling can you tell me what size the bolt you have is..a 7/16 with a thread count of 20..24?


Senior Member
7/16 is the top of the bolt that sits in the eye I think..the threaded bottom is obviously larger and so far as close as I can tell it's something maybe closer to 5/8?..but I can't tell the thread count..
Any banjo bolt would do I suppose but to drill out a hole to tap for a generic bolt,,well not sure how much material there to work with..


Senior Member
Thanks to all who tried to help but I have solved the mystery.. Why I didn't think of this sooner..gee whiz! I was able to extract the banjo bolt from an exact duplicate tank I took out of a parts car many many years ago..thought I threw that thing away but anyway I discovered the bolt is 1/2-20. So I have been indeed dealing with one that is not original to the tank..It's bigger and was soldered in which was the cause of all the aggravation. Don't know why that was done unless the previous owner was concerned about leakage on hard corners everyone talks about and thought it to be a cure..dunno..
Anyway, I'm thinking a relatively quick and easy fix, although a ridiculous overkill, is to insert a helicoil giving me the option to either use the existing vent or make for an easy cap off...
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