SU Fuel Pump Clamp Screw Size? (non-Minor).

[Chief]

Hi,
I'm looking for a second opinion against an AI answer I obtained for the following.

What I'm trying to find is a replacement screw/nut that secured an SU AUB513 fuel pump within the mounting bracket itself (so not the mounting bolts) as to free the old pump we ended up using a hacksaw on the screw and then discovered we don't have any new screws that fit, and that the clamp has a threaded hole.

Doing the best I could with a ruler, the information I can provide is:
The TPI appears to be 24
The diameter was 2 16ths and between maybe 1/4 to 1/3 of a 16th.
The length of the screw would have been a little over an inch in length.
It had a slotted (flat head screwdriver) domed top.

AI is saying it's probably 3/16" BSW, but before going and hunting down one online, I wondered if anyone knew for sure if this was the most likely answer.

Thanks

[geoberni]

I've never heard of the AUB513 pump, so have no idea of the bracket you refer to.
I did a search for both AUB513 and AUB 513 but got no results.

You could always try asking on a group that concerns the car you're asking about....or give us folk here some more details to work with.

[Bill_qaz]

Don't you have any taps you could try in the captive nut?
It would also help if you told us what car you are working on.

[Chief]

I've never heard of the AUB513 pump, so have no idea of the bracket you refer to.

I managed to somehow delete the section of the post where I said it appeared the modern equivilent was the AUF 214, and I've since discovered that the modern pumps have AUB 513 stamped on them, so it appears to be a part number for a specific piece of the pump, rather than the overall identifier as I first thought.

The pump in question doesn't belong to the vehicle, it was retro-fitted by a previous owner, which is why I was asking in a generic way giving the info I could work out from the screw and relying on other peoples knowledge if they recognised the screw information as likely sounding right.

It isn't a captive nut, it's a threaded hole (and I don't have a tap that small), now my phone cable has decided to work again I've been able to get photos of the clamp attached so that you can get a better idea of what I'm looking at:

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20260826_170423.jpg (1.88 MiB) Viewed 356 times

I admit we could buy any modern bolt that jams through the hole, but since we have to buy a new one anyway, figured we may as well try and just buy like-for-like if possible.

Oh and the nut itself is very slightly larger than 8mm.

Thanks.

[svenedin]

It's an ignition coil bracket. Quite likely the thread is metric although by the age of it maybe not. Electrical stuff commonly used BA threads so my guess would be 4BA. f you cannot match the thread, drill it larger and just use a long metric machine screw that goes through both holes and put a nut on it to clamp the bracket. Fun fact, the screws that attach the faceplate of domestic electrical sockets were 4BA (about 3.6mm) but modern ones are M3.5

Stephen

[Chief]

Thanks for the reply, the irony is I was looking at a coil bracket earlier (as in physically, in my hands - when hunting out my spare Minor SU pump to see what the bracket was like) but while it was similar it didn't have a threaded hole and the mounting holes for the bracket itself weren't as long.

[svenedin]

Thanks for the reply, the irony is I was looking at a coil bracket earlier (as in physically, in my hands - when hunting out my spare Minor SU pump to see what the bracket was like) but while it was similar it didn't have a threaded hole and the mounting holes for the bracket itself weren't as long.

Yes they do vary. I know what you mean. Some do have the holes in the metal bracket threaded. If it's old my guess is 4BA but if more modern M3.5. Some coil bracelets have slots for the bolts that attach the bracket to the car, some have elongated holes, some have slots one vertical and the other horizontal. With all my coil failures (different thread entirely) I have seen a lot of different bracket designs! Coil brackets also come in different diameters as not all coils are the same diameter. The metal is too thin to hold the clapping bolt by the thread alone, it also needs a nut.

Just measure the diameter of the hole and that is at least a start.



Stephen

IMG_3694.jpeg (1.61 MiB) Viewed 312 times

[geoberni]

I concur with everything Simon has said about it being a Coil mounting bracket.

SU 'back in the day' had a few different mounting brackets for different cars, where the designers didn't use the base mounting option.
They still have one version listed...
.

SU bracket.JPG (19.8 KiB) Viewed 211 times

MGBs on the other hand, used a far grander design, pt no AHH6709....
.

MG Bracket.JPG (14.93 KiB) Viewed 211 times