AJS & Matchless Owners Club

I have just received a painted petrol tank, it's on the heavy side and I think it's of Indian origin (i.e., a repro). The buttons at the rear are larger than those at OEM tanks. Filler opening has a diameter of 58mm (2-9/32") and neck has a hinge bracket at the rear (see enclosed picture). There are no hooks for the filler cap lock to interact with, just a ridge of approx 47 mm opening diameter further down the neck. I don't understand how a bajonet type of cap lock can interact with a closed ridge at the filler neck.

Will filler cap 033001 fit this tank? If not, what kind of cap will fit? There is a type providing 3 fingers moving outwards which may suit this type of neck. See images below.
What is the difference between 033001 and p/n 900525, fitting 1953-63 models according to AMOC Parts?

- Knut

Knut assuming the hole is the correct diameter for the cap then the one you have illustrated us the one you need. The ridge around the bottom of the hole is to help stop the fuel slopping back under acceleration or braking when full.

Clive,
thanks for your input. I thought the ridge was to provide a restraint for a finger type lock. However, depicted lock is too large for the ridge opening. If the ridge is NOT intended as a restraint, the cap holds down by friction between neck and fingers only. Correct? Neck is plain and circular, there are no tracks.
How can this kind of lock be considered safe?

Does anyone have a tank cap of this type and may share their experience?

- Knut

mdt-son wrote: ↑Tue Aug 08, 2023 7:36 pm Clive,
thanks for your input. I thought the ridge was to provide a restraint for a finger type lock. However, depicted lock is too large for the ridge opening. If the ridge is NOT intended as a restraint, the cap holds down by friction between neck and fingers only. Correct? Neck is plain and circular, there are no tracks.
How can this kind of lock be considered safe?

Does anyone have a tank cap of this type and may share their experience?

- Knut

The design looks the same as the WD pie crust cap that has a dimple in the filler neck to register on of the expanding claws, see this ebay item: https://www.ebay.co.uk/itm/234917280862 ... R6L6_-e6Yg

Hi Duncan, dimples in the filler neck to register on expanding claws would have made sense, but there are none unfortunately. I will make an enquiry with one of the tank cap distributors.

- Knut

Original tank, Indian cap.

Original tanks, Enots caps.

Indian tanks, Indian cap

The expanding type caps never feel like they are pulling down that much... But they don't leak (I don't brim them full) and they have never come undone.

mdt-son wrote: ↑Tue Aug 08, 2023 8:23 pm Hi Duncan, dimples in the filler neck to register on expanding claws would have made sense, but there are none unfortunately. I will make an enquiry with one of the tank cap distributors.

- Knut

The hinge will resist the rotation of the cap so the dimple (just one) is unnecessary.