7" KN Minator offsets

[Mike Bees]

I've got a boxed pair of these from Caterham. The box says ET24.

 

I fitted one (gently) and it fouled on the DD tube. Took it off, looked inside, thought "blimey that's dinged it, it's made of cheese" and then noticed that the casting says ET5. Took the other one out of the box, it's also ET5 and it's also identically dinged so someone's had a go at fitting that one too.

 

Took a tape measure to a wheel - total width from outer rim to outer rim is 8". Backdepth from contact face to outer rim is ~126mm. So that gives approx ET24. So why does the casting say ET5

 

Is it normal to have to take a fair amount of meat off the DD tube to get these to fit?

 

How much clearance should I aim to achieve between the tube and the wheel at their closest point?

 

Mike

[SLR No.77]

Mike - my cars a '95 DeDion and I needed to grind quite a bit off the ends of the tube. However, It was only necessary to grind the top and bottom rounded corners - the mid section (vertically between the corners) was fine. There's a massive amount beyond the weld anyway. The clearance I have is now around 3mm - no issues yet discovered

 

Stu.

 

[Mike Bees]

Thanks Stu.

 

Bit puzzled about the ET5 on the wheels though!

 

Mike

[Irrelevant]

I'd be a bit puzzled why they were 8" wide

 

If you assume they are 8" wide and do the maths, does it come out to ET5?

If so, I think you have some incorrectly boxed ET5 8" Minilites. Did they come from Millwood, they sell 8" Minilites and could have got them muddled up?

 

Suffering serious sprint cold-turkey. Must get this finished

[Iain A]

Had the same question with my 31" x 7" compomotive MLs... I measure the offset at 24 mm but they are stamped ET15. When I checked with the supplier I was told that they are stamped with the minimum offset that those castings can be machined to... not what they actually are.

Confusing huh?

[Mike Bees]

They came from Caterham (Dartford). I wondered about the 8" thing myself - they're 7" across the seating area measured just inside the rim. The offset if from the 'centre' so if you add/remove the same amount from either side then it doesn't change.

 

Thanks Iain, that makes sense even if it is confusing!

 

Mike

[Graham Perry]

Its quite common to have to remove some of the back end of the tube with the wider tyres. Even with barnby 13 inchers which have a large internal diameter we had to remove a good bit of the tube.

[SLR No.77]

All rims are measured for width across the tyre bead face. If a larger width is stated by using the outer face they're lying

 

Stu.