I have been wondering what the difference is between a LZX2085 and LZX1505 carb damper

The LZX2085 is the one to use for modified Mini's so they say

Trying to figure out why

Ta

Kiwiinwgtn

The difference is the speed of the piston drop down.
The LZX2085 fixes the flat spot on the upchange.

What did they change on the LZX2085

I think it is probably related to this...



But don't do anything till someone who has done it posts a reply.

Thanks Morris 1100

Thats what I am after

Hopefully some one has both dampers and we can do a measure up

I cannot find anyone with a LZX2085 damper close to home

Interesting BMC kept it secret

If am brave enough to go outside (its zero degrees) I will measure mine

Ta

Kiwiinwgtn

Is is not a secret, we know about it.

I have heard of people modify them by trail and error, just shortening them a little at a time till they run right.
I have also heard of people making them longer by adding a washer.

There must be a LZx2085 damper out there

I have both, I will try to remember to do a measure on the weekend...

cheers

Kevin

Thanks Kevin

That would be great

Ta

Kiwiinwgtn

Hi,

i was comparing both LZX1505 and LZX2085 dampers, actually both have same piston length ( 3/8" ) but the LZX2085 has two grooves in the lower part of the piston, each has about 0.020" large x 0.020"deep allowing somehow more oil to flow in the bore.

not sure how easy to cut these grooves, probably shortening the piston as suggested before will achieve the same.


Cheers
Luis

Interesting then that they knew about it in 1959, but didn't do anything about it for the HIF44 until well into it's life presumably?

_________________

Interesting

Any chance of a picture of them side by side

Cheers

Kiwiinwgtn

Just taken some pics and some measurements, gimme a sec and I'll post it all up. Essentially, they are identical apart from 1 bit...

BRB

Kevin

OK,

The difference is in the bevel diameter and height (or thickness, see the first image for reference as to which bits I'm talking about), and the 2 grooves machined into the outer circumference of the piston. Everything else is as near as identical as measured with a pair or verynears. By making the diameter of the bevel at the top of the shaft smaller, more oil can move from above to below the damper piston as the suction chamber piston falls but as the suction chamber piston tries to rise, the piston seals against the bevel and works the same as a std damper. The grooves in the damper piston appear to hold oil so it moves with the suction chamber over the short distance it can move more effectively than the standard damper would be my guess? The bevel itself is also thicker with a more pronounced radius.

LZX2085 Fast Drop Damper
Shaft Bevel Height (thickness measured from the flat to the base of the bevel)
3.52mm
Shaft Bevel Top Diameter
7.9mm
Shaft Inner Diameter
3.97mm
Piston Outer Diameter
8.58mm
Piston Inner Diameter
5.34mm
Piston Length
9.6mm

LZX1505 Standard Damper
Shaft Bevel Height (thickness measured from the flat to the base of the bevel)
3.38mm
Shaft Bevel Top Diameter
8.5mm
Shaft Inner Diameter
3.97mm
Piston Outer Diameter
8.54mm
Piston Inner Diameter
5.33mm
Piston Length
9.6mm

Length from bottom of shaft top bevel to E clip is the same on both. I didn't write the figure down.

For reference, so we all know what bits I am referring to -


LZX2085 fast drop on the left, LZX1505 Std on the right in all the photos -

Oh and just for reference, the 2085 did make a big difference to the flat spot I had with the std damper.

cheers

Kevin