shocks

Post by **andrew.searston** » Wed Oct 28, 2009 8:44 am

hi people
i bought some shock oil (500ml) will this be enough to refill all the shocks front and rear once ive drained out the old stuff?????????

thanks
andrew

Post by **mike.perry** » Wed Oct 28, 2009 9:33 am

Nearly a pint in proper money. Should be ok.

Post by **bmcecosse** » Wed Oct 28, 2009 10:26 am

What is 'shock' oil ?

Post by **katy** » Wed Oct 28, 2009 3:44 pm

Expensive.

Post by **andrew.searston** » Wed Oct 28, 2009 3:55 pm

the oil is made by penrite and it says shocker oil no-1 for piston type shock absorbers.
its 6 pounds for a 500ml bottle
i got it from the restoration show last week

Post by **mike.perry** » Wed Oct 28, 2009 4:00 pm

At that price I will keep to the occasional squirt of engine oil.

Post by **bmcecosse** » Wed Oct 28, 2009 7:46 pm

What I really wanted to know - was what viscosity it claimed to be ! The dampers (not 'shocks') are filled with mineral oil - nothing special about it. Standard fare is SAE20 (ie 20W50!) but they give better damping if filled with SAE30 or even better - SAE40 oil. In all cases - drain off the horrible smelly thin oil that's in them just now - and refill. ANY new oil will show an improvement. Sorry to say - I reckon you wasted money on that 'shock' oil!

Post by **andrew.searston** » Wed Oct 28, 2009 9:03 pm

the oil is sae 15 grade if this helps

Post by **bmcecosse** » Wed Oct 28, 2009 9:18 pm

Well - if you use it - I recon the damping will be even poorer than standard.

Post by **andrew.searston** » Wed Oct 28, 2009 9:33 pm

how do you mean
explain????????

Post by **Bazzalucas** » Wed Oct 28, 2009 9:34 pm

Bear with us, bmcecosse, here in the colonies dampers are "shocks".

Post by **bmcecosse** » Wed Oct 28, 2009 9:52 pm

A but you are all wrong - the 'shock' is absorbed by the spring - and then it is 'damped' by the dampers!
Andrew - the more viscous the oil - the more powerful the damping. It works by squirting oil through small holes - with 'relief' valves built in to allow overloads to pass through without bursting anything! So - more viscous ('thicker'') oil is more difficult to pass through the holes - but of course the relief valve will still open at the same point - although the thicker oil will again be slower to move through the valve too. When you remove the valve assembly for draining - you can see how the valve works. It is possible to pack it up slightly with tiny washers - just make sure you don't lose any of it!

Post by **Bazzalucas** » Thu Oct 29, 2009 1:35 am

bmc, I'm not arguing in favor (or 'favour') of the term, I'm simply explaining the use of it, and why it wound up on a bottle of oil. I couldn't afford to antagonize my friends across the pond- I depend on this forum's advice too much...plus, my wife is from Banbury.

Post by **bmcecosse** » Thu Oct 29, 2009 9:00 am

It's ok - many over here call them 'shocks' too - especially the Mini lads!

linearaudio · Post by **linearaudio** » Thu Oct 29, 2009 9:58 am

bmcecosse wrote:It's ok - many over here call them 'shocks' too - especially the Mini lads!

Calling them shock absorbers may be technically incorrect, but I would venture that BMC's "many" should read "almost all". Try going into your local motor factors and asking for dampers- blank look! Ask them for shock absorbers- they go for the parts book without query!!

As the Scots sage says, though, if you are filling your shock absorbers with sae 15 oil then you are likely to be underwhelmed by their performance- if it were me, at this juncture I would put the bottle at the back of the shelf and fill the shock absorbers with 20w50 engine oil!

Post by **minor_hickup** » Thu Oct 29, 2009 10:24 pm

SAE 15 is about the grade the dampers were originally filled with. Penrite have done their homework on this and the reps tend to be very knowledgable about lever arms. Just because BMC said the shocks could be filled with SAE20 doesn't mean they were originally, maybe they just realised it was more suitable oil, or even that a straigh 20 weight is easiest to obtain?

Post by **bmcecosse** » Thu Oct 29, 2009 10:39 pm

I'm sure I have read that original oil was SAE20. ANY new oil will be better than the horrible old oil that is likely in the dampers at the moment. But they certainly 'damp' better with 30 or 40 oil ! Even better with EP90 - but I don't really suggest you try that for a road use car, although I did use it in my Rally Minor.

Post by **alanworland** » Thu Oct 29, 2009 11:13 pm

My workshop manual suggests SAE 20 - so I've put in SAE 30!

Post by **bmcecosse** » Fri Oct 30, 2009 12:16 am

Exactly - and does it work well ?

Post by **jonathon** » Fri Oct 30, 2009 8:00 am

I know that you are concerned about M/C modifications Roy and maybe the need to inform your insurance company, do you feel the same for this damper mod. Do you know the thoughts of the experienced damper companies or oil companies (Penrite) re this mod, and its suitability/longevity/safety.
Not criticising the advice, just curious