Shock gas options

[Jakobi]

Stock oil is Fuchs TITAN SAF 5045 EU 137 RED
12.3cSt at 40C
4.43cSt at 100C

[swazi_matt]

thanks have printed out your tips, guess i will try to get my sons to help me - have seen those spring compressors you are talking about but figured that since i can get some movement happening without them i will not fork out more money for unnecessary (hope the karma monkey is not listening to this!) tools

[swazi_matt]

Originally Posted by Jakobi

Stock oil is Fuchs TITAN SAF 5045 EU 137 RED
12.3cSt at 40C
4.43cSt at 100C

my belray 2.5 wt comes in at 9.2cSt at 40C, 1.9cSt at 100C and VI of 60, so now we need a quick tutorial on what is better to use (bearing in mind that there is a good chance i will strip it down and revalve pretty soon - possibly reuse the oil)

is it better to use the "thicker" silkolene with high VI or the "thinner" bel-ray with much lower VI???

[Jakobi]

The higher VI (viscosity index) simply means the oil will have less variance between temps. A low VI will thin out more, a high VI less. For a shock that works at higher temps, a low VI has the ability to come across as fade/a lack of damping, being that thinner oils flow faster (in both directions, comp and rebound).

If your local shop can get some 2.5wt RSF it'll be good for the job. If they can't I'd go the 5wt over the belray. It just means you're valving will feel firmer and rebound a bit slower. If you're revalving you could take this into account. Oil is just another variable, but if you keep changing oils you keep moving the posts.

With some husky Sachs shocks in the past I've had a lean on them while the missus snuck the retainer out. Getting them out is generally a tad tricker than slipping it back in (from memory).

[swazi_matt]

Thanks Jake

i will post a pic of my simple spring compressor, single handed (rephrase that to one person - must have all limbs working) removal and then measured the oem shim stack that i had in storage (except my vernier only measures to one decimal place so have no idea if there are any 0.15 or .25 shims) and then studied the manual to work on my confidence for the operation.

One difference i have noted from the manual and your post and the technician that i watched when it was revalved was that i seem to remember him removing the compression adjuster and filling all the oil in through the port. Are there any benefits in doing this? The manual posted for the Betas seems pretty specific and clear to follow so will most likely not remove the compression setup (mostly because they involve springs and ball bearings - both of which tend to disolve into thin air in my garage!)

[Jakobi]

Some people like to fill from the comp adj as you can keep it at the highest point and potentially burp any air out of it.

If you entirely fill the ressie, overflow oil as you drop the piston in, and then push it down with some force it will displace oil past the comp adj back into the body and in theory the flow should move any air through with the oil.

[swazi_matt]

this is my simple and effective solution to spring compression:



and you can still use the ropes to pull ktms ;-)

[swazi_matt]

Ok so a bit of an update.

I did it! and the only mishap is some slight scoring to the bottom of the shock where the rag i wrapped around it slipped and the vice jaws made a bit of a mark.

The reservoir pressure was still at 150Psi and i almost thought i should stop there - it is fine!!

anyway figured i should give it a bash and glad i did. The oil was black and smelly. As a result i stripped down the shims as well to give them an individual clean.

followed the manual provided in an earlier post and it is honestly quite a simple process - i would say it is easier than doing forks (maybe because the shock is smaller, easier to work with and ther is only one of them!)
Following the manual i skipped the full rebuild of the shock, basically did what jakobi mentioned in his post and I hope it is fine. Will take it for a spin this weekend and do some proper testing to see if i can get it to work well with just clickers or if i need to revalve.

if it is a revalve i will be calling for help because having seen the shim stack i have no idea where to start - they are so small and thin, how will i know weather to go with 0.1mm or 0.25mm they look and feel almost the same, and i think if i have to strip it down and do it again the novelty of stripping shocks will wear off. mostly it is the peripheral stripping that i find frustrating, it would not be so bad if i could just remove the shock like, i think you can with the ktm (did i really say that!)

gassed the shock up with a bicycle shock pump so if you do not hear from me you will know that i died as a result of air-oil shock explosion ;-)

[swazi_matt]

Well that has made a huge difference!! Obviously are benefits to regular maintenance!

Didn't get a chance to do any proper testing of the shock as I got a bit excited in some boulders and dropped the bike bending the gear lever under the magneto leaving me to ride home in 1st

[swazi_matt]

Have a feeling I may have to reduce high speed compression though