Hagon rear shocks

[RocketmanBristol]

Those are pretty emotive comments! Its so easy to criticise without being in full command of the realities. ( And frankly forums are notorious in this respect ) Any company, including Ohlins only have so much R&D and production capacity. They will therefore concentrate on the most important areas of return and demand attainable within their capacity, like any successful company.
They have never for example prototyped rear shock units for Rocket 3 and with any such product they need to be assured of sufficient volume to recover their R&D time and to make something important to all businesses, PROFIT. This in an increasingly crowded marketplace where there is a lot of contamination from many lower cost but also poorly engineered products. The market is of course obsessively price and discount driven, this places even further pressure on pedigree level companies whose manufacturing costs are already high because they are not selling their soul to ''bastardisation'' ( quality cheapening ) of product by accountants. So, as in a previous post, I mentioned that margins on premium level product are somewhat squeezed because of such pressures. And then consumers think they are being ripped off!
Spare a thought also that companies like Ohlins have international ISO accreditation. Thats further layers of compliance and cost that has to be worked through
Of our own volition we here in NZ developed our own Rocket 3 spec and have now made and sold in excess of 60 sets. Even then I figure that we didnt recover our own R&D costs etc until we sold at least 15 sets and then started making a profit. Thats a risk in such a tiny and open market that has suffered the effects of worldwide internet sales, most especially from brazen discount predators based in the USA. We will not export because we respect other distributors appointed sales territories and in any event we are struggling to fully service our own market

I will not be posting anything further on this forum due to huge time pressures that require productivity

I think KSS has used my quote mistakenly in his reply as I would presume his reply is in reference to the slagging off of Ohlins USA, mine was an attempt at a little humour.................

 

[Claviger]

indeed

 

[Tal]

Shocking!!

 

[Claviger]

After really giving it a hard think, and speaking with some of the smarter guys in the business in the US, I’m doing something a little different as an experiment until I am decided between Traxxion or Maxton.

I’m going to shrink the air gap a bit, and go with 12.5 instead of 10 weight oil.

From the Beemershop guys I am the ideal weight for the Wilber’s springs, just out riding the damping with 10w (really I think it has more to do with the power). So here I go, off into “doing it my way” land again

 

[Paul Bryant]

this is what Robert Taylor (Kiwi Suspension) told me, that to get the Rocket forks to work properly, you need to use a heavier oil.
He has supplied me No.20 Ohlins oil along with a pair of RaceTec springs.
I've no idea what weight the Ohlins No.20 is.

 

[Claviger]

Yeah, there was a big improvement going from the stock girly weight springs and 0w to Wilber’s springs and 10w.

The biggest change was dive under braking which was massively reduced.

I think what’s the most frustrating about the forks, they’re really close to just right, it’s just that small increase in rebound damping I’m after, just a smidge, to calm the front tire chatter around turns that have texture in them. Other than that they’re pretty compliant and communicative as is.

 

[Speedy]

What rate are the Wilber's fork springs? As you increase spring rate the rebound damping needs to increase as well. The problem with going to heavier oils is that the viscosity change due to temperature variations increases. Therefore the dampening is greater when they are cold. The amount of change in feel with 20F change is significant. The other issue is that heavier oils are more prone to aeration. Bubbles simply take longer to rise to the surface and then add the increased surface tension which slows the bubbles' collapse and you end up with an emulsion shock. 20w is about as heavy as you want to go and even that is pushing the limit.

You can make your own shock oil to experiment with. It is not special. I use ATF, straight weight engine oil, and an oil based moly lube (used for camshaft installations) mixed in carefully measured volumes. You can use a tiny funnel, a graduated container, and a stop watch to conduct viscosity measurements. I don't usually care what the weight is, just use what works best for the application. (Oil is cheap: re-cycle and start fresh each time so you know the change is valid.)

You can also buy 5, 10, 15 and 20 shock oils and mix them to achieve 9.6w or 13.4w or whatever viscosity desired.

Air gap changes are very effective in controlling brake induced diving. As the gap is reduced the pressures generated in the fork increase greatly. The oil seal will be the limiter and will blow out at some point. Most likely the seal just wears faster. The big challenge is in getting the gaps equal in both forks.

Enjoy the challenge!

 

[warp9.9]

this is what Robert Taylor (Kiwi Suspension) told me, that to get the Rocket forks to work properly, you need to use a heavier oil.
He has supplied me No.20 Ohlins oil along with a pair of RaceTec springs.
I've no idea what weight the Ohlins No.20 is.

Because its oil and lighter then water I'm going guess somewhere around 7.2lbs. Per gallon

 

[KSS]

What rate are the Wilber's fork springs? As you increase spring rate the rebound damping needs to increase as well. The problem with going to heavier oils is that the viscosity change due to temperature variations increases. Therefore the dampening is greater when they are cold. The amount of change in feel with 20F change is significant. The other issue is that heavier oils are more prone to aeration. Bubbles simply take longer to rise to the surface and then add the increased surface tension which slows the bubbles' collapse and you end up with an emulsion shock. 20w is about as heavy as you want to go and even that is pushing the limit.

You can make your own shock oil to experiment with. It is not special. I use ATF, straight weight engine oil, and an oil based moly lube (used for camshaft installations) mixed in carefully measured volumes. You can use a tiny funnel, a graduated container, and a stop watch to conduct viscosity measurements. I don't usually care what the weight is, just use what works best for the application. (Oil is cheap: re-cycle and start fresh each time so you know the change is valid.)

You can also buy 5, 10, 15 and 20 shock oils and mix them to achieve 9.6w or 13.4w or whatever viscosity desired.

Air gap changes are very effective in controlling brake induced diving. As the gap is reduced the pressures generated in the fork increase greatly. The oil seal will be the limiter and will blow out at some point. Most likely the seal just wears faster. The big challenge is in getting the gaps equal in both forks.

Enjoy the challenge!

I stated I was going to make no further posts, but its the weekend and suspension oil viscosity and misconceptions / assumptions are a very relevant topic.

Certainly I totally agree with what you have stated and the aim when rebuilding and as is often neccessary re-engineering the abysmal tolerancing in too many forks is to do so in such a way that allows being able to run as thin an oil viscosity as possible. Thereby much reducing ambient temperature sensitivity and raising the threshold at which foaming / cavitation on constant stroke reversals will occur. We see this on our suspension dyno as distortion on the ''eggshell'' force versus displacement plots.

Of course with the standard Rocket 3 cartridges which are sealed for life there is little option but to run an oil that delivers suitable rebound speed, the first priority. In conjunction with heavier rate suitably preloaded linear wind springs we use Ohlins 1316-01 oil rated at 98.1 centistokes at 40 degrees celsius. Indicatively its also called number 20 and that is a token recognition of the only thing that customers and dealer staff are prepared to understand, SAE rating. Note that in the Northern hemisphere climate during winter this viscosity might be a step too far. Here in this sealocked old colonial backwater ( New Zealand ) we dont suffer the same temperature extremes.

If the oil viscosity is too aggressive that will slow down rebound speed, thats a big contributor to harshness and also crashing.

Using a motor oil rating to rate suspension fluids is TOTAL BOLLOCKS, but the market and dealers would throw their arms up in horror were it overnight be replaced by a correct way of rating suspension fluids. Buying brand ''A'' rated at 10 weight and then substituting with brand ''B'' also rated at 10 weight is no guarantee your forks are going to perform exactly the same. It may be that brand ''B'' rated at 10 weight more closely follows the real world flow rate of brand ''A'' rated at 15 weight. Believe me, we evidence this nonsense all the time

The centistokes scale is also a poor indicator as we have directly found out. Fork temperature and therefore internal oil temperature will at all times run a few degrees either side of ambient air temperature. Conversely rear shocks will run at anything between 30 to in excess of 100 degrees celsius. ( But are still oil viscosity sensitive )

There are of course many things to consider when selecting fork ( and shock ) oil. But our over riding and first pre-occupation is flow rate through any given orifice. Mass flow is taken care of by deflective shim stacks in piston cartridge style forks, very low speed flow is via a restrictive bypass either fixed or adjustable. If the true flow rate through the bypass is changed by filling with a different oil the rider will very much feel the difference. And then wonder what the hell is going on if the adjusters then need to be maxed out in either direction, etc.

SAE ( and centistoke ) ratings are therefore only VERY ROUGHLY indicative. If you are using an oil brand and viscosity rating that is working well DONT change it for anything else. Unless you need to change viscosity, but use the same brand of oil.

In lieu of there being no fully credible rating for true real world flow rate we have made our own simple test rig. A 500ml burette that we fill to the top mark, flowing through a restrictive tap. Temperature for temperature we time how long it takes for the level to drop to 250mls. This relatively crude device is a hell of a lot more accurate than using a motor oil rating for selecting supposedly like for like performance.......... A few months ago we were offered a bulk buy of suspension oil and it would have cost us about only $2 per 1 litre bottle to purchase 250 bottles. But it tested poorly for flow rate so it didnt matter how cheap and therefore profitable it was going to be. CAVEAT EMPTOR

 

[1olbull]

BTW - WELCOME to our forum!