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Snow rally dampers setups

Posted by lelikmed 
lelikmed
Alex Kuklov
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Snow rally dampers setups
November 25, 2015 07:36AM
What dampers/coilovers can I use for snow/ice rally that is CHEAP and STRONG ENOUGH to withstand the pounding and allow me to use softer springs.
I don't want to use my Proflex and swap soft springs, because they are calibrated for 290lb gravel spring.
In my opinion stock spring works best (170lb).
I have KYB Agx shocks - which is better than OEM.
Also people use stock STI dampers
Thank you for input.
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john vanlandingham
John Vanlandingham
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Re: Snow rally dampers setups
November 25, 2015 07:58AM
Don't those Proflex have adjustments on them?
Turn the adjusts down all the way.
Buy soft spring.

problem solved.



John Vanlandingham
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lelikmed
Alex Kuklov
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Re: Snow rally dampers setups
November 25, 2015 08:09AM
I know John.
I did that for Perce Neige. Each time we ran it I used 180lb spring and each time in 2014,2015 rear dampers started loosing pressure and needed a service. I think with soft spring and rough snow- dampers has to work more.
In fact after Waste Management winter rally- rear shocks started leaking oil on top.
I was thinking getting some cheap shit that lasts two winter rallies and replace them.
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john vanlandingham
John Vanlandingham
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Re: Snow rally dampers setups
November 25, 2015 08:35AM
Quote
lelikmed
I know John.
I did that for Perce Neige. Each time we ran it I used 180lb spring and each time in 2014,2015 rear dampers started loosing pressure and needed a service. I think with soft spring and rough snow- dampers has to work more.
In fact after Waste Management winter rally- rear shocks started leaking oil on top.
I was thinking getting some cheap shit that lasts two winter rallies and replace them.

Those Prolex I just service for a guy in Chicago they don't use a floating piston as gas divider between the oil and gas. Instead they have a rubber thing like a Soviet era Industrial thick condom..maybe 4mm thick rubber. I think the idea is they use less gas pressure. Gas pressure decreases when gas is cold. The rod wiper seals seal without a spring around the seal lip, they use the oil pressure to push on the seal to make the seal. Low gas pressure means leakage...
I had the same problem years ago on gas shock on moto-cross bikes in winter in Sweden.. Then it was say -25, cold gas, normalstuff damper and now OIL is thick so too stiff, hit square bumps, and blow all the oil out..Then they worked better..

For you the choice really depends on temp. How cold? REALLY cold? Maybe old OEM KYB.



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lelikmed
Alex Kuklov
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Re: Snow rally dampers setups
November 25, 2015 08:57AM
That exactly what I feel. When road is smooth and not too rough- I feel dampers compression and its all nice and smooth. But as soon when you get on the rough stuff and hit some square bump- you feel like they have no travel- feels like sitting on a hard brick. Temperature wise- id say- -15/-20C.
This does not happen on a gravel with above freezing temperature. NEFR, Charlevoix- no matter how rough- just push and suspension just takes it and car just floats through.
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edward mucklow
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Re: Snow rally dampers setups
November 25, 2015 09:19AM
Murry at TAD told me they would run stock springs and shocks on their cars



I would rather drive a slow car fast as a fast car slow!
first rule of cars: get what makes you happy, your the one paying for it!
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lelikmed
Alex Kuklov
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Re: Snow rally dampers setups
November 25, 2015 09:31AM
Quote
tdrrally
Murry at TAD told me they would run stock springs and shocks on their cars

What car they running and what rally?
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edward mucklow
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Re: Snow rally dampers setups
November 25, 2015 09:51AM
the cars they maintained for customers, at winter events. the subject is winter dampers



I would rather drive a slow car fast as a fast car slow!
first rule of cars: get what makes you happy, your the one paying for it!
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lelikmed
Alex Kuklov
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Re: Snow rally dampers setups
November 25, 2015 10:14AM
Quote
john vanlandingham
Quote
lelikmed
I know John.
I did that for Perce Neige. Each time we ran it I used 180lb spring and each time in 2014,2015 rear dampers started loosing pressure and needed a service. I think with soft spring and rough snow- dampers has to work more.
In fact after Waste Management winter rally- rear shocks started leaking oil on top.
I was thinking getting some cheap shit that lasts two winter rallies and replace them.

Those Prolex I just service for a guy in Chicago they don't use a floating piston as gas divider between the oil and gas. Instead they have a rubber thing like a Soviet era Industrial thick condom..maybe 4mm thick rubber. I think the idea is they use less gas pressure. Gas pressure decreases when gas is cold. The rod wiper seals seal without a spring around the seal lip, they use the oil pressure to push on the seal to make the seal. Low gas pressure means leakage...
I had the same problem years ago on gas shock on moto-cross bikes in winter in Sweden.. Then it was say -25, cold gas, normalstuff damper and now OIL is thick so too stiff, hit square bumps, and blow all the oil out..Then they worked better..

For you the choice really depends on temp. How cold? REALLY cold? Maybe old OEM KYB.

So John you think gas shocks work better than oil/gas. ? I feel fronts works okay, maybe due to that oil canisters are inside the engine compartment. The rear are cold and stiffer.
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ElectroTech
Steve Wheeler
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Re: Snow rally dampers setups
November 25, 2015 10:20AM
Change to a lighter weight oil and keep the gas pressure at regular settings. Wrap the shock body in neoprene.



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Robert Culbertson
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Re: Snow rally dampers setups
November 25, 2015 11:06AM
That whole loosing pressure thing might be a bit of an issue that needs to be addressed. As John mentioned, motocross bikes have been using a bladder to separate the oil and gas since the early 80s instead of a sliding separator piston. The bladders rarely get a puncture, but it does happen. They usually leak around the o-ring seal (if they have an aluminum top bonded in), or there can be a tear at the top/opening from the cap to the canister not being installed properly. They can also get holes if someone decides to push a flat-blade screw driver through the bladder or if they are run without a charge for a long time.

When you mentioned that the damping went away and the shock started leaking oil, that is a sign that the bladders have lost pressure. When they loose pressure, the oil is not forced through the damping piston as quickly (and aeration usually happens, making everything worse). I recently picked up an old air-cooled 2-stroke mx bike with an early mono-shock suspension design. It has about 2in of travel where there was zero damping. I whipped out the shock pump, and the canister only had about 40psi in it, instead of the 190psi specified. Filled 'er up and all is well.

As far as gas pressure go, all of the piggy-back canisters I have worked with ran 180-250psi of Nitrogen. You also don't HAVE to use nitrogen. We often tune the bladder pressure with just air, using a high-pressure shock pump intended for mountain bikes ($40). After an air pressure is settled on, we will replace with nitrogen when we get the chance (slightly more stable with temp changes, it also has ZERO moisture in it).

Now as far as what to use, I have no idea. More people are switching to really thin oil (0wt or lower) to help with the change in viscocity vs temperature of the shock. Some lighter weight oils also transfer heat faster as well (according to my fancy motorsport engineering friends, seeing a drop in oil temperatures of 30deg with certain fluids is common). So they re-valve for the lighter weight oil and all is better. YMMV.
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john vanlandingham
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Re: Snow rally dampers setups
November 25, 2015 11:10AM
Quote
lelikmed
Quote
tdrrally
Murry at TAD told me they would run stock springs and shocks on their cars

What car they running and what rally?

Murray Thomas, NZer who came to 'Merikuh with Rod Millen last century. Lived in LA and was Rod's No1 guy till a guy Named Henry Bourne Joy III hired him away and he move to Chicago or someplace like that. To fill the time he worked on lots of Misterbitchy Talons, and Esclipse because his BIG customer was Henry Bourne Joy III and his Evo
He favored Tockicos who were frankly pretty grim..but were "inexpensive" ....
Personally I think they were what many street boys do: chop off the spring seat, slide a threaded collar over and call it a coilover and jack the price up 10x.

Junk for the consumers.

On Millens old RX7 they used MkII Escort components for everything except the body shell and engine so the suspension was inverted 40mm Bilsteins with nice thick tubes which worked excellently. Always was puzzled why he would use what really were cheap street junk instead of known good stuff which was very reasonably priced back then.It seemed like maybe his philosophy was good stuff for the big dollar customers who never asked for --or got- a reciept, and tarted up street stuff for the low-rent guys.

Oh well, he's a hero mechanic and famous and I am an idiot who never did anything in rally ever according to many experts.

When Henry Bourne Joy III dropped out, after a few years Murray closed shop and disappeared back to New Zealand (06)



John Vanlandingham
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ElectroTech
Steve Wheeler
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Re: Snow rally dampers setups
November 25, 2015 11:20AM
Another issue to consider is ice buildup on the shaft and if the dampers have provisions to deal with it. If there is not some form of scraper before the seal then ice will tear the seal up or let moisture into the body and also let the gas out. Some form of shock/spring cover is needed if that is not accounted for in the seal design.



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john vanlandingham
John Vanlandingham
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Re: Snow rally dampers setups
November 25, 2015 12:21PM
Quote
Robert Culbertson
That whole loosing pressure thing might be a bit of an issue that needs to be addressed. As John mentioned, motocross bikes have been using a bladder to separate the oil and gas since the early 80s instead of a sliding separator piston.

I didn't mention that. And that's news that bike stuff use the Soviet era Industrial strength condom.
Everything I worked on up to the mis 1980s --which was Bilsteins from 1976, Öhlins from 1977 thru 1984, WHite Power aka WP -which were originally modded car Bilsteins, inverted 40mm inserts chopped to desired length and the excess was the remote reservoir, Corte e Cosso (internally same as Bistein---we used Bilstein parts at 1 st rebuild) and then seeing works bikesä factory KYBs and Showa , ALL were ordinary DeCarbon design...with floating piston.



Quote

The bladders rarely get a puncture, but it does happen.

The Pro+flex I just sent off last week had one with dead condom...

Quote

They usually leak around the o-ring seal (if they have an aluminum top bonded in), or there can be a tear at the top/opening from the cap to the canister not being installed properly. They can also get holes if someone decides to push a flat-blade screw driver through the bladder or if they are run without a charge for a long time.

Yeah, a lots of ways and importantly, a LOT of area on that big honking thing.

Quote

When you mentioned that the damping went away and the shock started leaking oil, that is a sign that the bladders have lost pressure. When they loose pressure, the oil is not forced through the damping piston as quickly


You were doing so good. The RATE the oil is forced thru the piston is entirely a function of the shape
of the bump and postion of the shock is mounted and the resultant shaft speed...
Example round edge bump and this old school design:


Slow shaft speed, oil is forced thru piston slowly

Example:

Shock in this position, even with square edge bump, shaft speed slower than old position back by axle, oil forced thru piston slower.

Later, mid 80s shaft speed very slow even if axle moves at 15m/s



Piston forced thru oil slowly..
It is shape of bump, speed of vehicle, shock geomentry and placement that moves the rod and the piston is on the rod..



Quote

(and aeration usually happens, making everything worse).

Once a quantity of oil is lost, yes.



Quote

Now as far as what to use, I have no idea. More people are switching to really thin oil (0wt or lower) to help with the change in viscocity vs temperature of the shock. Some lighter weight oils also transfer heat faster as well (according to my fancy motorsport engineering friends, seeing a drop in oil temperatures of 30deg with certain fluids is common). So they re-valve for the lighter weight oil and all is better. YMMV.

Interesting. Thinner is recent? In mid 70s the trend began to thinner oils for more consitant damping over the length of heats in serious racing.. There was a lot of leverage on shocks---and it just kept going up. If we valved for a 30 oil, and it heats up...and we would see enough heat to "blue" or "straw" color the shack shafts

Quote

Differentially tempered steel. The various colors produced indicate the temperature to which the steel was heated. Light-straw indicates 204 °C (399 °F) and light blue indicates 337 °C (639 °F).[1][2]

And it lost 50% of its viscosity, then that was like a 15w oil and thats a LOT different than 30..
So we were down in 5W by '76--a0 it wouldn't heat as much and loss of 50% of viscosity is like a 2.5w which is not so far from the 5 we started with..

In winter we'd mix AFT and diesel 50/50 for the forks, and just hope and pray on the back shocks.



John Vanlandingham
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CALL +1 206 431-9696
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john vanlandingham
John Vanlandingham
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Re: Snow rally dampers setups
November 25, 2015 12:22PM
Quote
ElectroTech
Another issue to consider is ice buildup on the shaft and if the dampers have provisions to deal with it. If there is not some form of scraper before the seal then ice will tear the seal up or let moisture into the body and also let the gas out. Some form of shock/spring cover is needed if that is not accounted for in the seal design.

Yeah the top most seal is a scraper seal...



John Vanlandingham
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