Apex GT bottoming

[rhoag]

If you are only bottoming occasionally then you are using your full suspension and that's a good thing.
I was reading the pages about suspension tuning from the manual I got from the dealer and it called the RA aduster a rebound damping adjustment and the mono EC compession damping. I am assumiing that's a typo and both the RA and EC control compession damping? I also found in the manual it says the minimum unloaded spring lenth on the ohlins monoshock is 265mm (10.43 in). What is .43 of an inch? My spring is at 10 3/8 which gives my 225 pounds a 44mm sag. I would like to get this closer to 40mm, it looks like I have alittle room to adjust. Maybe I should buy a metric tape measurer. I would like to be on the high end of ride height.

 

[jimmie d]

7/16ths of an inch =.43 approx.

Jim

 

[GodfatherPC]

Where do I get the heaver spring

 

[MrSled]

on the RTX, the adjuster on the side will change the ratio.. little different then the GT

Can get heavier springs from your dealer.

 

[GodfatherPC]

o ok.Someone posted olins part number

 

[Reaper]

If you can not avoid frequent bottoming out, even when using the maximum amount of compression damping, you should consider getting a stiffer spring.
The american Apex GT is delivered with a 48 N/mm (274 lbs/inch) spring.
Yamahas stiffer option is a 54 N/mm (308 lbs/inch) spring (Ohlins part number 696-11).
If the bottoming out problem is bad you should consider getting the shock absorber spec from the scandinavian RX-1 GT (Apex is still called RX-1 in scandinavia).
This one is delivered with much stiffer valving and a 70 N/mm (400 lbs/inch) spring (Ohlins part number 696-19).

 

[SledFreak]

The rebound adjuster DOES affect the compression damping, though not very much.
The rebound adjuster is an adjustable bleed (a needle/jet combination that sits inside the main valve at the end of the piston shaft) that bleeds oil flow off from the main valve instead of letting it pass through the main valve. The more oil flow that is bleeded off from the main valve, the less damping is produced (more open rebound adjuster = less rebound damping).
This bleed works in both directions and therefore the rebound adjuster affects both compression damping and rebound damping.
Since the main rebound valve is quite a lot stronger than the main compression valve, the rebound damping is adjusted quite a lot more than the compression damping.

The yellow thing on the piston shaft is normally referred to as a bump rubber. It adds spring rate to the end of the stroke to avoid bottoming out (kind of like a progressive spring but more extreme).

So does this approach work the same for the front shocks of the front suspension of the GT?

 

[Alatalo]

The rebound adjuster DOES affect the compression damping, though not very much.
The rebound adjuster is an adjustable bleed (a needle/jet combination that sits inside the main valve at the end of the piston shaft) that bleeds oil flow off from the main valve instead of letting it pass through the main valve. The more oil flow that is bleeded off from the main valve, the less damping is produced (more open rebound adjuster = less rebound damping).
This bleed works in both directions and therefore the rebound adjuster affects both compression damping and rebound damping.
Since the main rebound valve is quite a lot stronger than the main compression valve, the rebound damping is adjusted quite a lot more than the compression damping.

The yellow thing on the piston shaft is normally referred to as a bump rubber. It adds spring rate to the end of the stroke to avoid bottoming out (kind of like a progressive spring but more extreme).

So does this approach work the same for the front shocks of the front suspension of the GT?

I am not sure, I have never seen them taken apart...

Please note that the Ohlins rebound adjuster can easily be modified into a "rebound only" adjuster. This requires the use of a jet with a one-way valve that allows oil flow in the rebound direction only. Jets with one-way valves are normally used in short-stroke applications like streetbikes and roadrace bikes but not in long-stroke applications like motocross and snowmobile rear suspensions (they increase the very low speed compression damping that is usually not wanted in long-stroke applications).

The added low speed compression damping can be used in a snowmobile front end in an effort to reduce body roll. Ohlins have been using snowmobile front shocks both with and without this feature.

I do not know if this feature is in the GT front shocks or not.

 

[PaSledTech]

Apex Gt bottoming problem solved

Hey guys
The factory spring on the apex gt is for riders 150- 170 pounds. If you weigh more then this, you need to get the spring for your weight. I weigh about 240. I put a larger spring in mind. I have to hit big bumps hard to get it to bottom. Lets use a little common sense here guys. If your suspension bottoms out, crank it up or get a new spring. It isn't that big of deal.

 

[Reaper]

Well, I was stunned ! I increased spring tension to max and my sag was 45mm so I am in spec but at the limit. Went back out on the same 10 miles of junk and it was a little better but still bottomed out a lot. Turned around and went 10 clicks harder on the RA and it transformed the sled, It was noticeable instantly, I was hitting junk wickedly fast and no bottoming (comp damping was at 1/2 way mark). I must say I can not believe the difference it made. I am 220lb gear on. Thx for the advise guys it worked like I could not believe ! The setting is now 30 clicks hard the maximum and I did not notice any packing down of the suspension and I was hitting some 2 foot junk one after the other !