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Crf230 linkage mod

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Hello guys.. I I would like to understand the crf230 shock linkage operation principles. We all know that the operation of the stock shock-absorber is not the best.

The hydraulic compression reaction is excessively braking and the return extension also.

We can buy different billet linkage size, but it seems that these different billet size not resolve this problem but act only on the height of the bike. Obviously we can buy a aftermarket shock or we can make mods in our stock shock from competent technical.. but this is another story.

I have built a small shock linkage model.

I think I understand (see picture 1, 2, 3) that there are many factors in this scheme. This is a set of reaction progressive levers and this is not easy for me, unfortunately I am not an engineer.

However I would like to understand the ABC triangle linkage effect..

What happens changing the AC segment size?

And changing AB segment size?

It seems to me that approaching the C point to the A point, the lever ratio is more advantageous. (C point is the shock-absorber connection)

I believe that in this way you should get a less movement of the shock-absorber compared to a variation of movement angle of the Swingarm. Consequently the shock response should be better.

(It seems to me that increasing the segment AB size, increasing the billet length too, so you do not vary the C point.. you get the same shock absorber excursion result.

So lengthen AB segment or shorten AC segment.. same result?)

There is someone of you who has already studied these things and can give me useful tips?

Sorry for my English.. guys.

Thanks

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Edited by Crossplayer

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Even if you change the rates of the linkage you will still need to work on the shock. The stock shock is set up for the bike as a utility bike and the shock works well for that. we all use this bike as a toy and ride it in a different manner. so the problem is not in the linkage it is in the shock setup. It is an OK shock it is just not set correctly for our style of use.

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Surely.. I have already made the premise about the shock- absorber work.. this you should do.

But the reasoning on the link system is definitely interesting.

Often the best factories that build our bikes are involved in these links systems to get always something better.

So the racing team in the race fields.. they also change these parameters with regard to their needs.

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Surely.. I have already made the premise about the shock- absorber work.. this you should do.

But the reasoning on the link system is definitely interesting.

Often the best factories that build our bikes are involved in these links systems to get always something better.

So the racing team in the race fields.. they also change these parameters with regard to their needs.

definitely, but nobody races CRF230s, so aftermarket parts are almost nil. Your best bet is to install CR85 suspension, which is actually from this century, onto the bike. With some basic fabrication skill, it's possible.
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....We can buy different billet linkage size, but it seems that these different billet size not resolve this problem but act only on the height of the bike......

.....(It seems to me that increasing the segment AB size, increasing the billet length too, so you do not vary the C point.. you get the same shock absorber excursion result.

So lengthen AB segment or shorten AC segment.. same result?)

There is someone of you who has already studied these things and can give me useful tips?

You need to have this conversation with Ochster - he's someone that's actually machined AND redesigned the linkage ratios on our bikes to be more like race bikes. He says by doing so, they can use lighter springs not only for more plush action but to also get the weight towards the rear, since our crf-f's tend to bias towards the front so much. PM him or.....@ochster are u out there?

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Well.. finally a positive attitude ;).

I think that the first approach should be technical, to ponder what you can get.. then each of us when will make his free choice will have a larger number of options.

I did some tests :huh: with the crf linkage scale model and the result it seems to me encouraging.

Using a triangle with the largest AB segment (1, 2, 3 picture), I got this.

At the Swingarm movement will pay a less C point movement, ( C is the connection point with the shock- absorber). Then Swingarm more advantageous lever.

The AB segment length limit as not exceed is the Swingarm movement, which will come to his term before than it will do the shock.

So I have applied two elastic :D , one to simulate the bike mass strength and one to simulate the shock-absorber reaction.

In the modified triangle option the two forces equilibrium point was with the more moved Swingarm and the less compressed shock-absorber. According to my interpretation by the AB segment length action, you get this:

AB long = softer shock response.

AB short = harder shock response. The AC segment instead has the inverse function.. but its modification is more delicate because it will modify the C attack. Could so the shock motion hit the nearby parties?

I hope this can be of interest for many.. because the stock linkage triangle is easily editable, by cutting and welding its parts. To intervene on the shock absorber is more expensive for our money :D. Hello guys.

Edited by Crossplayer

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I totally see where you're coming from Crossplayer, and you can see one configuration that would apply more movement to the spring, thereby needing less spring rate to support 'X' kg weight thru the same swingman travel, right? This is what Ochster is talking about with me, and I can tell his engineering level is way higher than most of us that just want to ride. PM Ochster and he may be able to give you some proven, tested numbers for your link modification. Let us know how it goes....

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I believe by the scale model observations that have a spring response as you ask ( lighter spring and more movement) we need to:

1° option = decrease AB segment measure.

2° option = increase AC segment measure.

3° option = Both changes.

Obviously the AC segment increase could create interference problems of our shock with the surrounding parts.. But whereas for logical constructive reasons we have the AB segment shortening limits. Here is that a small AC segment increase could be indispensable.

Obviously our billet will change each time its size to leave unchanged the seat height.

The ideal would use adjustable triangle ( difficult to do?) While it is easier build the adjustable billet.. many have already done this with Uniball.

Edited by Crossplayer

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Hmm, I think I'd hesitate reinventing the wheel, I'd get in touch with Ochster, he's already created those pieces for factory riders and R&D departments. He stated that the linkage ratio of the Crf150r (race) was a more appropriate design than our f's received. Know anyone with a 150r that you could take some measurements from?

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Hello guys.. today I started my linkage mod. I have made a triangle from a steel bar ( picture 1,2,). My goal is build a provisional linkage triangle to be able to do all the real evidence. I will call this "experimental linkage triangle." My experimental linkage triangle is different from the stock triangle, in more than B hole (standard), it has also the holes B1e B2 (picture3) positioned in order to change the shock reaction. Surely something happen. :huh:

My mod is to have lower compression and extension hydraulic brake.. You will, however, load more the shock spring because otherwise will be too soft. :unsure:

If everything will go as I believe will pass to the second project phase.. I will revise my stock triangle changing the position of the B hole,

as well as result from experimental linkage triangle:huh:. Of course also the billet length will be modified. I think that the calculation of the new billet length will not be easy.. definitely before I will have to adjust the shock spring preload and after I will get the right billet measure. I believe for this goal I will use provisionally two adjustable tourniquets. Picture4 :D

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Edited by Crossplayer

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I'm not an expert on this topic but I do know that the 150f rocker link is longer in the AB and along the BC side. This rocker provides a 25 mm lift at the axle and most importantly softens the ride about 25%. I am using this linkage on a 230f with a heavier spring in a Works shock to compensate and it is very reactive to small bumps and gives extra travel. I know for a fact it also even improves the stock shock to a point where it is a reasonable ride.

Edited by Landerz

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Landerz .. This is very interesting. ;)

I read something about this possibility in Rick Ramsey site .. but your information is more complete.

Greater AB segment length is my goal.

It would be useful to measure the holes distances in the crf150f triangle linkage, can you do this? :D

Edited by Crossplayer

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I'll try to do this today. Could be a little tricky as its on the bike but I'll see how I go

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230f rocker link

AB = 42 mm

BC = 52 mm

AC = 46 mm

150f rocker link

AB = 47 mm

BC = 58 mm

AC = 44 mm

230f straight link = 94 mm

I hope this helps !

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My 150F notes show as noted:

AB = 47mm

BC = 59.5mm

AC = 44.7

150F straight link = 97.5mm

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Thanks Ochster. I measured as accurately as I could with the part bolted up on the bike. I'm sure yours are more accurate.

I heard you remanufactured these bits in alloy, is this true?

I would love to buy such bits in alloy just for the weight saving. The straight link from BBR alone saves 500g or about a pound. The 2 bits should save a full kg if made from alloy. That part of the equation would interest me!

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Thanks Ochster. I measured as accurately as I could with the part bolted up on the bike. I'm sure yours are more accurate.

I heard you remanufactured these bits in alloy, is this true?

I would love to buy such bits in alloy just for the weight saving. The straight link from BBR alone saves 500g or about a pound. The 2 bits should save a full kg if made from alloy. That part of the equation would interest me!

 

Glad to have Ochster in on this, even if it's on the 'Down low'! He's beaten this path before you Crossplayer, and has done some of your experiments... I believe Ochster said he liked the 150f's 'more agressive' ratio better than the 230f's? For that reason I picked up an extra 150f swingarm and link, but I don't want to negate some of that ratio with that lengthened link. 

 

Work in progress, first things first: 43 mm Ktm 85 WP forks for the 230f...

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Thanks guys for your information.. they are really useful for me. Landerz has already given to me the right direction where look.

I believe that the Ochster experience is important and its measures are precise and reliable.

The time now I am convinced that the crf150f rocker is the right thing for me.

I have already found a complete crf150 linkage in ebay store here in our half of the world.. however is not specified if it is R model or F model. Probably the crf150R linkage is different from crf150F linkage, not? someone knows this?

I emailed to the eBay dealer to ask the exact its linkage model. Thanks guys

Edited by Crossplayer

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