E.Marquez

So, I've heard they can be done, and Race Tech says call, then Jamie posts that above..
So, Jamie, others, have YOU used the OEM Showa for a re valve? Where do you drill and tap for the schrader valve? Adding a remote res at that point would be very easy, it's no more work then just adding the valve. I've done a fair amount of suspension work, and a ton on Showa units... though none on these "OEM NON rebuild able" versions .. So ,, a good used cheap aftermarket shocks are just not popping up..

If a race tech gold valve is available,,, and they have a recommended shim stack.. I may go this route. Be kind of a fun project, I own the shock already, and all the equipment to d the job.. Would just need the parts. Think a email to RT is in order.

reaper

I will be interested in your results. I have a extra shock that has the schrader valve installed and an aftermarket spring. If the Showa can be rebuilt to make it better, this will be a nice Pre-Spring project.

Here are some pictures of said rear shock for reference.

E.Marquez

Who installed the valve? Why? How? was the shock disassembled?

Truckinduc

http://www.peterverdonedesigns.com/05shock.htm

may be of some help

E.Marquez

Thanks for the link...

But I must be missing something, was there a page on that site dealing with the rebuild or valving of a Showa shock like the SH uses? Or installing a schrader valve in the same style shock body?

JamieDaugherty

Pretty much everything shown is right on. You have to drill the body to release the nitrogen first in order to be able to disassemble the shock. Once it's assembled again, you need a way to recharge it - that's where the schrader valve comes in. I just tap the body 1/8NPT and install the valve with some Teflon tape. It's not something for the amateur but any shock builder should be able to handle it. RaceTech has data for the VTR (as do I) so setting it up properly is not a problem.

reaper

Not sure on any of your questions, I bought this shock from Redbeard a while back.

E.Marquez

jamie, thanks.. Ya I understand what the valve is for...LOL, installing one is not hard... thinking, as ling as I'm drilling and tapping a hole.. might as well as an external rs. Should be able to get one used from some other app cheap.

So that leaves disassembly of a normally non rebuild-able showa shock body.

It would appear the end cap is pressed in to place, Vs snap ring or threaded collar retention used on most body's.

How do you get the body apart after releasing the Ni pressure?

I charge most my shocks to 175 ~180 that about right for this shock?

reaper

RaceTech now has information about rebuilding the rear shock on their website, http://www.racetech.com/evalving/eng...ngname=english

E.Marquez

Rear Shock Valving Kits Shock Gold Valve Kit - Standard Type 1RT Only Call Rebound Separator Valvecall Call Rebound Separator Valve Bleed (Must be drilled in Separator Valve if required)call
No valve part numbers just call..

JamieDaugherty

The shock is assembled just like any other, only the dust cap is pressed in. The seal head is retained with a snap ring just like normal. Showa shocks usually call for 225psi, that's what I use.

Adding a remote reservoir is not quite as easy as just tapping the body and threading in the hose. There is a separator piston inside the shock that acts as a barrier between the nitrogen and the fluid. You'd have to remove this part, which usually means destroying the shock body. You might (very doubtful) be able to drill a hole in it but I'm not really sure how well the shock would function in that arrangement. On top of that, what are you going to use for a reservoir? By the time you factor in all of these you could have modified a CBR shock to fit and have been done with it! Shock conversions like this are what I do all of the time, but I rarely mess with extensive modifications to a non-reservoir shock.

E.Marquez

Jamie, I noticed from your web site, shock conversions were a large part.. So, tell us what you can do with CBR shock?

another option is always a good idea.

I have a remote res in the spares pile from an Ohlins shock,, and ya, I understand it's not as easy as just screwing it to the body with a hose.... and nope,, I have no idea how it would work out.. But was just thinking, as I have the shock, res, lots of AN hose and fittings, what the heck.

Thanks on the heads up on the cap for this Showa shock,. I was wondering what the deal was.... never worked on this type of Showa before.

JamieDaugherty

Pretty much all that needs done is fabricating a new lower clevis to make the shock the correct length for the VTR. Currently I'm working on a design that should make this pretty easy while also giving it adjustable ride height at the same time. To convert a CBR shock would be $175-200. Depending on the shock you start with, it might also need a new spring, which is another $85.

I do a lot of this kind of thing for the older VF's where the stock shock is junk. For the VTR you probably wouldn't want to go through this conversion without also doing the RaceTech valving. The performance difference between the stock VTR and stock CBR shocks isn't that much and I'm not sure it would be worth the cost. An F4/F4i shock performs really well so it would really be up to the individual if the gains justify the cost.

E.Marquez

OK,, so,, installing a RT valve and shim stack is not the hard part, charging it is in house as well. The clevis is something I can not make at this time till I get my mill set up. What shock would you start with? Perhaps I'll find "that one" and send it off to you for modification I have to deploy here again in a few weeks,, so time is not important. I can surf Ebay from Iraq as well as home,,,,

JamieDaugherty

I'd probably start with an F4/F4i shock. Those are good quality units and generally sell cheap on eBay. If you've got time to wait, the adjustable ride height version should be ready in a couple of months. With those parts it would be something you could do yourself (if I understand correctly, you have the equipment to charge the shock once it's back together). That means I could just send out a kit of parts and you could do everything yourself. I'm getting a little ahead of myself here because that's not quite ready yet, but it should be very soon.

Tweety

Regarding the F4i shock... What lenght difference is there? Would spring and valving need to be changed?

Also what adjustment options do the F4i have compared to the VTR shock?

Edit: Never mind... you where faster than me...

So, ok... I'll have to wait for the development, and then it would have one key benefit, being adjustable ride height? That could really come in handy when doing the swingarm thingie...

One problem though... Waiting... Ain't my strong suit... 3 year olds have more patience than me...

JamieDaugherty

The length difference would be taken care of during the conversion process. The valving wouldn't need to be changed, but of course that always makes it better! I would suggest matching the spring to your weight if you can afford it.



The CBR shocks have both compression and rebound damping adjustments. The remote reservoir also keeps the fluid cooler so they aren't as prone to fade when pushed hard.

killer5280

OK. I bought an F4i shock (there are a zillion on eBay). Now what?

Tweety

Um... ok... the plan here is I get my lard *** on a scale and tell you what weight to match spring and valving to... I can do forks, they are easy peasy as long as I have all the parts... Shocks and I however are not on speaking terms... I tried fiddling with one and I still have to hole in the plaster wall to prove it... Na-ah... not trying that again anytime soon...
Atleast not unless someone talks me though it and provides a list of items needed for the re-charging... Other than that I'd rather pay you to do the work...

Ok, so one last Q then... How about the stroke length of the F4i vs the VTR shock... It's obviously shorter since the shock is shorter, but how much? And does it make any difference?

killer5280: You read my mind...

JamieDaugherty

Shoot me a PM and let me know what you are interested in!


Actually, the stroke is about the same (it might be exactly the same, I don't remember off the top of my head). The overall length is shorter because it doesn't need the room for the divider piston and nitrogen chamber.

Tweety

Ah gotcha...

Once you have figured out the adjustable thingy let me know and I'll send you a shock to work on...

divingindaytona

[QUOTE=JamieDaugherty;195300] To convert a CBR shock would be $175-200. Depending on the shock you start with, it might also need a new spring, which is another $85.QUOTE]

Looking at e-bay I see that the F4I shocks have different color springs. I would imagine that the color coding stands for spring tension. I looked at Showa's website and they make no mention of this. Any guidance for this?

Tweety

Actually I'm pretty sure it's just painted to match the bike's color... In Honda's own pics the different colors of bike have different color on the spring...

JamieDaugherty

[QUOTE=divingindaytona;195456Looking at e-bay I see that the F4I shocks have different color springs. I would imagine that the color coding stands for spring tension. I looked at Showa's website and they make no mention of this. Any guidance for this?[/QUOTE]

Nah, it's just color. There is no difference in spring rate between the yellow and red springs. As mentioned, it's just to match the color of the bodywork.

Tweety

On a note of springrate... How close to optimal would I be with an unmodified F4i shock with me at 205-210? Is it a question of want to replace springs and revalve/shim or need to or must?

killer5280

I received my F4i shock yesterday and started doing a little research. I guess the linkage for the VTR and the F4i are quite different because the stock springs are different and the springs recommended by the RaceTech spring calculator for my weight were different. The stock F4i spring is much lighter than the VTR spring. So, even though I sorta fall into the weight range (175) for the stock spring on the F4i, it appears that for the VTR the same spring rate would be waaaaay too soft. For you it would be even more out of the range. In fact, the heaviest spring that RaceTech sells for the F4i would only get me in the ballpark on the VTR, and wouldn't be close for you.
I don't know if this is a good option for a heavier guy. Maybe Jamie has some thoughts on this.

JamieDaugherty

The stock spring on the CBR600F4/F4i shock is right at 800lb/in. For reference, the stock spring on the VTR shock is about 925lb/in. That means an F4 shock with it's stock spring on the VTR would be optimal for a rider weight of about 75lb (not a typo, it really calculates to 75lb). For a rider in the 200lb range I would suggest a 1000lb/in spring no matter what shock is used.

On the topic of valving, there is a relationship between the valving used and the spring rate. Since both are matched to the application they will roughly follow each other. Even so, the stock valving on the CBR shock would be ok on the street for most riders. To get the most out of the shock you would want to upgrade the valving, but that's the case for all shocks.

No problem getting springs, I can get spring rates far beyond what RaceTech lists and can pretty much suit any application. Having options is nice but it can sometimes become confusion, I think this is starting to become apparent in this thread. If anyone has specific questions you can feel free to e-mail or PM me and I'll help in whatever way I can.

Hawkrider

I have a 1000# spring on my Fox.

Jamie's right about the damping/spring rate relationship. To clarify, say you take a stock shock and put a heavier spring on it. Great, so sag works now but the compression damping required for the softer spring will be higher ("stiffer"). When you put the stiffer spring in now you have too much comp. damping and the shock resists compressing. Conversely, the rebound damping requirements for the softer spring are less, so a stiffer spring will leave you with insufficient reb. damping. Unfortunately, the OEMs don't allow enough adjustment capability to account for the change. That's just part of the equation since the adjuster is the bleed (slow speed damping) and the shim stack accounts for the high speed damping (which would remain unchanged).

JamieDaugherty

You know, I thought the same thing when I first started doing shock valving. When you increase the spring force you should need less damping force (compression direction) because the spring is helping you, right? In reality the opposite is the case. The application demands more force, and the spring is only one part of that.

A properly setup shock with a 1000lb/in spring will have a stiffer compression and rebound stack than one with an 800lb/in spring. Once again, on the street it's probably not that critical for most riders. To optimize the performance you should always match things up, that is true, but I've found the stock Showas to have enough compression damping to handle close to a 950-1000lb/in spring for street riding.

killer5280

Jamie,
I'm really not trying to be argumentative here, but what you're saying (that a stiffer spring requires more compression damping) goes against what I have read and what I have heard suspension "gurus" say about damping rates. It also makes sense intuitively (to me, anyway) that more spring (stiffer) requires less compression and more rebound.

There may be applications where the damping rates are so out of whack that compression needs to be increased even with a stiffer spring, but I think as a general rule of thumb the conventional thinking applies:

Stiffer spring=less compression+more rebound
Softer spring=more compression+less rebound