Fabricator - good timing on the post. The valves showed up in the mail today and prior to starting I decided to re-read your spec's. Haven't done anything yet, and I'll probably hold off 'til you speak with Brian concerning the spring rate. If there are new considerations to be made please let me know.

One more question. Did you stay with the 1/2 qt. oil recommendation from Racetech?

The springs from Howard showed up this morning also, so all parts are here to get this done. Problem is the dealership won't have my new fork tube and cap 'til next weekend. Hopefully you'll have some info by then and I can find a shop to do the milling while waiting...

One more thought - could spring rates be checked by measuring static position with pistons on springs? If both are the same dimension from, say, the collar, then the rate would have to be different to compensate for the difference in weight, right?

 

Fab, did you ever think to take up cancer research or something along those lines? Good write up man, I am still staying with race tech until ohlins comes up with a cartridge.

 

I'll mill 'em for you no charge, just pre-pay return postage, PM me. If you do get them done by someone, just a caution on clamping; I put them between the vise jaws long wise, it doesn't take much force to adequately hold them for the cut, but it doesn't take much more force to crush them, because there isn't much compression strength in the remaining material in the corners around the 4 ports.

I wouldn't worry too much about the new piston weight and spring rate for now, not much you can do about it immediately anyway, either way the port mod will still be an improvement over the original configuration. The piston spring has to provide enough resistance to keep the valve closed when its not managing wheel inputs, otherwise the front end would bounce up and down like a pogo stick just from the motor shaking the front end. I’ll post whatever I find out about the springs.

Use only the recommended Amsoil 5wt Shock Therapy with the Intiminators, fill to the same level as recommended in the service manual. Everything is a variable, so you only want to change one thing at a time in order to accurately assess the effect. The light fluid performs more consistently across a broader temperature range, changing the fluid wt will effect every circuit in the Intiminators differently. I have not observed much tuning effect to be gained by changing the fluid level with the Intiminators, stick with stock level.

The piston springs are so light; any field expedient measurement would likely be corrupt. It takes a specialized rig to precisely measure force weight in conjunction with compression distance. You pretty much have to rely on the word of the supplier, but if you want to be absolutely sure you would need a spring dyno to achieve tweak perfection. Really to do it “right”, both Intiminators would need to be as close to identical as possible, matched springs, matched pistons, matched flow in all the circuits, but that is unrealistic.

I did entertain messing with all the variables, but you have to remember that the whole front end has to come apart if you want to change something. It would take an unbelievable amount of time and effort to find the "perfect combination of piston weight and piston spring rate. There just isn't a lot of data collected that will help folks make decisions about how to make adjustments to move characteristics in a favorable direction. I do appreciate the few who have taken a chance on my results and elected to try this mod, I’m confident they will have similar results. I hope to capture their info also, so I can add to my notes for further tuning and set up to accommodate more people. I'm sure the Gold Valves started out the same way with little to no tuning info, but over time people have learned to tune them with great success. I'm a little disappointed that Ricor hasn't taken the lead to develop tuning guidelines and strategies; it would be in their best interest. By the construction changes I have witnessed, they've obviously figured out how to make them cheaper, but they haven't yet figured out how to make them better. They came out of the chute strong with a fantastic product but they fell way short by not improving the performance or offering tuning guidance. Personally I think these inertia valves have virtually unlimited tuning potential but there’s a lot to figure out. I wouldn’t discourage anyone from experimenting; just give some thoughtful consideration to the variables you want to play with, approach it with moderation, be patient and persistent, and make notes along the way.

 

Naw man, I've always had a knack for mechanical type stuff, over the years it just sort of morphed into a twisted passion. If you're set up good with the Race Techs, I wouldn't change either. I was just looking for a decent performing alternative to a $2k cartridge set up.

 

I'm happy enough with my Intiminators right now, but down the road.....maybe.

Regardless, absolutely amazing work figuring all this out. Well done.

 

Thanks. Gonna check with the local machine shop and a couple of buddies first; if I don't like the looks of it I'll be in touch.

 

Mine just arrived, loose fit by Brian so that I could get them apart to mod the ports. My package specifies "Bagger Tune" on it. What does this mean?

I have a set of RaceTech .95kg.mm springs to add to my front end mod.

Have you ever seen fork caps with adjustable pre-load capability, for the 41mm Softail fork?

 

"Bagger Tune" refers to the shim pack configuration; could be 3 x .015, or 2 x .015 and 1 x .012, or 1 x .015 and 2 x .012 shims. It has changed over time, so I'm not sure what it means now. Best bet is to call Brian and ask him or just measure the individual shims in the pack when you pull them apart. Sorry but I have no experience with the adjustable preload fork caps for Softails. Racetech may be able to point you in the right direction.

 

I spoke with Brian about the piston weights and springs, unfortunately he doesn't have any info specifically related to how the different weights affect the performance. However, he wasn't concerned that it might a "problem", and actually a piston too heavy would be more of a concern because the inertia valve would be prone to fire errantly on very small inputs. He did tell me the springs are the same but didn't have a rate value for them. The good thing is the consistency of the springs, that's one variable we don't have to account for. I will assume that there will be some difference in the way the Intiminators perform with a different weight piston; in general a lighter piston should require a greater wheel input to activate the inertia valve, but I can't say how this will translate into what the rider feels. Also there is a possibility that there will be no noticeable effect, but time and testing will tell. I just opened the ports on another set for another member and those pistons were 12.9g, so they were lighter yet but they were matched which I think is probably more important. That’s about a 10% difference in piston weight from my brass pistons so I'm curious to see what the difference will be, really I would need to try these myself to feel the difference. Guess I need to build an Intiminator Dyno, to test operations and measure the values of all the circuits, I don't imagine that will happen anytime soon.

 

" I don't imagine that will happen anytime soon."

Amen. Beyond a point you just smile and ride. Sounds as though you've done yer time.

Looking forward to getting back with you on ride impressions, although I'm dealing with limited expertise when it comes to suspensions..