Fine Tuning BTS

[Chouinard]

Before I grind 3/16" off the length of the bottom spring I would like to know if anyone has a different method to bring the boot back down to my comfort line shown in the attached pictures.

[digger jr]

That’s what I did with red springs and have ridden them for several years. Another way is if you were to stack a stiffer spring on top and a softer one on the bottom.

[bruincounselor]

5 hours ago, digger jr said:

That’s what I did with red springs and have ridden them for several years. Another way is if you were to stack a stiffer spring on top and a softer one on the bottom.

I used different springs top and bottom with preload to get the lean angles I wanted.

[JRAZZ]

I wouldn't grind them.  These are die springs and are available via most hw suppliers (McMaster, Grainger, eBay, and sometimes Amazon)

The shop used to have the spring rate.  I would go off of that and not the color as that does not seem to match the industry standard (probably repainted to match the TD's color scheme)

 

You can get a stiffer spring or a shorter spring (or both). 

[barryj]

Yeah.........I also run mixed springs/colors -  red longer with a blue shorter spring on my Track 700's with my Swoard EC......but all blue springs on Track 425's with my Moss PQ60     

But I still had to grind down the lower springs on both boot (435 and 700's) setups  to get to my  "comfort" zone and have had no problems

There is so much micro tuning for Alpine riding before your ever riding! !   On my boards I'm trying to keep track of angles, stance width, 3 F toe and 6 R heel lift,  Gilmour bias,  boot flex, boot rigidity,...now add BTS     Man......any of those could be a really useful workshop at the non official ATC!!   

I got my BTS working where I like it....but have no idea if it's ...correct! ......or how much more I could or should adjust it, and to what effect that adjustment would have  on my carving!  

[Chouinard]

Thanks for the feedback.

Short term I am going to grind the spring since we just got 6"-10" fresh snow today and I need to go Saturday.

Long term I am going to buy some springs from McMaster Carr after I spend some time to pick out the correct size & spring rate. 

 

 

Edited December 14, 2017 by Chouinard

[JRAZZ]

These can get confusing quickly.

Here's three tables that I put together to make some sense of what I was seeing. 

I make no claims on accuracy or the data being error free but it helped me. Hope it helps you as well :)

 

p.s. Just a heads up.  Shipping from Mcmaster is really expensive.  Keep that in mind - your total cost will be higher.  Just do what I did and find someone who orders regularly and use them unscrupulously. 

Edited December 14, 2017 by erazz
added mcmaster shipping warning

[Chouinard]

21 hours ago, erazz said:

p.s. Just a heads up.  Shipping from Mcmaster is really expensive.  Keep that in mind - your total cost will be higher.  Just do what I did and find someone who orders regularly and use them unscrupulously. 

I ended up cutting 0.25" off of a short blue [320 lbs/in] and added a washer.  I used a long red [340 lbs/in] on top because a long blue [140 lbs/in] was too soft to move the boot back.  I am going to run the setup and see how it performs and then buy a set of new springs thru a work account.

Edited December 15, 2017 by Chouinard

[Eric Brammer aka PSR]

Why grind the Spring? Grind the Receptacle Either Up, Or Down, to accommodate the spacing in travel you want? The SPRING in the INTERNAL, COMPRESSION RESTRICTION, UNDER FLEX/LOAD/DISPERSION, While grinding the SPRING merely lowers the Honda/Acura until the Exhaust hits the manhole cover..... So, Range of Motion, or, BASS, And Broken Spoilers, all the while being COOL, but SORE AS HELL as your BUTT grinds on the TAR Loudly!  Kinda, like, Lowriders VS. Blomqvist, Who might WIN!? Stig, in my Vote!!

[Chouinard]

5 hours ago, Eric Brammer aka PSR said:

Grind the Receptacle Either Up, Or Down, to accommodate the spacing in travel you want?

This is the best option if material was available in the lower end. Unfortunately the only option is in the upper end.  I would need the spring seat moved up in the upper block to accommodate the required geometry while maintaining the full length spring. The problem is not the BTS. The problem is that even with the lower nut against the lower block and the top spring under extreme tension the boot cuff digs into my calf.  Correct me if I am wrong but I would rather have forward range of motion with a moderately tightened top spring than backward motion and an extremely tightened top spring if I could align the boot back but I cannot.

The attached BTS installation image shows the lower adjustment nut above the lower block which tells me that my setup is outside the target design space. If someone has access to a machine shop I would gladly test out a prototype with the spring seat in the upper block moved up 0.375".

Thanks for your feedback. 

[Beckmann AG]

If I understand correctly, you're trying to tune the forward cuff angle so you can stand comfortably?

And this is your front boot?

 

If so, replace the lower spring with a section of PEX (or similar) tubing. Easy enough to trim 'on site' with a utility knife until you find the correct length.

Odds are you won't miss the lack of 'backward' flex anyway.

 

During the discovery process, it's generally a good idea to modify the consumables, rather than the 'hard' parts, particularly when unsure of what you're doing, or where the best solution lies.

[bruincounselor]

11 hours ago, Chouinard said:

I ended up cutting 0.25" off of a short blue [320 lbs/in] and added a washer.  I used a long red [340 lbs/in] on top because a long blue [140 lbs/in] was too soft to move the boot back.  I am going to run the setup and see how it performs and then buy a set of new springs thru a work account.

I would have started with removing the lower nut - it's clear you won't be cranking on that anyway and a properly sized washer stack could accomplish your needed range of movement.

Edited December 15, 2017 by bruincounselor

[Chouinard]

8 minutes ago, bruincounselor said:

I would have started with removing the lower nut

I thought of that but it is 0.875" thick and I only needed 0.25" of movement. 

 

12 minutes ago, Beckmann AG said:

If so, replace the lower spring with a section of PEX (or similar) tubing. Easy enough to trim 'on site' with a utility knife until you find the correct length.

Odds are you won't miss the lack of 'backward' flex anyway.

I think I will look for a solid block of high durometer material [rubber] to replace the lower spring and provide some measure of "backward" compliance. A solid block cut to length would be easier to dial-in than fiddling with spring rates AND would allow me to modify the upper spring as desired.

[Beckmann AG]

12 minutes ago, Chouinard said:

I thought of that but it is 0.875" thick and I only needed 0.25" of movement. 

You do realize that lower nut is for lower spring preload, not a jam nut to lock the shaft to the lower mount?

As such, you can use a 'short' solid spacer in place of the blue spring, and then move that spacer/nut assembly up the shaft until you have the 'correct' forward lean.

[Corey]

I'd look at skateboard truck bushings first.  Diameter is likely too big, but there are tapered ones.  The vast selection will make your head spin, so just try whatever is local and cheap first.  Just take the BTS parts into the local shop. 

[Chouinard]

1 hour ago, Beckmann AG said:

You do realize that lower nut is for lower spring preload, not a jam nut to lock the shaft to the lower mount?

Yes, I need to reduce the distance between the lower mount and the upper block.

 

1 hour ago, Beckmann AG said:

As such, you can use a 'short' solid spacer in place of the blue spring, and then move that spacer/nut assembly up the shaft until you have the 'correct' forward lean.

Great idea. I am going to use a high durometer rubber spacer to allow some measure of flex.

[Corey]

Another thought: Toe lift on the front binding.  If you need the cuff that upright, you may be artificially forced there by the boot's internal ramp towards the toe.  

[pokkis]

Here pic with shorter low spring to get boot more upwards, same time also upper spring extended longer.

[Chouinard]

3 hours ago, Corey said:

Another thought: Toe lift on the front binding.  If you need the cuff that upright, you may be artificially forced there by the boot's internal ramp towards the toe.  

I do use a toe lift and it does counteract the internal ramp. Before I installed the BTS I would pivot my boot back as far as I could and then lock that position. That is how I first marked the setup. No matter how tight I made the springs I could not fully adjust the cuff back.  We have been hammered with Lake effect 8"-12" the last few days [For SE Michigan that is a decent amount of snow] so my next step is to try out the new set-up. 

[bruincounselor]

7 hours ago, Chouinard said:

I thought of that but it is 0.875" thick and I only needed 0.25" of movement. 

I tend to prefer the non-permanent adjustments first. I probably have enough washers in a drawer. YMMV.