1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Discussion Heli-coil -v- time-serts

Discussion in 'Tech Tips' started by ruckusman, Nov 20, 2021.

  1. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

    Messages:
    2,688
    Likes Received:
    1,142
    Trophy Points:
    818
    Joined:
    Oct 1, 2013
    Gender:
    Male
    Location:
    Narrabeen, NSW Australia
    My Bike:
    Yamaha FZR250 3LN1
    Guys,

    Soliciting opinions on helicoils vs time serts - this isn't for thread repair to keep that in mind.

    It's to put a thread into the ZXR250 fork lowers - the brake caliper lugs specifically
    There's enough material there, I could go straight to a M10 1.25mm thread and be done with it...

    Current bolts in there which go through to hold the caliper plate below are 8mm, hole is larger than than and both helicoil and time sert use an 8.3mm drill for an 8mm 1.0 and 8mm 1.25 pitch thread

    I've read that helicoils can be stacked to get deeper thread and I've seen them in longer versions - downside with helicoils is that they are somewhat porous, being a spring, so thread locker kinda sorta doesn't work

    The drawback with time serts is the tooling cost, the bits and pieces to do them properly

    Basic aim is to make an easy to fit brake caliper adapter for the ZXR250 forks, that doesn't involve hogging out heaps of billet material to make the adapter, if it bolts on from the top for both the forks and the calipers it is much easier

    This is to be able to use decent brake calipers [PFFT - OEM scooter brakes] on the forks

    Initially that will be the FZR250 calipers, but it's easy enough to adapt the basic design to take other calipers.

    thoughts?
     
    Last edited: Nov 20, 2021
  2. thebeefsalad

    thebeefsalad Well-Known Member Premium Member

    Messages:
    349
    Likes Received:
    206
    Trophy Points:
    248
    Joined:
    Feb 28, 2015
    Gender:
    Male
    Location:
    San Antonio, Texas USA
    I would still prefer time serts for this application since they are staked in place, will not back out, and do not rely on thread locker. I'm willing to bet if you call machine shops, you can find one with the installation tool/proper drill that will not charge an arm and a leg for it. (had a plug hole timeserted at a local bike shop, $25 was well worth it in my opinion)
     
    • Like Like x 1
    • Informative Informative x 1
  3. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

    Messages:
    2,688
    Likes Received:
    1,142
    Trophy Points:
    818
    Joined:
    Oct 1, 2013
    Gender:
    Male
    Location:
    Narrabeen, NSW Australia
    My Bike:
    Yamaha FZR250 3LN1
    Thanks - I was veering that direction

    I'm thinking on making either the adapters available or the design available - wanting to have a secure mounting solution for safety, security and peace of mind is formemost.

    Making it simple to fit needs to happen also at a reasonable cost, that's the challenge
     
  4. Gen

    Gen Well-Known Member

    Messages:
    238
    Likes Received:
    239
    Trophy Points:
    248
    Joined:
    Aug 16, 2014
    Gender:
    Male
    Location:
    50 K's from South Australia, in NSW
    My Bike:
    blown CBR250r
    • Like Like x 1
    • Informative Informative x 1
  5. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

    Messages:
    2,688
    Likes Received:
    1,142
    Trophy Points:
    818
    Joined:
    Oct 1, 2013
    Gender:
    Male
    Location:
    Narrabeen, NSW Australia
    My Bike:
    Yamaha FZR250 3LN1
    Thanks - I was swerving away from helicoils anyway because thread locker doesn't work as good as desirable already - I had pondered what I read about stacking them and thought that first one goes all the way down/in, but then the second one wouldn't go hard up against the first because of the installation tang - so pretty much ruled them out

    2x length might be suitable, but they're not optimal
     
    • Well said! Well said! x 1
  6. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

    Messages:
    4,560
    Likes Received:
    3,016
    Trophy Points:
    998
    Joined:
    Dec 23, 2012
    Gender:
    Male
    Location:
    Thailand
    Home Page:
    My Bike:
    Yamaha FZR400 3TJ1, Honda MC22
    My two cents. Helicoils are used in aerospace. I wouldn't use anything else, and yes I have tried the others.
     
    • Like Like x 1
    • Informative Informative x 1
  7. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

    Messages:
    2,688
    Likes Received:
    1,142
    Trophy Points:
    818
    Joined:
    Oct 1, 2013
    Gender:
    Male
    Location:
    Narrabeen, NSW Australia
    My Bike:
    Yamaha FZR250 3LN1
    Makes my life much simpler and the cost is much less

    Now I'm off to research longer helicoils of the appropriate depth

    If they're installed with some threadlock, do they back out when bolts are removed?

    In this application, there should only be need to do up the bolts to the adapter plates once
     
  8. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

    Messages:
    4,560
    Likes Received:
    3,016
    Trophy Points:
    998
    Joined:
    Dec 23, 2012
    Gender:
    Male
    Location:
    Thailand
    Home Page:
    My Bike:
    Yamaha FZR400 3TJ1, Honda MC22
    • Like Like x 1
    • Winner Winner x 1
  9. Gen

    Gen Well-Known Member

    Messages:
    238
    Likes Received:
    239
    Trophy Points:
    248
    Joined:
    Aug 16, 2014
    Gender:
    Male
    Location:
    50 K's from South Australia, in NSW
    My Bike:
    blown CBR250r
    I checked my "stock" , I have plenty,,,
    Do you have the tools to insert 8mm Helicoils ruckusman ?
     

    Attached Files:

  10. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

    Messages:
    2,688
    Likes Received:
    1,142
    Trophy Points:
    818
    Joined:
    Oct 1, 2013
    Gender:
    Male
    Location:
    Narrabeen, NSW Australia
    My Bike:
    Yamaha FZR250 3LN1
    I haven't got any tooling at all for doing them yet, but it's not expensive - I did find a local store which lists the 2.5D length ones on their website

    They are not expensive which is excellent

    Question for any ZXR250 owners or anyone that's done the front end conversion, what would be your preference for front calipers?

    I've converted the FZR250 wheel to suit the forks, which was a simple bearing change - make the inner bearing spacer and remove 1.55mm from the ZXR250 speedo drive - I'm going to adapt the FZR250 calipers as much because I have them to hand as anything else.

    Of note - the FZR250 calipers wouldn't be suitable for ZXR250 front discs with standard pads installed as the depth of the contact patch differs between the two - something to consider - other pads with less depth may be available - I just took a different pathway to keep the wheels matched

    thoughts?
     
    • Like Like x 1
  11. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

    Messages:
    4,560
    Likes Received:
    3,016
    Trophy Points:
    998
    Joined:
    Dec 23, 2012
    Gender:
    Male
    Location:
    Thailand
    Home Page:
    My Bike:
    Yamaha FZR400 3TJ1, Honda MC22
    What do you mean? You said you are going to modify the calipers to fit the ZXR mounting points. It doesn't matter if the contact depth of the pads are different.
     
  12. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

    Messages:
    2,688
    Likes Received:
    1,142
    Trophy Points:
    818
    Joined:
    Oct 1, 2013
    Gender:
    Male
    Location:
    Narrabeen, NSW Australia
    My Bike:
    Yamaha FZR250 3LN1
    I don't have the ZXR250 calipers and pads to hand but ZXR250 uses 298mm front discs, whereas FZR250 uses 282mm front discs

    Where the difference lies is the depth of the contact patch on the discs themselves - it's raining and I'm feeling like a wuss right now, but I'll go and photograph the differences shortly

    BUT if you were to put straight FZR250 calipers with FZR250 brake pads onto ZXR250 discs the pads would be either over the edge of the of the contact patch of those discs - think outer diameter minus inner diameter of the pad contact patch ZXR250 is less [thinner] than the FZR250 - larger v- smaller outer diameter aside

    So for argument sake - let's say a ZXR250 owner wants to put other calipers on their forks - that part is eminently doable as long as pads to suit the discs are available

    For example I've got a ZX6R front wheel down stairs also, same outer diameter discs as the ZXR250 I think, BUT the outer disc diameter minus the inner brake pad contact patch area is different
     
    Last edited: Nov 21, 2021
  13. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

    Messages:
    4,560
    Likes Received:
    3,016
    Trophy Points:
    998
    Joined:
    Dec 23, 2012
    Gender:
    Male
    Location:
    Thailand
    Home Page:
    My Bike:
    Yamaha FZR400 3TJ1, Honda MC22
    Caliper mounts have to be designed to place the caliper in the optimum position. If the pads are too deep and you cannot lower the calipers any further then the only recourse is to remove some pad material from the backing plate. This has to be done as a precaution to ensure that as the pads wear down the unused section at the top cannot touch.
    Make a drawing like this.
    BremboExample.jpg
     
    • Informative Informative x 1
  14. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

    Messages:
    2,688
    Likes Received:
    1,142
    Trophy Points:
    818
    Joined:
    Oct 1, 2013
    Gender:
    Male
    Location:
    Narrabeen, NSW Australia
    My Bike:
    Yamaha FZR250 3LN1
    Too much detail for my purpose, but that is very informative - what has eluded me is the geometry between the caliper mounting lugs and the disc itself

    Removing pad material isn't an option realistically, too much complication - my situation is simple, wheel got swapped to forks, calipers are going across also...

    So from that diagram - the measurement which I am talking about is the 34.3mm depth of the pad

    Yamaha look to vary disc diameter - from the two Kawasaki wheels I have here, they have varied the brake pad depth for the same disc diameter - tiny sample size though...

    I'll get sensible shortly and take some photos, but I think you get the drift, it's been visual gags on radio thus far..
     
    • Like Like x 1
  15. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

    Messages:
    4,560
    Likes Received:
    3,016
    Trophy Points:
    998
    Joined:
    Dec 23, 2012
    Gender:
    Male
    Location:
    Thailand
    Home Page:
    My Bike:
    Yamaha FZR400 3TJ1, Honda MC22
    According to the information I have at https://litetek.co/Guide_USD_ForkDatabase.html, the pitch for the ZXR250A calipers is 45mm and I am guessing the Yamaha FZR250 might be the same as the FZR400 at 83mm. How do you plan to marry those two dimensions?
     
  16. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

    Messages:
    2,688
    Likes Received:
    1,142
    Trophy Points:
    818
    Joined:
    Oct 1, 2013
    Gender:
    Male
    Location:
    Narrabeen, NSW Australia
    My Bike:
    Yamaha FZR250 3LN1
    Stay tuned - I've simplified it down to a simple stepped plate which bolts from to both the caliper which is threaded already to the top of the fork tube caliper mounting lug - which can also bolt from the top [outside] with the helicoil - ZXR250 forks aren't threaded, thus the helicoils

    This marries the edge of the caliper lug hard up against the fork tube caliper mounting lug, the edge which goes against the fork tube is also sculpted to that form

    It should be rock solid, is mounted in compression when the brakes are applied and is easy to make

    I could make an adapter with a threaded part which has bolts that go through the fork caliper lugs which as per the ZXR250 calipers, which then comes al the way up to go over the caliper mounting lugs as FZR250 calipers are threaded also - too much starting material, too much machine time, ergo too expensive to be feasible
     
  17. Andych

    Andych Moderator Staff Member Premium Member Contributing Member

    Messages:
    3,598
    Likes Received:
    1,993
    Trophy Points:
    898
    Joined:
    Oct 6, 2016
    Gender:
    Male
    Location:
    Wodonga
    My Bike:
    1987 Yamaha SRX250, Honda 1975 CB400F, Honda 1974 SL125 K1, Honda CB400SF (NC42)
    I sort of ran into similar issues when I upgraded the calipers I was going to use on the SRX (FZR250 forks, calipers wheel etc).For a few reasons I eneded up buying FZ8 (2010) calipers but they didnt suit the FZR forks. There are plenty of caliper adapters out there but none that worked straight up and the cost of Custom made adapters was a bit rich so I ened up with FZR400 discs (correct offset for what I needed) and FZR600 forks. You will also need to consider disc offset and mounting pattern if you are going to swap stuff around. The other issue you will have is potentially getting a blue slip. Most places now wont even look at a modified brake setup unless you have it approved by an Engineer.
    As far as Timesert vs Heli-coil, both have their pros and cons. When I put 6 pot Brembo calipers from a Porsche Cayan onto my VW Scirroco we had to use Heli-coils in the calipers to enable it all to bolt up correctly, this was checked and approved by an Engineer for the princly sum of about $900 (just for the Engineers certication). He was happy enough to use Heli-coils and in the 4 years I had it there was never an issue... including a few track days.
    Pics etc of my brake adventures here
    https://2fiftycc.com/index.php?threads/yamaha-srx-250-3wp.9076/page-20
     
    • Informative Informative x 1
  18. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

    Messages:
    2,688
    Likes Received:
    1,142
    Trophy Points:
    818
    Joined:
    Oct 1, 2013
    Gender:
    Male
    Location:
    Narrabeen, NSW Australia
    My Bike:
    Yamaha FZR250 3LN1
    Good info - thanks

    What was the issue with the FZ8 calipers onto the FZR250 forks?
    Hole spacing or location or both?

    I have read much of your thread, now I'll go back through it

    At this point I'm trying to avoid swapping discs, because of both the expense and all of the other variables you've correctly identified

    An engineers cert at more than the bike's value, that's to be avoided
     
  19. Andych

    Andych Moderator Staff Member Premium Member Contributing Member

    Messages:
    3,598
    Likes Received:
    1,993
    Trophy Points:
    898
    Joined:
    Oct 6, 2016
    Gender:
    Male
    Location:
    Wodonga
    My Bike:
    1987 Yamaha SRX250, Honda 1975 CB400F, Honda 1974 SL125 K1, Honda CB400SF (NC42)
    FZR250 are 83mm centre to centre and FZ8 are 100mm. The good thing with Yamaha is plenty of stuff swaps between models. The FZR250, 400 and 600 are all 38mm and the discs bolted straight on... mostly offset and diameter varies.
     
  20. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

    Messages:
    2,688
    Likes Received:
    1,142
    Trophy Points:
    818
    Joined:
    Oct 1, 2013
    Gender:
    Male
    Location:
    Narrabeen, NSW Australia
    My Bike:
    Yamaha FZR250 3LN1
    That RZ350 brake adapter video is excellent, what I am planning if almost the same but differ [because I don't have a CNC mill to start with] - so rather than the bolt which goes through the fork mounting lug as his does to bolt below into the threaded adapter he's just made

    I had been through your thread previously keeping track of it, good refresher though

    For my solution, the helicoil threads the fork lug to bolt from the top - that plate then goes across to the caliper in the same plane - with material which is snug to both the fork lowers AND the calipers

    All told, similar but different
     

Share This Page