What's the wisdom on these?

http://www.ebay.co.uk/itm/BMW-K75-S-1990-Tsuboss-Front-Standard-Brake-Disc-/262069781864?hash=item3d04938568:g:GbcAAOSwVL1WCaA0

Hello!

Never heard of the company tsuboss 
171, Archimidou Str., 19400 Koropi. Greece
Before.

The price is real good, since the the oem and replacement disks for a K Bike are way over payed, compared to normal car or other motorcycle disk.

Would be interesting how they work.

Cheers

Off-road gear
TsuBoss

This forum conversation might be worth reading.
http://www.bikechatforums.com/viewtopic.php?p=1479848

Sounds like TsuBoss make wavey discs however the ebay adv describes those as "standard".
Price certainly looks good. Might be worth messaging the seller to make sure they aren't wavey.
cheers

The subtitle of the listing says wavy, bit odd. Anyway, are you supposed to attach these to your old disc carriers yourself? K75s are the same as the 8v K100s when it comes to brakes, right?

I would be inclined to give them a go. The price seems to be an honest price and as Chocolate says we have been paying far too much for consumable parts for a long time.

Snod Blatter wrote:The subtitle of the listing says wavy, bit odd. Anyway, are you supposed to attach these to your old disc carriers yourself? K75s are the same as the 8v K100s when it comes to brakes, right?

This is the front disc and carrier (riveted) listed on realoem.com
Part 34111457386 was found on the following vehicles:

• K589 (K100, RS, RT, LT)   (05/1982 — 10/1991)
  
• K569 (K 75, K 75 c, K 75 s, K 75 RT)   (12/1984 — 06/2005)
  

It's easy to remove the old disc from the carrier and bolt the new one on.

1. Remove the disc carriers from the wheel (4 bolts).
   
2. Using a 4" angle grinder with a metal cutting wheel (not a grinding wheel), cut the rivet heads off from the disc side, NOT the carrier side. You don't want to damage the carrier. A grinding wheel will take ages because the rivets are quite hard but a cutting wheel will slice the flat head off quickly I found. Took me about 15 mins per wheel (I got nowhere fast with drilling). Don't worry about damaging the old disc. Carefully knock the rivet out of the carrier with a drift. Support the carrier to prevent damage and warping.
   
3. Use *M6x20mm 304-stainless steel socket head-button head bolts with 304-ss nylock nuts (*you might need to check that size as its off the top of my head and its been a while). Tighten these up incrementally in a cross pattern as you would on an engine head to prevent any warping due to uneven tension. They will need tensioning fairly high. I didn't use lock-tite and mine have been in for 2 years, no problems.
   
4. Clean the disc with brake cleaner before fitting.
   

Re bolts: 304 SS (A2-70) is reasonably high tensile corrosion resistant stainless steel. A4 bolts are slightly higher tensile and more corrosion resistant. Some say you should use titanium. I think that's over kill. Your local bolt shop should be able to find something more than suitable.
My bolts came with the discs and I think they were 304 (A2).

Careful using an angle grinder if you're not used to them. Use protective gear and gloves. Make sure the guard is fitted. 
Story... A good friend of mine works with a trauma surgeon at a major hospital here. A couple of weeks ago a guy was admitted to their A&E with an angle grinder lodged in his neck  . They got it out ok and the guy recovered... just lucky I guess.

Careful using an angle grinder if you're not used to them. Use protective gear and gloves. Make sure the guard is fitted. 
Story... A good friend of mine works with a trauma surgeon at a major hospital here. A couple of weeks ago a guy was admitted to their A&E with an angle grinder lodged in his neck  . They got it out ok and the guy recovered... just lucky I guess.

A common reason people end up in A&E with pieces of angle grinder sticking out of their body is because they remove the guard to put on a larger sized disc.  One that is above the design parameters of the grinder. 

Some cynics would refer to this as natural selection and eligibility for a Darwin Award. 

I’ve finally undertaken my brake disc changeover as per the directions posted by Holister. I am using A4 grade dome head Allen bolts and my lock nuts.... just wondering what torque I should nip em up to? Any advice welcomed!

A2 and A4 SS bolt torque

6mm 8.7N-m dry 7.8N-m Lubricated


or per Fastenal
7.61 Dry 6.52 Lubed


This is the standard recommend torque for these bolts. I would use the lower ones myself.

Hope that is of help

Perfect! Top man!

There it is! So the bolts were a slight pita, but eventually came out with some vigorous persuading with a drift and hammer.
New disc looks the part....hopefully will be noticeable under braking conditions, although to be fair, I don’t use them much...apart from slow riding....so hopefully the “pulsing” will go!

BooG wrote:I’ve finally undertaken my brake disc changeover as per the directions posted by Holister. I am using A4 grade dome head Allen bolts and my lock nuts.... just wondering what torque I should nip em up to? Any advice welcomed!

Looking good, hope it works well.
Sorry to be casting doubt, but I notice your "locknuts" appear to be "nylock". I wonder if they are correct in this application given that they may get very hot in extended braking.. maybe enough to melt the plastic inserts.
Conventional nuts may torque better with a longer threaded section. Maybe an engineer could give an opinion.

check for runout on the disk carrier , just a heads up 

good luck

Nylon has a melting point well north of 200C. It's pretty unlikely that the nylon inserts are going to melt and let the discs loosen up.

Thanks for the replies. Yes, the runout could be an issue regarding the nylock nuts. I’ll post back when I’ve attempted fitting the disc. 
I wonder what my options are if the nuts do interfere with anything.?? I wonder, could I cut the bolts back a bit and ( with the help of my persuading tool, encourage them to behave like rivits ?!?

Point-Seven-five wrote:Nylon has a melting point well north of 200C.

According to the manufacturer U.S.Fasteners, their common locknuts have nylon inserts made from Zytel 101 which has a melting point ≤121ºC; their special order insert's melting point is ≤177ºC.

You can always source out some top lock nuts. I know they are available in a lower profile as well. They use a small section of distorted threads to lock them in place thus eliminating the nylon insert and having a lower profile.

Might do the trick.
https://www.imperialsupplies.com/item/9157997

Mmmm. You really don't want to know this. Really, really, really don't want to know this

If you use button-head allen bolts, you can put them button-head side out. Looks a lot prettier and there's no clearance problems.

Okay I'm going

Laitch, I suspect that the U.S. Fastener data sheet inadvertently copied the temperature from the DuPont technical data incorrectly. DuPont lists the Vicat softening temperature as 240C(465F) and the deflection temperature as 200C(390F). Melt temperature is 263C(505F). Nylon/Zytel has a rapid transition from solid to melt. As a result, it doesn't soften and maintains its mechanical properties at elevated temperatures until rapidly changing to a plastic state. I think the U.S. Fastener guy misread the C as an F when they copied the data.

If Zytel melted at 121C(250F), it wouldn't be one of the most used polymers in automotive under hood applications. As a point of reference, the polyethylene used in milk bottles melts at a higher temperature(>300F).

I doubt that the wheel hubs would get hot enough to melt it, and if they did, the larger problem would be rotor warpage.

http://www.engpolymer.co.kr/product/molding_guide/zytel_product_guide_V1.pdf

I have to say.... I am humbled by the depth of knowledge and detail around this issue! Tremendously appreciated!

A long while ago I replaced my front discs with an Italian brand called BRAKING , same deal , had to grind the heads off the rivets and tap them out , got a bit physical with a few and bent the carrier , when I fitted them I had pulsing as well , ended up having to replace one of the carriers

John Re

Melbourne Australia

Have placed the nuts the other way around now, (rotor-side). I’ll post back when I’ve attempted fitting again.

Well....that worked then!
Isn’t it “Occam’s Razor” which states that the simplest explanation is usually the best?
So anyone else doing this: face the dome heads towards the hub, and the nuts facing the exhaust side. Job done!
Haven’t been out for a test run yet but I will shortly so watch this space!

Dai......you da man!!

BooG, How are the Tsuboss discs going? are you happy with them?

Yeah….seem fine. I think they were a great deal. That said, I don’t tend to use the brakes much. K bikes have excellent engine breaking, so I use that a lot. I do a lot of slow riding in town, so the disc gets dragged frequently, but it seems to be holding up pretty well… I put new pads in as well when I replaced them. The nyloc nuts and bolts are holding fast also. A happy result.

Cheers, I'm replacing my discs and saw those Tsuboss on Oz Ebay, there's also 4mm fronts by MTX parts for about $100 each . Good to know there's an option.....