Triumph Rat Motorcycle Forums banner
  • Hey everyone! Enter your ride HERE to be a part of this month's Bike of the Month Challenge!

1 - 13 of 13 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter · #1 ·
Hello , I have a front brake seal kit for the triumph sprint front brakes . It has two seals for each piston. On removing the pistons I found the top dust seal with a little groove in it and replaced it with the new no problem. However the second inner groove had no existing seal and the seal in the kit supplied was to thick to go in. I have now put it back as it was without the second inner seal and after a lot of pumping and bleeding the front brakes work. So I have I done the right thing ? after all we all need brakes that work ! Any thoughts would be appreciated
Ed
 

·
Registered
Joined
·
9 Posts
Your calipers will need two seals per piston.
The inner seal is the oil seal, this keeps the oil in the caliper and allows the build up of brake pressure.
The outer seal is the dust seal. This keeps dirt and dust out and helps keep the piston free from debris.

I can not recommend riding on calipers with only one seal fitted. It can only be a matter of time before a seal gives way and you lose all front brake pressure.

Remove the calipers and take them to a dealer or trusted mechanic. The fact this question is being asked suggests that this would be the best course of action.
 

·
Registered
Joined
·
4 Posts
Discussion Starter · #3 ·
Your calipers will need two seals per piston.
The inner seal is the oil seal, this keeps the oil in the caliper and allows the build up of brake pressure.
The outer seal is the dust seal. This keeps dirt and dust out and helps keep the piston free from debris.

I can not recommend riding on calipers with only one seal fitted. It can only be a matter of time before a seal gives way and you lose all front brake pressure.

Remove the calipers and take them to a dealer or trusted mechanic. The fact this question is being asked suggests that this would be the best course of action.
Yes thank you for your advise , As the seal supplied is to thick to go into the second groove and it being absent in the first place has lead me to the follow on 'as it was'. the reason I am asking about it on the forum is to gain knowledge and this is why the "question is being asked " So have you replaced piston seals and did your second thicker seal fit easily into the groove ? I look forward to your reply
 

·
Registered
Joined
·
9 Posts
I apologize if my reply came across a little brash. I find it’s best not to beat around the bush when it comes to this kind of thing.

As far as me and my experience? I’m a motorcycle mechanic who works as an engineer for a race team.

My side gig is a mail order brake refurbishment service and I average about 10 pairs of calipers a week.

I’m more than happy to pass on my experience of course, that’s why we are all here. Like you said, you reassembled things as you found them which is the logical course of action to take. But in this case, as you suspected, they had been assembled incorrectly prior to your arrival.

That’s not to say the seals won’t hold pressure, because they might! But that isn’t how they were designed to be assembled.

Which calipers has your bike got fitted and what seals did you purchase? Let’s do some digging and see if we can’t find the issue! Inner seals can be a faff to fit at the best of times!
 

·
Registered
Joined
·
1,222 Posts
+1 on what notsocoolguy has advised. Running without the piston seal and relying on the outer dust seal is courting disaster. I'm astonished you found it had no seal when you disassembled it and am surprised it even worked. Is it possible the seal was in there but it's so old and perished it had basically retreated into the groove giving the impression of a very shallow groove making you think your replacement was too big? Might have been just enough edge contact to maintain pressure.
 

·
Premium Member
2018 Kawasaki H2 SX SE, '73 Yamaha RD350, '74 Kawasaki H1E 500
Joined
·
2,042 Posts
Is it possible the seal was in there but it's so old and perished it had basically retreated into the groove giving the impression of a very shallow groove making you think your replacement was too big?
I'm with Terry on this. You have a black seal sitting in a black caliper. At first it can appear to be part of the casting and the very narrow groove is a just a small gap at the edge of the seal. This is how it looks with the seals in place. The thicker seal doesn't exactly jump out at you. Get in there with a sharp pointy thing and you'll find it.
743895
 
  • Like
Reactions: red ed

·
Registered
Joined
·
4 Posts
Discussion Starter · #7 ·
I apologize if my reply came across a little brash. I find it’s best not to beat around the bush when it comes to this kind of thing.

As far as me and my experience? I’m a motorcycle mechanic who works as an engineer for a race team.

My side gig is a mail order brake refurbishment service and I average about 10 pairs of calipers a week.

I’m more than happy to pass on my experience of course, that’s why we are all here. Like you said, you reassembled things as you found them which is the logical course of action to take. But in this case, as you suspected, they had been assembled incorrectly prior to your arrival.

That’s not to say the seals won’t hold pressure, because they might! But that isn’t how they were designed to be assembled.

Which calipers has your bike got fitted and what seals did you purchase? Let’s do some digging and see if we can’t find the issue! Inner seals can be a faff to fit at the best of times!
OK thank you, I will now in the next couple of days take it apart again! The calipers are Triumph with 4 pistons I will take a picture . I bought the bike in september for a good price the engine runs lovely with a good service book but I am finding maybe the bike lived outside. Thanks again Ed
 

·
Premium Member
Joined
·
1,119 Posts
I’m more than happy to pass on my experience of course, that’s why we are all here.
I certainly appreciate peoples' willingness to share knowledge. And I have a question. Is not one of the seals sided? As one side goes to the outside of the bore. It is my understanding the the cross section of one of the seals is not square but trapezoidal or some other none square figure. The purpose being it is the mechanism that retracts the piston back to it's resting position once the brake lever is released thus reducing the brake pads dragging.
 

·
Premium Member
2018 Kawasaki H2 SX SE, '73 Yamaha RD350, '74 Kawasaki H1E 500
Joined
·
2,042 Posts
Is not one of the seals sided? As one side goes to the outside of the bore. It is my understanding the the cross section of one of the seals is not square but trapezoidal or some other none square figure. The purpose being it is the mechanism that retracts the piston back to it's resting position once the brake lever is released thus reducing the brake pads dragging.
Yes, the seals do act as a "return spring". It's a long time since I worked on Sprint brakes but I don't recall anything about installing the seals a certain way for correct orientation. I checked the service manual and there was no mention in there about installing the seals a certain way.

I would add that I installed Daytona 675 pistons and seals in my Sprint. This is a common upgrade that overcomes the "sticky piston" issue that affected some early Sprints. Not only that, but the piston and seal kit is (was) cheaper than just buying Sprint seals.

743958
 

·
Registered
Joined
·
1,222 Posts
....Is not one of the seals sided? As one side goes to the outside of the bore. It is my understanding the the cross section of one of the seals is not square but trapezoidal............
The standard seals are square however I believe there are aftermarket seals like you describe. OEM manufacturers often machine the bottom of the groove at a slight angle to give the same effect with square seals.
 

·
Registered
Joined
·
724 Posts
Some info on the D675 piston option:

The Daytona pistons overcame the 'sticky piston issue' by adding a coating of nickel nitride, it has a dull grey appearance rather than shiny steel. The nickel nitride coated pistons later became standard on the Speed Triple (around 2006) and eventually made it to the Sprint with the commencement of the GT (around 2011).
All this can be verified via checking part numbers on parts supply sites such as Bike Bandit or Fowlers Triumph.
eg:
T2020465: "Piston Set" : Sprint ST1050 05-10, also compatible with: D675 07-09, SP3 05-10, STR3 09-10, TGR 06-12
T2020471: "Piston Set, NYMFRON, Dished" : coated piston set, compatible with D675 07-09, SP3 05-10, TGR 06-12
T2020573: "Piston and seal set 1/2, NYM,DISH : Single caliper kit. compatible ST/GT1050 11-12, Rocket 11-18, Tbird 09-16.

I did a lot of research when establishing whether a Titanium pistons/caliper bolt kit sold by Titan Classics for the Suzuki Bandit1200, GSX750 and RF900 would fit the Sprint. This line of thinking started after reading a TriumphRAT.net thread on rebuilding the front brakes of a Sprint900 where the thread starter noted the high cost of Triumph parts and another contributor (who had access to an aftermarket brake parts provider) proved that certain "Suzuki" parts were compatible and cheaper, and I took it further. (Note the front calipers on the 900cc bikes are not the same as the later 955/1050s but the concept of cross compatibility of Nissin brakes on various makes holds true.)
The hard part was finding some source that included numbers which could be cross checked. After much searching I found that the Brakecrafters site lists a part number for each seal kit, and I was able to establish that the Sprint kit (BC29N) is the same number required for the Suzuki's listed above, and also the Rocket-III and T-Bird1600.
The pistons within the front Nissin calipers are the same size (30 & 34mm) regardless of whether the calipers are axial (like the Sprints) or radial mount (like newer Daytonas and S3's). Brembo calipers use Brembo sizings and are likely different (ie, I don't know).

I then purchased two of the Titan Classic kits for a Suzuki RF900 (each kit does one caliper).
The pistons are coated with Titanium Nitride, so have similar advantage as the Daytona Nickel Nitride coated pistons, with the added benefit of reduced weight. The kit also replaces the caliper pinch bolts, banjo bolts, pad-pin and bleed screw.
It was all compatible EXCEPT the bleed screw had a different thread pitch and was not used. I informed TC of this and they now sell a kit for the Sprint, however I do not know whether they changed the bleed screw or not. Regardless, it was the cheapest component of an excellent value kit.
I used the torque values from the Sprint work-shop manual for all bolts except for the caliper pinch-bolts, which the manual doesn't list the value for. However I found the value of 24Nm in the Thunderbird1600 manual which also uses compatible pistons so I used that.
The weight savings for both calipers combined = 308g.

20200815_2nd Pair in.jpg 30/34mm Titanium Pistons fitted to Triumph Sprint Triumph/Nissin caliper
Titan Classic Ti Caliper piston.jpg Titanium Piston and Bolt kit

So, to wrap up. The Daytona pistons have a Nickel Nitride coating applied which reduces sticking. These pistons became available on later Speed Triples and Sprint GT's.
Nissin use the same two piston sizes on all their 4-pot front calipers, 30 and 34mm, regardless of whether axial or radial mounted.
The Nissin calipers on the 1050 Sprints use the same seals/pistons as the Nissin calipers on some Suzukis such as RF900, Bandit 1200 (not 1250) and early GSX750.
The part number of the Genuine Suzuki RF900 brake piston kit is: 59100-17830.
The actual Nissin part numbers for these parts (sourced from Ron Angel Wholesale Import website) are:
N4NCK20: Nissin Caliper Seal Kit 4P 34/30mm
NC3023: Nissin 30mm Caliper Piston
NC3423: Nissin 34mm Caliper Piston
N4CHP53: Nissin Pad Retaining pin 53mm (suits Sprint)
Brembo piston sizes are likely to be different, (ie don't try taking pistons from the 2010+ Brembo-fitted D675's).
Sprint GT and ST caliper bodies are interchangeable, but the GT's have the coated pistons.

cheers, keef.
 
1 - 13 of 13 Posts
Top