Bridgestone BT-021 Suffix Letters

I got such great mileage out of the original BT-020's (>9K/rear, front 11K) that I wanted to try the BT-021's. After spending way too much time trying to figure out what the heck the suffix letters in the Bridgestone part numbers stood for and/or implied, I finally just emailed Bridgestone;

My email
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Hi.

I have a 2007 Honda VFR (non-ABS) which was originally fitted with BT-020 tires. I have already replaced the rear with a BT-021, and now we come to the fun part; I have several different "models" to choose from for the front tire, which is a 120/70-17.

The original BT-020 was;

120/70ZR-17 BB

The choices in the BT-021 are;

120/70ZR-17 --> No suffix shown
120/70ZR-17 E
120/70ZR-17 G
120/70ZR-17 F

I have tried to find some sort of cross reference table, and no luck. I even tried looking up the different bikes that had the BT-021 fitted as OEM, but two bikes that were very similar in weight and performance had different suffix letters.

Any info you can provide would be great.

Thanks!
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Reply
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The different letter codes are just designations for different OE specifications, just like your OE BT020 had the "BB" designation. The best thing to do would be to put the aftermarket spec on your bike (the one with no letter code). It is not recommended to use an OE tire on any motorcycle that the tire was not designed for.

Thanks,

Adam Kaempf
Sales Engineering Manager - Consumer Products
Bridgestone Americas Tire Operations

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My thanks to Adam for clarifying the mystery (and for being so prompt). Live and learn, as usual.

I hope this saves somebody else some time. I lose sleep over stuff like this. :smile:

 

Thanks, LGN!
I've got the 021s on my VFR and on my Buell. I'll have to check and see what version of the fronts I have! I hope it's the no-suffix version...

Cheers!
Craig :smile:

 

How are you liking the bt 021?

 

I'm glad to hear that you had great luck with the BT-020 tires. I just put a brand new set on my bike. My bike came with the Metzlers and I too got about 10K miles on them, but I wanted to switch to the Bridgestones because I run them on my older bikes (BT-045) and really like them.

 

Hi Dominator,
I really like the bt-021s. Good thing, since I have them on two bikes! They feel good in the corners and have decent grip in the rain. I haven't done any track days with them, but they have been great on spirited back road rides.
I think they are good tires, especially for the money. I'd buy them again.
Cheers!
Craig :smile:

 

How sad is this? Since the front brake caliper bolts are "single-use" and I have to remove the caliper(s) to remove the front wheel, I figured I'd change the fork oil (and check the brake pads) just so I don't have to keep replacing the damn bolts...

Anyway, the front tire and the fork oil have been sitting in the garage for two or three months, along with a new back tire for the SV. A short-term contract job I accepted has been extended several times, so the time hasn't been there to disassemble or ride.

So, Dominator, I can tell you that the rear tire works well, but the front tire is an unknown.

Edit: Now that's funny! Craig responded while I was typing out my response, so you can ignore my "unknown"...

 

Hi Lgn,
So the brake caliper mounting bolts on the newer bikes are single-use? Why in the world would they do that on a part that potentially could be removed several times a year? I've had a bunch of bikes, but none of them specified replacing the caliper mounting bolts each time they were removed. When did Honda start that?
Cheers!
Craig :smile:

 

I think it's true for all 6th Gen, since my shop manual is for '02 and on. I don't get it, either. I can see connecting rod bolts, or main bearing bolts, and I even understand cylinder head bolts on modern engines. But brake caliper bolts? They're used in a couple of other strange places, too. Bizarre, and more than a little bit annoying.

NorcalBoy replaced his with some fasteners from... Probolt? I don't remember the name... it's in a recent thread. I'm tempted to do the same, just because I'm irritated with Honda. :biggrin:

I've got to get over my attitude problems... :smile:

 

Say What???

You don't need to replace the brake caliper mounting bolts everytime you remove them. If that were true I'd be replacing mine at least a dozen times a summer on my bike. Honda recommends that you replace your front brake rotor mounting bolts when you remove or replace your front brake rotors,and there are two very specific reasons for that. One,all of the bike's front braking force is transmitted through those tiny little 6mm brake rotor mounting bolts into the wheel rim. After awhile they can actually stretch and deform. And two,there's a Red plastic thread locking agent that's applied to those bolts at the factory. When you back those rotor mount bolts out that thread locking agent gets sheared off in the threads in the wheel rim making that locking agent completely ineffective the next time you screw those bolts back in. HOWEVER that being said,it does state plainly in my shop manual that those front brake rotor mount bolts CAN be reused if you clean off all the old thread locking agent and apply new locking agent to the threads. It's then up to you to assess the structural integrity of those bolts. Examine them carefully,if even one of them shows ANY signs of stretching or deforming replace them all. Be sure to clean the threads in the wheel rim with a thread chaser or the proper 6mm thread tap.That way you get a nice clean surface for the Loctite that you apply to the threads of the new rotor mount bolts to grip on. In the interest of safety I simply just replace all my front brake rotor mount bolts whenever I remove them.



Here's a pic of a couple 6th gen. front brake rotor mounting bolts. The one on the left is a stock steel rotor mount bolt. In the pic you can see the Red thread locking agent on it.
The bolt you see on the right is a Titanium brake rotor mount bolt from Probolts. It's slightly stronger than the stock steel bolt and it's about 42% lighter as well. Note the bevel on the bottom surface of the stock rotor bolt's head,and how the bottom of the Titanium bolt's head is flat. That spreads the Ti bolt's load over a wider surface area. Titanium bolts are trick and cool and they'll make your bike lighter,but they'll also make your wallet alot lighter as well. A set of 12 stainless steel replacement front brake rotor bolts from Probolts will cost you about $71.00. A set of 12 Titanium replacement front brake rotor bolts from Probolts will cost you a cool $126.00.
Choose your poison wisely Lgn001.

 

Hmm. Maybe we have different shop manuals... The rotor bolts make complete sense to me. Like you have pointed out, they are small bolts that are highly stressed. My shop manual (Honda Service Manual, FWIW), says on page 16-40, "Install and tighten the new caliper bolts". It also clearly labels the bolts with the little pictures that say "NEW" on them. Page 16-41 says the same thing with regard to the left caliper pivot bolt and the secondary master cylinder joint bolt.

And it is entirely possible that I misread or misunderstood NCB's comments. I thought he said that he reused the caliper bolts several times but had replaced them and the rotor bolts with Probolt products.

I'm not being argumentative here. Trust me; I would be really happy not having single-use fasteners on normal maintenance items. I believe Honda uses the same one-shot bolts on the CBR600 calipers. I remember this subject coming up before, and a member who previously owned a CBR stated that he was used to buying them. Well, that's if I read the response correctly...

Great. Now I'm gonna be paranoid that my English comprehension ability is starting to go, along with all the other acquired skills.

Oh, and thanks for the heads up on the cost. Looks like Honda might get my money after all.

 

cia and lgn,
Thanks for the feedback. I was looking at some 016 but would prefer higher milage.
Yes Honda "recommends" replacing the caliper bolts too but you do not have to. Just clean of all the old thread locker and apply new stuff.
I have owned a dozen bikes race and street and never have come across this recommendation before.
Maybe they had a few problems where the old thread locker was not cleaned off good enough resulting in under torqing and loosening of the bolts - I don't know.
Remember they also recommend using only Honda lubes too.

 

many tire MFGs use the suffix. I use tire without


The bolts may just need more locking agent. I bet the dealers dont replace the bots when they change your tires.

 

Yeah, that thought has crossed my mind. If I sold caliper bolts, I'd recommend replacing them at every oil change, just to be safe. :biggrin:

Actually, I have thought that maybe what I'd do is bite the bullet, buy new bolts and measure them. After that, every time I removed them, re-measure just to see what percentage of stretch they were exhibiting. WAY more energy than I care to put into something so... trivial? benign? unnecessary?, but now I am curious.

I would just hate to be the first one to find out that they fail unexpectedly at the time it really matters. :smile:

 

A thousand pardons Lgn001. You are correct that NCB does indeed mention the caliper mount bolts in his post.
I've corrected my prevoius post accordingly. My bad.
The same note applies to the front brake caliper mount bolts as the front brake rotor mount bolts. What Honda's trying to do here is a little CYA. They want to be sure that when you install the front brake caliper mount bolts they have some fresh thread locking agent on them so they won't back out and cause a brake failure. The only way that they can be sure of this is to tell you to install new bolts every time you remove them. I work on heavy construction forklifts for a living and every factory tech manual I've ever read will tell you to replace a bolt once it's been removed. I agree with Dominator,it isn't always necessary. You gotta use your head on this one Lgn001.Those caliper mount bolts are 8mm bolts which are much stronger than the 6mm rotor mount bolts. Again just clean and carefully examine the bolts for any stretching or deforming. Remember,no metal is immune to cracking or fatigue. Clean the threads on the fork sliders and apply some fresh Loctite on the threads before you install the bolts.
The only reason that I've ever replaced a brake caliper mount bolt is to get rid of those crappy looking hex head stockers. I replace them with either a stronger polished allen head bolt for better looks,or a titanium bolt for less unsprung weight.

I'm not trying to be argumentative here either Lgn001,just trying to pass along some info to you. I guess in the end it's your butt in the saddle,if you want to spend the money for new bolts everytime you remove them that's up to you. Me,I'd rather spend that money on beer.
MMmmm.......beer.

 

Which book is it that you are referencing, Stosh? I like it more than mine...

Seriously, the book I have, service manual or not, is lame on a lot of things. It tells you how to remove the cartridge from the fork, but absolutely nothing about servicing the cartridge unit itself. It tells you that you need to make your own tool to de-tension the cam chains (Honda doesn't make one, I guess) before you pull the cams, but there are no reference dimensions to make the tool from, etc.

I have zero experience with single-use fasteners, other than researching and reading whatever I have been able to find via Google, hence my quandary on how to deal with them. I expect that I'll probably defer to the experience of others and reuse them at least once.

So thanks! I'll find out how much Honda wants for the bolts, and put the money towards a beer fund for deserving members every time I reuse the bolts. And now that I've said that, I'll probably find out that they're $10 each...

Maybe I should just send you a keg now and we'll call it even...