Would these fit my stock '87 and be an improvement ???

[ribbert]

Wouldn't 2 ,60mm pistons (120mm total) have more surface area than a single 90mm piston?
All I know is that I hated my stock 91 front brakes until I changed them out for the blue dots and FZ1 master cylinder.

Leon

It's not about hydraulics. If you increase the size of a single piston, you have to increase the size of the pad, and, with a round piston the pad needs to retain it's roughly square shape. The bigger it gets the more the pad contact area moves towards the centre of the disc and becomes proportionately less effective (like having discs that are an inch smaller in diameter)

By having side by side smaller pistons, allowing for a narrower and longer pad, you are using the most efficient part of the disc, the part with the greatest diameter (or maximum torque radius) This really does make a big difference.  Think about rear sprocket size and the effect it has on acceleration, same deal, but for deceleration.

To address offer a humble opinion on Simi Eds point.

I'm not a model expert but I believe the piston size is the same with late model caliper and the blue dots. That just leaves split vs monoblock as the difference. Technically, with enough force applied they will flex. I remain skeptical about observing this with the naked eye though. A sluggish or seized piston will cause the rotor to flex and may give the impression of the caliper spreading.

In the real world, IMO, the amount of force applied, especially with grippy pads, for maximum braking is insufficient to feel any difference between the two. Squeezing hard on the lever for the purpose of a demonstration applies many times more force than the two fingered load required to lock the front wheel and any observed abnormalities are not going to be experienced on the road.

I also think there are far more original calipers not working at 100% efficiency, some way under, than you would imagine. If they don't leak, they never get touched.

I believe the improvement attributed to the blue dots has more to do with the other components.

I would rate the order of improvement by component like this:
Pads (there are some terrible pads out there) The motorbike world seems to largely agree that the EBC HH pads are a standout
SS lines
Adjustable M/C ( I think the adjustable leverage makes a way bigger difference than the bore size)
Calipers

None of this is worth a cracker if your system is not bled properly.

These views are not just theoretical speculation. I have ridden for a considerable time with every configuration of these components letting me evaluate the impact of each one.

Noel

Disclaimer
Before anyone lets the attack dogs out, this is just my opinion.

[Flynt]

Wouldn't 2 ,60mm pistons (120mm total) have more surface area than a single 90mm piston?

area of circle = Pi*(Radius)^2, so is 2*Pi*(30mm)^2>Pi*(45mm)^2...  turns out not.  The single 90mm piston has 12.5% more surface area than the 2 60mm pistons.. 

I think extending the pressure further along the rotor circumference combined with less flex is why the blue dots would work better objectively (here the linear 120mm is greater than the 90mm, so you press a longer pad more uniformly), but matching the right MC for the smaller piston area would be important to get the right "feel".  Just slapping on the smaller piston area without changing the MC would give more travel for the force applied making the brakes feel worse most likely.

Frank

[FJmonkey]

I have Blue dots, SST lines, HH pads and stock MC and my impression is less force is required with better feel.  I don't notice any issue with lever travel. Perhaps it is not enough for me to notice. That is my $0.02

[Pat Conlon]

Don't forget unsprung weight.
Smaller multiple pistons allow the use of narrower pads, and thus narrower rotors, lighter in weight.

[Capn Ron]

Noel...that makes a lot of sense to me with the better distribution of multiple smaller pads and where on a rotor they are applying force.

I'm already running the '92 calipers with stainless lines.  They are serviced well and properly bled.  Short of dropping a slight about of weight, I'm not compelled to change out the calipers and go through the ABS bleeding again!

Cap'n Ron. . .

[Capn Ron]

Lots of good info coming through, but, has anyone addressed Jeff's original question?  Was there an improvement from early to late model calipers?  What year?

Cap'n Ron. . .

[movenon]

Lots of good info coming through, but, has anyone addressed Jeff's original question?  Was there an improvement from early to late model calipers?  What year?

Cap'n Ron. . .

Need to fine someone with stock 84-87 and a stock 88-93 to get an answer.

Jeff if I were you I would keep my eye out for a set of 88-93 front forks or at least 2 lowers from a bent set.  Once you have those you have some options.  Up grade to 88-93 brakes, 87-88 FZR wheel, blue dots etc..

You are welcome to the parts I have if and when you need them.
George

[Pat Conlon]

Lots of good info coming through, but, has anyone addressed Jeff's original question?  Was there an improvement from early to late model calipers?  What year?

Cap'n Ron. . .

I have both early and late model FJs and after riding both in stock form, comparing oem to oem (m/c, calipers and Yamaha pads) the late model brakes 'feel' better.
In the USA, FJ brake upgrade was made in '89 when they went to the 17" front rim and the lighter single faced rotors.
In fact the whole front end assembly on the late model FJ's is superior with a lighter wider rim and rotors.
The early 16" FJ rims are narrow and pig heavy.

[ribbert]

I don't notice any issue with lever travel. Perhaps it is not enough for me to notice. That is my $0.02

The adjustability of the M/C is not about travel (although it does change) but it increases the mechanical advantage or leverage, that what improves the feel.

Noel

[ribbert]

Lots of good info coming through, but, has anyone addressed Jeff's original question?  Was there an improvement from early to late model calipers?  What year?

Cap'n Ron. . .

My disclaimer may have been confusing. It applied to the second half of my post, blue dots vs standard calipers.

The first part about single piston vs multi piston (early vs late model) is fact. It is ALL about where the pad operates on the disc. It is not speculation or opinion. It has nothing to do with weight or flex or spreading load.
It allows more of the pad to operate on the most efficient part of the disc for reasons already explained.

Noel

[CatTomb]

Fjowners is like a box of chocolate hornets, you never know what you're gonna stir up and get in return.

Thanks for all of the feedback. Kelly and I got a great 130 mile ride in today. Beautiful day and great to be back on the bike. I rode four days in the last eight, two on the KTM in the dirt.

Today's loop took us past Smith Rock and the Prineville Reservoir. We stopped for a picnic in a OHV staging area. Loved the looks from the Offroaders as we pulled in.

https://goo.gl/maps/NEPIm

Bike ran great, brakes worked ... good?

I had the pleasure to ride Baldy's FJ one day at Randy's. It is a very different bike. I like the looks of stock and I like the feeling of riding something that is almost 30 years old.

But, it is no longer stock. RPM fork valves, springs, brace, oil filter, unipods, radials ...

I guess 17" wheels and blue dots are gonna have to be next ... or right after the RPM rear shock  

I could definitely feel the difference in braking with Kelly on the back.



Thanks again for the chocolates.  

[CatTomb]

Oh, and in the meantime I ordered some EBC HH pads 

[1tinindian]

Ron, I'm assuming you have upgraded to SS brake lines. right?  The difference in brake feel is due to (lack) of swelling/expansion of SS vs. rubber OEM lines.  Now watch your (89) calipers (off my 89) swell as you squeeze the front brake.   It's not much. But they DO flex!  I saw them do it-I promise. The gold/blue dot calipers flex A LOT less.  That's the difference! 
I don't necessarily go along with group-think in general (no slight intended to my FJ brethren). But this is a case of group-think being spot-on.
Go blue dot, don't look back. ( sounds like this needs auto-tune)

Ed, I don't need to remind you of how I felt about the stock brakes on my 91, but to you others, I was a hard sell on updating the brakes on the FJ.
I did it, finally, and will never look back.

I now have two complete sets of 91 and 93 front calipers, never to be used again.

Leon

[aviationfred]

I have owned a 85' with a stock brake system. My 89' came with a stock brake system and a 16" front wheel. My 87' came with 89' forks, 17" front wheel and 89' calipers.

The 85', I bought in 88' so the brake system was still fairly fresh. It was always a complaint of mine that it needed stronger brakes. The bike could very easily over cook a corner with the lack of forceful brakes.

The bikes I currently own,

The 89', I slowly upgraded the brakes and the front wheel. First was the Blue spots with rubber lines and the 16" wheel and vented rotors. The 89' OEM calipers were an improvement over the 84'-87' calipers, but the switch over to the Blue spots made a large difference. Added the 17" wheel with new rotors and noticed a small improvement. Next was the braided lines, another noticeable step in braking force. Finally I added a 98' VFR800 master cylinder and WOW is all I can say for the stopping power of the whole system. The brake system easily overwhelmed the OEM suspension enough to have the fairing contact the fender. Resolved that with new springs and fork valves from Randy.

The 87' came with 89 forks, calipers and FZR wheel. The braking was very marginal when I purchased the bike. I never saw any fluid leaks, but I suspect the calipers needed to be rebuilt. I put a 10' ZX10 master cylinder, braided lines and gold dots on at the same time and cured the braking issues, braking power is almost on par as the 89'. The rotors still need to be addressed as they are near the end of their life.

Fred

[ribbert]

I put a 10' ZX10 master cylinder.........

Fred

Of course the brakes are going to be good with a 10 foot m/c!!