Upgrade Brakes vs. Frone End Swap?

[Misterobotto]

Hey Guys,

So I'm going to need to do something about my front end in the near future, and I would love to get some advice from some of the more experienced 650ers.

I just got a 1980 XS650 Special, and the PO had put lengthened front forks on the thing which need to go. I am going to want to improve the handling and breaking so the way I'm figuring it I have a couple of options.

1. Get some stock length fork tubes, and try to upgrade those (fork braces, springs etc.) and try to figure out a way to get some performance brakes that will fit my spoke wheels.

2. Swap out the front end for something with beefier suspension, better brakes etc.

So my real question is... after sifting through countless threads on front end swapping, and performance breaks on an XS650, I have no clue which is going to be easier/cheaper/better. Any advice would be greatly appreciated.

Wes

 

[gggGary]

there are several options and the best one will probably depend on what you can find in the local boneyard or craigslist. Tapered roller bearings for all versions Here's a few;
A. Stock fork tubes, stock caliper, teflon/stainless brake line, Larger bore mastercylinder designed for the handle bar you are going to use. Add; mikesXS rotor. an XS1100 Special rotor (slotted) or drill the stock rotor

B. XS750 (not XS750 Special) front end. The triples forks brakes rotors will all bolt on EXCEPT you need to grind out and swap the steering stem with the one from your XS650 triple. Add ons; Teflon/stainless brake lines, Rotors from a 750 maxim (lighter, slotted better looking)

C. Early FZR 750 front end you will need to make or buy spacers for the rotors because the FZR wheel is wider flange to flange.

D. 1999 -2001 SV650 front end, you would need to weld shut the old holes and redrill the rotors to match the XS650 wheel bolt pattern. Steering stem height may need some adjustments.

E. Any thing else you are willing to engineer/machine to fit. I am currently started on a KTM Supermoto wheel, rotor, Brembo caliper swap.

 

[sgallaty]

The problem you are seeing is that moving the front wheel away from the engine has drastically changed the bike's geometry. The force of braking now operates at a tangent to the fork tubes rather than parallel to them, which means that you are shedding a ton of potential braking force lost to the front wheel losing traction.

Return it to stock forks and the single disc will stop you. If that's not not enough, go get yourself a set of dual calipers from an xs750-1100 and another rotor and slap them on. You should be able to pretty much lock up the front with a single disc as is, unless you are racing and then you're dealing with brake fade due to constant braking, which I don't think is your issue.

Drilled rotors only help exhaust hot gas on the pads which helps elminate bernoulli effect, which is what causes brake fade on super hot disks. It's fanciness that doesn't technically matter unless you're riding twisties. In very hard twisty riding you are hammering the front brakes into every turn to preload the front end so that your line around the turn ends up loading both front and back evenly so that you can lay equal load on front and back....

pretty much only california coast highway type stuff or flat track racing you need to ever worry about that.

None of the silly shit that people do to these bikes makes them safer or better to handle. I don't object to silly shit, just know what you're getting into.

 

[rawxs]

Suzuki Intruder VS1400 ( 41mm tubes ) or VS800 ( 39mm tubes ) are close to bolt on and go. I had to cut the bottom of the neck tube on the frame 1/8" and make stops so the forks don't hit the tank. XS650 taper roller bearing fit and you get a choice of 19" or 21" wheels. Brakes are not bad stock, but I mounted a six piston caliper with a bracket I made. The length of the trees to axel is longer so I need to make a sleeve to put on the damper rods to lower them ( have not had time to do yet ).

mock up before makng anything.


Uploaded with ImageShack.us
41mm intruder forks with a 19" wheel and a six piston caliper just laying on the rotor. rawxs

 

[Misterobotto]

First off, thank you all for the quick replies and awesome information. So now for a few follow up questions.

I have a feeling that as Sgallaty said, I will notice a huge difference in both braking and handling by just getting the bike to a better geometry (Not just stock forks, but planning on adding about an inch of height to the back when I get some new shocks). That being said, one of the things that has always been really important to me is the way things feel... and although I'm absolutely in love with this bike, I'm not so excited about having to grab a fist full of break to get it to stop.

And gggGary, how much of an improvement should I expect from modifying the stock front end and breaks. Would the larger master cylinder and brake lines get me to 2 finger braking? Also, is there any (Easyish) option to upgrade the caliper if I stick with the stock front end?

Any recommendations for where I might want to look at master cylinders? Is Mikes the best place to get new stock fork tubes?

I'd sure like to have a 650 version of this some day. http://wrenchmonkees.com/monkee04.html

Oh and I'm in Salt Lake City, so there are plenty of fun canyons to ride... And I'm all about silly shit.

 

[bluebikerblan]

The guy for guidance and sourcing of XS 650 braking and suspension mods is widely conceded to be MMM - Michael "Mercury" Morse of 650 Central & Vintage Brake in California and he is also an excellent source supplier and advisor re same and much else XS 650 wise. gggGary's advice is excellent as will be others. Here are the links you might want to look into re the braking mods.

http://www.650central.com/

May want to go through this site in detail and especially the brakes section which will bring up "Vintage Brakes". As you will discover Michael "Mercury" Morse is one of our 650 enthusiasts treasures, as are many others you're meeting on this site. Best of luck with your changes for maximum twistiness....The Nebo Loop and Hwy. 12 Torrey to Escalante. Make sure to do the Tapered roller bearing change out, stainless brake lines, pads & rotors and a personal favorite a Tkat fork brace.

http://www.tkat.com/forkbrace.html

Contact via PM if there's something I might help you locate. Been doing intermountain
650's and bikes in general for way more than a few years and have much of what you may be looking for....trees, forks, rotors, wheels, etc. if need be though I'm much more of a user/collector/builder than a seller. Welcome, Blue

 

[gggGary]

I don't think you will get "two finger" out of one stock caliper. Sadly, although I have all the front ends I mentioned none have made it to the road yet........ But on my "restored" 83 the front brake is the #1 "needs improvement" item, the stone stock front brake is wooden even when overhauled and in good shape. There is a brembo caliper, rotor mod that should improve it quite a bit. But the XS650 is more of pigs ear than a silk purse, no matter what you do to it, a stock late model 600 rocket with a good rider will leave you in the dust. Check your swing arm bushings and plan on your ride being a bit "stately". Keep us in the loop I hope to be able to do some back to back comparisons of various front end mods "soon" LOL.

 

[sgallaty]

[ Other useful info removed... ]

Contact via PM if there's something I might help you locate. Been doing intermountain
650's and bikes in general for way more than a few years and have much of what you may be looking for....trees, forks, rotors, wheels, etc. if need be though I'm much more of a user/collector/collector/builder than a seller. Welcome, Blue

Hey blue, thanks for this. I've noticed that your posts are generally right on the button, and I appreciate it.

For my econo upgrade I am pulling the dual calipers and master C from an xs1100...

 

[5twins]

I'm quite happy with my stock front end components now that I've modded them as mentioned above. One thing not mentioned but that I think makes a world of difference is running more than the stock amount of oil (about 7 ounces instead of the spec of just under 6). This provides an "air spring" effect and greatly reduces the nose dive during braking. I replaced my springs but may not have needed to with the extra oil.

My brake is stock, including pads, with the only mod being the stainless line and drilled disc. It has a rock hard lever and works very well. My buddy put aftermarket MCs on both of his 650s and, frankly, they don't work as well as my original. Both have soft, spongy lever pulls. I've had to panic stop several times now and the brake performed flawlessly. I had that front tire howling, right on the edge of adhesion. That's about the best braking you can get. Once you start skidding, you're screwed, so I'm not sure I would want to make the brake too much better.

I have a few more improvements lined up. I have Ferodo pads to install and a second set of forks I'm working on. The forks will be sort of a hybrid set, using what I think (or hope) are the best stock components. They will be mostly '77 components (tubes, lowers, damper rods) with '78-on springs, adjustable top caps, and top out springs. Damper rods will have my version of the Minton mods.

So, cheapest and easiest?

-stock components
-more oil in the forks
-S.S. brake line
-fork brace
-tapered steering head bearings

And to improve things a bit more .....

-new brake pads
-new fork springs
-Minton modded damper rods

It will be interesting to see how my "hybrid" forks perform compared to my originals. I plan on Minton modding the damper rods in the originals if that turns out to make a major difference.

As far as silly shit goes, you could go through all the trouble of adapting better, stiffer 41mm forks and then hardtail it, lol.

 

[bluebikerblan]

I don't think you will get "two finger" out of one stock caliper.... the XS650 is more of pigs ear than a silk purse, no matter what you do to it. A stock late model 600 rocket with a good rider will leave you in the dust. Check your swing arm bushings and plan on your ride being a bit "stately"

He may be a "white-eyes" but; he speaketh not with forked tongue....

Though we love them truly.... it is well said that: "One should not try to make chicken salad of chicken shit".

"Stately" ??? yes...Stately! Beats the Hell out of Fat & Old

Enjoy your new Vintage Bike! Best, Stately Ol Blue

 

[gggGary]

These guys are your buddies, good advice from all and I hope you don't follow it.
And report on a new exotic front end setup instead!
PS I also have a set of the Mikes XS knockoff cartridge emulators in a bin somewhere.

 

[gggGary]

While a near squealing tire means you got full range from the brake, being there with light moderate lever pressure for accurate modulation is a better solution for those who send significant time near that edge.
I can mash a nail home in one blow with a sledge hammer but a finish hammer will flush the head with no "moon marks" on the board

 

[5twins]

The problem as I see it is that in a panic stop situation, most riders won't be applying "light moderate lever pressure for accurate modulation", they'll grab the sledge, lol. I like the way the stock set-up modulates. Grab a little lever and it stops a little, grab more and it stops more. I find it very progressive and easy to control the amount of stopping power you need or want. I failed to mention that I am also running a thinner SR500 disc (5mm thick). I'm not sure what effect, if any, that is having. When I swap the other forks on, I'm going to put another wheel in with the stock 7mm thick 650 disc so maybe I'll see then.

 

[sgallaty]

Bear in mind that if your fork compression isn't parallel to the braking force, you'll have less force on the contact patch and a lower shear point on the tire->surface friction, possibly much less.

The other function that compressing forks provide, is to 'soften' the impact of braking on the shear point of traction. Without compressing forks, when you hit the brakes, the initial force of braking is applied immediately to the traction contact patch, and done so 'hard'. Also without proper fork compression you are unable to 'load' the front end prior to entering into a known 'boundary condition' when balancing traction.

In a typical high speed, edge-of-traction situation in a turn the biker will 'prebrake' to compress the front end before leaning into the turn, and then throughout the line the biker will accelerate through the line to load the rear end. Success in such a scenario involves loading as much traction onto the rear as possible to balance to avoid a 'low side' crash, where the front end loses traction.

All of this depends on a bike geometry that handles with even balance and reacts sensibly to force and traction changes. Moving the wheels away from the center of gravity and balance affects those handling characteristics significantly.

The point of all of this rambling is that no amount of braking / rotor changes are going to make up for a small change in fork rake. Raking the front wheel out will lower your maximum possible braking force, as does making the tire profile smaller.

Rake changes do not necessarily have to take place at the neck. Rake can be accomplished by lengthening the fork tubes as well, which changes effective rake.

again, I am in no way chastising anyone for changes they make to their bikes. I mean we're all already doing something essentially unsafe by getting on a bike at all, in a world of blind, stupid and reckless idiots in SUVs whose only concern about hitting us is their own culpability.

I just want people to be fully aware of the consequences of such a change. Don't think you can slap brembos on a chopper front end and get the braking you have eliminated, and dear lord please do not eliminate your front brakes because it's cool, and because the 'barhopper' orange county chopper bikes inspired it.

Those bikes get shown, not ridden.

 

[retiredgentleman]

I have to agree with a couple of the posters,.................the stock single disk brake works extremely well on my 78SE. I use stock pads, stock m/c and calipers with braided steel lines (rotors are drilled).

I had a close encounter with a deer last month, and my front brake saved my ass when I had to do a full bore speed reduction. My tires were squealing for mercy as I hit the deer's rear leg.

Say 5twins, I would like to hear more about those Ferodo pads, when you get them installed. I thinking I may get some of those as well, even though my stock pads are working fine. My rear brake does squeal, which is just annoying, and does not affect its performance.

 

[gggGary]

It's not a problem, it's riding style. The OP mentions two fingers so he knows what that is about. Once you have a bike that stops that way it's hard to go back to liking the sledge hammer. That's why I have a shop full of solutions waiting for a running bike. LOL The real world answer is ABS you MASH it the computor does the thinking. I had an ABS ST1100 for 4 or 5,000 miles. That damned ABS is better than I'll ever be at "on the edge braking" Hate to admit that but true none the less.

 

[retiredgentleman]

Gary; I don't know why you have a "wooden" brake on your 83. My stock front brake (and rear brake) has excellent modulation and feel.................very easy to control the amount of braking.

 

[sgallaty]

I strongly prefer a light touch on the front brake, which is why I am upgrading to dual disks , steel brake lines and uprated pads.

Steel brake lines make a difference. Since they don't flex, you end up with a crisper and more linear response from the brakes.

 

[retiredgentleman]

sgallaty;

I strongly agree with your comment about some riders removing the front brake. I few days back, a poster said he was running without a front brake. I replyed, urging him not to do it, but I don't think there was a reply from him. You can only do so much to save people from their own folly.

I think dual disks on the front of these bikes is a bit of overkill. I can't see why I would need more braking , unless I rode wih a passenger and extra gear a lot. Adds more unsprung weight to the front end.

 

[sgallaty]

I like dual disks because they tend to give more braking with less effort, and a higher degree of control of the amount of braking. It's not that I want to brake 'harder', but I want to have more fine control over how much braking I do, and I want to quickly go to a full non-locked braking situation and know exactly what that feels like on the lever.

If I have to pull the lever hard, I can't make that judgement as easily.

It's just a preference, from long years of riding aggressively on old bikes. Not saying it's better, it's just what I like.

Also, and I know I seem like I am bitching at people but I never intend to save anyone from their own folly. I only want them to know what their folly is, so that they go boldly into that dark night.