[Geeto67]

What happened to your train of thought on Selective Thinning?

I'm not a monster.

And this dude really as clueless as he appears, is asking reasonable simple questions and has a genuine interest in making his shit work - not making his shit cool. I'll help anybody who wants to learn, it's the know it all newbies who sacrifice safe stuff just for style that piss me off.

 

[iamalmostcrazy]

I think you figured out the issue right there. What the fuck do you think you are doing riding a bike around with a bad shock? you have money for tires and you can't come up with the $150 a set of progressives or hagons would cost you?

Here is the deal - suspension doesn't work in isolation - it affects the whole chassis. Chances are if you have that vibration you have it because you are riding around with a blown out dampner transmiting every spring movement straight through the chassis. The reason why you think you feel it in the front end is because that's where the vertical pivot point is - the steering stem. Go replace the shocks and I bet you the vibration starts to improve.

Looking at the absolute pile of shit project you started with, I would wager you have other problems in the chassis - namely swingarm bushings, steering head bearings, water in the fork fluid, shock absorber rubber mounting bushings, who knows. Your forks could have been bent at one time and now the tube has turned in the slider and you are getting a little bit of stiction as it moves up and down. Systematically go through the chassis and check everything - there are testing procedures for all these things are in your manual. Don't rule out anything you replaced or rebuilt already, everybody makes mistakes.

I understand that the suspension is a system, not isolated parts, obviously. There is no stiction in the front, i've check for this. also in the rear, if it were as you say the shock absorber that is causing the issue, wouldn't it have to bottom out or be close to, to feel the vibration? im saying that its coming from the front because there is no feeling in the rear, its solid. i'm more apt to thinking its some sort of parallelism offset from the front to rear tire (shouldn't be any)



I felt like resurrecting this thread because it was left off with a newb who knew nothing. I'm not here to sup-up my bike, i understand its a POS but its MY POS.

Geeto is actually on the money, and i don't care. i have reasoning for not caring. No, i haven't done any of those bushings, mainly because they felt "good enough" for what i was doing, which is riding down the road at 40 mph. It is in the back of my mind to change the swingarm bushings, rear shocks, and steering bearing. there is no water in the frame, i had it completely apart twice i don't know why you'd say that. you say "go buy some" but the thing with this bike is total, it cost me less than $400 with the bike, parts and reg/insurance to ride this so im' not going to just throw $150 at two parts. I'm going to shop around and make what i want. In the long-run i'm going to a mono-shock design but i've yet to fab something up, and i am fully aware of the implications involved with engineering a new swingarm.

Any other comments wannna try and touch this?

 

[kenessex]

I really enjoyed reading through this thread again. We are certainly some amusing people on here. As an educator and well known self appointed voice of reason, ( as a side note: I recently took a couple of the stupid quizzes that made the Facebook rounds about which movie character you would be and when I answered them as honestly as I could (I really might be an egotistical dick based on the multiple choice selections I made), I am Yoda and Albus Dumbledore), so you should all pay attention to my summary of this thread.

1. The CB400/450 Hawk is essentially worthless except as a beginner learner bike as long as it doesn't need any work to get it running and safe.
2. As the basis for a cafe bike, don't bother. If you replace all the pieces that would need to be replaced to give it any kind of acceptable performance upgrade, you will have 2 to 3 times as much money and even more time into it than could ever be recouped and it would still be a Hawk.
3. There is no aftermarket support for a Hawk.
4. It is justly considered to be the most boring bike Honda ever made. It has enough power to be boring. Good enough handling to be boring and is comfortable enough to be boring. It doesn't suck so it is boring, which sucks. It doesn't even suck enough to be interesting.
5. Geeto is a dick.

 

[Geeto67]

I understand that the suspension is a system, not isolated parts, obviously. There is no stiction in the front, i've check for this. also in the rear, if it were as you say the shock absorber that is causing the issue, wouldn't it have to bottom out or be close to, to feel the vibration? im saying that its coming from the front because there is no feeling in the rear, its solid. i'm more apt to thinking its some sort of parallelism offset from the front to rear tire (shouldn't be any)

The purpose of a shock absorber is to...absorb shock. Simple I know but by shock this also means vibration. Ever ride a skateboard on old asphault? at 5mph the thing vibrates like crazy, Why? because roads are not smooth, they are pockmarked uneven surfaces full of rain gutters and scrapes and all sorts of stuff that can cause vibration.

No the shock does not have to be bottomed out to transmit vibration, it just needs to lack compressable fluid. The Fluid absorbs the shock, without the fluid the shock just transmits through the spring straight to the shock mount. this not only includes vibration but whatever occilations the spring normally goes through.

What do you mean by the rear is solid? there is no slop in it? Does it move freely around the pivot? A bike at rest or low speed is not the same as a bike at highway speed. Every drive a car with one blown out rear shock? once you get going about 60mph the thing is all over the road and will push the steering.

Either way, you can't diagnose what's going on until all your suspension bits are in good shape and you can start ruling stuff out. I'll say it before start checking stuff and knocking it off the list.

as far as wheels offset, it's possible. It's not hard to check. Use a chalk line to mark a straight line on the ground and then roll the bike straight on to the line. mark the center of the tire tread before rolling over and use that index mark to see if you are off or not. You are going to need someon to hold the bike upright while you check/measure.

I felt like resurrecting this thread because it was left off with a newb who knew nothing. I'm not here to sup-up my bike, i understand its a POS but its MY POS.

Geeto is actually on the money, and i don't care. i have reasoning for not caring. No, i haven't done any of those bushings, mainly because they felt "good enough" for what i was doing, which is riding down the road at 40 mph. It is in the back of my mind to change the swingarm bushings, rear shocks, and steering bearing. there is no water in the frame, i had it completely apart twice i don't know why you'd say that. you say "go buy some" but the thing with this bike is total, it cost me less than $400 with the bike, parts and reg/insurance to ride this so im' not going to just throw $150 at two parts. I'm going to shop around and make what i want. In the long-run i'm going to a mono-shock design but i've yet to fab something up, and i am fully aware of the implications involved with engineering a new swingarm.

Any other comments wannna try and touch this?

when it comes to shocks - my advice is yeah...go buy some. You are what... a year away from the monshock at least, what could new shocks really hurt in that regard? Or not even new, just working properly. Progressive makes pretty cheap servicable shocks, might even be able to find them for less than $100 if you look hard. Shocks are a service item, like tires and oil filters. They were never intended to last forever, and certainly not 30 years in a bad enviornment. If the stockers were rebuildable I would advocate rebuilding them, but they aren't. they weren't even that good when new. You can try to find a set of mullholland shocks from the 70's for a cb750 and rebuild them - but you won't get the new bushings like you would with a proper pair of brand new shocks.

 

[Geeto67]

( as a side note: I recently took a couple of the stupid quizzes that made the Facebook rounds about which movie character you would be and when I answered them as honestly as I could (I really might be an egotistical dick based on the multiple choice selections I made), I am Yoda and Albus Dumbledore),

I took that Quiz, I came back Han Solo. Suck on that Ken. Everybody wants to be Han Solo, he gets Carrie Fisher in the end.

 

[iamalmostcrazy]

Well i guess what i'm caught up on is the pricing of things. it seems that the type of shock i need, with two clevii (not sure if its pluralized like radius) is very costly. So what i planned on doing was taking the existing top clevis and threading it onto a new shock that had a bottom clevis. Of course when i do this, im going to push new bushings in. But what my issue with buying just any shock, is i need to know something like how much spring pre-load is there on the original shocks, i shouldn't need to mention that i need the same length, and how much each shock is or should be rated at.

I'll give in and buy new rear shocks, but i will have to bet money against geeto, and say that although they indubitably need to be replaced, the vibration will persist.


And ken, no. just no.

^ i don't plan on doing any of those things. i am running the bike as is for now, and i'm just having an issue making it safe and ride-able. I'm going to keep the bike just for sh*ts and giggles, but as a second bike and being new to riding motorcycles, i want to test my limits and be able to "feel" how the bike interacts with the road. what better than a reliable, rather safe, cheap, bullet-proof machine? i've already downed it just from doing figure 8's on an incline (to improve my balance and turning control) and i've taken it in the woods many times. I'm probably not riding the bike as it is intended to be ridden, and thats probably half the reason i enjoy it so much.

As for the parts, i'm not so much into specific parts made for the hawk. I'm willing to adapt things as necessary, as long as they're well thought out and done to perfection. example, front shock seals are new, but not intended specifically for the bike, instead just the proper measurements.

 

[nicebikemate]

I don't have a manual, if anyone could link a downloadable copy. (1978 CB400 TII matches other models like cm400, cb400a, cb400tI)
Just a friendly word of warning, i'd delete that comment...

 

[kenessex]

I took that Quiz, I came back Han Solo. Suck on that Ken. Everybody wants to be Han Solo, he gets Carrie Fisher in the end.

2 things:
1. Han Solo was kind of a dick, too.
2. You can have Carrie Fisher. She is a wack job and a half and have you seen her recently?


BTW, while you are wrong in how you described shock function, you are correct in that a blown shock can be the cause of a front end "vibration". The fluid in a shock is not compressible, it flows through orifices or past shim stacks to provide damping. Bottoming out is controlled by the spring. I shock with no damping at all, as in a blown seal has allowed all the oil to come out, will not bottom out on bumps as long as the spring will support the weight. Now comes the interesting part. The Hawk has a weak swingarm which will twist under loads. Unequal damping between the two shocks will put unequal loads on the two arms of the swingarm. If they do not stay parallel, the rear wheel will not stay in line with the front. The Hawk has marginal swingarm bushings when new and when worn will allow unequal forces shift the swingarm in relation to the frame. When that happens the rear wheel will not be in alignment with the front. The Hawk uses loose ball bearings in the steering head and they will pound divots in the races over time, especially if they have not been adjusted and greased on a regular basis. Because of these divots there is a self centering action. If the rear and front wheel get out of alignment, the steering will try and self center which can be felt as a vibration. While the undampened rear shock may be the initiating force, the lack of swingarm rigidity, the stacking of marginal tolerances in the swingarm pivot and steering bearings cause the "vibration". I would suggest that "good enough" for the intended purpose actually is not. Put the bike up on a stand that supports it by the frame cradle. Remove the rear shocks and then see how much side play you get at the swing arm pivot when you put a side load at the rear axle. If there is any ( i really do mean any) detectable movement at the front of the swing arm it is too much and the bushings need to be replaced. Now, since you have the bike supported get the front wheel off the ground. Remove the top triple clamp and adjust the steering bearings to spec. Then move the bars through the range of motion from left to right and feel for any notchiness throughout the range of motion. If there is any, then the steering bearings need to be replaced. Finally, while you have the front wheel in the air, give it a spin to make sure you don't have a wheel or tire with too much axial runout. Then make sure that you loosen up all of your axle and pinch bolts and fender bolts and bounce the suspension a few times to make sure nothing is tweaked or bound up and the tighten the axle into place first and the fender bolts last. Just to make sure.

 

[iamalmostcrazy]

So it seems like you're putting blame to the swingarm bushing, which is creating the off-set in parallelism. See i wasn't too far off, thats probable.

I'm going to take a swing at it within a day or two and i'm sure i'll find that the bushing/bearing on the swingarm needs replacing. The front bearing has no hiccups in its radius, i've tested before. <-- but that doesn't mean i won't replace it anyways just to be sure.

If the rear shocks are conceivably the issue, from what you've said, two bad shocks with good springs would be better than 1 bad shock and 1 good shock, both with good springs?

 

[o1marc]

Two bad shocks are not as bad as one but not good or better. There's nothing to stop the pogo action of the spring if the shocks don't work.

 

[Geeto67]

Ken, by compressable I meant the seals werent all blown out so that when you passed a piston through it, it didn't just shoot everywhere. My bad for choosing the wrong word.

Almost Crazy,

I can see the flaw in your logic. You think that wet noodle of a tiny swingarm is not flexing or moving around on its own. Rest assured it is. And in fact if you have two different shocks in the rear, such as one blown and one working you'll def get weird defelction angles in the wheel as the suspension moves up and down because the arm is twisting (not at the pivot but at the rear axle). Basically everything Ken said. The pivot bearings will wear out because of this movement eventually if they haven't already.

 

[iamalmostcrazy]

But what my issue with buying just any shock, is i need to know something like how much spring pre-load is there on the original shocks, i shouldn't need to mention that i need the same length, and how much each shock is or should be rated at.

So back to my question of: if i want to buy new shocks, that aren't oem and aren't specifically aftermarket for this bike, how much pre-load is on the springs, and how much dampering/rating do i look for?

 

[Geeto67]

at your budget, take what you can get. The cheapest generic shock is usually a progressive 412 in 13" eye to clevis (stock for your application). Preload is determined by the rotating collar (like your stockers - infact these are basically OEM replacements with better fluid and variable valving and they are new).

Here is the spec sheet on them:
http://www.progressivesuspension.com/pdfs/7100-105.pdf

Honestly, I can't tell you what you need because I don't know how much the bike weighs, how much you weigh, what kind of riding you are looking for, etc...Really we are talking about spring rate because the modern stuff is just set up for a wide array of dampning.

Dave Quinn sells Hagons for $194 a set and he will set them up for your weight, but you will have to answer his questions. My advice is to call him and talk to him in person:
Hagon

 

[8ball]

How much pre-load depends on the spring rate that you use on whatever shock you get. What spring rate you get is dependent on the weight of the bike...and you, and the type of riding you intend to do. Pre-load is just the means to set "sag" (it is the method not the goal). Sag is how much the suspension compresses when you sit on it (geared up). I generally like to set about 3/4"-1" static sag on my sporting type bikes.


Oh, and the front should work about the same. Generally I set the front to 1- 1.25", as a starting point But the point is to get the front and rear to move together.

 

[Joep7]

Anyone who comes on here and says their hawk is a blast to ride, handles curves like a champ and accelerates great has obviously never actually ridden anything with some measurable standards of performance.


That it is all.

 

[o1marc]

Anyone who comes on here and says their hawk is a blast to ride, handles curves like a champ and accelerates great has obviously never actually ridden anything with some measurable standards of performance.


That it is all.

X's2, I have the same comment for those who say their bikes run great with pods.

 

[iamalmostcrazy]

Anyone who comes on here and says their hawk is a blast to ride, handles curves like a champ and accelerates great has obviously never actually ridden anything with some measurable standards of performance.


That it is all.

Well joe, there are two things true with your statement, the rest is shit you made up to feel adequate. All i said was yes, it is one of my first bikes, the first was a 100cc. No, it isn't an amazing machine, but its reliable, easy to work on/repair, and cheap to maintain. What else could i ask for? i even get 45-52 mpg depending on what kind of mood i'm in.

The bike no doubt has no power, its not made to. its a toque machine. the reason it handles curves the way i like, not like a champ, but the way i prefer, is because i don't have to change gears. i can accelerate moderately at 1.5k rpm in 4th up a hill, or at 3500 rpm in fifth up that same hill. My point is that you can shit on it all you want, but shit on it for what i'm defending it for, not what you neglected to read.

 

[Geeto67]

I guess Joe's point is - with broken suspension bits and only the experience of one bike previous, how can you say it handles curves at all? The way you like? that's moot. That's like saying all beef tastes the way I like based on eating a macdonald's hamburger once.

Let's get back on topic before you take "offense" to anything further. Really you need a real life mentor to kind of guide you through this adventure but I no longer live in NY, and to be honest Stoneonta was too far for me anyway (Do they even still call it that? are there still lots of stoners in that town?).

 

[Joep7]

Well joe, there are two things true with your statement, the rest is shit you made up to feel adequate. All i said was yes, it is one of my first bikes, the first was a 100cc. No, it isn't an amazing machine, but its reliable, easy to work on/repair, and cheap to maintain. What else could i ask for? i even get 45-52 mpg depending on what kind of mood i'm in.

The bike no doubt has no power, its not made to. its a toque machine. the reason it handles curves the way i like, not like a champ, but the way i prefer, is because i don't have to change gears. i can accelerate moderately at 1.5k rpm in 4th up a hill, or at 3500 rpm in fifth up that same hill. My point is that you can shit on it all you want, but shit on it for what i'm defending it for, not what you neglected to read.

I was just lumping your retarded comments in with all the other asshat hawk owners who think there bike is "awesome". As far as you personally...anyone who thinks it ok to ride with one shock that is shit and one that works fine probably should t be allowed to ride anything less boring than a hawk.

 

[o1marc]

Well joe, there are two things true with your statement, the rest is shit you made up to feel adequate. All i said was yes, it is one of my first bikes, the first was a 100cc. No, it isn't an amazing machine, but its reliable, easy to work on/repair, and cheap to maintain. What else could i ask for? i even get 45-52 mpg depending on what kind of mood i'm in.

The bike no doubt has no power, its not made to. its a toque machine. the reason it handles curves the way i like, not like a champ, but the way i prefer, is because i don't have to change gears. i can accelerate moderately at 1.5k rpm in 4th up a hill, or at 3500 rpm in fifth up that same hill. My point is that you can shit on it all you want, but shit on it for what i'm defending it for, not what you neglected to read.

Chrome clevis to clevis shocks are only $98 a pair delivered. If you can't afford $100 to fix your bike you shouldn't be riding it.

New and Unused Honda CB400T Hawk Chrome Shocks 1978 79 | eBay