Author Topic: Progressive spring install question (Read 5713 times)

alltherightpills · « **on:** July 01, 2009, 06:21:00 AM »

First a story...

When I got my bikes, I found out from the PO (he was a buddy of mine) that the front end of the '78 550k that ran had accidentally been backed into by a pickup. It wasn't bad, and there was no obvious damage, but one of the first things I decided to do was swap the entire front end with the '77 550k just to be safe. When I pulled apart the forks on the '78, I noticed that the springs were different than the ones on the '77. I didn't know much about these bikes at that point, so I didn't think much about it. Well, as I was looking at progressive springs for my forks recently, I remembered that the springs that were originally in the '78 looked a lot like the progressive springs I was seeing online. Sure enough, when I pulled those forks apart, there they were.

Obviously I don't have any installation instructions, so my question is do the tighter wound coils go at the top or bottom or does it matter? Also, I've been seeing that people with 750's have been putting a PVC spacer in to preload the spring. Is this necessary on the 550's?

The other question I had was about fork oil. Most of the posts I've read suggest filling the tube to between 5 1/2 and 4 inches from the top of the tube with the spring out and the fork fully compressed. Does the fork need to be vertical to do this, or can I do it with the forks on the bike? I'm assuming I can do it with the forks on the bike, but I thought I'd check.

Thanks in advance for your help.

razor02097 · « **Reply #1 on:** July 01, 2009, 06:30:47 AM »

I don't think it matters which way they go in but I can check the instructions when I get home. I think I read something that the fork oil should not exceed 5" from the top but I will have to check the book I read it from. Wow I guess I wasn't much help

I do know on the 650 you can change the fork oil without taking the forks off the bike its just way more difficult to get the caps off.

cycleman · « **Reply #2 on:** July 01, 2009, 06:45:37 AM »

From what I've read on progressive's, it doesn't matter which way the spring is put in the tube.

Also the quantity & type of oil would be in the manual ( on line versions ) or in any aftermarket manual for your bike.

I'm sure somebody will be along with the volume you need. I always measure mine & pour it in. I know it's a different amount if you are just doing a drain & fill or taking the spring etc completely out & replacing seals etc.

HondaMan · « **Reply #3 on:** July 01, 2009, 07:08:18 AM »

Generally, progressive springs are mounted with the closer-spaced coils on the "sprung weight side". In the case of shocks and forks, this is the top. The reason: the progressive section of the spring is heavier, and you want to reduce the weight on the unsprung components. Unsprung (that's the wheels and stuff attached to them) weight robs power and makes handling feel heavier.

This is why modern sportbikes have so much money in their monoshock swingarm systems: it is a way of reducing unspring weight back there, giving the ground more HP and the bike an edge in the marketplace (especially with the big, heavy tires they roll). If someone were to take, for example, a CB750K3 and add bracing to the frame midsection so as to support a monoshock, then used an aluminum or magnesium monoshock swingarm that weighed the same or less than the original design, the rear would lose about 1/2 the shock's weight. This will put almost 1 more HP on the ground back there. For most of us, it's easier to add 1 HP to the engine, then use lighter tires and wheels to accomplish this trick.

CBdave76 · « **Reply #4 on:** July 01, 2009, 05:55:43 PM »

I have installed new Progressive springs on my CB750A. The instructions that came with the springs stated that it did not matter, but suggested putting the tighter wound end in first to eliminate noise. I had to put in spacers to make up the length difference between the new and old springs. I made up the difference with a flat washer and rod end collar that matched the gap to the top of the tube. I filled the tubes with ATF on the bike with the forks collapsed and springs out using a 6 foot folding ruler with a brass slide out scale on the first 6 inches. I set the brass scale to 5 and 1/2 inches and filled until I saw ATF at the end. I ether did this task darn simple or I'm a darn fool!

razor02097 · « **Reply #5 on:** July 02, 2009, 05:23:22 AM »

The Honda manual says 170cc of fork oil for each of my 650 forks. Is volume measurement not the way to go?

mystic_1 · « **Reply #6 on:** July 02, 2009, 05:43:01 AM »

I've always been a bit untrusting of the "inches from the top of the collapsed tube" thing. Filling by volume seems the better approach to me, assuming you're 100% sure you got all the old oil out.

mystic_1

razor02097 · « **Reply #7 on:** July 02, 2009, 05:46:50 AM »

Quote from: mystic_1 on July 02, 2009, 05:43:01 AM

I've always been a bit untrusting of the "inches from the top of the collapsed tube" thing. Filling by volume seems the better approach to me, assuming you're 100% sure you got all the old oil out.

mystic_1

In the manual there is 2 different volumes 1 for assembly and 1 for changing the oil. The one to change oil is 150 cc

alltherightpills · « **Reply #8 on:** July 02, 2009, 06:32:53 AM »

I went with the volume approach, since filling to 5 inches from the top would have required 2 oz over what Honda recommends. It's also easier to put more in than it is to take some out, so I figured I'd go with what my owner's manual tells me. I did use a tape measure to measure the depth of the fluid in the forks to make sure I had the same amount in each fork. Worked easy enough. The suspension felt a lot better after doing this.

alltherightpills · « **Reply #9 on:** July 02, 2009, 07:12:22 AM »

I did notice that I must have 2 sets of progressive springs. One set measured 18.75 inches in length, the other set measured 19.25 inches. The shorter set had fewer coils and there is about a 9/32" gap between the coils. The longer set had more coils, but the gap between coils is more like 3/16 of an inch. I didn't count the coils to figure out the maximum travel for each spring, but I decided to go with the shorter set My thinking was that the spring with fewer coils is both stiffer and probably has a longer travel before the spring collapses and turns into a solid rod.

Anyone think I made the wrong decision?

DavePhipps · « **Reply #10 on:** July 02, 2009, 07:20:54 AM »

First get the coils to the same length and put a PVC spacer in to make up the difference. Next on some bikes the progressive springs displace more volume than the original springs so less oil needs to be used. I'm not sure if this is true on the CB550 or not. Hopefully on of the more experienced members here can help with this question.
Good luck and happy riding

razor02097 · « **Reply #11 on:** July 02, 2009, 08:20:07 AM »

when I got my progressive springs they where longer then the stock ones I pulled out. I was thinking it may have sagged but noticed the springs I pulled out where progressively wound also... I'm wondering about that. The progressive springs I bought where much stiffer then what I had in there.

I don't know whether or not Honda made OEM progressively wound springs or not.

DavePhipps · « **Reply #12 on:** July 02, 2009, 08:40:36 AM »

I can try and check my stock springs later today. I get off work in about 4 hrs. I love working IT, I can browse and post between Helpdesk calls.
I'll get back later with the wind info.

Sporkfly · « **Reply #13 on:** July 02, 2009, 08:44:17 AM »

Tighter coils at the top. Hands down.

As for oil, 150ml will do the trick. I have progressive in my 550 and 150 has done the trick, I've noticed nothing abnormal about my fork response. If somebody knows otherwise for progressive springs then chime in. As for what oil ATF will do, but a proper fork oil will likely have a better feel to it. ATF is relatively light so if you want stiffer damping don't use it. As for me, I'm using hydraulic jack oil and am pretty fond of the response it gives me.

And Dave, I'm in the same boat as you, go team Help Desk SOHC4 owners.

DavePhipps · « **Reply #14 on:** July 02, 2009, 09:06:00 AM »

Heck, if you want some good damping get the Front Fork Damper Valve Set from mikesxs
http://www.mikesxs.net/products-19.html#products
From what I've read they are really worth it.

I wonder how many others here work helpdesk, or IT jobs?

mystic_1 · « **Reply #15 on:** July 02, 2009, 09:19:18 AM »

Quote from: davephipps on July 02, 2009, 09:06:00 AM

I wonder how many others here work helpdesk, or IT jobs?

Guilty as charged.

mystic_1

SUELZER · « **Reply #16 on:** July 02, 2009, 10:38:57 AM »

Quote from: mystic_1 on July 02, 2009, 09:19:18 AM

Quote from: davephipps on July 02, 2009, 09:06:00 AM
I wonder how many others here work helpdesk, or IT jobs?

Guilty as charged.

mystic_1

+1 (videogame designer...pretty close)

DavePhipps · « **Reply #17 on:** July 02, 2009, 01:00:16 PM »

Going to check the springs now

mystic1@ which studio? I didn't know there were any over there.
I used to want to do game art but the job security isn't there with many companies.

Mine are progressively wound, but then again they may not be stock. I also checked the manual and could get a definite yes or no there.

mystic_1 · « **Reply #18 on:** July 02, 2009, 01:09:16 PM »

I'm an IT manager, not a game designer, that was Suelzer.

mystic_1

SUELZER · « **Reply #19 on:** July 02, 2009, 01:22:19 PM »

i'm up around Toledo OH area. there actually are a few in the Chicago area though, have some friends that work at Volition, not sure how well known that place is. Job security is a tricky biz definitely, i've been here 6+ yrs

IHWillys · « **Reply #20 on:** July 02, 2009, 01:53:57 PM »

Tighter coils down or up.

First, noise:
The tighter coils are softer in rate and are the first to compress. They will make more noise sooner than the looser wound section. Thus putting the tighter coils down moves this noise down, further away from the rider's ears *perhaps* resulting in less noise heard by the rider.

Second, sprung/unsprung weight:
While the tighter coils are heavier for a given amount of spring length, they make up a much smaller portion of the spring vs the higher rate windings. Because the tighter wound springs are lower rate they "collapse" first. There is a small tuning affect here as the unsprung/sprung mass qualities of the springs change as compression occurs and the rate at which the spring is contributing to unsprung mass vs sprung is slightly different between the two installation positions.

Basically, if they are mounted up, the length of the spring that is not tightly wound will have to move with the unsprung mass of the lowers/hub/wheel/tire/etc as the tightly wound section compresses/releases at the top of the fork. Thus the result is in the initial compression phase(and end of rebound) of the spring with the lower rate spring to the top, the higher rate section(looser wound) acts as if it is unsprung weight. The higher rate section weighs much more than the lower rate section.

If putting the lower rate(tighter) coils down, the spring compresses down there first without the higher rate section having to move. So inital compression and late rebound occur with less unsprung weight. But this lower rate section becomes part of the unsprung weight as the spring further compresses into the higher rate section. So the mid to high range of compression has this section acting entirely as unsprung weight.

Clear things up? hehe.

Ken

DavePhipps · « **Reply #21 on:** July 02, 2009, 01:55:20 PM »

Wow I didn't know volition was there. I wish I'd stayed in WA and gotten an IT position at one of the Studios there. I bombed my interview with Monolith and missed the call from Bungie

Instead I got stuck working mscomhelp at Microsoft for 2 years .

/end thread hijack.
Can someone else check thier springs? Yes filing by volume is better IMO.

News:

Author Topic: Progressive spring install question (Read 5713 times)

cycleman

CBdave76