Author Topic: Cutting shock springs and non-traditional handle bars questions (Read 2802 times)

550_ko · « **on:** February 03, 2006, 03:56:00 PM »

Hey guys, I'm working on no budget rat bike project for a friend of mine. I'm basically building him a bike out spares in the shop. And I have a couple of questions.

I have a 7/8 stainless steel tubing of the right O.D. but a relatively thin wall thickness, .053" a little less than a 16th of an inch. My stock bars have a wall thickness of .074" Is this tubing rigid enough to use for a set of drag bars or is it to thin?

And also, I have read several posts on here about chopping the springs on the forks to lower the ride height, but could only find one on chopping the shock springs. Is this OK to do?

This isn't going to be a high performance bike, more of a poser, so as long as it's safe . . . it should be good to go.

By the way, this is a 350 twin, but the shocks I want to use are from a CB750 and the bar question is kinda universal. If this should go in the non sohc4 forum, I apologize.

8 Track · « **Reply #1 on:** February 03, 2006, 03:59:53 PM »

Can you slide the fork tubes up the triple tree clamps, in effect, lowering the front end? You can on a 750.

8 Track · « **Reply #2 on:** February 03, 2006, 04:53:12 PM »

Rear shocks? I'd cut the spring with a wiz wheel and be done with it. That's essentially what happens when you ride two up, or if your 360 pound neighbor rides it- the bike lowers and you run out of suspension travel!

8 Track · « **Reply #3 on:** February 03, 2006, 07:54:59 PM »

I'm guessing you're going to disassemble the shock to get the spring alone? I know it's a stupid question, but that's how I envision doing it. I've never had the rear shock completely apart and I wonder if there's a way to limit the extended travel now that the spring is shorter. Can spacers be installed to reduce the amount the rod comes out of the shock, to match the shorter spring and to keep the "new" shorter spring compressed at maximum stroke? When the suspension becomes completely unloaded (when bike leaves the ground) you don't want the spring to be loosy goosy! You know, when I first bought my bike, the PO had installed short solid struts in place of the shock to lower the bike and made it a hard tail in the process.

Gordon · « **Reply #4 on:** February 03, 2006, 11:53:33 PM »

Cutting the already much stiffer 750 shock springs is only going to make them more stiff. That's going to make for a very rigid 350 tail end.

Gordon · « **Reply #5 on:** February 04, 2006, 06:05:04 AM »

Quote from: 550_ko on February 04, 2006, 05:17:15 AM

On slightly more serious note, why does a shorter spring make for a stiffer spring? Less travel, I get . . . but why wouldn't the resistance be the same?

Because when you compress the spring, what you're doing is decreasing the distance between the coils. Fewer coils means you have to push harder to get the same amount of travel.

Let's say the stock spring has ten coils that each travel .25" when the whole spring is compressed 2.5 inches. Now, you cut off five coils, and in order to compress the spring the same distance, each coil now has to travel .5 inches. The smaller the gap gets between the coils, the more force it takes to push them farther.

8 Track · « **Reply #6 on:** February 04, 2006, 06:44:41 AM »

When you wanted to cut the springs, I imagined taking a coil or two out to drop it a little. I'm getting the feeling you want to slam this 350 down, am I right? If that's the case, I would try to locate rear shocks that suits your application and cut corners in other areas that aren't as important. After all, the suspension is going to affect how this bike rides, and if it's miserable, you will be too. That solid bar (in my pic in the earlier post) will work, but the bike won't hold the ground as well.

cb650 · « **Reply #7 on:** February 04, 2006, 06:58:41 AM »

Crazy thats how I have the race bike set up with the struts. Lowered and saved lbs.

Terry

8 Track · « **Reply #8 on:** February 04, 2006, 07:15:25 AM »

Yeah, I thought I would hear some disagreement about my comment about solid rear ends not holding the ground as well. Obviously, it must not be that bad- just look at all of the rigid harley style bikes running around! Personally, I didn't like the look or the ride of mine, so I changed it back to stock after owning it for one day. I didn't ride it enough to really find out how bad it may be.

marvsho17 · « **Reply #9 on:** February 04, 2006, 07:45:46 AM »

I cut a coil off of one of my springs and 2 off of the other to see how'd they look. I havent rode it yet so I can't tell you how safe it is. I've jumped on it a couple times and they held.

bill440cars · « **Reply #10 on:** February 04, 2006, 01:43:20 PM »

550ko,

Just wandering, instead of cutting the springs, why don't you get or even build a set of
lowering blocks. you've done some welding, right? Lowering blocks would angle the shocks more and
bring the bike down. Give it some thought. Later on, Bill

cb650 · « **Reply #11 on:** February 04, 2006, 02:08:24 PM »

Just a little drag. Wouldnt ride it on the street to much with solid ass.

Terry

heffay · « **Reply #12 on:** February 04, 2006, 02:15:42 PM »

marv... you know you shouldn't ride that bike very hard with lopsided shocks ok? things not gonna be right at all !

also, i think cb650's answer (dragracing) answers the does it hold the road question... um, well, actually it doesn't... cuz, there's no corners in a dragrace... of course,we should have a bendy version of a drag race (would at least be fun to watch!)

ohiocaferacer · « **Reply #13 on:** February 04, 2006, 03:15:45 PM »

Lowering blocks are the cheapest way to go.....dont cut the springs....you will have springs flopping around, unless you reduce the travel of the damper rod.

JCWhitney has some nice lowering blocks......cant remember the price. They have nice pics of them....I'd just weld yourself a set.

Later,
Greg

heffay · « **Reply #14 on:** February 04, 2006, 03:55:48 PM »

if you can get ahold of linda (username is smithrelo) she can probably give you a testimonial about those lowering blocks... she recently bought some and if memory serves... they were from jcwhitney

CB750F2 · « **Reply #15 on:** February 04, 2006, 04:31:16 PM »

G/Day. I have made my handle bars from 7/8" S/S tubing with a wall thickness of approx. .063". Recently I removed them to make them wider as they were some 3.25" narrower than the specs for my 750 F2. I did this by machining extension pieces from 7/8" solid s/s bar. The bars are now the normal width for my model and the "tingling" in the wrists which was present prior to the modification has disappeared - I think due to the extra weight of the extension pieces. Hope this helps, Pat from Australia.

volz1fsu · « **Reply #16 on:** February 04, 2006, 08:57:42 PM »

I've cut the rear shock springs on one of my bikes to lower it. I must have put a thousand miles on it since and I haven't noticed any difference in the way it rides, just the looks. There is no reason I can think of for why it wouldn't be safe because the springs always have a load on them; unless you decide to take some jumps with the bike. I still use the prop stand and yes the springs are loose then but the shock still puts the wheel where it used to be, no big deal really.
As for the stiffer ride with the 750 springs; people ride hardtail choppers just fine. (Beware of potholes!)

STLrocker · « **Reply #17 on:** February 05, 2006, 12:10:37 AM »

if you wanna cut the rear springs, you can do it, but you should shorten the damper rod also. this will keep the springs preloaded at all times like the shocks were designed.

the top shock mount will thread off of the damper rod. then cut the rod to the length needed to match what you cut from the springs. rethread the rod and put the top mount back on, and you have a free set of shorty shocks.

8 Track · « **Reply #18 on:** February 05, 2006, 01:01:47 AM »

Thanks, stlrocker, I suspected there was a way to do this and do it right. I guess if 550ko doesn't have access to a lathe he can just run a die down the rod. I may just do this mod myself!

Terry in Australia · « **Reply #19 on:** February 05, 2006, 01:36:09 AM »

Well that's the only safe way to go, but at the end of the day you'll still have crap shocks with virtually no damping, and now really stiff springs, so stay away from corners and bumpy roads mate, or you'll know what a rigid rear end is all about, ha ha! Cheers, Terry.

8 Track · « **Reply #20 on:** February 05, 2006, 06:28:36 AM »

Terry, Don't you like rigid rear ends? Or do they have to be tanned with kooler king oil smeared all over them?

marvsho17 · « **Reply #21 on:** February 06, 2006, 08:55:54 AM »

Quote from: STLrocker on February 05, 2006, 12:10:37 AM

if you wanna cut the rear springs, you can do it, but you should shorten the damper rod also. this will keep the springs preloaded at all times like the shocks were designed.

the top shock mount will thread off of the damper rod. then cut the rod to the length needed to match what you cut from the springs. rethread the rod and put the top mount back on, and you have a free set of shorty shocks.

Page 3 ownage. Alright, I'll cut another coil off of one of my shocks and do this to get them matched up.

I didn't think it would be to bad to leave as is b/c I dialed the shorter one up and left the longer one on the lowest setting. To get them apart it would be lefty loosey correct?

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Author Topic: Cutting shock springs and non-traditional handle bars questions (Read 2802 times)

550_ko

marvsho17

marvsho17