Rear shock for curvy. Opinions, advice please.
 

Hey all.

I have just spent nearly 2 hours reading through old threads about rear shock conversions for curvy's.

I am probably 15.5 stone with all my gear on.

I am looking to get a zx10r (2004) rear shock, from the mighty Fleabay.

I am just after people's opinions on this particular conversion, and what benefits i'll get over the standard shock.

Ive not been riding long (the SV is my first bike), but I would like it to be as good as it can be for reasonable money. So this seems a good way to spend £45.

Any input greatly appreciated.

Thanks

Richie K

Re: Rear shock for curvy. Opinions, advice please.
 

I put one on my curvy when I was just shy of 15st. There are two things I really noticed

1. Having a spring rate more suited to my weight and proper pre-load adjustment, meant that I got correct sag / ride height. The difference to the steering was quite noticeable and the general feel of the bike was much better as it rode level instead of tail heavy.
2. Damping!! Compression damping on standard shock is non-existent, so getting some damping on bumps was a revelation. A big compression on the road from my village would squash the life out of the normal shock, you could feel the damping resisting the squash and setting the tyre into the road with the ZX-10R shock. Was lovely!

You will notice the inadequacies of the front end more now though. I fitted .85 springs and emulators at the same time to get a well balanced bike (for the money).

Re: Rear shock for curvy. Opinions, advice please.
 

Am looking at new front springs. Not sure whether to go for 0.9 fixed rate or progressives. with some 15W oil.
Excuse my retardedness, but still not sure what emulators are?

Richie K

Re: Rear shock for curvy. Opinions, advice please.
 

SV forks are cheap damper rod forks, better (more expensive) forks use cartridges (with shim stacks). Emulators 'emulate' cartridge forks.

Druid

Re: Rear shock for curvy. Opinions, advice please.
 

Emulators are cartridge emulators, a little gizmo that can be fitted to crude damper rod forks (SV) to take over the damping with a bit of modding to the damper rods and operate like more expensive cartridge forks. They only operate on compression damping so not as good as a full GSX-R front end conversion, but a useful improvement on stock.

See here for piccies and stuff (scroll down a bit) http://www.pdq1.co.uk/racetech.htm

To help choose the correct spring rate, go here http://old.racetech.com/evalving/Spr...pringType=Fork

Re: Rear shock for curvy. Opinions, advice please.
 

I think emulators sound a bit too much for me at the moment.
Luckypants, are 0.85 front forks good for you at 15st? Will be looking at either 0.85 or 0.9. Not sure which ones though. Which weight oil did you use?

I have got braided brake lines now, so definately want to avoid the "dive" under braking, and the resultant weight transfer and light front end when letting off the brakes into a corner!

Cheers Guys

Richie K

Re: Rear shock for curvy. Opinions, advice please.
 

Unfortunately, even with the correct springs, you'll either get harsh fork action with heavier oil or poor damping plus dive under braking with lighter oil. Emulators for you, sir. Comparatively low cost satisfaction.

Re: Rear shock for curvy. Opinions, advice please.
 

I have set of used emulators for curvy if you interested for 1/2 price of new ($70).

Re: Rear shock for curvy. Opinions, advice please.
 

richiekuk, if you don't mind, may I have second dips ;)

cheers.

Re: Rear shock for curvy. Opinions, advice please.
 

The .85 fork springs were good for me. If you check the link in my previous post you will see that for 15st rider on a curvy you fall between .80 and .85 springs, .90 will be too much IMHO. I went with .85 on mine because I took pillions, so a bit of extra beef was ok.

I used 15wt oil, but remember because of the emulators (which are adjustable) I was able to tune compression damping to match the oil and alter the oil weight to suit the rebound damping, thus giving a smoother much better damped ride.

Zadar's offer of the second hand emulators is good, will work out less than half the price of the ones. They do not wear out, so don't worry they are not as 'good' as new ones. Zadar knows a lot about suspension on SVs, worth listening to him.

Re: Rear shock for curvy. Opinions, advice please.
 

I have .85 in mine. I could go up another half or rate to .90 or so without much issue. I am 12.5 stone.
But that is with long rear shock.

Whatever you do I would drop the yokes down as far as you can get away with.

Re: Rear shock for curvy. Opinions, advice please.
 

But would you have .85 in standard curvy forks Chris? With a heavier oil in there for the damper rods to actually do something, wouldn't that be harsh on broken surfaces? I'm assuming you are using a much lighter oil in the GSX-R forks you have fitted, with the valving set to suit? Not saying you are wrong, just that the OP may not want such a racy set up. :D

Re: Rear shock for curvy. Opinions, advice please.
 

Thanks for all the advice and Gen guys. My head hurts!
I am at a loss to really understand what emulators do, even after reading lots about them.
Having not ridden my bike for a while I am struggling to remember its weaknesses anyway. Need to get out and about so I can get a feel for her again.

Richie K

Re: Rear shock for curvy. Opinions, advice please.
 

Oil in mine is 5wt RSF. But because it is cartridge/shim damping there is actually much more damping.

You want the springs stiff enough to absorb hits, especially as the lack of comp damping means you are relying entirely on the springs for support on brakes. either rate will be a huge improvement. even more so with emulator valves.

Only difference which may or may not be significant is fact my setup means more weight is on front and rake angle is reduced. Probably will make some difference. It was about 4 turns of preload to get same sag when I changed from SRAD shock @350mm to ZXR shock @335mm. That was pretty significant change in ride height.


Emulators let the hydraulics help the springs out. They have a spring loaded valve, so when you brake oil flows through a bleed hole in valve, causing a pressure loss which resists the front end diving. When you hit a big bump the pressure spike overcomes the spring preload on the valve, letting it pop open and allow the wheel to move without damping.
On rebound stroke the valve closes again and the forks normal rebound stroke takes place.

Re: Rear shock for curvy. Opinions, advice please.
 

Problem with stock forks is when you ride over a dip, the fork does not extend, whole bike drops into the hole, then inertia squashes the fork springs down to the hydraulic locks, and then the springs push the bike back up but uncontrolled so you get a couple of bounces as it recovers.

Re: Rear shock for curvy. Opinions, advice please.
 

Cheers Chris. I sort of get it now. Why do people weld up the rebound hole on the damping rods and extend the compression holes?

Richie K

Re: Rear shock for curvy. Opinions, advice please.
 

Idea is you want the emulators to do the compression damping job not the holes... so you extend them to the point they don't affect flow.
They braze the rebound hole because there is enough free bleed that you don't need it there.

Re: Rear shock for curvy. Opinions, advice please.
 

Extending (enlarging) the compression holes is easy, it is to make them in-effective and allow oil to flow un-restricted. The emulator then takes over compression damping duties.

Welding up the rebound hole is full of debate. The idea is that the SV forks are underdamped, so that needs to be increased. Closing the rebound hole means that oil has to force / leak it's way past the valve assembly (I think) which slows the rate and so increases damping. Lots of folks argue that this is imprecise and a waste of time. In general for road riding this is overkill IMO.

Re: Rear shock for curvy. Opinions, advice please.
 

Zadar says to weld it up, is good enough for me :-P

Re: Rear shock for curvy. Opinions, advice please.
 

Would a garage know to enlarge the compression holes?
I wont be able to do the job myself as I am an electrician, and have no real knowledge of suspension!
Are the emulators top adjustable (as a proper set of shocks), or do you have to pull the forks apart to adjust them?

Sorry for all the questions, I need to have everything in my head sorted before I mess with as perfectly servicable motorbike.

Thanks

Richie K

Re: Rear shock for curvy. Opinions, advice please.
 

No. you can only adjust emulators by fishing them out of the forks and adding preload to valve spring.
Rebound adjustment is done by oil weight.

Enlarging compression holes is easy, you just drill them and deburr. Sure it's no harder than fitting socket boxes or whatever :-P

If you need external adjustment you need AK20s which are pricey or GSXR front end.

Re: Rear shock for curvy. Opinions, advice please.
 

Enlarging the compression holes is in the fitting instructions for the emulators. I'd be annoyed if they didn't follow them! The emulators can only be adjusted by fishing them out of the forks, but that is not so bad.

As an electrician you are a practical bloke, this really is within the capabilities of a DIY mechanic. I'm a computer geek, but I managed it no trouble.

Re: Rear shock for curvy. Opinions, advice please.
 

To be honest, i'm more lazy than incompetant. Its because I dont understand air gaps, sag, etc. All these terms are new to me.
I've been looking for a how to with pics, but can't find one anywhere.
My friend is probably more than capable of showing me what to do, but he's out of the country at the moment, and I dont realy have the facilities (maybe tap someone up for the use of their garage).
Or any fellow orgers fancy a nice job with plenty of tea (or stella), whichever is ya poison!

Richie K

Re: Rear shock for curvy. Opinions, advice please.
 

Righto, just bought these lovely items:

http://shop.ebay.co.uk/?_from=R40&_t...All-Categories

http://www.k-tech.uk.com/product_detail.php?id=49

Just need some emulators (from ZADER) and some oil, any recommendations on oil weight?

Thanks

Richie K

Re: Rear shock for curvy. Opinions, advice please.
 

If it's any use, I bought an 08 ZX10 shock, I'm 15.5 stone. The shock is standard & I dont have any issues with it at all, best thing I did was get rid of the original one.

Re: Rear shock for curvy. Opinions, advice please.
 

Bunged an 04 ZX10r shock on my curvy teh other week. Huge improvment over teh standard SV one. its nice to have actual damped suspension again, albeit at one end only! :)

Re: Rear shock for curvy. Opinions, advice please.
 

Rebound has almost nothing to do with valve. Oil just flows between two chambers under valve, back and forth. Valve (emulator) has check plate that opens whenever fork is in rebound stroke to refill damper rod for compression stroke.

Fitting instructions tell you to drill two more holes. Better way is to make existing holes bigger.

Oil weight will depend on springs you use. With softer springs you use thinner oil. Oil weight will control your rebound and should match spring.
Another factor with oil weight is outside temperature, on cold days thinner oil is better and on hot days thicker.

Re: Rear shock for curvy. Opinions, advice please.
 

Here is picture for record. Did not have curvy damper rod handy and used pointy but it is all same thing. Plastic piece on left is hydraulic lock on curvy, on pointy this piece is metal and little different shape.
http://i141.photobucket.com/albums/r...mperrodmod.jpg

Re: Rear shock for curvy. Opinions, advice please.
 

And here is why we close rebound hole. Black line is fork tube, green square is seal between tube and damper rod and second seal is ring on top of damper rod. This two points are where oil leaks more than we like.

http://i141.photobucket.com/albums/r...perrodmod1.jpg

Re: Rear shock for curvy. Opinions, advice please.
 

Change the front as well you can use zx6r front or GSXR I believe.

http://canyonchasers.net/gallery/tra...SC01654?full=1 - zx front

http://canyonchasers.net/shop/sv/636-forks.php - how to do it

Re: Rear shock for curvy. Opinions, advice please.
 

Zadar, shall I just get the rebound hole welded closed? Does it have to be perfectly smooth when its been welded up. I dont know anyone that handy with a welder!

Richie K

Re: Rear shock for curvy. Opinions, advice please.
 

Easier to braze it then polish it back smooth with fine wet and dry. I'm not sure that part is actually swept by seal anyway.

Re: Rear shock for curvy. Opinions, advice please.
 

I think trying to find someone to braze it willl be more difficult than welding. lol

Richie K

Re: Rear shock for curvy. Opinions, advice please.
 

All you need is a gas torch and a rod?
If you've got a torch I can send you a bit of brazing wire.

Reason I would braze is it is easier to file back to smooth

Advantages of welding is heat is much more concentrated so you can probably get away without removing the seals.

Re: Rear shock for curvy. Opinions, advice please.
 

I remeber doing brazing at school (many years ago). Would the molten brass not just spill into the tube (not necceseraly staying in the hole to be blocked)? Does that make sense?

Richie K

Re: Rear shock for curvy. Opinions, advice please.
 

No it should be viscous enough to fill the hole.

If you get stuck you can send them to me to TIG or braze, whatever zadar reckons is best way or your choice.

Re: Rear shock for curvy. Opinions, advice please.
 

Im fine with tools, but do not own a gas torch or anything of the like.

Do these holes definately need filling, seems like alot of hassle. (its one of those, never done it before, so am a bit dubious).

YC, I could probably drive to you, and back in only a few hours. This might be better as I dont want to take up my friends garage for any longer than is needed with a bike hanging from the roof. lol. Wouldnt be for a good for weeks though, as he's out of the country untill March 21st.

Richie K

Re: Rear shock for curvy. Opinions, advice please.
 

Drive up on the bike?
you're better off leaving it for a while if you can't do stuff at home, it's freezing here and my drive's iced over anyway.

Re: Rear shock for curvy. Opinions, advice please.
 

No, I'd strip the bike at my friends. Bring up the damping tubes. Let you braze them, and take them away and fit them myself.

I f you've done them before, I'd rather that than me **** them up.

Richie K

Re: Rear shock for curvy. Opinions, advice please.
 

I haven't.