Alternative shock linkages

There seems to be more and more members appearing that are racing the ZXR400 so i've created a special section just for you to show off results, discuss meets etc etc.

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Tirpitz
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Alternative shock linkages

Post by Tirpitz »

Although this is a suspension question I've put it in here as I think the racers will have more experience of this kind of fiddling.

So here goes - those of you who know me will be aware that I've owned my L4 from new. The suspension was fully serviced not that long ago and I fitted a new Nitron Sport shock built for my weight. This improved the back end of the bike over the OEM shock. Of course, the thing with just riding the one bike is you get used to its weaknesses and don't realise how bad they are......

Fast forward to now. I've recently finished restoring a GSXR750L and I upgraded the suspension with a Nitron Sport while I was at it. I've been riding that bike exclusively for several weeks setting it up and the other day took the ZXR out again. I was shocked (excuse the pun) at how bloody awful the back end on the ZXR is. Compared to the Slingy it just gets kicked about all over. You would expect a 400 to be a better bike on bumpy back roads than a heavy 750 but actually the Slingy pisses all over it as the suspension is way better.

So my question is, what can be done by way of further mods to improve the ZXR rear? I'm aware that the fundamental problem is that the rising rate of the suspension is not very good. I've heard about aftermarket linkages being available but an internet search throws up no suppliers. I've also heard that H linkages can be used but do these make any difference? And will the Nitron shock need changing in any way to suit any new linkages?

All advice most welcome.
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KwakKwak
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Re: Alternative shock linkages

Post by KwakKwak »

I've heard of the H linkage thing too, and am about to sell a professionally serviced one, it's mint with all grease nipples in tact etc, but I never actually tried it on the bike as I fitted an Ohlins which improved things mahoosively.
The rear end of the ZXR is indeed turd on the standard shock, rebound happens in instalments, bloody awful, I also completely stripped the rear and cleaned greased etc and replaced the bearing sleeves in the tie rods which helped abit on the standard shock.
A sunken manhole mid corner on the standard shock is quite thrilling, if you're into that sort of thing.

I've now changed the rear again, to a 600RR :pmsl so much nicer.
Does the low seat height reflect the low intelligence? Easier to get an asshole onto.
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Re: Alternative shock linkages

Post by cargo »

Suspension is a black art and only a very few truly know what the fook is going on with it.

I'm no expert but I know what I like a bike to feel like underneath me.

The standard set up is really awful. It really amazes me when I read about guys on here spending money of bits that will give nothing more than a very few extra horse powers ( if any at all) when the real problem lies in the crappy suspension.

I only have experience of the standard shocks including the SP ( I have one stashed away ) and of course Ohlins.................(got 3 of those little babies now on my ZXRs)

There is some variation in the stock linkages but dont ask me which is which or which is better. What I defo have found with all my bikes is that I very much prefer a lighter spring compared to what my suspension guru reccommends. This was also the case with my old Steelie ( it has an Ohlins too)
I just fitted the lighter spring and found there was an improvment.
Changing the linkage can have the effect of fitting a lighter spring of course the reverse is also true...............the variables are huge.

As a first step I would try a lighter spring..............most suspension places will do an exchange for you old spring plus a few quid.

And whatever spring you have get the static sag set up then adjust dampening and recheck sag after
From memory I have some thing like 8 mm of static sag
And as a basic starting point you want the rebound set so that the shock settles back to it's starting point quickly without an extra bounce.
Compression dampening is not so important just set it so it isn't too squishy..............nicely controlled is how it should feel.

There is no doubt that more modern bikes have much much better set ups than the bikes of 20 or 30 years ago and the gap between stock shocks and the likes of Ohlins is closer now days.

I've just done a count.........................6 Ohlins in my garage and a SP shock........................no wonder I'm poor
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Tirpitz
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Re: Alternative shock linkages

Post by Tirpitz »

There's a few suspension places not too far from me with good reps which do set up for not many quid. I think as a first step I might go see one of those as they would also be able to exchange the spring if I decided to go down that road. They might also know something about alternative linkages.

I don't know what the static sag is on the shock, I never checked, but as it was built for the bike and Nitron have a good rep I would guess it's pretty good. The rider sag needed a little bit of tweaking after I fitted it which I adjusted with the preload. I'm running one click more than as supplied by Nitron on the rebound / compression damping (it is combined on the Sport shock) as it pogoed slightly as supplied on bumpy roads. That improved things.

As I've had the shock for a couple of years now I might recheck the sag I'm running. Might be worth backing the preload off a touch and see if that helps.

What surprised me is that the Gixxer I've just restored is a four year older model than the ZXR. In the 90s 4 years of bike development was equivalent to a decade today. Yet the suspension is waaay better than the ZXRs'. I'm afraid Mr Kwak got his sums seriously wrong with the rising rate on those linkages.
ZXR400 L4, purple / black / pink
Hel braided hoses
Pirelli Diablos
Ohlins steering damper
A16 carbon fibre exhaust can
Nitron Sport shock
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Re: Alternative shock linkages

Post by cargo »

Tirpitz wrote: I'm afraid Mr Kwak got his sums seriously wrong with the rising rate on those linkages.
He certainly did

My 750 H was exactly the same

The suspension was as hard as a whores heart
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Re: Alternative shock linkages

Post by jake »

Its been a while since I fiddled a zxr, but its the h2 linkages you want.
All 3 model zxrs linkages are different, the h2 being the most linear if I remember.
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Re: Alternative shock linkages

Post by Tirpitz »

Cheers Jake. I had heard the H linkages were better but wasn't sure if this was cosha. That would be a cheap fix. I'll give it a go.
ZXR400 L4, purple / black / pink
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Re: Alternative shock linkages

Post by AFM327 »

I have an H2 link on my bike, I also have an aftermarket link, it's the same. It is more linear, you still need a light spring and appropriate valving. With the L link I couldn't run a soft rear without tearing no matter how hot it was, with the H link I can run a soft. I'm 215 lbs without gear, I have a 425 lb spring on my bike, penske shocks for me, I can do a spring change without any extra tools. Don't ask me what that is in Kg or Newtons? :) I'm thinking about putting a light fast kid on my bike, thinking I'll need a 350lb spring in the rear. Anyone know any fast kids racing that I could find out what they might be running suspension wise.
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Re: Alternative shock linkages

Post by Tirpitz »

Bear in mind this is for road use. So, are you saying that if I fit the H2 link I will need to have my shock resprung? It's Nitron Sport shock built for my weight for the bike. Would they have supplied it any different if I had specified it was for a H2 rather than an L? Suppose I could give Nitron a ring on Monday and ask them.
ZXR400 L4, purple / black / pink
Hel braided hoses
Pirelli Diablos
Ohlins steering damper
A16 carbon fibre exhaust can
Nitron Sport shock
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Re: Alternative shock linkages

Post by alanh »

mine has a custom shock linkage, not the 'dog bones' but the bit with the 3 bearings that attaches to the frame, shock and swingarm itself will have a look and see who its made by. Its the best handling zxr I've rode by far but also has a wilbers shock which my last one didnt
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shaggy69
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Re: Alternative shock linkages

Post by shaggy69 »

There is of course the fabled NWS linkage that is on the table with rocking horse poo and hens teeth, although the H1 linkage is almost the same ratio...I may have a spare
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Re: Alternative shock linkages

Post by alanh »

NWS, that's the one that's on mine. Rare you say? it worth a few quid then? :smt003
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Re: Alternative shock linkages

Post by shaggy69 »

They welded and painted black usually....pretty much the same ratio as H1 rocker. Last one on eBay went for about £50
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Re: Alternative shock linkages

Post by alanh »

Yeah this one's black, good to know cheers
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Re: Alternative shock linkages

Post by AFM327 »

Yep, I have an NWS and it's the same as an earlier model stocker, I thought it was an H2 model. Road or race you'll want it sprung and valved for you if you want it right. Everything else is a compromise.
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