vfr700 rear shock spring rate

hi guys does any one happen to know the stock rear shock spring rate of a 87 vfr700

mucho thanks

 

I'd like to know, too. Just what the hell spring did Honda put in these things?

 

Its around 170Newtons or 980Lbs

Front springs are about 0.65kg/mm std, I run 0.95kg/mm now and still not massively hard

 

Hey, thanks for the info.
Can I ask were you found it? I've searched and searched and came up empty.

 

I have an Ohlins shock with the wrong spring so I called Ohlins and they looked up the correct rate which is 170Newton metres, very hard becausee VFR's have a high linkage ratio.

I put some race tech 0.95Kg/mm springs in my 86 750

 

It sure would be nice if someone would make a chart showing lots of different bikes spring rates.

Penske and Ohlins probably have the info, but they don't share.

 

Seek and yee shall find LOL

Spring Rate Chart, Sportbike - Custom Fighters - Custom Streetfighter Motorcycle Forum

RT - Digital Product Search

 

Wait, I see a potential problem here dickypalm. When you called Ohlins did they tell you the factory spring rate or did they ask you what you weighed and then told you the rate they recommended? They are 2 different things.

I've seen these charts before many times. The Penske chart does not show any factory spring rates, only what Penske recommends for certain rider weights. Same goes for the Ohlins charts.

The Racetech does show rear spring rates for certain bikes, but not my bike and it's not in chart form.

I'm guessing no one has actually made a chart of factory spring rates and put it one the web. I might take a few hours and make one up.

 

Also, 170 newton meters per millimeter times 25.4 millimeters in an inch is equivalent to 4,318 newton meters per inch.

That comes out to 1,058 pounds per inch.

980 pounds is 4000 newtons.

Did Ohlins tell you the newton number?

 

Ohlins has the number printed on the spring 170, thats the recomended spring

Its probably a few pounds softer than std but not by much, I have 4 VFR's FG to FK so have a comparison, the Ohlins has much less low speed damping, the std shock has too much rebound damping and shreads rear tyres on the race track but feels reaaly good. Th best mod is to use the 89 shock with 86 linkage/bellcrank to jack the back end up and drop forks 10mm or untill the sliders hit the bottom yoke.

 

Yeah, thats the "recommended" spring. I'm trying to find the "stock" spring rate. I'll probably call Ohlins, Penske and Racetech and see if they will tell me.

What is different with the 89 shock?

 

The 88-89 shock is longer and linkage is shorter by 13mm to give same ride height, so if you use the short 86 bellcrank and longer shock jacks up the back nicely, too low as std

 

A different length shock with the same horrible ride quality is not any kind of improvement. For me at least. My 86 rides way too harshly due to excessive rebound valving. When the road drops, the bike drops out from under me. Then my butt and feet slam back down onto the bike. Cornering on a bumpy surface scares me badly and I have to slow way down.

If I can't find a cheap way to fix it, the bike has to go.

 

I think the online weight converter I used was just plain wrong. I tried a different one.

170 newton meters per millimeter is also 17.34 KG/mm and 38.22lbs/mm.
That comes out to 970 pounds per inch.

 

That sounds better.

A cheap way to improve the rear is to fit a Yamaha R6 shock, various people have done this so scan the forums

 

I'll look, but everything I see about the R6 shock is that it's setup with about a 10kg/mm spring. That's not even close to the 17kg/mm or so we need for the VFR.

 

buy a new spring they are ony £50 from Maxton

 

I did a search for "yamaha" in both this section and in the "Mechanics" section. 16 pages of threads, but no mention of the R6 shock.

Are you suggesting replacing the R6 spring with a stiffer one? You can't do just that. You see, the shock valving is based upon the spring rate. They are matched together with only a small amount of adjustment. So you could go with a little stiffer or softer spring, but I'm pretty sure a 70% increase in spring rate would require a teardown and revalve of the shock. Otherwise the bike would be like a pogo stick.

I was looking for a factory shock where the valving was already in the ballpark. The CBR1100XX Blackbird shock is a 16.8 kg/mm unit with rebound adjustment. I've heard good things about the XX ride quality. The only problem is it's 320mm long which is about 2" more than the stock 86 spring. I would need to fab up new linkage to compensate for the length as well as the different lower mount. See below.

The newer VFR's use pretty stiff springs as well and might be an option.

 

You are absolutely right - you cannot just replace the spring. You would also need to change the internal valving and adjust the stroke length of the shock, plus a few other tweaks in order for it to be correct.

There are lots of easy ways but usually those are not the correct way!

 

I just picked up an '86 750 and have the same hard tail problems but couldn't even contemplate selling it because of the crappy suspension. The bike is just too nice to let it go.

Jamie

It seems like the $300 or so for the CBR929 conversion is a cost effective solution since it comes with a spring tailored to the rider's weight. How much better is that compared to the rework/rebuild of the stock shock option?