kblackburn Posted March 17, 2012 Share Posted March 17, 2012 Hi Guy's I need some help, I have installed the 929 rear shock mod to my 97 vfr, works fine with just myself onboard, I'm a bit heavy 85kg so have the preload wound up to next to max. However, yesterday I had to transport my daughter to work, as her bike had a puncture, wound preload to max and unfortunatly the bike bottomed out, damaging the rear hugger,daughter weighs about 70kg, she's a big lass, tall I mean (before I get slapped), I run the bike with full givi luggage. What I need to know is, what's the internal dia of the shock spring and the free length, and any suggestions as to what weight spring I should be using. kev Link to comment Share on other sites More sharing options...
Baileyrock Posted March 17, 2012 Share Posted March 17, 2012 Hey Kev, kev here! The stock 929 spring is 15.3kg which is I'm guessing stiffer than a stock 3rd or 4th gen. If I'm doing it right you weigh 187 lbs and at that weight the range of spring you need would be in the 19-20kg area. A standard 2.25" ID spring will work and if i remember correctly it's about 7" long. The stock spring does tapper some on one end, but some shim or spacer will allow the 2.25 to work fine. Actually now that I'm thinking about it, I Don't know the rocker ratio of the 3rd or 4th gen rear suspension so my range is based of 5th/6th gen ratio's. BR Link to comment Share on other sites More sharing options...
kblackburn Posted March 17, 2012 Author Share Posted March 17, 2012 BR thanks for the reply, the supplier I have found rates their springs N/mm or lbs/ins, not sure on the conversion, is kg/mm the same as n/mm ? thanks kev Link to comment Share on other sites More sharing options...
Baileyrock Posted March 17, 2012 Share Posted March 17, 2012 BR thanks for the reply, the supplier I have found rates their springs N/mm or lbs/ins, not sure on the conversion, is kg/mm the same as n/mm ? thanks kev No kg and N are not the same but real close. You can Google the conversion needed to correctly calculate though. BR Link to comment Share on other sites More sharing options...
Member Contributer kgsmotorcycles Posted March 17, 2012 Member Contributer Share Posted March 17, 2012 Hi Kev... another kev here..... Am sure i need to re-spring and maybe re-valve my 929 Ohlins shock, VFR converted 4th gen ,....Think its a bit stiff? Have had better performance with cheaper replacement race shocks. Am unsure how to go about it... i have lost a shed load of weight on the bike and have no idea how to calculate the right shock needed. Also use a slipper clutch and wonder what adjustments i might want there also... any ideas? Also considering adding valve kits to the 929 forks..... worth it? Link to comment Share on other sites More sharing options...
kblackburn Posted March 17, 2012 Author Share Posted March 17, 2012 kgsmotorcycles, kev I've been running the 929 rear shock , in standard form, for the last 3'000 miles and until yesterday did'nt have a problem. It was only when I took my daughter to work that we had a problem, in that the rear hugger touched down on the rear subframe, over a fairly large undulation in the road, it handles absolutly fine solo, so much so that i can keep up with my mate (james ellison) when we have a ride out together. However, two up becomes a problem, so i think i'm going to try a stronger rate spring to get my sag figures back in spec, for a loaded bike. so have you got an ohlins shock or ohlins spring? kev ( just across the water near Arnside ) Link to comment Share on other sites More sharing options...
Member Contributer kgsmotorcycles Posted March 17, 2012 Member Contributer Share Posted March 17, 2012 hi kev.. Looks like you are loading up your VFR passengers, luggage, huggers, etc. Thats a lot and you will be close to the limits, which are normally great within a full range of riding activities. Using a 929 full race ohlins unit. Have also been riding using the shock with out too much problem... But.. I know there is a lot more to come yet as i have had a number of different shocks on the VFR and know for a fact it can perform better. When the rear is working well it does so amazingly well..... I notice mainly when i go round the TT course, at the Creg which is a fast knee down right hand normally, i have lost traction on the exit - to the amusement to pub followers present.(nothing like having a pub on a race track.) Also on the short circuit track i feel there is better to come yet as the EMC shock i used was a far better performer, road or race! Even 2 up it performed very well. When things are smooth and responding well at 150mph no question you know things are set. Normally happens for me with the correct set up especially on the rear and good rubber. Link to comment Share on other sites More sharing options...
kblackburn Posted March 17, 2012 Author Share Posted March 17, 2012 Hi Kev, I 'm just about to start as an escort rider for the national escort group, british cycling outrider for national cycling events, hopefully tour of britian, unfortunatly I missed out on the escort duty for the olympic's this time, so need the capabilty for luggage and some times a passenger.Could really do with a pan european, but funds won't go that far at the momment. Link to comment Share on other sites More sharing options...
kblackburn Posted March 17, 2012 Author Share Posted March 17, 2012 ok guy's just bought a spring, 7" length 2.25 internal dia and rated at 1100lbs/inches or 192n/mm so 19.5kg/mm, just hope thats ok Link to comment Share on other sites More sharing options...
timmythecop Posted March 17, 2012 Share Posted March 17, 2012 Where did you buy the spring? Link to comment Share on other sites More sharing options...
kblackburn Posted March 17, 2012 Author Share Posted March 17, 2012 timmythecop, I have purchased the spring from Demontweeks,uk company ,total cost £46.00 delivered Link to comment Share on other sites More sharing options...
Baileyrock Posted March 17, 2012 Share Posted March 17, 2012 ok guy's just bought a spring, 7" length 2.25 internal dia and rated at 1100lbs/inches or 192n/mm so 19.5kg/mm, just hope thats ok Sounds about perfect! Link to comment Share on other sites More sharing options...
kblackburn Posted March 24, 2012 Author Share Posted March 24, 2012 Well spring arrived, it's slightly larger than the stated 2.25" internal dia. So I removed the shock from the bike, purchased a set of spring compressors, and set about removing the spring, got it off the shock, standard 929 spring internal dia is 2" and not 2.25" and is a snug fit to the shock body, the new spring will not sit central on the shock without making up a collar, and as the heavier spring is made from larger dia coils, it will run very close to the swing arm if not centered, and possibly foul the swing arm, so I have had to refit the standard spring back on, as I do not have any machine shop facilities,anybody need a 1100lbs spring ??? Link to comment Share on other sites More sharing options...
NakedViffer Posted March 24, 2012 Share Posted March 24, 2012 Yes, actually, thats exactly what I need. What do you want for it? Link to comment Share on other sites More sharing options...
kblackburn Posted March 25, 2012 Author Share Posted March 25, 2012 well it cost me £46.00 and I've only taken it out of the packaging, not sure about shipping costs to the USA, would imaging it would be fairly expensive, just looking to get my investment back, plus shipping costs Link to comment Share on other sites More sharing options...
tinkerinWstuff Posted March 29, 2012 Share Posted March 29, 2012 Well spring arrived, it's slightly larger than the stated 2.25" internal dia. So I removed the shock from the bike, purchased a set of spring compressors, and set about removing the spring, got it off the shock, standard 929 spring internal dia is 2" and not 2.25" and is a snug fit to the shock body, the new spring will not sit central on the shock without making up a collar, and as the heavier spring is made from larger dia coils, it will run very close to the swing arm if not centered, and possibly foul the swing arm, so I have had to refit the standard spring back on, as I do not have any machine shop facilities,anybody need a 1100lbs spring ??? I ran into the same problem doing this on my DR650. Nothing was exactly what it said on paper. Ended up fabricating a collar and got it to work. Link to comment Share on other sites More sharing options...
Member Contributer JamieDaugherty Posted March 30, 2012 Member Contributer Share Posted March 30, 2012 The 7" spring too long for the 929 shock, you'll need a 6" long part with a spacer to generate the correct amount of preload. Also, an 1100lb/in spring is pretty heavy for your weight, I would suggest a 1000lb/in spring instead. Good luck! Link to comment Share on other sites More sharing options...
kblackburn Posted March 31, 2012 Author Share Posted March 31, 2012 Thanks jamie, I will be using the givi hard cases most of the time and pilion 50% of my rides, with pillion weight of around 60-70kg, so I thought the 1100 spring would be more in line with the additional weight.I presume I will need to up the rebound damping a notch or two and reduce the compression damping a touch, to compensate for the heavier spring.I will be intouch shortly for a spacer. Link to comment Share on other sites More sharing options...
Member Contributer JamieDaugherty Posted April 1, 2012 Member Contributer Share Posted April 1, 2012 The hard bags do factor in for sure, but I normally suggest not taking into account any passenger weight unless they ride with you 100% of the time. When riding a passenger you won't be able to push nearly as hard as by yourself, so there is no sense setting it up for that (and sacrificing the performance when riding alone, when you need it). In these cases I would recommend making sure you have enough preload adjustment to allow you to bump it up when a passenger is on board. 1100lb/in is not terribly out of the ballpark, so it's certainly worth a try. Everyone is different so you might actually prefer it. As for damping, you'll need to increase the compression. The higher spring rate won't do much to control the damping, so when you need more spring you also (generally speaking) need more damping too. The stock valving's biggest weakness is excessive high speed, and increasing the external low speed adjustment will only make that worse. The low speed adjustment does have an effect on the high speed range too. The only way to really make things "right" is with replacement valving. Link to comment Share on other sites More sharing options...
kblackburn Posted April 3, 2012 Author Share Posted April 3, 2012 jamie, are you saying the 1000 spring is more suited to my weight regardless of the givi hard luggage, which is always on the bike, all be it not loaded up all the time,it's just that following your reply the other day I returned the 1100 spring in exchange for a 6" 1000 spring which is due to arrive today, kev Link to comment Share on other sites More sharing options...
kblackburn Posted April 7, 2012 Author Share Posted April 7, 2012 Well spacer machined, didn't realise a mate had a lathe, so I made a spacer yesterday. Measured the original 929 spring and the made spacer and the new spring(1000lbs/in) to same length as the 929, plus 2mm. So now have 10mm free sag and rider sag of 15mm, so total sag 25mm, with preload ring on setting 3 from base setting, so plenty of scope for luggage and pillion. Many thanks for all the replies and info, big thanks to Jamie :fing02: :fing02: Link to comment Share on other sites More sharing options...
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