The Robert Taylor suspension thread

**Robert Taylor** · 8th August 2007, 00:02

Originally Posted by Drew

Fair enough, with said two fingers, tell me if it's a dumb question though, I'd rather not ask it in public where people can SEE me go bright red as I proclaim myself an idiot.

All questions are good questions, I think I can fairly say that I have an accomodating and approachable demeanour and will give honest answers to honest questions, from my own experience and accumulation of knowledge that has been derived from working with lots of riders, and ongoing dialogue with the engineers at Ohlins in Sweden.

All of who at all levels have something useful to say.

**roogazza** · 8th August 2007, 10:07

Originally Posted by Drew

The front forks diving to the end of thier travell under brakes, decreases the fork rake, making the stearing quicker, then as you pitch the bike over, the bike levels off, but not completely, which still leaves you with more feel, then on the exit they extend fully, giving a far less twitchy bike than when they are steep. Also, the freedom of movement allows more traction than a stiff shock. So how are all these things bad?

Eureka ! sounds just like the basics of how a bike works to me ? Now , we have to control all those functions ! Gaz.

**Drew** · 8th August 2007, 18:10

Originally Posted by roogazza

Eureka ! sounds just like the basics of how a bike works to me ? Now , we have to control all those functions ! Gaz.

My point was it makes sense to me, that the softer the better, not weather I think the bike is doing is what's actually happening. But the sarcasm was well funny

**Robert Taylor** · 8th August 2007, 18:20

Originally Posted by Drew

My point was it makes sense to me, that the softer the better, not weather I think the bike is doing is what's actually happening. But the sarcasm was well funny

Its actually a balance between compliance and grip. It should not be so soft that there is a''disconnected'' feel etc. Suspension SHOULD move, but controllably. It is possible to have both compliance and grip.

**Drew** · 8th August 2007, 18:41

Originally Posted by Robert Taylor

Its actually a balance between compliance and grip. It should not be so soft that there is a''disconnected'' feel etc. Suspension SHOULD move, but controllably. It is possible to have both compliance and grip.

Yep, I get that too, we'll continue with the extended answer to why, at one of the seminars.

**Paul in NZ** · 14th August 2007, 09:15

Well.... I've put spectro 20w oil in the front, got the tyre pressure about right and I plan to back off the rear shock on the 88 FZR400 a little more from it's current hard as it goes thunk thunk status... What else (if anything) can affordably be done to improve these bikes suspension. Currently the engine rather easliy overcomes it's suspension and since it will probably be purchased by an inexperienced rider I want to do my best to make sure it's as good as it can be without going into bankruptcy...

**Robert Taylor** · 14th August 2007, 13:09

Originally Posted by Paul in NZ

Well.... I've put spectro 20w oil in the front, got the tyre pressure about right and I plan to back off the rear shock on the 88 FZR400 a little more from it's current hard as it goes thunk thunk status... What else (if anything) can affordably be done to improve these bikes suspension. Currently the engine rather easliy overcomes it's suspension and since it will probably be purchased by an inexperienced rider I want to do my best to make sure it's as good as it can be without going into bankruptcy...

Paul, thats pretty much all you can do without spending money. At both ends the weight ( and to a degree height ) of the rider is going to determine whether the fitted springing is ''livable'' or way off the mark. Its great you mention ''engine overcoming the suspension'' Torque induced squat is always one of the factors we have to contend with, especially on the litre class bikes.

The rear shock has fairly rudimentary internal valving, it could be improved but it inevitably costs money as a full strip is neccessary. Squat control is something that involves playing with shimming, more so than springing. There is always a danger of overspringing and creating other issues rather than dealing with the valving. A few years back Andrew Stroud was having a squat problem coming off one of the turns at Invercargill, we didnt touch the spring or the clickers, we lifted the lid on the shock and altered internal shimming a little bit. Job done, and in deference to a reference elsewhere this works just as well for ''rockstars'' as it does for everyday riders ( who provide most of my bread and butter! )

The big achilles heel of damper rod forks is you have to run quite thick viscosity oil to control rebound stroke. ( Note that emulators only really address compression stroke deficiencies ) Whilst there is very often a rebound control hole drilled in the damper rod the awful truth is there is a lot of ''loosely toleranced'' bleed past the piston ring, around the check plate washer inside the fork tube and in other ''clearanced areas. This neccessitates a thick oil. Unfortunately these thick oils are more sensitive to the atmospheric temperature of the day, and forks run at that temp or slightly below. This can often mean that on a cold frosty morning the forks are very ''lethargic'', especially in rebound. But in the middle of the day when the sun is out and temperatures in double digits the fork action is a lot faster.

Summer to winter does require a viscosity change, and be aware that many of the budget fork oils have a narrower range of compatibility with temperature change.

SV / ER650 pilots please take note! Hope this all helps....

**Paul in NZ** · 14th August 2007, 13:22

Thanks for that...

Initially i thought it was the front that was terrible (well it is but..) but I think the rear is over sprung and under damped which makes the front feel worse than it is!

So - can a shock from a 1988 FZR400 actually be rebuilt??? If so - what would it cost and would it be worth the effort??

The front end is tricky - it's not bad if the road is smooth but if it hits a bump mid corner - look out! (I've only done 150km on it so this is just an initial observation) Given that most FZR400's end up on the track, there MUST be some mods to be done? I know the SP model has a more sophisticated set up...

Its quite interesting really - one day I'd like to try and fit modern internals to some older forks - my experience from my Moto Guzzi tells me a few minor mods can make a big difference..

Either way I need to sort the fueling first and try to get the bike right - it's got all the elements of a fun bike - modest weight and power in and exciting chassis but its got to be done on a budget.... ;-)

**F5 Dave** · 14th August 2007, 13:32

Jap imports are usually undersprung. With your Manly proportions it would be interesting to see where the bike is sitting under usual riding conditions.
Wrapping a cable tie around the forkleg (they usually never get full stroke showing) & sliding the bump rubber up on the shock (may require a cable tie around it if it isn't very tight, then go for a sedate ride not hitting large bumps or braking heavily. This should tell you if you are flattening it & bouncing off the bumpstops. [mental picture of a Walrus humping a seal pup- arrrgh!]

Also with 'stiff' rear ends it is worth propping the back up & either removing of undoing the rear shock to see how well the swingarm moves unhindered. I'm sure more than one story will emerge with people trying to tune this out.

**Paul in NZ** · 14th August 2007, 14:58

Thanks Dave - thats very good advice... It will give me a chance to grease all the linkages and other assorted things down there as well - Oh goody - more laying about on concrete floors.. (sigh)

I guess it's not a huge job?? I mean at least not a huge job for a walrus?

**F5 Dave** · 14th August 2007, 15:44

haha sorry Paul, you know what I mean though, those 400s are small.

Yeah I'd try not to open the can of worms further than you have to. Linkages can get quite costly to rebuild. I'd just check to see that it doesn't feel tooooo bad.

As far as single shock systems go while the KTM approach has its disadvantages (& I'm sure RT would have comments bordering on derogatory) the more I have to do with the maintenance of linkages, esp on dirtbikes, the more I'm given in a dark moment to wonder if it really isn't worth the loss of performance to trade to the ease of maintenance (the KTM is direct mount to SW).

**Paul in NZ** · 14th August 2007, 15:52

Hmmm Walrus... Wadda ya thunk? Should I grow one o dem american chopper paul senior mostaches? Not sure Vicki would like it much..

**Robert Taylor** · 14th August 2007, 18:02

Originally Posted by F5 Dave

haha sorry Paul, you know what I mean though, those 400s are small.

Yeah I'd try not to open the can of worms further than you have to. Linkages can get quite costly to rebuild. I'd just check to see that it doesn't feel tooooo bad.

As far as single shock systems go while the KTM approach has its disadvantages (& I'm sure RT would have comments bordering on derogatory) the more I have to do with the maintenance of linkages, esp on dirtbikes, the more I'm given in a dark moment to wonder if it really isn't worth the loss of performance to trade to the ease of maintenance (the KTM is direct mount to SW).

Sorry to dissapoint, the loss of a linkage transfers the complication into the insides of the rear shock. In terms of top level road race, linkage systems are very much in vogue, despite the external complication. Maybe another day I will elaborate. But also, if the linkless system is such a great leap forward why havent all the other manufacturers of MX bikes followed suit? I think thats a fair question without any political sentiment.

Paul, after deciding whether the linkages are servicable a full measure up will determine if the spring rates are ''in the window'' or otherwise for you.

If you are going to be at Manfield Friday / Saturday I will be happy to measure it for you. There is no charge for this work.

In the front it is also blowing through its stroke hydraulically. If you speak to anyone of the now hundreds of people we have supplied and fitted emulators to they will tell you that this is a great bang for buck mod.

The shock would indeed be servicable and modifiable ( within the limitations of stock ) but I would need to determine first if there is a spring rate issue and if it is a model that has ''checkplate'' damping rather than proper shim stacks.