Fork spring rebuild queries

[Egee]

After stripping down my series 3 TV forks, I intend to replace all of the spring assembly etc. The rubber buffers are bolt-in, the lower buffers are bigger than the upper but both are considerably flattened. I note that some suppliers are asking if the forks are for disc brakes, if so, then different sizes are suggested, i.e. 20mm - does this include the steel mounting bracket bonded to the rubber? Also. are uprated springs worth the effort and which way round are they fitted, narrow pitch coil up or down? Still looking for a reputable spring compressor, the last model I tried nearly wrecked the casing! Any help would be gratefully received.

[Warkton Tornado No.1]

Unfortunately, it is my belief that up-rated springs can vary in quality. Good ones are worth having, IMHO.

My own experience has found none better than original Innocenti TV175 S II but they are rare, as are the fork links, although they don’t have to be used together.

However, with no clear instruction upon which way up they go, I’ve always fitted the heavier part @ the bottom, which means the closely coiled part is lowest.

I hope that helps.....

[HxPaul]

I have a series2 and 3 with progresive springs,I've fit both pairs with the tightly wound part of the spring to the top.This is how MB say they should be fit,but the most important thing is that both springs are fit the same way around.As for the buffers,I always fit large buffers,top and bottom.I have a fork spring compressor that I bought from Buzzsolomoto,I have had it for some time and used it quite often and up to now its been fine.

[Warkton Tornado No.1]

I’ve just trawled t’internet & opinion varies on bike forums.

There are opinions on having a low C of G or lower un-sprung weight, which are obviously opposite to one another.

TBH, I doubt there’s any noticeable difference in either way, but it would be best to have the pair with the same orientation

[dickie]

Fit them any way you like.

Valentino rossi couldn't tell the difference.

Stiffer springs are much better and soft ones aren't necessary on the comparatively smooth roads we ride on compared to the sixties. Especially if you fit dampers with a higher rate to stop them springing back at your chin.

[HxPaul]

I have to take issue with you on your last statement,I rode a scooter in the sixties and I can asure you that you didn't have to keep one eye on the road looking for potholes.

[dickie]

I’ve just trawled t’internet & opinion varies on bike forums.

There are opinions on having a low C of G or lower un-sprung weight, which are obviously opposite to one another.

TBH, I doubt there’s any noticeable difference in either way, but it would be best to have the pair with the same orientation

You could lower your cog to similar effect by putting your phone in your trouser pocket instead of your breast pocket. However, it would still be sprung mass which is nice. But lowering your cog also reduces stability. If you want a low cog (for example to tip into a corner quickly) just put your chin on your headset and it will be much much more effective than turning a spring round.

The unsprung mass that your suspension has to deal with is a complex area and not really one we need to worry about (IMHO). That is unless we start looking at FAR more significant factors like alloy rims, tubes and tyre mass.

It's a big complex area and makes diddly-squat difference unless you're racing. And racing well as well.

[dickie]

I have to take issue with you on your last statement,I rode a scooter in the sixties and I can asure you that you didn't have to keep one eye on the road looking for potholes.

It's not about potholes; you're f#cked either way on that one. Unless you want to fit trials bike suspension and 21" wheels. It's about the lower amplitude variations on the surface which modern Road laying techniques have massively reduced.

[HxPaul]

I have to take issue with you on your last statement,I rode a scooter in the sixties and I can asure you that you didn't have to keep one eye on the road looking for potholes.

It's not about potholes; you're f#cked either way on that one. Unless you want to fit trials bike suspension and 21" wheels. It's about the lower amplitude variations on the surface which modern Road laying techniques have massively reduced.

I dont understand any of that,I just know that I would rather ride a scooter on the roads of the 1960's than on the roads of today.

[Digger]

Modern road laying techniques?

Scrape the top off and throw a bit more tarmac on?

[dickie]

Modern road laying techniques?

Scrape the top off and throw a bit more tarmac on?

I don't understand the point of your comment. Are you suggesting that nothing has changed in this field in 50 years? If so, then you're mistaken. Railway lines are much straighter and smoother than they were 50 years or even just 20 years ago, primarily due to the computer revolution. My car is much better than the beetle I first owned but in essence it just makes a crank go round by burning petrol rapidly and using the resultant energy to turn the wheels.

I'm not trying to be smart, but it's pretty much impossible to explain mechanical dynamics in suspension in a meaningful way on a forum where there is surely a huge variation in understanding. That's why I used the phone in the pocket and chin on the headset examples; they're real world and you can try them yourself.

What I'm trying to say is yes, things may make a difference but not necessarily one you care about. Before you drive your car, take the owner's manual out of the glovebox; it will be faster and more economical but I'll bet my left b0llock you won't notice. In fact, no, I'll bet both my b0llocks.

[Egee]

Well, that elicited a mixed response! I'm guessing the upshot is suck it and see. HxPaul you said you fit large buffers top and bottom and use progressive springs, does this lead to a very rigid front end and are you using standard shocks?

[Tractorman]

I have to take issue with you on your last statement,I rode a scooter in the sixties and I can asure you that you didn't have to keep one eye on the road looking for potholes.

+1 We had proper roadmen then and I can never remember seeing potholes like what we see today

[grandpa]

Hi Egee,
You could make a fork spring compressor."Heres one I made earlier"
viewtopic.php?f=10&t=144&p=538&hilit=fork+spring#p538
I agree with HxPaul,I don't remember having to watch out for potholes in the mid sixties going to work on my NSU Prima and later a TV175.Speed and traffic density was much less,a Ford Anglia would not do much more than 70mph.Wet manhole covers could catch you out though.
Grandpa

I don't really need a Lambretta as I have a bus pass

[HxPaul]

I fit the large buffers top and bottom to prevent the front end diving as far under heavy braking,under normal riding conditions they dont tend to make a lot of difference (unless you hit a large pothole)The progresive springs do give a slghtly firmer ride but dont seem to compress to far over slight undulations in the road.As for the front shockers,there slimline after market shockers and they seem to do a good job of smoothing the ride.Making a fork compressor is a great idea,but you need all the parts to build it.The compressor I bought cost £15 and works as it should.

[Egee]

Hi Egee,
You could make a fork spring compressor."Heres one I made earlier"
viewtopic.php?f=10&t=144&p=538&hilit=fork+spring#p538
I agree with HxPaul,I don't remember having to watch out for potholes in the mid sixties going to work on my NSU Prima and later a TV175.Speed and traffic density was much less,a Ford Anglia would not do much more than 70mph.Wet manhole covers could catch you out though.
Grandpa

I don't really need a Lambretta as I have a bus pass

I've had a look at the compressor, seems like a good design, maybe you should patent it. It does appear to allow hands free to fiddle with the buffers. I don't think I have the time or facilities to construct one, but well done.

I too have a bus pass, but after 43 years of looking at a pile of scooter bits, I can feel the mod rising up in me - not sure my old joints are looking forward to it, hopefully, memories will dull the pain.

[Egee]

I fit the large buffers top and bottom to prevent the front end diving as far under heavy braking,under normal riding conditions they dont tend to make a lot of difference (unless you hit a large pothole)The progresive springs do give a slghtly firmer ride but dont seem to compress to far over slight undulations in the road.As for the front shockers,there slimline after market shockers and they seem to do a good job of smoothing the ride.Making a fork compressor is a great idea,but you need all the parts to build it.The compressor I bought cost £15 and works as it should.

Thanks Paul, I'm tempted to follow your lead, good roads here in Powys.

[JETEX]

If I could just add my view....... ?. I put my fork springs in with the close coiled bit to the top. The reason being that you get 'soft' springing over undulations, but you hit the firmer part of the springs when going over rougher ground.

[Egee]

If I could just add my view....... ?. I put my fork springs in with the close coiled bit to the top. The reason being that you get 'soft' springing over undulations, but you hit the firmer part of the springs when going over rougher ground.

The more I think about it, there probably is no wrong way to fit the springs. Whether the tight coil is at the top or bottom, the force going through them is omnidirectional. There has to be equal resistance at either end acting as a compressive force. The spring wouldn't be able to differentiate the direction. I guess the main criteria is to fit both springs in the same orientation.

[smacmax]

Here is a pic of the spring compression tool I made works great in situ springs out in 15 mins