suspension question this time

[horror]

I have had another chance to look at the 400.

I noticed that since last time I worked on it (1st time since collecting it off ebay) The rear shocks have collapsed. They have squashed down completely.
I get the impression that they may have been weak ones from another bike added for the purpose of the sale.
Has anyone encountered collapsed rear shocks before?

Also, I have worked on bikes for years but I have never tackled front forks before. I noticed that my forks when compressed they make an air squirting noise.
Also they do not spring back up. I.E when compressed they stay down, and when lifted they stay up. The chrome on the legs is in good shape.
Would the fork seals cause this lack of strength in the forks?

[matthewmosse]

sonds like tired springs to me? I get a bit of this on my 500 outfit but that has 6 inch preload spacers apparently and massive milage, new springs are on the wish list. Rear socks wise I've had shocks stick on a low hight, turned out the luggage rack it came with held the tops of the shocks at a funny angle so they wern't parellell top to bottom and were also unable to move at the top because the rack was too close, the damper rods had actually bent from the combined abuse. solution must be to retire them and put on a replacement set.

[horror]

Its quite interesting that I was toying with the idea of lowering it anyway. It seems to have lowered itself 

It's lowered itself but now there is no suspension. And I reckon the forks are an MOT fail as they are.

[andy120t]

Keep your eyes on ebay for a replacement set - I think most of the SOHC range will fit as the mounts are the same, athough some are longer than others - so if you find a cheap pair of 750 springs you'll have a higher back end...!

[horror]

Yea I'll do that, I have never seen rear shocks collapse like this. I suppose the bike could be fitted with 125 shocks or something, and maybe they
were too weak.
I would like low rear shocks, Have You seen this one?

It's lowered at the back with some posh rear shocks by the looks of it. I haven't got the dosh for this but it would be nice to get some like that

[Yoshi823]

Keep your eyes on ebay for a replacement set - I think most of the SOHC range will fit as the mounts are the same, athough some are longer than others - so if you find a cheap pair of 750 springs you'll have a higher back end...!

It won't matter how long the springs are...the shock will only ever extend to its standard length.

I have a set of Koni shocks meant for a 500/550F or K...but they'd probably be too long for a 400F.

[matthewmosse]

I'm not 100% on this but I think the shocks and forks are about 1 inch shorter than 550 on the 500's. New shocks cost me

[horror]

Managed to get the rear shocks working now. I oiled the stem and bounced them a load. they have gradually started working again.
The bike is now MOT'd and roadworthy. I patched her together with a temporary fuel cap, got that master cylinder thanks to yoshi823.
not sure whats happening with my front forks but they are completely collapsed still. maybe yea its tired springs.
I removed the top covers and the fork spring stuck out of the top about an inch.

I used gaffa tape to patch up the rear mudgaurd  ha ha

[Yoshi823]

Looking good & i'm glad that the master cylinder worked well.

For tired fork springs you could make sure that they are not snapped first of all, then if necessary use some spacers or old imperial sockets to preload them. I did this on my CB550F2 & it worked well. Either the front springs are suffering from age or a previous owner may well have inserted a spacer under the damper rod in the bottom of the fork leg which together with the topping out spring, would reduce the front height.

[florence]

That bike is looking good and I'm glad to hear it's back on the road.  It's excellent to see another natural and functional looking bike.  I have found that a liberal coat of old engine oil or grease keeps things looking good and keeps the harmful kind of rust at bay.  Also,  it is worth painting the insides of your mudguards with hammerite.

 

[horror]

Re the front frorks, I pulled the springs out the top and they are complete, I havent dissasembled the forks, but
yea the springs stick out of the top of the forks about an inch when the tops are off, which makes me think maybe it's been lowered.
It has rubber gaiter things over the legs so thats evidence of front end tampering i suppose.

It got an advisory on the mot regarding the corroded mudgaurds. they are scrap really but as long as they dont drop off onto the wheel theyl do for now.
I oiled up most of the dry rust areas, I may paint it if I keep it long enough