MG Cali front suspension travel?

[MotoKuzzi]

why not try some SAE30W oil from a can. dribbled down the outside of the forkleg. Would look more authentic.

Appreciate the input

[Robert Taylor]

So far what I've established is that one damper was indeed hydraulicing? i.e not compressing as far as the other and also noticeably a fair bit of crap drained with the oil from that side. Both fork legs had about 270mm of oil in them. ( I made a note in the hand book when I refitted them last yr ). Is it possible that amount of oil is needed to overcome poor spring performance? I have a mate who is an engineer with some experience working with race car set ups, looking at the dampers for me with a view to machining the suspect damper to accept a better quality seal to match the one done last yr. Replacement all round with better quality gear would be my ideal but unfortunately my motor cycling hobby is only affordable if I can either do the work myself or keep the existing set up going with sensible affordable quality repairs. Will give an update in a few days when my mate has had a look at the dampers for me.

Yes with a bit of nous and machining you could make and instal better seal holders. My preference would be that you use viton grade ''x'' ring seals. Several years back we worked out such a fix for a Guzzi similarly afflicted and I believe it has worked out successful in the long term.

Remind me what the diameter is of the damper shafts? If its common to sizes that we use with our OPhlins stuff we may be able to supply the appropriate ''x'' rings ( which are very affordable ) and give you the precise i.d of the bore that they need to be installed into. This is critical to create just the right amount of seal tension without creating undue drag.

[Shaun]

Yes with a bit of nous and machining you could make and instal better seal holders. My preference would be that you use viton grade ''x'' ring seals. Several years back we worked out such a fix for a Guzzi similarly afflicted and I believe it has worked out successful in the long term.

Remind me what the diameter is of the damper shafts? If its common to sizes that we use with our OPhlins stuff we may be able to supply the appropriate ''x'' rings ( which are very affordable ) and give you the precise i.d of the bore that they need to be installed into. This is critical to create just the right amount of seal tension without creating undue drag.

I think his shaft size, is bigger than the one you wake up with every morning in your hand mate

[Robert Taylor]

I think his shaft size, is bigger than the one you wake up with every morning in your hand mate

Im too tired to think of a devastating comeback to that one....

[Shaun]

Im too tired to think of a devastating comeback to that one....

stop playing with ya self then, and get to bed

[MotoKuzzi]

Yes with a bit of nous and machining you could make and instal better seal holders. My preference would be that you use viton grade ''x'' ring seals. Several years back we worked out such a fix for a Guzzi similarly afflicted and I believe it has worked out successful in the long term.

Remind me what the diameter is of the damper shafts? If its common to sizes that we use with our OPhlins stuff we may be able to supply the appropriate ''x'' rings ( which are very affordable ) and give you the precise i.d of the bore that they need to be installed into. This is critical to create just the right amount of seal tension without creating undue drag.

Thanks Robert, will talk to my mate tomorrow and discuss your info with him.

[Dodgyiti]

When I said the standard springs are cheap, they are around $60 a set.
Robert's advice about using a better seal is great, because they use ATF in them, it tends to penetrate seals better (or is it worse) than normal fork oil.

[MotoKuzzi]

When I said the standard springs are cheap, they are around $60 a set.
Robert's advice about using a better seal is great, because they use ATF in them, it tends to penetrate seals better (or is it worse) than normal fork oil.

Spring price is pretty good at $60, I'll see how they go after the dampers are fixed. Any idea how much ATF per damper?

[SS90]

why not try some SAE30W oil from a can. dribbled down the outside of the forkleg. Would look more authentic.

This thread is about a 1997 Moto Guzzi California......not a Suzuki.....

[SS90]

Any idea how much ATF per damper?

Maybe Robert Tayler will be able to explain it better, but just remember that it is only a hydraulic damper.......just set the damper adjustment to full soft, fill the unit, keep plunging it until all the air is out (repeat till full, when fully compressed), and bob's your uncle..........

[Robert Taylor]

Maybe Robert Tayler will be able to explain it better, but just remember that it is only a hydraulic damper.......just set the damper adjustment to full soft, fill the unit, keep plunging it until all the air is out (repeat till full, when fully compressed), and bob's your uncle..........

No, it needs to have an internal air cavity as ( originally! 0 it is a one piece sealed unit and must have air to allow for the displacement of the shaft volume at full closed distance.
As it is a one piece non servicable unit in an ideal world it would just get replaced, to that end there is almost certainly no fill quantity as such. So you have to work out the volume of shaft inside the unit at full closed position, relative to full open and allow a further volume of air over and above that. This is trial and error unfortunately. If they were on my bench I could do it by perception of feel quite readily.

[MotoKuzzi]

No, it needs to have an internal air cavity as ( originally! 0 it is a one piece sealed unit and must have air to allow for the displacement of the shaft volume at full closed distance.
As it is a one piece non servicable unit in an ideal world it would just get replaced, to that end there is almost certainly no fill quantity as such. So you have to work out the volume of shaft inside the unit at full closed position, relative to full open and allow a further volume of air over and above that. This is trial and error unfortunately. If they were on my bench I could do it by perception of feel quite readily.

Fortunately or unfortunately events have overtaken me a bit. I never got a chance to talk to my mate about your recommendations Robert, he had already done them over the weekend. He stripped and cleaned both, the problem damper was the same one that had work done last year, Mike seemed to think something had gone amiss during re-assembly and the seal was munted. He has put in new viton? seals both sides and used the oil volume retained on the good side as a guide to how much to add. The damper bores are apparently both in good cond. He was able to test them in a spring rate machine and both now fully compress and measure to within a pound of pressure difference at full compression. Fitted them to the bike tonight and after a couple of pumps they started to rebound positively and smoothly. Rider sag was easily adjustable and I have it set at 45mm at present. Travel under braking ( hand push ) in the garage has increased to 110mm which is 81% of full. Haven't road tested it yet but will tomorrow. I have put the owner manual recommended 70mls of ATF in the fork legs but wonder If I should increase this as the last person to work on them put 270mls in. Will I gain anything from doing this? Given the difficulties of removing the bars to get at the caps to add oil, I would probably be better to add the full 270 and control drain away any excess through the lower bung if needed. Thanks for your help so far it's been an interesting learning curve.
Cheers,
Mark.

[Robert Taylor]

Fortunately or unfortunately events have overtaken me a bit. I never got a chance to talk to my mate about your recommendations Robert, he had already done them over the weekend. He stripped and cleaned both, the problem damper was the same one that had work done last year, Mike seemed to think something had gone amiss during re-assembly and the seal was munted. He has put in new viton? seals both sides and used the oil volume retained on the good side as a guide to how much to add. The damper bores are apparently both in good cond. He was able to test them in a spring rate machine and both now fully compress and measure to within a pound of pressure difference at full compression. Fitted them to the bike tonight and after a couple of pumps they started to rebound positively and smoothly. Rider sag was easily adjustable and I have it set at 45mm at present. Travel under braking ( hand push ) in the garage has increased to 110mm which is 81% of full. Haven't road tested it yet but will tomorrow. I have put the owner manual recommended 70mls of ATF in the fork legs but wonder If I should increase this as the last person to work on them put 270mls in. Will I gain anything from doing this? Given the difficulties of removing the bars to get at the caps to add oil, I would probably be better to add the full 270 and control drain away any excess through the lower bung if needed. Thanks for your help so far it's been an interesting learning curve.
Cheers,
Mark.

Theres a HUGE difference in resultant trapped air volume between 70mls and 270mls! And therefore secondary air spring compression ratio. If the manual states 70mls do that. If it bottoms add 5mls at a time through the top with syringes until it just precludes bottom out. That may be a pain but does more accurately ensure that the oil levels are the same side to side!

[MotoKuzzi]

Theres a HUGE difference in resultant trapped air volume between 70mls and 270mls! And therefore secondary air spring compression ratio. If the manual states 70mls do that. If it bottoms add 5mls at a time through the top with syringes until it just precludes bottom out. That may be a pain but does more accurately ensure that the oil levels are the same side to side!

Under full braking at low speed ( 30kph or less) it feels as though it momentarily bottoms, but travel only measures 110mm vs 135mm full. Could this be to do with the transition from the softer spring to the stronger one? Although its a reasonably solid feel to it when it happens.

[Robert Taylor]

Under full braking at low speed ( 30kph or less) it feels as though it momentarily bottoms, but travel only measures 110mm vs 135mm full. Could this be to do with the transition from the softer spring to the stronger one? Although its a reasonably solid feel to it when it happens.

Possibly yes but Id really need to see the stripped assembly to reply more accurately.