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 Post subject: AST upgrade
PostPosted: Fri Jul 28, 2017 8:19 pm 
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proff. patpending
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Not sure how many other AST users are of the opinion that the damping is too harsh. I was, so too was Beef. My biggest issue was the high speed damping circuit, which does not work as the shock was designed for as it is back-to-front, pulling rather than pushing on compression, hence you end up with adjustable high-speed rebound adjustment rather than high-speed compression adjustment.

Beef and I went to see the 'old AST UK' in Cheltenham, or ACD Motorsport as they are now called. AST UK are now based in Bristol, however they don't have the experience that Curtis (now under ACD) has with the AST product, especially related to Buell.

The shocks were serviced and the shim stacks modified to reduce compression and rebound damping with a focus on making the compression compliant to shocks in the road surface with a high speed damping capability.

Lots of pics and I'm sure will just pass at this point, however read on, as my AST was doomed to imminent failure, the rear eye was about to pull off the damper rod (oo-err). Worth getting your shock checked...

Beef was up first... Ooo nasty...
Image

Beef's shock had the spring removed before it was put on the shock dyno. To get the spring off, the top collar had to be removed and to do this the top (or rear, when on the bike) eye had to be removed. This needed the nitrogen to be released. Not a DIY job to powdercoat your spring, take note...:
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The shock dyno cycled the damper at a range of frequencies to simulate use at varying speeds, with the resulting transmitted load detected by the S shaped load cell sitting above the top shock eye. This gave us a baseline for the modifications:
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After the baseline run, the nitrogen was discharged again and the damper stripped. The shim stack is shown laid out (all the 'washers'):
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The chosen fluid is an aerospace quality hydraulic fluid, something that would normally be moving control surfaces or landing gear screws on your holiday (or war) jet:
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Then, when the shim stack was revised, the shock was back on the dyno to understand the change:
Image Image

Although, not shown here, the new max damping was more or less the same as the old min damping, for both compression and rebound, however the damping was lower at the higher frequency of operation. This meant that Beef had a lot more adjustment to give him lower damping.

Then, the shock was assembled:
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And fitted to the bike:
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Beef turning the footpegs around (had been used to support the bike on axle stands):
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At this point, Beef took it for a test ride and was much happier with the bike. The damping, on its lowest settings, was a bit underdamped for him.
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Shortly after, he increased his damping and left to crack on with fitting his kitchen...

My shock was up next:
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Mine wasn't as clean as Beef's as mine has seen all weathers ( :run: ). Note the rose joint full of rust, this is sealed (not very well) by a pair of O-rings sitting behind a pair of collets. I think I'll be stripping mine to put some grease on them to make the seal a little more waterproof:

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It was then stripped in readiness for the shock dyno:
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But on inspection, it was found that the threaded portion of the rear shock eye was cracked ( :o :shock: :? ). Failure of this would have resulted in me coming a cropper, undoubtedly. This was worth the trip alone.
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At this point, I was so hungry I walked the half a mile or so to the nearest cafe for a bacon and egg sandwich and toffee cake, washed down with a white americano (white coffee in old money).

When I got back, the shock was ready to be fitted. I had a quick look at the dyno runs. Initially mine wasn't as overdamped as Beef's was, however the new shim stack had reduced the damping to the same levels as Beef's now was. However, interestingly (to some maybe), although min damping was the same, I had a higher rebound damping setting than Beef's.
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I was bored of taking pics by this point... The shock was fitted to the bike with the minimum damping settings and was noticeably better.

A big thanks to James, Steve and Curtis at ACD Motorsport for a very educational day...

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 Post subject: Re: AST upgrade
PostPosted: Fri Jul 28, 2017 9:13 pm 
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This sounds serious!

Was this a free of charge service and was the reason to let the shocks serviced because of the dampning issues or worries about the state of the shocks?

How many miles did you with the AST shocks?

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 Post subject: Re: AST upgrade
PostPosted: Fri Jul 28, 2017 9:43 pm 
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proff. patpending
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brother in buells wrote:
Was this a free of charge service and was the reason to let the shocks serviced because of the damping issues or worries about the state of the shocks?

It was serviced and re-shimmed cos of the damping dissatisfaction. The cracks were discovered on strip. It wasn't free as it wasn't done by AST themselves, or rather because of this I had no expectations and was happy to pay for their time and expertise. And besides, the shock is well outside warranty. AST UK has recently changed hands, it is now in Bristol (a few miles from me) however they don't hold the experience nor the facilities to strip and rebuild shocks. The experience is with Curtis and his troops at ACD in Cheltenham, in the old AST UK premises.

brother in buells wrote:
How many miles did you with the AST shocks?

10 or 15k miles over 7 years on this one.

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 Post subject: Re: AST upgrade
PostPosted: Sat Jul 29, 2017 7:56 am 
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Milf Hunter
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I can't help thinking that there is a bit of the old "Emperor's New Clothes" with regard to AST shocks. Everyone who has them raves about them, but they either break, or need a lot of work, or rework, relative to mileage.
Am I wrong?

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 Post subject: Re: AST upgrade
PostPosted: Sat Jul 29, 2017 8:09 am 
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proff. patpending
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mojomick wrote:
Am I wrong?

Yeah

But in all seriousness they are a replacement shock that appears to have not been set up to be compliant with the way I use my bike. The Showa is probably no worse, you tell me that Beef squeezed all the oil out of yours so how good can that be?

Again it's what works for one may not work for others, I like my Maxxis tyres, to others they are dogshit. I like my PM wheels (and my Dymags) but to others they are dogshit (or an accident waiting to happen).

I'm sure if I had a Showa there would be the opportunity to make it better and that's precisely what I am doing with my AST...

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 Post subject: Re: AST upgrade
PostPosted: Sat Jul 29, 2017 12:44 pm 
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Interesting write up on the shock Nick. It does highlight how so much of the skill in the companies goes missing or is totally lost when they move or are taken over.

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 Post subject: Re: AST upgrade
PostPosted: Sat Jul 29, 2017 7:02 pm 
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I don't really understand about suspension and what makes it good or bad. How do you know when it's gubbed, what are the signs?

Magz X1 has a Penske, will that have the same problems?

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 Post subject: Re: AST upgrade
PostPosted: Sat Jul 29, 2017 7:42 pm 
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proff. patpending
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t965m wrote:
I don't really understand about suspension and what makes it good or bad. How do you know when it's gubbed, what are the signs?

Magz X1 has a Penske, will that have the same problems?


Lots to read about setting up damping on the interweb, but the bottom line is that you want the wheels to follow the road, with all the load absorbed by the damper (not by the tyre and not transferred to the rider). If your shocks are knackered on your car, it bounces all over the road cos there is not enough damping, the same with a bike, it will wallow all over the place. My AST was the opposite, every bump was being transferred to me rather than being absorbed by the damper.

Your Penske is probably OK. You and Mrs Teague have some fine motorcycles in your stable, you would know if the shock was badly set up after riding your other steeds...

Although a lot better, my AST is still overdamped on the high speed circuit, i.e. if shocks from the road are transferred to me rather than being absorbed by the shock absorber... I need another shim stack session...

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 Post subject: Re: AST upgrade
PostPosted: Sat Jul 29, 2017 8:45 pm 
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:yup: enjoyed the write up Nick, thanks for sharing :mrgreen:

i dunno if it's my pooter , but when i click on the pics ,
it says account needs updating for 3rd party viewing ?

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 Post subject: Re: AST upgrade
PostPosted: Sat Jul 29, 2017 9:11 pm 
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proff. patpending
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Yeah, I think photobucket are sick of doing things for free. Just another nail in the coffin of everything that isn't facebook...

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 Post subject: Re: AST upgrade
PostPosted: Sun Jul 30, 2017 12:55 pm 
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Nutah wrote:
:yup: enjoyed the write up Nick, thanks for sharing :mrgreen:

i dunno if it's my pooter , but when i click on the pics ,
it says account needs updating for 3rd party viewing ?


Yeah, I get that too.

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 Post subject: Re: AST upgrade
PostPosted: Sun Jul 30, 2017 2:30 pm 
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proff. patpending
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I think they want me to pay for stuff

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 Post subject: Re: AST upgrade
PostPosted: Sun Jul 30, 2017 7:41 pm 
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proff. patpending
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pash wrote:
I think they want me to pay for stuff

Yeah, they want $399 per year to allow me to put links to photos...

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 Post subject: Re: AST upgrade
PostPosted: Sun Jul 30, 2017 7:48 pm 
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Nanny Brown
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Just post smaller photos on line.

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 Post subject: Re: AST upgrade
PostPosted: Sun Jul 30, 2017 7:54 pm 
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proff. patpending
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Jill Brown wrote:
Just post smaller photos on line.

OK

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