OzVMX Forum

Clubroom => Tech Talk => Topic started by: LWC82PE on August 08, 2021, 10:57:30 am

Title: External rebound adjustment on pre 75 shocks?
Post by: LWC82PE on August 08, 2021, 10:57:30 am
Are you allowed to have external rebound adjustment on pre 75 VMX shocks? I read the MOMS but it does not say anything about this. I know you cant have piggybacks or remote reservoirs.
Title: Re: External rebound adjustment on pre 75 shocks?
Post by: Wasp on August 09, 2021, 01:09:14 pm
Yes you are 100% . Why do you ask ?
Title: Re: External rebound adjustment on pre 75 shocks?
Post by: bigk on August 10, 2021, 06:59:53 am
Correct re: remote reservoir shocks being disallowed for pre'75, however your theory of no piggybacks would mean 1974 Yamaha Thermflow shocks (standard fitment to some models) would also be disallowed, which is incorrect. Most modern, replacement shocks (piggyback or otherwise) are built with some sort of external adjuster, you'd be hard pressed to find a scrutineer who would exclude them from competition.
K
Title: Re: External rebound adjustment on pre 75 shocks?
Post by: Wasp on August 10, 2021, 10:48:39 am
Correct re: remote reservoir shocks being disallowed for pre'75, however your theory of no piggybacks would mean 1974 Yamaha Thermflow shocks (standard fitment to some models) would also be disallowed, which is incorrect. Most modern, replacement shocks (piggyback or otherwise) are built with some sort of external adjuster, you'd be hard pressed to find a scrutineer who would exclude them from competition.
K

This ruling has been the case all those years .(in theory ) However I have built many pre 75 with Piggy back (even hi-low speed ) at customers request . The fact that it was not allowed did not stop them .I always make that clear at the point of sale .With only a short travel and little race distance , the advantage to a purposely built emulsion shock is minimal . https://www.facebook.com/VMX-Shocks-made-in-Australia-108450797260282       So far, no one has been knocked back in any event . (bums on seats .... )So I think after 25 years running like that , would be a tough nut to crack now .Although should the rule change , I can change the 3612 shock design very quickly , to have NO external adjuster.

Very interested ,as to what the motivation or reason is , to bring this question up  ;) ;)
Title: Re: External rebound adjustment on pre 75 shocks?
Post by: LWC82PE on August 10, 2021, 09:38:28 pm
Needed some for 74 DT250. I knew Piggybacks and remotes were not allowed unless they were Thermalflow, but just was not sure about the rebound adjustment. Thanks.
Title: Re: External rebound adjustment on pre 75 shocks?
Post by: Wasp on August 11, 2021, 10:40:12 am
I did a set for a customer with a DT  just down the road from you  in Grenock . He is in the classic club same as your Dad  and very fussy . Bike looks better than new now . I made him upside down  piggy backs with no adjusters ,#hyperproforksprings and PD Valves as well .The only let down is the lack of brakes now . I will help him blueprint the front shoes and then it should fine .
Title: Re: External rebound adjustment on pre 75 shocks?
Post by: Dungar Pilot on August 14, 2021, 07:19:27 am
The only let down is the lack of brakes now . I will help him blueprint the front shoes and then it should fine .
Hey Walter, what do you mean exactly by blueprint?
Thanks in advance
Title: Re: External rebound adjustment on pre 75 shocks?
Post by: Hoony on August 14, 2021, 10:06:38 am
The only let down is the lack of brakes now . I will help him blueprint the front shoes and then it should fine .
Hey Walter, what do you mean exactly by blueprint?
Thanks in advance

Probably match the shoes to the Hub lining to ensure maximum surface area coverage
Title: Re: External rebound adjustment on pre 75 shocks?
Post by: Wasp on August 14, 2021, 01:49:22 pm
Correct Hoony .
Title: Re: External rebound adjustment on pre 75 shocks?
Post by: Dungar Pilot on August 15, 2021, 07:13:21 am
The only let down is the lack of brakes now . I will help him blueprint the front shoes and then it should fine .
Hey Walter, what do you mean exactly by blueprint?
Thanks in advance

Probably match the shoes to the Hub lining to ensure maximum surface area coverage
Correct Hoony .
Oh, is that all?
For some reason I thought Blueprinting meant:

To assemble something exactly to the manufacturers Blueprint including clearances!
Title: Re: External rebound adjustment on pre 75 shocks?
Post by: Tomas on August 16, 2021, 04:24:03 am
old brake shoes= asbestos. Be careful