Whats The Toughest Rear Shock

[draino]

Guys whats going to be the best rear shock for my pitty?, I had a brand new DNM from Pit Pro and it just snapped in half when I landed and it was the pissiest little single jump ever, The shock shaft just sheared clean of and I ate shit fourth gear pinned! I dont know if it is warranted either but this shock is rubbish if it aint because the standard shock that came on the Pit Pro has done this jump 100 times and more and is still fine, I got the DNM because it had comp/reb adjust.

 

[tubes380]

mate i would go back to pitpro and complain like crazy, i have been using a dnm shock like yours for 6months now and i love it, been the best thing i have ever done, they shouldnt snap like that either, so it would have to be a bad shock or something like that, go back and get a refund or exchange it for another one.

 

[coolmodee01]

man you lucked out big time i've hit 50 footers with that shock i'n my vert and it held up sweet as
so i dont know what you did to snap it
but if you want better than that your gunna have to go with i shock and your gunna hand over 3 weeks wage and good luck with that

 

[Cactus Jack]

Guys whats going to be the best rear shock for my pitty?, I had a brand new DNM from Pit Pro and it just snapped in half when I landed and it was the pissiest little single jump ever, The shock shaft just sheared clean of and I ate shit fourth gear pinned! I dont know if it is warranted either but this shock is rubbish if it aint because the standard shock that came on the Pit Pro has done this jump 100 times and more and is still fine, I got the DNM because it had comp/reb adjust.

I knew it ....... whenever people tell me that something is better than my instincts tell me , it ALWAYS turns out to be junk .......... People said I-shocks were fantastic ...... they're junk ....... they snap just like that ...... people reckoned DNM is better than Fast Ace but I knew they snap like that since I saw all the failed shocks posted on Planet Minis .....Let's see IF the DNM sellers stick by their guns and give you a new replacement hi "QUALITY" DNM shock .........

 

[Sidney]

So, what IS a good shock?

 

[Maylands Performance]

Hi Guys.
Just as Cactus said there have been a few DNM shock failures this year,and because of this we stopped selling them [Note.. Even tho none of the DNM shocks we sold failed !] we have adopted a wait and see attitude with the DNM shocks.....
There seemed to be a heat treatment issue with the shock shafts from what I could gather.
I've got to say the good old faithful "cheap" Fastace shocks seem to take a good beating and survive day in day out !

Cheers Brian

 

[MITTZ]

my DNM shoch is holding up great, its not the same as that 1 but its good

 

[motoXXX]

im gunna get a fast ace soon glad i seen this thread first lol norrows my choice down to FAST ACE lol

 

[Cactus Jack]

Yeah , I bought Fast Ace ....... but ELKA is supposed to be the best ........ I actually know the guy at Vickers Motorcycles in East Maitland .... he races Thumpstars and he said DNM were'nt as good as people make them out to be so he gets rid of his and runs a custom made ELKA ..... same goes for Marzocchi forks , he said they didn't impress him in the slightest ........so he races with Fast Ace AS-02 forks and said he has tried the LOT ....... he said most people simply 'aint got a clue on how to set them up ..... he showed me what most people do wrong with 'em and even demonstrated it on several customers bikes that were in for services .

I bought an I-shock for our triangle swingarm bike but now it's only going on my lightweight daughters bike . Whenever a shaft snaps near the end , you know it's faulty and risky - IF it broke in the middle then that's a totally different story since there's tons more rotational leverage force at that point . Anyone can get a broom handle and snap it in the middle pretty easily but try to snap it off one inch from the end and see how much extra force it takes :

Planet Minis Forum

What I CAN tell people is that the shafts appear to be mostly snapping at the inner apex of the thread groove which acts as a stress riser in the same way that a tile or glass will snap along a sharp score line ........ they need to go to larger thread groove and apex radiuses and make sure the threads are tight and ends of the shafts are a super tight fit in the bottom mount part .... the ground part of the shaft should go in a fair way (to act like the shank of a bolt) before there's any thread to thread ..... ANY shock that only has a screw thread right to the edge is stupidly engineered crap and will DEFINITELY snap sooner or later .........

As pictured ..... the I-shocks have too short a thread so they'll either snap off in the grooves OR the thread will tear out with a stronger spring tension than stock ......

For the record ...... a bolt has a shank and ONLY has thread on the end ......... anything that has thread all the way up to the head is a SET SCREW ... NOT a bolt ......... a screw is piss weak , a bolt is strong and resists shearing .

 

[themountain]

sorry to interupt the beating on DNM, but couldn´t it have been a simple failure in mounting that thing???
If he had wrenched up the bolt like crazy there is no way that even a Elka withstand a beating!! BTW Elka´s got their share of probs too and nobody stops selling them !
My 50cents on fastace(besides the RC66) is that they are far weaker then DNM´s!!

 

[Cactus Jack]

Yeah , it's possible that it could have been caused by an alignment problem ! But I don't care to think that he might have tightened the bolts way too tight and snapped the shock thru sheer incompetence ........

This is how I check for proper alignment :

1) With the shock bolted in the swingarm only , the top of it should be able to be freely swung back and forth so that the lower shock bush can rotate on the mount bolt without binding .

2) When the shock is put into the top mount it should be dead in the centre of the bracket with the top bolt EASY to put in by hand .

3) The reverse procedure should then be tested with the shock bolted in the top mount and be able to freely rotate on the bolt . It should swing freely and line up dead centre of the lower mount lugs on the swingarm with the bolt easy to put in .

4) IF the shock has to be forced sideways at all to centre it ....... then there's a DEFINITE alignment problem that will side load the shaft and cause it OR the shock seals to fail ........

IF the top and bottom shock mounts aren't precisely aligned when the shock is squared up , then the swingarm will need to be moved over on the pivot by taking metal off one spacer and packing the other side with washers until they DO align ........

DNM shock bushes do look like they require perfect frame geometry ..... whereas the stock shocks and Fast Ace BS 66 RC and BS 66 RCL shocks have steel in rubber bushes which can flex to absorb poor alignment ...

When the shock mount bolts are tightened .... lock nuts and loctite should be used . The mounts should NOT be crushed in or be clamping in on the shock .... there should be play either side to allow for frame flex .......

Better still .... the shock mount bolts should have shanks on them that are the full overall outside to outside width of the upper and lower mount brackets .... that way the nuts can ONLY be tightened 'til they jam on the end of the shank and can't possibly crush the mount lugs in on the shock ..... excess thread length would need to be trimmed and chamfered since the bolts would be a lot longer .

A good way to test how smoothly the suspension is working would be to put the shock in with the spring taken off it to check for binding throughout the full range of swing .........

 

[themountain]

=Cactus Jack;133618]Yeah , it's possible that it could have been caused by an alignment problem ! But I don't care to think that he might have tightened the bolts way too tight and snapped the shock thru sheer incompetence ........

you never know!!.. ..and he won´t tell

 

[cass38a]

I have been told that a bolt has 25mm + the diamater of the bolt as thread. (ie a 10 mm bolt should have 35mm thread). Is a M10 35mm length bolt a bolt or a set screw? Does anybody but me and cactus care?

 

[pickaninny]

Please correct me if im wrong but it seems most shocks for pitbikes have been manufactored by predominately mountainbike shock makers. Much more R&D needs to be applied for pit bike technology. Hence so many broken shock horror stories. and hence the crazy prices for so called top shelf shock. Elka rear shock $750. Fastace $150-$200. Gotta be a reason for huge price difference.. DNM M-200 forks from factory in China(price list direct from factory)BTW you can buy 1 part or 100.

DNM MT-RC USD115 (rear shock) DNM M-200 USD285 (Front forks ) fastace AS-01USD250(front forks)
Marzocchi Longer adjustable Copy forks 750mm USD150

 

[Cactus Jack]

If you see a bolt stated as M10 X 1.5 X 35 mm ...... that means it's 10 mm in diameter , the thread pitch is 1.5 mm (peak to peak) and it's 35 mm long from under the head to the end ......... a bolt is actualLY like a pin ie as in a bolt on a gate ...... anything without a smooth shank (bolt) section is purely a screw ....... bolts are used where parts need to be held tightly in position and where thread stretching is a problem ... the smooth shank acts like a locator dowell .......

Most bolts used for shock mounts on pit bikes are too short ...... they have a bolt section on one side but thread on the other side so they tilt slightly in the mounts and one side can chew into the swingarm lugs , gradually making one hole sloppy ........ that can put side loading on shock shafts etc .......

Shocks should really have smooth hardened pins held in by circlips or split pins and the shock bushes should be configured like a ball joint .......

Most people won't bother with all this info but it's there anyway ...... LOL......

Am I the only fitter / machinist on here ???? You had to know what every type of thread , screw and bolt was when I was an apprentice ...... and you had to be a visual mathematician ....... no BS calculators were allowed back then .....

British Tools & Fasteners: HEX SCREWS

 

[foolsp33d]

I NEED these!!!

 

[themountain]

Elka rear shock $750. Fastace $150-$200. Gotta be a reason for huge price difference.....

since when stated ONLY the higher price the higher quality?? Let me be honest...stuff from USA is waaaay overpriced , everybody knows that and they have there problems too

 

[binking]

since when stated ONLY the higher price the higher quality?? Let me be honest...stuff from USA is waaaay overpriced , everybody knows that and they have there problems too

Your right about that. Pitster must be shaking in their boots after reading this thread. I think they should replace all their DNM shocks now!!!

 

[Cactus Jack]

Elkas are supposed to be made in Canada and they have subsidiary branches in the US ....... They have a lot more overhead costs since they run a shock rebuilding , diagnosing and custom set up service ........ all the costs of maintaining the entire juggling act are tacked onto the final price .....

Most things are made in China these days because people won't pay heaps of times the price for the same quality products made here ........ And when things ARE made here there are way too many idiots hell bent on monopolizing them to control prices and keep them artificially high ....... as a response , people stop buying ...... and that opens the way for the chinese market to grow .....

 

[draino]

I sent an email to Josh at PitPro yesterday but no reply yet. The shock was mounted correct it moved very plushly and easy but it simply failed and I ate turd medium rare The standard shock the bike came with has hit the same jump a 100 times or more and is still going its now back on the bike pogoing around like a bitch The jump was a single at the York track in West Aus its about 4 feet high to a down slope it aint nothing extreme