Hey guys, I need some advice on shock replacement. I am prepping a 250 for CC and would like to replace the 45 degree Koni's with a performance type shock. I prefer the lower seat height and less travel of the vertical mounting but don't want to give up handling. With many mounting options and spring rates I would like to get it right the first time. I am about 170 pounds with gear. Any advice. I looked back through several posts but didn't find anything on this topic.
Thanks.
Put the brand name you're interested in the search mode and you should find what you need. There have been discussions on Ohlins, Works and Progressive, take your choice. thx
Jerry,
How much travel are you looking for in the rear?
Progressive , Works Performance , Olins , Koni ( you can still get them , new production, from the land down under )
Drop the seat height with just the rear shocks and it will change the rake and trail, so shock length comes into play.
http://www.worksperformance.com/pdf/app_guide/dirtbikes.pdf
It would be worth a call to the Works Tec help line with the following info.
(http://farm4.static.flickr.com/3251/2959548671_a44414ab68_o.jpg)
The Engineer I always get ( I think Sandy is his name ) is a wealth of information on setup for front and back suspension. Have a pad of paper and pen in hand and take notes. We have bought 3 sets of Works tailored for a specific bike and they work great.
You may opt for another brand of shocks but you will know from the conversation what length of shock to look for and how much stroke you need from that length to get what you want in travel. If you ask he will probably give you the spring weight needed also.
We went with longer shocks last time on my bike for more travel and ended up using forks with longer tubes to get the rake and trail right on the front.
Hope this will help.
John D.
Thanks guys, after reading several posts found when I used the search I am convinced the Works is the way to go. I will use the info when I call Sandy to come up with my need. I want to be ready to enter a vintage event so it appears I cannot exceed 4 inches of travel although my riding style falls between the 4 inch and the maximum. Hopefully that makes sense. I also want to rebuild the Koni shocks, where can I find parts and manuals?
Jerry,
To the best of my knowledge you cannot find parts and they are not available for Koni's.
I did find an individual that does rebuild them, but it is not cheap.
This is the infor I posted a few weeks ago -
For those of you who have Koni shocks and want to get them rebuilt, you might want to check out this individual. I have no connection to him, just passing on information. His name is Steve and he can be reached at King Koni 724-285-6202. He is located in Butler. PA.
Here is his pricing information– If they have not been taking apart in a long time, are hard to get apart and everything inside has to be taking apart and cleaned, this takes many hours. Pricing on 12-12.5" =$300.00, 13"=$350.00, 13.5" or larger=$450.00. They are done right, just like in my pictures with reconditioned collars and paint and sticker, then after that I will service(oil change and seal check) them anytime you want for about $50.00 a shock. I specialize in rebuilding vintage Koni's that is what I do for a living.
I found him on the internet and saw one of his auctions on eBay. His current item # 160271066135, can be found on eBay.
Tony
Thanks Tony,
I'll check him out and in the meantime I guess I'll order some WP's.
Jerry, if the bike is going to need fit the 4" rear travel rule mounting the shocks in the lay down position gains nothing. The bikes dont handle better purely because of the shock position, the position itself is irrelevant. Bikes with the lay down shocks handle better because shock will give more travel at that mount position.
If you build and spring a shock to give 4" of travel in the lay down position the bike will handle the same as with a shock built and sprung to give 4" in the upright position. There will be no difference unless you build the shock to exceed 4" in the lay down position.
Brian
'73 Berkshire Team d-Con
//www.d-conproducts.com America's #1 Rodent Control Brand
Sorry to burst your bubble Brian but laydown or forward mount do produce better traction even when restricted to 4" travel, look at how elaborate modern sportbike suspension is for the pavement yet it only yields 4-5 inches of travel. This is why you see so many "forward mount" Maico's racing in the sportsman classes, even though restriced the leverage ratio is vastly increased as well as the type of travel produced compared to a true coventional type.
Quote: Thomas Jefferson, We are all born ignorant, some work to remain that way.
Quote:Merlin, "it is impossible to teach those that wish not to be taught".
Jerry.
If you do opt for the non lay down lower shock mounts, you might not want to run the shock too far into the vertical ( the most forward holes ). The swing arm will probably bend. You can tell when that happens. The gusset that runs on the top of the swing arm will get a wrinkle in the 90 deg bend on the top.
There were 3 Still Keeping Track's with articles on how to set up for MX that went into all the things that should be addressed. One of the Issues covers the frame and swing arm and went into this..
Hope this will help you out.
Merlin,
CZ hop? Always wondered about that and thought we could get my 74 TNT 175 working better if we had moved the top mount forward some.
John D.
Merlin, as you well know, modern sport bikes use mechanical linkages and shock technology to make the most of that travel. You can get a modern shock, but a lay down position like the 74.5-76 Penton with the lower mount at the axle gives you a decreasing rate not a rising rate so the shock must make up for it with valving and dual or triple rate springs. Shock position is a minor detail that I think Jerry need not worry about too much.
Brian
'73 Berkshire Team d-Con
//www.d-conproducts.com America's #1 Rodent Control Brand
I didn't mean to cause so much controversy but I do appreiciate all the input. I intend to mount the shocks in a somewhat vertical position (but not too far forward per John). I am currently trying to contact Sandy at WP for the part number and cost but have not been able to reach him yet. Everyone has been very helpful on this matter, thanks.
Oh, no problem Jerry, its not controversy its just back and forth. Sandy will get you set up, he really knows his stuff. The one thing I learned from Dwight Rudder is WP tends to under spring, so tell them you weigh 20-30lbs more than you really do.
Brian
'73 Berkshire Team d-Con
//www.d-conproducts.com America's #1 Rodent Control Brand
Under spring? I have read such and for expert riders, like Brian and Dwight, it may be advisable to fudge a little to get what you need. However, for me and the 3 sets of Works currently used on our small bore CMF Pentons and 1 set on the large Maico, I told Sandy our rider's weight, skill level, the type of riding (primary CC & occasional VMX) and how I want the ride (plush). Ride height is also important (If you are a tall rider and also want to sharpen the steering, you may want a longer shock). We're very satisfied with the Works product and the excellent support from a guy like Sandy. Works offers a ride guarantee as well where they will re-tune the shock if they miss it the first time. We have a season and half on the Works with no problems.
We also have new Ohlins running on a 74 Harescrambler and 74 Mag Husky with good results. But, it is too early to tell if they are superior to Works. Steve Marpes, 828-243-3520, is your point of contact for Vintage Ohlins. Tell him Ernie sent you.
Works $429. Ohlins $613 (or more). Depending on how busy Works is, it has taken up to 6 weeks to get shocks. Both sets of Ohlins were received in less than a week! Premium suspension, dialed in to your bike and riding ability, will do wonders.
Ernie P.
Chattanooga, TN
I worked with Sandy today and got the shocks ordered. He was very helpful and I think what we came up with will do the job. I did fudge the weight by about 10 pounds looking for a happy medium between a cushy ride and enough spring to accomodate my riding style. And yes, he did offer to rework the shocks if we missed the setup. I am very thankful for everyones input on this subject, it has been too many years since I last set up a Penton (34 to be exact). We went with a shock that will allow me to enter some vintage events when the time comes.
Brian, go back and reread my post, the point was you said the laid down mount made no difference, I begged to differ by reason of if it were strictly a "travel issue" why would the manufacturers of 4-5 inch travel sportbikes go to all the trouble of the elaborate linkage? The fact is even a poor design forward mount or laydown with 4 inches of travel will still produce more traction that will equal better performance, hence the Maico example. Not opinion, fact.
Quote: Thomas Jefferson, We are all born ignorant, some work to remain that way.
Quote:Merlin, "it is impossible to teach those that wish not to be taught".
Quotequote:Originally posted by john durrill
Merlin,
CZ hop? Always wondered about that and thought we could get my 74 TNT 175 working better if we had moved the top mount forward some.
John D.
John, part of this classic trait is two fold. First, most people (myself included) read and believed more damping was better, it was if you did not over do it. Most of us made the mistake of turning up the damping too much on our Koni's (Curnutt and Girlings had fixed damping thus no problem), what it caused was "packing" that is the suspension would travel 50% and only return 1/2 the distance hit the same size bump again with only 75% of the travel available so 50% of 75%= less than a 1/3 after rebound and so on until the suspension stayed compressed causing the infamous "hop". The second was CZ made a rear section frame change when they "revised" the twinpipe design to the sidepipe/yellow tank design. What they did was take the rear tubes that on the twinpipe went from the swingarm pivot straight up to the seat/tank junction to the swept forward to a 1/3 of the way up under the tank design. The latter design allowed the rear section to flex helping cause the "hop" unless the suspension was perfect, even then the upper limit of the design was low. The next version of the CZ( pre Falta short travel red frame type) reverted back to the twinpipe rear frame design, problem solved.
Quote: Thomas Jefferson, We are all born ignorant, some work to remain that way.
Quote:Merlin, "it is impossible to teach those that wish not to be taught".
Brian,
This is not a fact LOL but the lay down did work better on Hodakas back in the day over moving the shock forward on the swing arm. That was my impression from riding bikes done both ways. I think that was one reason in 72 when the Wombat came out it worked so well on the trails.
My bike does seem to work better with the shocks layed down even when i am not using 1/2 the travel that is their.
I think Merlin must be right. You may also be correct. The reason i think that is there are a lot of things that contribute to how well the shock works. Things like how big is the oil reservoir , leverage loads , etc. So it may be one of those design deals where its a trade off to use one over the other. Dictated buy how the rest of the pieces and parts of the bike fit together and affect each other as an assembled tool
I would think if the shocks were built by someone like Works to be used in the canted position any design changes needed to optimize the shocks performance are their.
Same thing with the mount setup you were talking about. I dont "know "
But i bet there are design trade offs that are taken into account for each setup.
I do Know a lot of bikes used the canting setup and had very good bikes that handled well.
John " still in the dark about a lot of things " D.
John that has been my experience as well, A couple of years ago, several of us were talking with the late Jim Pomeroy and he was talking about his least favorite Bultaco.. strangly it was the Pomeroy replica. The reason was the shocks were nearly straight up and down... It was as if the only change to the bike was forward mounting of the shocks on the swingarm. He said it tended to hop on down hill bumps and high speed braking into tight corners... Which is why it makes me wonder why the rear suspension on modern bikes works as well as it does. Maybe it is because of a superior shock technology rather than superior shock position.
Thom Green,Still crazy after all these years!
76' 250 MC5 (orginal owner)74'
250 hare scrambler (project bike)
72'sixday (project bike)
Merlin,
Thank you. I will print your reply and put in a ring binder I keep.
Months or a year or 2 from now i will need that very good information and have it on hand.
My memory is not worth two hoots anymore i am afraid
chuckle chuckle!!!
John D.
OK, I guess looking back my statement was a bit too emphatic. Merlin and John are right shock position does effect the suspension, but I stand by my statement that it is a minor issue not to be fretted over. You are not going to win or lose because of how your shocks are mounted on a bike limited to 4" of travel. More important is the shocks you get are of high quality and set up properly for your application, and the rest of the bike is also prepped properly.
Brian
'73 Berkshire Team d-Con
//www.d-conproducts.com America's #1 Rodent Control Brand
Brian, I agree with you that it's not a win/lose situation with just 4 inches of travel. I rode 360 CZ in 70-71 (orange tank single chrome pipe)and there was never a better hole shot MX bike built but the Penton outperformed in every event except MX. I really enjoy getting all this feedback from you guys.
Like John my memory from 35 years ago is a little faded but I remember one thing for sure, the older I get the faster I was. ha ha