1980 390or Suspension

[FirstEliminator]

Hey guys,

This past weekend I picked up a 1980 390or. The rear suspension is terrible. It has those black shocks with the step adjusters for the springs. I jump on it and it won't compress. I think it's the wrong springs or worn shocks. They measure 15.5 eye to eye. What is the maximum eye to eye shock I can put on there? I hear the Ohlins with remote reservoirs are the best shock to get. Before actually seeing this bike I thought it was a 78 so I bought some 15" Ohlins. I'll save them for one of my earlier bikes. I've seen shocks that are piggy back, are they also Ohlins? All in all what are the best recommended rear shocks for a 1980 390or to be ridden in Northeast?

Not sure what to do with the front end. I might just leave what is there and rebuild it. I do have a set of Ohlins forks from an '04 Gas Gas 450. The thought crossed my mind to put that front end on this 390or. What I determined would be a better idea is to piece together a bunch of extra '87 stuff hanging around. I have an 87 XC frame and rear swing arm, old seats, plastic and misc. I recently bought an 87 430xc engine on ebay. This is a perfect place for the GG450 forks. With a bit of work I can make a bike where there was none.

thanks,
Mark

 

[fran...k.]

When the shock compresses the wheel should almost hit fender.

There are piggyback type shocks that are not Ohlins and look very similar.
By mounting the shock to the side of the swingarm a longer shock became possible. To answer some of this stuff need to know if frame or swingarm changes are allowed.

 

[Kartwheel68]

I think the length of the stock shock on the 79-80 OR/CR was 16.5 and the WR was 15 or 15.5" and I think the side mount 81-82 were 16.5 for the WR and 17.25 for the XC/CR.

 

[ruwfo]

Drop on a pair of 40mm forks & shocks off an 82 (17"?) and you'll have something you can ride as hard as you like, as long as you have
a tall inseam, I'm 6'2".

Here's my 80 390CR, with these upgrades..

 

[vintagecs]

79-80 CR/OR stock shock is 16.5", I had one and sold it off, too tall for me I'm 5'11" and ride the WR bikes now because of the inseam thing. 40mm forks came on several years, be careful because the WR 40mm forks are shorter, too.

 

[FirstEliminator]

Perhaps I should go with 13" eye to eye shocks as I am 5'9" with a 32 inseam. Oh well, I've been riding big bikes forever. If it's too tall perhaps that will motivate me to put together one of the 76 or 77 wr.

 

[fran...k.]

I like the height of the wr/ae/te bikes as well. Supposedly if your suspension is shorter than the rest of the guys it leads to problems in the ruts. That bike in my avatar has great ground clearance.

Strangely I tried to sell off some shocks last year. Not the itc ones and had played mix and match with the springs of the remote reservoir ones. I guess no one wanted to pay my prices so I listed a gas tank kind of low to start just to sell something. I stripped 3 hemi joints as I actually rode these things into worn out at one point in the past. I can not even recall what these came off. the 81 420 two had remote reservoir and the piggyback one went to the center of the swingarm and is installed on a bike, the one I registered in Michael's thread.

I suspect the axle is shorter for the 35mm front end, obviously one needs the clamps to upgrade the forks to the 40mm ones. Plenty of discussion about fitting entire other front ends as well.

 

[fran...k.]

"Perhaps I should go with 13" eye to eye shocks as I am 5'9" with a 32 inseam. Oh well, I've been riding big bikes forever. If it's too tall perhaps that will motivate me to put together one of the 76 or 77 wr. "

When you go back farther the swingarm tube is significantly smaller.


One creation I made I enlarged that pocket on top of the swingarm with a hole to put the lower shock mount in every half inch or so. There were banana shaped swingarms for fox air shocks and perhaps longer regular ones.

 

[FirstEliminator]

Fran, I sent ya a PM about those shocks if they are still for sale.

 

[Kartwheel68]

Dont go shorter than 15" on the '79-'82 frame.

 

[Bigbill]

Food for thought,

One problem I had was I purchased one of my 70’s 390cr that had the black progressive 15” rear shocks that didn’t budge. I found out the PO installed the 17” springs on the 15” shocks. Once I installed the 15” springs on the 15” shocks she was rideable.

 

[oldbikedude]

A little thing called coil bind

 

[FirstEliminator]

Hi Bill,
I think that is exactly what is going on with the 390 I have. Perhaps these are your old progressive shocks? They don't budge. If I am going to try Netra VHS then I am going to need some movement in the rear suspension. Otherwise, I'd take the 73 with only 4" of travel.

 

[Kartwheel68]

WR length 15-15.5" shocks should be fine, I am 5'8" and I dont feel any need to go shorter than that, but XC/CR length is definitely way too tall for me unless the bike is strictly an MX bike.

 

[ruwfo]

Dont go shorter than 15" on the '79-'82 frame.

I agree, even 15.5" is too short in my opinion, for those with short in stem, I'd go with closer to a 16-16.5" with
a less stiff spring, you'll thank yourself for that extra 1" of travel.

 

[vintagecs]

Keep the stock length for your bike: WR = 15, CR/OR = 16.5 changing lengths affects handling adversely, although a slight increase from 13 to 13.5 or 15 to 15.5 is not bad. DEFINITLEY don't go shorter, your bike will ride like a chopper!

 

[Picklito]

If you still have that set of "wrong length" Ohlins, you may be closer than you think...

You can build Ohlins to just about any length you want. In fact, the factory frequently included length-setting spacers on the chrome shafts, internally, and new chrome is still available in many lengths for roughly $55 each.

All it takes is to determine what you want for fully extended and fully compressed lengths, and "do it up." The precautions mentioned above are spot-on, of course... you definitely don't want to build a shock that lets the wheel bottom into the fender, nor create coil bind, but that's step one on any suspension design.

The recommendation for 40mm front fork swap is great, and it's a bolt on. If you want it a touch lower, use 40's from a WR up front, and then finalize the stance with a matching shock length. I'm sure this sounds complicated, but it's not! And you have CH to help!

 

[Kartwheel68]

Dont go shorter than 15" on the '79-'82 frame.

I agree, even 15.5" is too short in my opinion, for those with short in stem, I'd go with closer to a 16-16.5" with
a less stiff spring, you'll thank yourself for that extra 1" of travel.

Keep the stock length for your bike: WR = 15, CR/OR = 16.5 changing lengths affects handling adversely, although a slight increase from 13 to 13.5 or 15 to 15.5 is not bad. DEFINITLEY don't go shorter, your bike will ride like a chopper!

If you use 15" shocks you would need WR forks and/or damper rods to make the bike sit level, no shorter than 15" for sure. If you have CR/OR/XC forks you would need 16.5" shocks otherwise the bike will be like riding a chopper as noted above. I built an '82 250XC with a 79 swingarm (which makes the rear suspension exactly like what you have) for a 5'4" woman using 14.5" shocks but the only reason I could do that is I had a set of 83 175WR forks which only have 9.5" of travel, where the bigger bikes have 10.6". Even with the shorter 175WR forks the 14.5" shocks were too short and the bike did not ride level, so for sure 15" is the limit.

 

[Bigbill]

I was taught to stand on a milk crate and push down on the left peg to see if the front and rear suspension compresses even when it goes down.

You can make the bike sit level by adjusting the fork tube height in the tripple clamps. Then comes setting the front fork up correctly so it matches the rear compression.

 

[ruwfo]

Have the bike sitting level, is fine, when there is no weight on it, but more important is how does it sit with the rider on it.
Too light of fork oil & weak or too soft of rear springs , you can lose 2 inches of travel just sitting on it ,never mind when your
riding it.