Anyone ever install progressive springs on an 82 GS550L?

[mike_of_bbg]

So I started my job this evening, replacing the seals and springs on my 82 GS550L. I should have known things were going bad when I snapped off one of the lower pinch bolts. Everything else seemed to be going pretty well though, and I got through the rest with little fuss. My surprise came when I tried to fit the new springs - they're too wide to fit into the fork! The springs which came out are 25.4mm, but the Progressive 11-1115s are 26.7mm, and will not fit in. Plus they're about 35-40mm shorter than the stock springs I just removed! (Progressive notes no spacer on 82 GS550).

So I called Progressive and talked with tech support there. First, it seems that the wrong springs are in the box - the 11-1115s should be 22mm. Still, the real 11-1115s are about 19" long, which is not going to be enough. I think their GS550 is an M, not an L. *sigh* I'll send an e-mail and maybe they'll find something which will work.

Has anyone put springs into an 82 GS550L? And if so, what model did you use?

What other options might I have? The front end sags about 3 inches now. I suppose I could cut some 1-2" spacers to re-install with the stock springs...

Oh, and how bad would it be to ride with just one lower pinch bolt?

 

[twr1776]

Yesterday, 07:30 PM mike_of_bbg Oh, and how bad would it be to ride with just one lower pinch bolt?

I would not run it without the pinch bolt. I am not 100% sure what would happen but the front forks are not an area I would take any chances on.

Is it possible a PO changed the forks from the originals?

The L should have the leading axle type fork tubes. I would measure the old springs and call Progressive tech support to see if they have a recommendation, I would think the 650L springs could be similar to yours.

I do know the 850, 1000, $ 1100L's all use the same Progressive fronk fork springs. Can you post a pic of the fork tubes you have? On the 850/1000/ & 1100 the replacement springs are slightly shorter than OEM's but you just add an additional spacer on top to take up the difference. Let us know what Progressive tech support says, it would help others out doing the same mod.

IMHO the Progressive springs and modern sticky tires are mandatory upgrades for safety on these bikes.

 

[bwringer]

When installing new springs, it doesn't make any difference if the new springs are shorter than the originals. You will have to cut spacers to preload the springs somewhere between 2 and 5cm, depending on your weight and riding style.

Sounds like Progressive's application data is faulty, which is not surprising. Just get whatever springs fit in there diameter-wise, then cut spacers as needed.

What is the outside diameter of your fork tubes? Most of the bigger bikes use 37mm OD forks, but I'd guess the 550 uses 35mm forks.


As far as the pinch bolt, use the time until the springs arrive to drill out the remains of the bolt with a good sharp cobalt bit and fix it right (do NOT, under any circumstances, try using an EZ-out -- it WILL NOT work and it WILL break, and EZ-outs are impossible to remove with normal tools.)

You don't need to worry too much about the threads -- simply install a new 8mm bolt that goes all the way through and use a nut on the other end.

 

[mike_of_bbg]

Thanks for the reply.

Yeah, I'm probably not going to risk it with the pinch bolt, though in looking at it I don't think it would do any harm. With the vanity plate off it should be easy enough to dremel a slot into the back side and get it out using impact, PB Blaster and a little heat.

There were definitely some parts swaps before on this bike, but the front forks do seem to be original. Can't snap a pic right now but yep, it's leading axle. The 82 GS550L was an odd-ball before they came out with the TSCC models. Prior years used two springs and either flat clip caps or screw-in air caps. 82 has a clip-in with air valves, and I pulled out a single spring which seems to match up well with the unique 82 service limit. The specified fork oil level was also quite a bit different in 82, and travel was a touch longer.

Good call on a 650 - I'll have to look into that. They don't spec a spring for an 82 650L. The 650G and 650GL call for the 1106s. I'll present my case after I get all my facts in a row and see if they can offer a good alternative.

 

[mike_of_bbg]

When installing new springs, it doesn't make any difference if the new springs are shorter than the originals. You will have to cut spacers to preload the springs somewhere between 2 and 5cm, depending on your weight and riding style.

Sounds like Progressive's application data is faulty, which is not surprising. Just get whatever springs fit in there diameter-wise, then cut spacers as needed.

Yeah, I'll see what they can offer me. If they can just match up spring rate, inside diameter, and travel, PVC should take care of the rest.

What is the outside diameter of your fork tubes? Most of the bigger bikes use 37mm OD forks, but I'd guess the 550 uses 35mm forks.

Yes sir, the little bike has 35mm forks. Don't think my calipers will reach down to measure the ID, but we know it's <26.7mm and >=25.4mm.

As far as the pinch bolt, use the time until the springs arrive to drill out the remains of the bolt with a good sharp cobalt bit and fix it right (do NOT, under any circumstances, try using an EZ-out -- it WILL NOT work and it WILL break, and EZ-outs are impossible to remove with normal tools.)

You don't need to worry too much about the threads -- simply install a new 8mm bolt that goes all the way through and use a nut on the other end.

If I can't get it out with a cut slot and screwdriver, I'll take that route. Hmmm, should also take this opportunity to re-pack the steering stem bearings :-\\\

 

[mike_of_bbg]

OK, I found Progressive's spec list here:

http://www.progressivesuspension.com/pdfs/7100-105.pdf

So the stock spring I removed is 25.4mm OD, currently 21.25" long with a service limit of 20.8" length. What I suppose I'm looking for then is a 25mm OD spring. The 1115s they originally called for the GS550 have the 30/40 rate. The 1116s are 25mm, 20.75", with that same 30/40 rate. That could make for an awfully short spacer. Could go with the stiffer 1111s or 1108s, or 1106s with a longer spacer. The 1109s look like a good candidate too for a stiffness somewhere in between, thought that rate+length is only available in 22mm OD. That shouldn't really be a problem though, should it?

Any experienced opinions out there on which might be a good choice?

 

[twr1776]

I would call the Progressive tech support and go with thier recommendation. My guess is the 1116's with the same spring rate and OD.

 

[mike_of_bbg]

They're recommending the (actual, correct) 11-1115s, and add spacers to 19mm pre-load. Dunno, guess I'll try it and see how I like it. Certainly they'll be better than stock. Seems odd that they would recommend a 22mm spring when 25mm springs closer to the factory spring diameter are available - and closer to the factory spring length. But what do I know?

 

[bbqdiguana118]

I just checked the box from my progressive springs I installed last year. (I tend to not throw things out much) The 11-1115's are the ones I used for my '81 gs550L.
Yes they do need a spacer which is easy to make out of some pvc pipe.
I was in the same boat because the data sheets said no spacers for the '81 gs550.
My guess might be that the L had longer forks than the other versions.
It's been working fine since I swapped out the old springs.

 

[mike_of_bbg]

Thanks for the encouragement and validation there. Did it make a big difference in the way she handles?

The L's probably have more room for springs because of the angle and the leading axle. If you add up the two springs on the 81 GS550L, they're over 23 inches IIRC.

I just checked the box from my progressive springs I installed last year. (I tend to not throw things out much) The 11-1115's are the ones I used for my '81 gs550L.
Yes they do need a spacer which is easy to make out of some pvc pipe.
I was in the same boat because the data sheets said no spacers for the '81 gs550.
My guess might be that the L had longer forks than the other versions.
It's been working fine since I swapped out the old springs.

 

[bbqdiguana118]

I can honestly say I don't know how different they felt.
Last time I'd ridden her I had been in a lowside accident due to a car stopping short and the bike taking a nosedive. More damage to me than the bike fortunately. Engine guards saved some heartache.
By the time I felt good enough to ride again I'd already swapped the new springs in.
I don't notice as much dive but I'm still making improvements to the bike which includes a new front rotor and pads, new tires front and back. So I feel she should be working quite well handlingwise once I put her back together again. Just waiting on a small part atm.

 

[mike_of_bbg]

Well, I got the "real" 11-1115s on Thursday. I also replaced the front wheel bearings (old ones were definitely rough) and the front tire (back to the stock 90/90-19 in a Bridgestone S11 like the rear from a 9-year-old 3.50-19). The forks got new leak-proof classic seals and fresh 15W Maxima fork oil. Went with 42mm spacers (plus washers =~ 44mm total spacer) made from 3/4" PVC. This also is hot on the heels of new EBC organic brake pads and A&N SS brake line up front. So, lots of changes up front.

WOW

What a different bike!

It was easy to see that the springs were going to be quite different even on the side stand. Sag with rider is down to ~1.75", or 30% from 3" or 50%. Brake dive is much more manageable despite the more effective braking. It may be more of a factor of the tire but the bike so wants much more to turn now. It may never be flickable, but it's a much more maneuverable and responsive bike now.