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Tell Me About Shock/Spring Upgrades

  • Thread starter Thread starter MisterCinders
  • Start date Start date
M

MisterCinders

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I've done several searches on rear shocks, but they leave me pretty confused.

I'd like to improve the rear suspension on my 1978 GS 750. Based on various forum searches, the consensus leads to Progressive and/or Hagon.

What I cannot figure out is which shocks/springs from either company. Their web sites allow me to plug in the make and model but other posts on GSR suggest that I may not be limited to just those findings.

For instance, Progressive tells me to go with their 12 series of vintage shocks.

Other posts indicate that I can use more modern options from Progressive.

Is there a baseline for identifying replacement shocks (e.g., distance from eye-to-eye or eye-to-clevis), such that anything in the correct size will fit?
 
Based on your link I'd say you're looking for some 13" eye-to-eye shocks with appropriately-rated springs. On the surface any 13" eye-to-eye should do, but you have to consider clearance issues if they get too big around.

My understanding with the Hagons is that you call up Dave Quinn and they'll calculate your spring rate needed, etc., and get you a better shock than Progressive for about the same scratch.

http://www.davequinnmotorcycles.com/cgi-bin/webc.cgi/HAGON_TWIN_SHOCKS.html
 
Last edited:
Take a look at IKON shocks.

They list your bike...
I have IKON shocks on both my 1100E and my BMW K1100RS...
 
I've had some interesting email discussions with the Works Performance guys recently, and there is more to shock than eye to eye length (i.e. not all 13" eye to eye are the same; some are offset, some have different travel lengths, etc). You SHOULD be ok with anything listed for the GS series, but there are variations based on whether one is dealing with chain or shaft drive.

Your best bet is to talk to them directly. Just like the people on here, they have a vast amount of hands-on knowledge of the gear and bikes.
 
Agreed with the idea of calling Dave Quinn and talking to him. He'll set you right up after asking you series of questions.
 
Mr. Cinders, if memory serves me correctly, the shocks that are already on your bike look like they might be from Progressive.
 
In my view shocks come in two major categories:
1) the emulsion type eitheir std or nitrogen charged
2) De Carbon type where oil and air are separated by a piston
There was a very good article about shock technology in "Cycle" dated December 1981 ( it also had a test of the GS 1000 SZ Katana;))
The emulsion type shocks rely on the fact that the air and oil mix up like in a mayonnaise to work:confused:
The cheaper shocks all work on this principle up to and including the Ohlins entry level...
The more evolved shocks separate the oil and air ( nitrogen) by a membrane or a piston ( De Carbon licence).
Both types of shocks can come in a pressurized form to avoid high speed
cavitation.
The more evolved shocks have a separate reservoir that aids in cooling the oil in the shock.
When motorbikes evolved to a monoshock design, the shocks moved away from the emulsion principle.
Too bad that when we want to replace our shocks we still rely on the old technology:eek:
 
MisterCinders said:
I've done several searches on rear shocks, but they leave me pretty confused.

I'd like to improve the rear suspension on my 1978 GS 750. Based on various forum searches, the consensus leads to Progressive and/or Hagon.

What I cannot figure out is which shocks/springs from either company. Their web sites allow me to plug in the make and model but other posts on GSR suggest that I may not be limited to just those findings.

For instance, Progressive tells me to go with their 12 series of vintage shocks.

Other posts indicate that I can use more modern options from Progressive.

Is there a baseline for identifying replacement shocks (e.g., distance from eye-to-eye or eye-to-clevis), such that anything in the correct size will fit?
Click to expand...

I did the progressives with the HD spring to match the Racetech matched fork springs with emulators and a fork brace.

The progressives work pretty well but much of that impovement has to go the spring rate being closer to optimum.

If I did it again the Hagons with the matched springs sound about right.
 
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