Spring size for a 1997 M750

Started by Mike Qube, February 25, 2011, 12:56:38 PM

Previous topic - Next topic

Mike Qube

I'm looking at upgrading the spring on my stock shock. I would rather replace the whole thing, but don't have the cash right now to buy an ohilns or a penske. I went to the race tech site and they didn't have anything listed for the 97 M750, I called and there was nothing in their database for a stock shock size. The I went to Traxxion and placed an order there, I got a call and they didn't know what the stock spring size was. They asked me to take the shock off and send it in, i would rather avoid having to do that. I did some searching and found an old thread that someone with a 96 M900 replaced his spring and he used a;
SRSP S5818116    RT SHK SPR 58.2x178mm 11.6kg
Would this be the same size for a 97 M750?

hooligan machinist

 I'm interested in reading any responses you get.
Been needing to do the same thing for a while now.
cell # (931)-316-2020

Speeddog

I'll try to measure up an early Monster shock tomorrow, but I'm pretty sure that spring size will work.

That's a metric description of a 2.25" ID x 7.0" long spring, 650 lb/in.
That's a *very* stiff spring, moreso for an early Monster.
- - - - - Valley Desmo Service - - - - -
Reseda, CA

(951) 640-8908


~~~ "We've rearranged the deck chairs, refilled the champagne glasses, and the band sounds great. This is fine." - Alberto Puig ~~~

Mike Qube

Quote from: Speeddog on February 25, 2011, 09:15:33 PM
I'll try to measure up an early Monster shock tomorrow, but I'm pretty sure that spring size will work.

That's a metric description of a 2.25" ID x 7.0" long spring, 650 lb/in.
That's a *very* stiff spring, moreso for an early Monster.

That would be awesome if you can measure one!
The description came from the race tech site, I believe. I'm looking for a spring for a heavier rider, I'm about 220 and I don't think the stock one is made for someone my size.

ducpainter

I'm pretty sure the spring for an early Monster is longer than 7 inches.

The weight should be close....maybe one rate too stiff.

I'm 180 ish and I run a 10.0
"Once you accept that a child on the autistic spectrum experiences the world in
 a completely different way than you, you will be open to understand how that
 perspective
    is even more amazing than yours."
    To realize the value of nine  months:
    Ask a mother who gave birth to a stillborn.
"Don't piss off old people The older we get, the less 'Life in Prison' is a deterrent."



koko64

#5
There's only a 1/4 of an inch in it. That's if the stock yellow spring from my 95 M900 is typical.
My Eibach spring is shorter but the preload thread runs way down.

Yeah, I'm about 190 and running a 550/10kg ish spring. I think you're right about it being close to one step above. With gear on, dinner and a beer he should be right.
2015 Scrambler 800

Speeddog

The spring off of the '95 M900 shock is 7 5/16" long.
Looks like a 7" spring would work to me.
You can't put a whole lot of preload on, but should be sufficient.

If that 220 is without gear, I'd say fit a 10.7kg/mm or 600 lb/in spring.

Run the preload collars down until the spring is ~6.5" when the shock is on the bench.
That should get you in the ballpark on sag, but check and adjust as necessary.
- - - - - Valley Desmo Service - - - - -
Reseda, CA

(951) 640-8908


~~~ "We've rearranged the deck chairs, refilled the champagne glasses, and the band sounds great. This is fine." - Alberto Puig ~~~

ducpainter

Quote from: Speeddog on February 26, 2011, 02:33:51 PM
The spring off of the '95 M900 shock is 7 5/16" long.
Looks like a 7" spring would work to me.
You can't put a whole lot of preload on, but should be sufficient.

If that 220 is without gear, I'd say fit a 10.7kg/mm or 600 lb/in spring.

Run the preload collars down until the spring is ~6.5" when the shock is on the bench.
That should get you in the ballpark on sag, but check and adjust as necessary.
That much pre-load?

"Once you accept that a child on the autistic spectrum experiences the world in
 a completely different way than you, you will be open to understand how that
 perspective
    is even more amazing than yours."
    To realize the value of nine  months:
    Ask a mother who gave birth to a stillborn.
"Don't piss off old people The older we get, the less 'Life in Prison' is a deterrent."



Speeddog

Quote from: ducpainter on February 26, 2011, 03:11:58 PM
That much pre-load?

SWAG.... precious few 1st gen Monsters come in for suspension upgrades.

How much do you have on yours?
- - - - - Valley Desmo Service - - - - -
Reseda, CA

(951) 640-8908


~~~ "We've rearranged the deck chairs, refilled the champagne glasses, and the band sounds great. This is fine." - Alberto Puig ~~~

ducpainter

Quote from: Speeddog on February 26, 2011, 04:12:46 PM
SWAG.... precious few 1st gen Monsters come in for suspension upgrades.

How much do you have on yours?
The optimum preload as I was taught by the vet is 15 mm. My Ohlins has exactly 15mm of preload with a 10.0. That is why I think an 11.0 or 11.5 will work for the OP.

A spring that is preloaded more than that will react harsher initially and then over compress. Believe it or not a stiff spring with very little preload will feel softer than a soft spring that has a ton of preload wound in.

Try it.
"Once you accept that a child on the autistic spectrum experiences the world in
 a completely different way than you, you will be open to understand how that
 perspective
    is even more amazing than yours."
    To realize the value of nine  months:
    Ask a mother who gave birth to a stillborn.
"Don't piss off old people The older we get, the less 'Life in Prison' is a deterrent."



Speeddog

May be the difference between 1st gen and 2nd gen Monsters.
- - - - - Valley Desmo Service - - - - -
Reseda, CA

(951) 640-8908


~~~ "We've rearranged the deck chairs, refilled the champagne glasses, and the band sounds great. This is fine." - Alberto Puig ~~~

the_Journeyman

I've got the OEM spring for my 1999 M750.  I put a spring kit that was supposed to fit an earlier M900 and no issues.

I can measure my OEM spring if you need me to ~

JM
Got Torque?
Quote from: r_ciao on January 28, 2011, 10:30:29 AM
ADULT TRUTHS

10. Bad decisions make good stories.

ducpainter

Quote from: Speeddog on February 27, 2011, 12:37:54 PM
May be the difference between 1st gen and 2nd gen Monsters.
Pretty sure the 15mm is universal.

The spring rates for the different gen monsters are different due to linkage ratios.
"Once you accept that a child on the autistic spectrum experiences the world in
 a completely different way than you, you will be open to understand how that
 perspective
    is even more amazing than yours."
    To realize the value of nine  months:
    Ask a mother who gave birth to a stillborn.
"Don't piss off old people The older we get, the less 'Life in Prison' is a deterrent."