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SM spring rates and length for heavy springs

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OK, I'm dizzy from searching and reading. :worthy::ride: If anyone can give me some answers on this, I would be most appreciative :) :

I'm going to order new springs to finally get my '07 SM correctly set up for my weight (350 lbs with gear). I used 340 lbs with the RaceTech calulator, and it gave me 0.570 kg/mm for the fork springs and 6.82 kg/mm for the shock spring. (4345 fork and 6727 shock) They don't carry springs this heavy, so I contacted Cannon to have some made. They actually have some fork springs in stock at 0.58 and 0.59 kg/mm, but they are 495 mm long. (43495) This is a bit longer than stock (450 mm if what I've read is correct). Would this pose a problem other than just providing a bit more preload? How would it affect the ride? I've read conflicting opinions of having the springs cut, and I would like to avoid doing that if possible.

I was also advised by Cannon that 6.8 kg/mm for the shock would be way too soft. They recommended a 7.8 kg.mm, which they have in stock. Should I go with these, or should I hold out for the rate recommended by RaceTech? :D I'd hate to think they are just trying to sell me what they have as opposed to selling me what I need. :banghead:

Thanks guys,

Rob

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No, but I spoke to Jessie at Keintech. He carries Eibach and advised me they don't make springs at that heavy of a rate.

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rob h I had that dizzy crazy sh;t to I bought a hyperpro spring kit # sk44a with 20 / w fork oil I'm 290 and I can even put my wife on back with no worry on a 2006 drz sm hope this help's out

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Thank you all for the replies... I may consider the Hyperpro kit...

I contacted Eibach and was told to either contact Jessie at Keintech or call Factory Connection. They (Eibach) confirmed that the heaviest they make is 6.3 kg/mm, but Factory Connection makes a 6.7...

I still don't have an answer about the length of the fork springs, or if I should strictly go by the RaceTech calculator. Does anyone have input on either of these?

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Rob H,

So what did you end up with? There seems to be a few different opinions about the length of the fork spring on the SM. Im looking to upgrade my suspension as well.

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Nothing yet... I'm still mulling it over. It takes me forever to decide to spend money. :D

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have cannon make the correct springs.thats what they do.im not sure whyt hey are trying to steer you to the wrong springs.

45mm extra preload is way too much.

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Rob H: Do it man, it will be like a new bike!

I was riding the 3 sisters yesterday and I really need get the suspension done.

Eddie: Thanks for the clarification on the length of the fork spring.

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have cannon make the correct springs.thats what they do.im not sure whyt hey are trying to steer you to the wrong springs.

45mm extra preload is way too much.

Holy snarking crap!! I hadn't checked on this thread in months because I didn't think I would get an answer about the correct spring length. I still haven't gotten the springs, but all the OT I've gotten lately is going to make it happen. I was going to start a new thread, but I searched first... Eddie, thank you. I may be 5 months too late, but I really appreciate your input here, man. 🤣

If I may, would you give your input on the rates I should get?

350 lbs with gear, mildly aggressive commuting...

Per RaceTech calculator: 0.570 kg/mm for the fork springs and 6.82 kg/mm for the shock spring.

Per Cannon: 0.58 or 0.59 kg/mm for the forks and 7.8 kg/mm for the shock.

🤣:worthy::banghead::busted:

Just in case anyone else stumbles here in the future, here is the info from the online manual:

DR-Z400SM

Item...................................Standard.........................Service Limit

Fork travel ...........................260 mm (10.2 in) ------

Caster (rake)...........................26° 15' ------

Trail.....................................94 mm (3.70 in) ------

Inner fork tube OD..................47 mm (1.90 in) ------

Inner fork tube runout .......................------....... .4 mm (.02 in)

Fork spring free length........450 mm (17.7 in).......441 mm (17.4 in)

Fork oil type........................Suzuki fork oil SS-05 ------

Fork oil capacity, per leg.....182 mL (6.15 US oz) inner rod

......................................350 mL (11.8 US oz) outer tube------

Rebound damping 17 clicks from hard ------

Compression damping 13 clicks from hard ------

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I'm larger than you (385 when I did mine) and MX-Tech had an 8.6. It is great for mr and stiff enough for SM riding and carrying a little gear. PM John Curea TT suspension specialist and he will set you up exactly. He did shock springs, fork springs, valves oil and labor for cheap.

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Thanks, man. I don't know why that didn't occur to me... I'll shoot him a PM. 🤣

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Well if the springs are the right diameter & have the right coil diameter to clear any baffles etc & thus length is the only issue, just ask them to cut them to the right length for you. They make the springs right. If they can't cut them, then just angle grind them yourself one coil above the max length as the heat will kill that first coil, unless you have a coolant supply just below the cut.

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Just got off the phone with Cannon... $175 to custom make the fork springs. :ride: They have 7.2 kg/mm, 7.6 kg/mm, and 7.8 kg/mm shock springs in stock. Any suggestions? (350 lb with gear) :p

(I got no response from John Curea...)

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just do as cannon says. thats what i did and im Very happy with mine. The front springs just dropped in. they were the correct length. Nice and easy. And yea thats what i just paid for them too :p

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