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Old 12-02-2007, 09:32 AM   #1 (permalink)
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I am posting for a close friend who has a 1998 MXZ 670HO, the sled has 144 studs and it like brand new (1100 miles) One problem, every once in a while when going through whoops or coming down hard the suspension will bottom out enough that the studs will contact the bulkhead. This has not caused any issues yet with the exchangers or the bulkhead, but you can see contact marks. My question is, is there anything we can do to change the setup so that is won't happen or won't happen as often. I know on some sleds it is as easy as removing the rear suspension bolt and dropping the whole thing down but this sled doesn't appear to have that option. As far as setting the suspension up underneath, I will admit I am not that informed so any advice that anyone can give us would be appreciated. Thanks so much in advance. If the changes to be made are going to be complicated, pics would be a HUGE plus. Thanks again in advance!
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Old 12-02-2007, 10:22 AM   #2 (permalink)
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Did you drop the set of wheels in the tunnel 1"????? there are 2 wheels on a shaft that is not connected to the rear suspension that need to be moved . Did you put in the bigger tunnel protectors????
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Old 12-02-2007, 10:33 AM   #3 (permalink)
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Quote:
I am posting for a close friend who has a 1998 MXZ 670HO, the sled has 144 studs and it like brand new (1100 miles) One problem, every once in a while when going through whoops or coming down hard the suspension will bottom out enough that the studs will contact the bulkhead. This has not caused any issues yet with the exchangers or the bulkhead, but you can see contact marks. My question is, is there anything we can do to change the setup so that is won't happen or won't happen as often. I know on some sleds it is as easy as removing the rear suspension bolt and dropping the whole thing down but this sled doesn't appear to have that option. As far as setting the suspension up underneath, I will admit I am not that informed so any advice that anyone can give us would be appreciated. Thanks so much in advance. If the changes to be made are going to be complicated, pics would be a HUGE plus. Thanks again in advance![/b]
How tall of track lug and stud height are you running? I have a 1999 MXZ 500 (same chassis as the 1998 670) that I used to be having the same problem with. I am running 1" track with 168 1.25" studs down the middle. I lowered the rear bolt of my slider assembly 1" (your rear suspension) and I lowered the upper carrier axle 1". Thise is the axle that has two boogie wheels on it and it is towards the top of the tunnel and about right in the middle (front to back). Once you lower each of these you will gain 1" of clearance between the exchangers and the track but not nesseccarly any clearance between the bulkhead and the track. You will have to drill new holes in your tunnel for this. Once you lower these than re-tighten your track. Take a fish scale and hook it on one of the track window clips (the openings in the track) between the rear track wheel and the middle track wheels. Pull down on the scale until it hits 16-20lbs and measure between the top of the track and the hyfac (your slides) and you should be at about 1 3/16" to 1 3/8". Somewhere in there. Do this to both sides. To tighten the track loosen the rear track wheels and then screw the track tension screws in and than retighten the rear boogie wheels. This should fix your problem. Also, if your are continually bottoming out I would stiffen the settings on each shock. The front shock you should be able to spin the bottom of with a shock tool that should be in your tool kit. It looks like a 3" half circle. The rear shock is adjusted by rotating a plastic rectangular block that has four sides that are all different heights. This block is on the top of your slider assembly and should have you suspension tensioning arm resting on it. If you spin this untill it is on its tallest side than your shock will be in the stiffest position. There should be a tool in your kit that fits the head on the plastic block. The tool is about 4-5" long and is a 1/8" thick piece of aluminum with 4 bolt patterns cut out of it. Put the wrench on it and pull hard and the block will spin. It will spin easier if there is no pressure on the track. Have your friend lift the sled up while you spin the block quick! You should first check your track tightness and if it is loose tighten it to the above standards, than try making the quick suspension adjustments first since they literaly can be done in seconds. Even while you are on the trail if you want to do it while you are riding. If those adjustments fix your problem than I would be done. Those should fix your problem. Last thing I would do is lower your slider assembly and carrier axle as that involves drilling new holes in your tunnel and will only add clearance between your exchangers and track not your bulk head. Hope this helps!
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Old 12-02-2007, 10:36 AM   #4 (permalink)
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I forgot to mention that I talked to a guy on doo-talk who is running 1 3/8" studs on his 1996 583 (still the same chassis) and all he does is run his track a little tighter. Running your track tighter only causes more friction which may slow you down a bit but unless you are racing or a serious powder rider you will probably never notice this power decrease on tight or open trails.
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Old 12-02-2007, 10:55 AM   #5 (permalink)
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How tall of track lug and stud height are you running? I have a 1999 MXZ 500 (same chassis as the 1998 670) that I used to be having the same problem with. I am running 1" track with 168 1.25" studs down the middle. I lowered the rear bolt of my slider assembly 1" (your rear suspension) and I lowered the upper carrier axle 1". Thise is the axle that has two boogie wheels on it and it is towards the top of the tunnel and about right in the middle (front to back). Once you lower each of these you will gain 1" of clearance between the exchangers and the track but not nesseccarly any clearance between the bulkhead and the track. You will have to drill new holes in your tunnel for this. Once you lower these than re-tighten your track. Take a fish scale and hook it on one of the track window clips (the openings in the track) between the rear track wheel and the middle track wheels. Pull down on the scale until it hits 16-20lbs and measure between the top of the track and the hyfac (your slides) and you should be at about 1 3/16" to 1 3/8". Somewhere in there. Do this to both sides. To tighten the track loosen the rear track wheels and then screw the track tension screws in and than retighten the rear boogie wheels. This should fix your problem. Also, if your are continually bottoming out I would stiffen the settings on each shock. The front shock you should be able to spin the bottom of with a shock tool that should be in your tool kit. It looks like a 3" half circle. The rear shock is adjusted by rotating a plastic rectangular block that has four sides that are all different heights. This block is on the top of your slider assembly and should have you suspension tensioning arm resting on it. If you spin this untill it is on its tallest side than your shock will be in the stiffest position. There should be a tool in your kit that fits the head on the plastic block. The tool is about 4-5" long and is a 1/8" thick piece of aluminum with 4 bolt patterns cut out of it. Put the wrench on it and pull hard and the block will spin. It will spin easier if there is no pressure on the track. Have your friend lift the sled up while you spin the block quick! You should first check your track tightness and if it is loose tighten it to the above standards, than try making the quick suspension adjustments first since they literaly can be done in seconds. Even while you are on the trail if you want to do it while you are riding. If those adjustments fix your problem than I would be done. Those should fix your problem. Last thing I would do is lower your slider assembly and carrier axle as that involves drilling new holes in your tunnel and will only add clearance between your exchangers and track not your bulk head. Hope this helps![/b]
When you say lower the rear bolt of my slider assembly 1" (your rear suspension) do you mean the two bolts in the very back that hold the suspension in by the back part of the footwell? It appears that where I need to drill new holes, it already has smaller holes drilled there from the factory??? Do I just need to open those holes up more or do I need to drill them in another spot? Just want to make sure I can open those up before I went ahead and did it and then the bolt holes won't line up. As far as I know the upper carrier axle has not been lowered at this point either (are those holes already predilled to do this)??? Thanks again in advance!
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Old 12-02-2007, 01:12 PM   #6 (permalink)
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When you say lower the rear bolt of my slider assembly 1" (your rear suspension) do you mean the two bolts in the very back that hold the suspension in by the back part of the footwell? It appears that where I need to drill new holes, it already has smaller holes drilled there from the factory??? Do I just need to open those holes up more or do I need to drill them in another spot? Just want to make sure I can open those up before I went ahead and did it and then the bolt holes won't line up. As far as I know the upper carrier axle has not been lowered at this point either (are those holes already predilled to do this)??? Thanks again in advance![/b]
Sorry I was a bit vague, but you are exactly right. Drill out those existing smaller holes for the rear bolt and that is all you need to do there. Then you will have to drill new holes for the carrier axle. Just go a bout 1 inch below the existing holes and drill a new one and you should be set.
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Old 12-02-2007, 01:22 PM   #7 (permalink)
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I forgot to ask you: Are you hearing the studs hit the bulkhead when you bottom out, some kind of grinding noise? Or how do you knw it is only happening when you bottom out. Also, How big of studs are you running?
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