Breaking Swingarm pivot bolt

[BadA$$440]

OK, i have snapped 2 swingarm pivot bolts. It always snaps right were the threads start. Does anyone know why? Am i the only one with this probmlem? I try to keep to bolt greeased up with Anti Seize as much as i can. I think it might be that the bearings are shot. What gives?

suspend your quad's rearend off the ground and shake it... you got somethin goin dude because your the only one that has this problem...:confused:

[BadA$$440]

ya i know, its weird, every body that ive told, said they never heard of that happening, if you want i can go take a pick of it

[RIDER11X]

I've heard of that in 250r's and one Raptor, but not in a 400ex. Baldwin does advertise a cromoly replacement, that i'd think should be stronger.
Bad bearings could make that more likeley to happen though I would suppose.:(

P.S. The Raptor has a similar motor mount set up as the 400ex with the swingarm bolt being used as the rear engine mount. On the Raptor I heard of, the Swingarm bolt broke and since the bolt was not supported by the frame on that side anymore, a hit to the swingarm cracked the engine cases causing oil loss and motor damage.:eek2: :eek2: But that was a Raptor, not a 400ex.

[jlhughes750]

thats not that strange. i've seen a bunch get broken. a few people advertise chromoly or stainless. if u want the best bolt out there for the price, go to a GNCC and find #12 R. Hertz. he makes stainless bolts , nearly all the Pro's are running his bolts, which says alot for the quality. if u don't get out to the gncc's let me know and i'll ship u one. I can't give out his # and he's not on the net (too busy fabbing trick parts), he's a good friend of mine i could get the bolt for u.

later, J


267-374-0500

[Pappy]

hey whtas hertz gettin for them? maybe you can bring one to the sc race for me:p

[jlhughes750]

hey guys, i think there 65.

tell u what, i've never broke one, never seen them wear like stock. i always use that bolt, on every quad i build, its well worth it!!!!!!!! also if u ever seen those neat quick change studs that everyones using, those are his also.

the "Hertz bolt" is the original don't be fooled by imitations.


later, J

[Mxbubs]

Im on my 6th bolt at least. My dad makes them for me. I was running a 9/16" bolt, and they too were breaking at the threads. They break if you over torque them. However, on my bike, I gusseted that area, so I really have to get down on the bolt/nut to squeeze the frame tight to the swingarm. I have just recently broken a titanium one he made. Now we are stepping up to a 5/8" bolt that I know, will not break.

[forum]

I do know that a 250r pivot bolt is alot thinner walled then the 400ex. so guys with 250r's use 400ex bolts often. But Bubs thats crazy! are these solid! maybe you shouldn't have gusseted your frame there. don't tighten them so much and put a pin in the end.

[Mxbubs]

Originally posted by forum
I do know that a 250r pivot bolt is alot thinner walled then the 400ex. so guys with 250r's use 400ex bolts often. But Bubs thats crazy! are these solid! maybe you shouldn't have gusseted your frame there. don't tighten them so much and put a pin in the end.


Already tried that with 2 chromoly steel bolts. They break at the threads where I drilled the hole to put the pin thru. I should not have gusseted this frame....LOL....more trouble than its worth....however, a 5/8" bolt is gonna kick its a**.:D

[RIDER11X]

Has anyone had a broken or damaged case from a swingarm bolt breaking?

Also, how can you go to a larger bolt and still get through the bearings and the cases?:huh

[BadA$$440]

i was racing on mine and it was sticking half way out of the bike, but it didnt hurt the engine

[Mxbubs]

A 9/16" bolt would have to be custom made by a machine shop, however you can get a 5/8" bolt from any hardware store. I am running a 5/8 bolt on my bike, but I have a yz motor, that has the bigger pivot bolt hole in the motor to begin with. Im not sure you can drill a 5/8" hole thru 400ex pivot bushing in the motor.

HOWEVER, IF you decide to drill the bearings out, you WILL NEED a masonry bit. A regular bit WILL NOT drill the bushing/spacers out. It is essentially an inner bearing race, which is extremely hard, and will EAT up any diamond, titanium, or regular bit up. A masonry bit will do the job, trust me I know, I just ruined 50$ worth of drill bits.:D

[BadA$$440]

how much do hardware stores charge for bolts like theses? I paid $20 for a stock bolt. And they wanted like $4 or $5 for the nut, so i went to the hardware store and got one for a buck.

[Mxbubs]

5/8" bolt approx. 5$

[BadA$$440]

damn, them dealerships really like to rip you off. They originally wanted $30 but i said i can get it for $20 at service honda, so thats how much they gave it to me for.

[Pro400EXC]

Jesse Mine broke right slap in de middle,but the end,i dunno about that?

[quader400]

i just got all new bearings. are they supposed to slide right in or do they have to be pressed in. anyone know?

[RIDER11X]

They should press in if the 400 has the same set up as the 250x. Haven't done the 400's yet.