Bent Subframe How Do I Fix?

I think it is the subframe. It is the aluminum part of the frame on an 05 WR that the seat and rear fender rest on. Bent it a little to the right.

I have an 04 yz450f. It too has a bent subframe. It is minor so I have done nothing to fix it and don't really notice it. Excuse the pun but, if you're bent on fixing it, I think the only remedy is to put a new one on. Aluminum doesn't bend back well at all. It would most likely crack. I found decent prices on aftermarket subframes on Ebay.

Drop it exactly opposite of the way you dropped it to bend in the first place. Seriously though, take off the seat and fender and loosen the bolts that hold on the subframe (dont take them out) and lever it straight with a big bar (hydraulic jack handle or similar) you'll need a buddy or two to hold the bike while you do it. If its not bent too bad it's pretty easy.

I've straightened mine out a few times with success. I too have an aluminum subframe (but it's a CRF).

1) Remove seat, Rear fender and side panels.

2) On grass, lay down bike on side the subframe is bent to (on the right side for you).

3) Get 8-foot 2x4, place it so it is on top of the swingarm, but under the subframe rail, close as you can to the front of the subframe. Leave the longest part below the swingarm.

4) Gently sit down on the long part of wood about 2-feet from the swingarm, you may see the subframe flex up a little.

5) Bounce up and down **lightly** on the 2x4, slowly applying more weight until the swingarm flexes enough to stay straight.

6) Lift the bike up and check the alignment, you may have to do this a couple times until it is right.

7) When finished, loosen the subframe bolts and then re-torque. This relieves the stress that flexing caused.

Take your time, it will work. Use wood so it doesn't scratch/ding the bike.

PM me if you need more help.

Liquor

Park Tools makes a subframe straightener. Here's a link to it...SC

I've straightened mine out a few times with success.
Any issues with structural integrity afterwards? Is it weaker after being bent and thne bent back or does it seem just as strong?
Any issues with structural integrity afterwards? Is it weaker after being bent and thne bent back or does it seem just as strong?

I've ridden the bike for three years since the last adjustment. I have not seen any stress cracks, I don't think the bent part gets stretched very far.

Liquor

My son bent his YZ250F's subframe so bad to the left the rear tire would hit the muffler under suspension compression.

What we did to straighten it worked great. I will try to explain it the best I can without pictures. You cannot tell it was ever bent, no cracks at all.

First I took a ~20" long 2x4 and buzzed one end, on end a couple times through my table saw to put a "V" groove going in the 4" direction of the 2x4's end.

Next I used a beefy 2" wide ratcheting tie down strap (large handle) that I use for restraining my utility ATV. They are $14 at Home Depot.

I will describe locations on right side of bike that we used for attachment points to pull the subframe back to the right. It will take 2 people to do this. first pull seat, rear plastic and muffler off. I took off the front plastic skid plate to make it easier to attach strap hook.

Hook one end of strap on front of frame down near the front engine mount, next hook other end up on the rear of sub frame near the pipe hanger mounting point and cross bar leaving about 2 feet of slack.

Take the notched end of 2x4 and nest the notch over the main frame near the rear shock reservoir directlly inline between the two strap hook points.

Now forming a sideways pyramid with peak being the strap running over the square end of 2x4 sticking straight out from side of frame, this is where a extra set of hands is necessary.

Crank on the ratchet and release incrementally to see how much farther you need to go. We needed to pull the subframe nearly 2" past center for it to spring back to middle.

You probably don't need to groove the end of the 2x4 but it seems to help keeping it located & centered on side of frame.

i thought my subframe was tweaked.. well it still might be.. but i just put a new fender on and it looks straight again... :banghead:

I think it is the subframe. It is the aluminum part of the frame on an 05 WR that the seat and rear fender rest on. Bent it a little to the right.

The mechanic at my yamaha shop said (about clutch and brake levers, which are aluminum) that the only way to bend them back without breaking them is to heat them up.

Just his 2 cents. :banghead:

i just got some MSR levers for 21 bucks... why screw with bending the stockers when you can get a new set cheap..

The mechanic at my yamaha shop said (about clutch and brake levers, which are aluminum) that the only way to bend them back without breaking them is to heat them up.

Just his 2 cents. :banghead:

Yes if you heat the aluminum you will most likely anneal it and it will become soft and bend back quite easily. The problem is now it is soft and will bend out of shape super easily. The heating method would work nicely for steel but it is very tricky on aluminum. When I straightened my son's YZ250F sub frame, even though it was severely bent, it has shown absolutely no ill effects being pulled back into shape 6 months ago. It was good enough for third place in 201cc-300cc four stroke at the Carnegie hill climb last weekend. He beats the Sh*T out of that thing and it just keeps going. If bending back that subframe would cause it to fail, we would have found some evidence by now, he shows that machine no mercy.

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