Outter Fork Tube Deformed at Seal - DRZ400SM

[Roma706]

Hey folks, just purchased a 2008 DRZ400SM aont right fork was leaking pretty bad. Went to change the seal today and found that the outter fork tube is deformed a bit at the point where the seal goes in. Any way to fix this without purchasing a whole new fork?

[Kyli3_Boi]

The only way I would imagine getting that right is by having "something" that is the exact diameter as that inner diameter and heating the fork up on that part and then pressing the "something" into it.

Maybe consult a local shop that deals with motorcycle suspension, they could even possibly sort it out for you.

[drZ-tec]

Pipe expander?  just don't expand it too far!

[Roma706]

The pipe expander was my first thought too, but I think it will expand the whole thing. Think I can have a machine shop machine it back to round?

[707sumo]

Tapered bearing race driver or round edge or a ball peen hammer
Seals are somewhat forgiving so as long as you get it better than it is it should be OK make sure you pack the backside of new seal with grease to stop the spring from jumping over the lip when you install the new One

*round side of ball peen hammer*

[707sumo]

DO NOT HEAT FORKS

[Erik Marquez]

I can absolutely see how I would attempt a repair

And I’d absolutely try and talk the customer out of it

The amount of machining time to make the expanding mandrel and the support collar plus raw materials would exceed the cost of a good used fork leg

And that’s before fork service fee, fluids, seals, bushings

[Roma706]

Well, looks like a ball peen hammer is going to have to do. What do you mean by packing the backside of the seal. I've never heard that before. I usually just lube everything up with the fork oil. 

[ohiodrz400sm]

The actual seal is down below the spring ring groove. Is it deformed down there? The outer portion is for the dust seal. As the name implies it helps keep mud out but doesn't actually keep the oil in. If the outermost bore diameter is the only place it's dented I wouldn't worry too much about it.

[Roma706]

Hmmm, good point. Maybe it was just a bad fork seal and i assumed it was the flat spot. I think I'll just change the fork seal and see if it holds. 

[Michael Woodcock]

luckily it looks like the fork seal goes past that bent part.  If you bend it back you may want to anneal it first with some heat, but not too hot.  As high as you could make it with a heat gun, or very carefully with a propane torch.  Checking it with an IR thermometer as you do it.  

 

The last thing you want is to bend it back and crack it.  I'dd 3d print something to do it ?

[ss-racing66]

You can buy outer fork legs, but they're not cheap.  That looks like some crash damage, but it looks like it's confined to the dust seal area as mentioned,  put it back together  and see how it works with new seals. Worst case scenario, it leaks and you need to get another tube.

[rustynut2]

Don't use the hammer. Use a large round socket and hammer on the socket. As big of a socket you can fit in it.

No flame this is aluminum not steel. Heat treating is completely different 

Edited July 12, 2019 by rustynut2

[Barry Ries]

  If you have a lot of time and not much money.  You could go to a swap meet, get a socket that is close to the inner diameter, weld a section of the socket onto some mild steel to form a round end drift and the beat the fork into shape using the drift with a large hammer.   Getting the angles right on your blows is critical.  (Most people just aren't that good with a hammer, sometimes I get lucky but other times I just break stuff some more)     Install new seals and then hope it seals.        

[76xtdrvr]

If you're going to hammer on it,  I'd suggest doing it with the fork leg in a horizontal position. Vee out 2 short sections of 4x4.  Find a short section of pipe, or a long reach socket a bit smaller than the i.d. of the damaged area. Set the dented area of the leg at the 6 o'clock position in the vee of one block, then bridge the steel pipe, or long socket from inside the i.d. of the leg to the vee in the other 4x4 block. The dented area should bend back enough for functional assembly without a great amount of effort (?) when you hit the pipe/socket. If you decide to use an impact force on a socket for any means of repair, use caution as it can shatter.

[bumtarder]

I'd call Factory Connection,send them a picture and see what they say or recommend.

[Michael Woodcock]

People crack aluminum rims all the time trying to just bent them back with hammer blows.  

See:

it is kindof an advanced technique for a beginnner to use a flame.  I'd probably recommend seeing if a heat gun can get just hot enough to do the trick.  

Once you crack it, you won't feel it's right unless it's replaced.  If you overheat it, you won't feel it's right until it's replaced.  Right now, you may not feel it's right until it's repaired or replaced.  A real dilemma.  

 

https://www.liveabout.com/wheel-straightening-3234509

Some mechanics still offer to “hammer out” bent aluminum wheels. Never allow anyone to hammer out your aluminum wheels, because the most likely outcome is a cracked or destroyed wheel. Even if it doesn't crack, the alloy will be damaged and will never be the same.

[ohiodrz400sm]

Hmmm, good point. Maybe it was just a bad fork seal and i assumed it was the flat spot. I think I'll just change the fork seal and see if it holds. 

Did you put it together yet?

[Roma706]

Hey guys, just got back from a weekend trip hitting the trails with some buddies. Broke a rib in the process...anyway, i plan on putting it back together as-is tomorrow and see what happens. I'll keep you posted. 

[Owen Elderkin]

i have this exact problem, maybe a more severe flat spot tho.  i was thinking i could just throw new seals in until i find a outer tube but the dust/mud seal wouldn't be able to form to this shape and not really sure i can even drive the oil seal in

Edited June 23, 2021 by Owen Elderkin
typo