Swing Arm Bush Replacement

[RickGM]

Hi Guys, long time since I posted on here but in need of advice.

Took my 1980 DT175MX for its MOT today. It passed but only just - there's play in the lower swing arm mount.

 

Got home, read up on how to remove the pivot bolt, shims, washers, thrust covers, bushes etc and set to work.

After removing the nut the pivot bolt was solid - had to use a 1/2" drive socket bar with long extension tube just to get it to turn. 4 hours later, 3 knackered drifts and 1/2 a tin of WD40 the pivot bolt is jammed solid half out.  So... any advice on how to get it out.

[Airhead]

you just might have to saw it I'm afraid Rick but I once had success by placing a tube around te far side between the frame and a wall, this took the flex out ot of the frame as it was driven out with a hammer and saved me having to destroy the bolt, of course slacken the nut but leave it on so you don't bugger the threaded end

[drewpy]

might have to try heat, do you have a heat gun?

[Cynic]

Heat wont work, the crap holding it runs the full width of the sw arm. Either try what airhead said that might work or cut it. I had to with mine. With a decent hacksaw blade it doesent take too long and only damages whats already knackered. 

[NE0]

Hi Rick

I did a thread to this on my own MX a few years ago https://yamahaclub.com/forums/topic/28370-dt175mx-refurbishing-the-swinging-arm

having cut mine off, I used the socket and bolt to 'push' out the remains in the vice and also having re-read the post I even made a new swinging arm pivot bolt from an M10 stainless bolt and put a hole in the side for the split pin. it was a PERFECT fit and it's still there today working fine!

The socket was used to 'receive' the bolt remains whilst the shiney bolt there was used to drive the remains into the awaiting socket. The vice was tightened up and up until there was a loud 'bang' as the remains of the shaft gave up! then it just had to be pushed out.  I remember it well, such a sense of achievement!!

 

Edited June 16, 2018 by NE0

[RickGM]

Thanks guys. Not sure we're on the right track.  The bolt that's stuck is at the bottom of the swing arm connecting to the frame - Pg 151 of the Haynes manual.

I've already cut the head off (and an inch or so of the bolt) with a view to knocking it back in to clear the frame brackets and drop the swing arm out. Unfortunately it won't budge going back. Can't see anyway to cut through the bolt on the  inside of the frame which I need to do to drop the swing arm out. Tried to upload a couple of pictures but they won't load (user error clearly).

 

[Cynic]

There is room, you have to cut through the plastic top hat bushed that are between the frame and the sw arm. That gives just enough clearance to get the blade through. The sw arm bushes are brass so cut easy. The spindle is just case hardened so once you get through the skin so to speak that's ok too.

You will be using the proven highly accurate engineering tool known as a hacksaw blade wrapped in insulation tape. 

[NE0]

Hi Rick

Yes, my mistake I was indeed thinking it was the swing arm pivot bolt which is just as difficult to get out!

You're referring to the lower swing arm bolt (as you said in your first post!!) arrowed here!

 

I assume you've taken the engine out to gain better access???

Edited June 16, 2018 by NE0

[RickGM]

4 hours ago, NE0 said:

Hi Rick

Yes, my mistake I was indeed thinking it was the swing arm pivot bolt which is just as difficult to get out!

You're referring to the lower swing arm bolt (as you said in your first post!!) arrowed here!

 

I assume you've taken the engine out to gain better access???

That's the one and no the engine isn't out. 

 

5 hours ago, Cynic said:

There is room, you have to cut through the plastic top hat bushed that are between the frame and the sw arm. That gives just enough clearance to get the blade through. The sw arm bushes are brass so cut easy. The spindle is just case hardened so once you get through the skin so to speak that's ok too.

You will be using the proven highly accurate engineering tool known as a hacksaw blade wrapped in insulation tape. 

With the engine /box in the bike there's no room to get a stroke with your precision tool.

 

Still no idea how to post a pickie but here's a link;

 

https://photos.app.goo.gl/dsv4CdjTp7njL8KJ7

 

[Cynic]

That engine can be on the bench in 20 minutes, exhaust, couple of cables, some fuel and oil pipes, bit of electric and the carb rubber. That's it.

[NE0]

Rick , I think you'll find it very difficult to cut that bolt out with the engine in place.

As you can see, the amount of space available will make the job so much easier.

 

[jimmy]

Hey Rick

Sign up to Postimage.org. Upload pic and copy "Hotlink for forums" Paste the url in your post (sometimes you need to remove the letter 's' from the two https and away you go) and sometimes you don't. In this case I never

[RickGM]

Thanks Jimmy.  Uploaded a picture to Postimage.org, copied the "Hotlink for forums" and after editing the link got an image ! Copying and pasting "Direct Link" worked without and edit of the link text.  That problem's sorted now just need to sort the bike !!

[RickGM]

Managed to knock the remains of the bolt back into the tube and drop the swing arm. Top connection to the shocker came out fairly easily.

The bushes seen to be made of some kind of fibre. No idea how I'm gonna get them out - they seem to be bonded to the swing arm. Any ideas?

 

[finnerz89]

They're a hard plastic material, you can split them with a hacksaw blade and they'll loosen up

Sent from my SM-G950F using Tapatalk

[RickGM]

2 hours ago, finnerz89 said:

They're a hard plastic material, you can split them with a hacksaw blade and they'll loosen up

Sent from my SM-G950F using Tapatalk
 

Thanks, I'll give that a go. Don't want to scour the inside of the swing arm though.

[finnerz89]

Thanks, I'll give that a go. Don't want to scour the inside of the swing arm though.

As long as your careful you'll be fine. Stop just before it's fully cut through then snap it with a screwdriver or chisel

Sent from my SM-G950F using Tapatalk

[RickGM]

Worked a treat, thanks. Powder coating on the list now while it's all stripped down and the search for parts.

 

[NE0]

Yambits sell the kit

https://yambits.co.uk/dt175mx-swing-arm-repair-kit-p-3002.html

not a bad price at all, under £30.

Edited June 20, 2018 by NE0

[RickGM]

Thanks for that, order on its way.

The diagram in the Haynes manual shows a shim sitting between the top hat bush and the  thrust cover. There wasn't any when I took it apart and they don't show on the kit. The assembly was a snug fit between the frame so not sure whether they're needed (or what they do).