bent forks R75/5

[equipo5]

More on the R75/5 front end but I've just discovered my fork tubes are bent. (5mm). Anyone had experience with the cheaper replacement tubes (Italian made). I am hoping my existing damper system fit them ok? and that the ability required to do the job comes in at "Meccano level".

Thanks in advance for any advice.

Ian

[ME 109]

5mm is huge! Collision stuff.
How did you measure them?

[PITAPan]

5mm is huge! Collision stuff.
How did you measure them?

Yeah...what he said. WTF??


Rebuilding the forks is reasonable. You make a couple compressors out of beer cans and hose clamps is all.

[chasbmw]

I fitted some Tarrozi (?) fork tubes on my 90/6. They are straight and work fine. They have only been on the bike for 6 months so I can't comment on the chrome.....

Bought for £99 each delivered from Wemoto in the UK. Much cheaper than Motobins and they might deliver abroad.

If you are rebuilding the forks DONT replace the metal damper rod piston rings. I did and spent far too much time chasing stiction, which was due to the rings being the wrong size and binding the fork action. To fix the problem ,I had the damper rods machined to take the plastic wiper rings from the 81-84 bikes

[Ken in Oklahoma]

I wouldn't be afraid to buy used fork tubes. I'm thinking IBMWR or BMWMOA want ads and possibly eBay. It's true that there is some risk in buying used parts, but the dollar savings can be tremendous. In my view when you buy new you are buying convenience and security and paying for it with money. Prudence is, of course, called for in making sure you are informed about straightness, pits, scratches, etc.

There are some differences in the damper rods from year to year, but you will have your old damper rods which are presumably good, and which I think are pretty much interchangeable among the /5, /6 & /7, forks. I could be wrong on that last part though.

Ken

[chasbmw]

Various changes in ATE damper rods, mainly to improve damping and to reduce valve noise. Later would be better than /5 rods. But you can fit the later damper valve rings to the earlier forks.

[equipo5]

5mm is huge! Collision stuff.
How did you measure them?

Actually that was probably misleading. The distance between the tubes was 5 mm wider at the bottom end of the tubes than at the lower yoke. They seemed to splay out towards the bottom. I found by turning one of the tubes in the yoke the difference disappeared but then didn't pass Duane's glass test which made me suspicious. I couldnt percieve the bend but I found a flat surface, the back window of the house, and rolling it on the spot against the glass I could see the reflection at the centre of the tube move in and out from the tube.
The front suspension didnt seem quite right when I first got the bike and after putting in new seals, the forks would jam on compression. The top caps were really tough to get off and obviously Ive turned the fork tubes in the process.

Having owned an XS1 650 yamaha in a past life, I'm keen to optimize the front forks but unfortunately I have to balance that against "the wobbles" with my accountant.

Thanks for the feedback. It looks like it is do'able and I will chase up those tubes. Great tip.

Cheers

[Airbear]

Equipo, the fork stanchions on my bike were bent in a bingle with a cow in 2003. The bends were quite visible. I took them to a local motorcycle mechanic and he sent them and the triple tree off to a mob in Melbourne (sorry, don't know who) to be straightened. It cost me $200 including postage, and they came back perfectly straight, as tested by rolling them along a couple of lengths of angle iron. This approach may be less expensive than buying new or used stanchions.

Note: I just googled "motorcycle fork straightening melbourne" and came up with a couple of possibilities.

[SteveD]

Ian, you could also ask Chris or James...they'll have someone that does the work.

[equipo5]

That is great news.

Thanks for that guys.

Ian