Progressive Fork Springs

[179212]

I have a 1988 R100RT 93,000 miles, new YSS shock purchased from Ted Porter installed, now time to have front forks rebuilt , I have ordered an overhaul kit from Tom Cutter I also looking at new fork springs. Moto Bins has Progressive Model P11-1130 listed. I would like opinions on these springs.
Opinions on what springs I should use also would be appreciated.
Thanks

 

[20774]

Does Tom Cutter have any thoughts? He has done some senior level racing so should have a good idea of what works or doesn't.

 

[88bmwjeff]

When I rebuilt my forks on my 1988 R100 RT, I put the Progressive fork springs in. One thing that wasn't clear when I did it is that the springs require (or required) a spacer. Progressive provides a PVC spacer that needs to be cut to appropriate size. The spacers provided were rather small and I did not think I could make a 90 degree cut. Plus, I was wondering how well the plastic part would last. My solution was to use washers stacked up to the appropriate size. It's worked well. While I've been happy with the Progressive springs, I would consider an alternative spring if it didn't require the spacers.

On a side note. When I rebuilt my forks, I did not find a lot of information regarding the Type V forks. I did write up an explanation of my thoughts and process for the Airheads website. It's still there. I also had difficulty disassembling the damper rod. The "absorbing piece" (part 11 on the parts fiche, part #31 42 1 452 012), as BMW describes it, screws on to the damper rod. However, mine was attached with Loctite that required heat to remove. Unfortunately, the heat softened the part to the point they were destroyed in the removal process. I ended up buying new ones. I'm sure a lot of this was due to my inexperience. But, I wanted you to be aware of this in case you haven't done this before. If you have, then just ignore my comments.

 

[179212]

Forks

Thanks all
Tom has not got back to me on spring yet
I am not doing the work but having it done help when I can ( taking faring off if needed ) taking pictures or recording videos

Thanks 88bmwjeff very useful information I will look up your stuff on airhead site and get parts #11 you referenced

 

[88bmwjeff]

Thanks all
Tom has not got back to me on spring yet
I am not doing the work but having it done help when I can ( taking faring off if needed ) taking pictures or recording videos

Thanks 88bmwjeff very useful information I will look up your stuff on airhead site and get parts #11 you referenced

Part #11 is expensive. About $35 each. It might be possible to remove them without damaging them for an experienced person, so you might want to wait and see. But, that's up to you. You might want to run this past the person who will be doing the work. I'm just letting you know what to expect during the process.

FYI, if you're not an Airheads member, you should consider joining. Anyway, here's a link to my write up.

https://www.airheads.org/tech-tips/type-v-fork-rebuild-tips/

 

[ccolwell]

I do not like progressive springs (no shot at Progresive). They collapse too much under braking into corners and then stiffen too much. I had them in my R75/6. I put RaceTech straight wound springs in my R90S and was much happier.

That said, Progressive makes a good product. And I would go with Tom's recommendation. He's still recovering from some issues and may take a while to respond.

 

[kimjmoon@gmail.com]

I recently replaced my fork springs on my 78 R80/7 with progressive springs and added new 7.5 weight oil. I didn't use the spacers because the instruction said they wouldn't be needed. But now when I go over some bumps I hear a knocking sound which I think is the top of the spring coil hitting the top cap. I'm going to assume that I need to go back in and add probably a half inch to one inch spacer. Is that correct? The forks seem to work fine, but the knocking sound is really kind of unsettling. I have looked closely at everything and I'm certain that this is the issue.

 

[pglaves]

The spring would always be in contact with the top cap unless the fork goes to full extention, as in unloaded. But the noise you do hear is probably the middle of the spring slapping the side of the fork tube. Adding a little pre-load will generally keep the spring slightly curved and against the fork tube.

 

[collingsbob]

The spacers provided were rather small and I did not think I could make a 90 degree cut.

Don’t use a saw…use a pipe cutter. The spacer can be made from any material with a wall thickness sufficient that it won’t deform upon compression.

 

[Omega Man]

We used to use washers, stacking them if needed.
OM

 

[kimjmoon@gmail.com]

The spring would always be in contact with the top cap unless the fork goes to full extention, as in unloaded. But the noise you do hear is probably the middle of the spring slapping the side of the fork tube. Adding a little pre-load will generally keep the spring slightly curved and against the fork tube.

Thank you. That makes perfect sense.