sti shifter problems

[unelite]

i just acquired some used dura ace 7400 sti shifters. the right hand/ rear derailleur shifter sticks when i shift to a larger cog, and i have to physically pull the brake lever back to its normal position. the lever that shifts to higher gears works fine.

i know they're not worth having a shop fix them, i may as well buy a new set of shifters that go that route.

is there any way i can save these?

[531Aussie]

This happened to me the other day, and it was caused by the small screw behind the brake lever coming loose then getting stuck on the body of the STI when I shifted up. I was lucky it didn't fall out.

The screw is in the back of the lever, high up

[Bikesalot]

If the loose screw solution mentioned above doesn't work out, here's another idea.

STI shifters gum up after years of use. I've had good luck with this method and since it's nearly free it's probably worth a shot--

Get a can of WD-40 or a similar light solvent/oil solution. Pull the brake lever back to the bar to partially expose the shifting mechanism and generously hose down the interior with your solvent. I mean really get it in there from all directions, using the little red spray tube if possible. Let it sit for a while and then drizzle in some light oil like Tri-Flo or similar. Then wipe down the exterior of the shifter with some Simple Green or other degreaser (to keep the overspray off your hands).

I've rescued two sets of STI-type shifters with this method. Hope you get your problem solved one way or another, because new Dura-Ace sure ain't cheap.

Cheers!

[unelite]

thanks, but that screw is nice and tight on my shifter.

upon removing the shifter from the bars to get a better look, i found that the shifter returns normally about 1/4 the time of its own accord.

i've oiled innards of it as best i could.

another thing i noticed was that, when at rest, the shifter a gap of about 2 millimeters where the lever meets the brake hood, as opposed to the other side.

any information at all is greatly appreciated.

[Bikesalot]

You could have some tired or broken return springs, in which case I think you'd have to have them replaced with new springs, if that's even possible. While I'm no expert by any means, I haven't heard too many stories about STI units just up and refusing to function any longer without a history of abuse. Have these been hard used or crashed? Taken apart by a previous owner maybe?

Did you try solvent as well as oil on the innards? The solvent is necessary to remove any buildup of old grease and dirt to make room for the unit to function smoothly. When doing this on my levers, the initial runoff was brown with gunk.

In all seriousness, the solvent trick is all I know. It's worked before on various types of mystery STI ailments. If it doesn't work this time, I'm out of ideas.

Good luck!

[sydney]

While I'm no expert by any means, I haven't heard too many stories about STI units just up and refusing to function any longer without a history of abuse.

They have a history of going TU, with no abuse and sometimes with little use. Sometimes they run forever.It's just part of shimano STI.

[unelite]

bikesalot, i retried your technique, this time very liberally soaking the inner workings with wd-40.

after three rounds of that, and another application of oil, everything works great!

thanks, im just glad i didnt have to open the shifter up. i found an
<a href="http://tandem-fahren.de/Mitglieder/Christoph_Timm/ST-7400.gif">exploded diagram</a> and i ain't no swiss watch maker.

[Bikesalot]

That's great!

I've put about a year's worth of light riding on the first set I tried this technique on. I haven't had a recurrence, but I can't vouch for the longevity of the fix. Hopefully they hold on for a while longer.

If I were Shimano, I'd market a line of STI "upgrade" kits consisting of solvent, a rag and light oil. Slap the name Dura-Ace on it and there you go.

[531Aussie]

bikesalot, i retried your technique, this time very liberally soaking the inner workings with wd-40.

after three rounds of that, and another application of oil, everything works great!

thanks, im just glad i didnt have to open the shifter up. i found an
<a href="http://tandem-fahren.de/Mitglieder/Christoph_Timm/ST-7400.gif">exploded diagram</a> and i ain't no swiss watch maker.

I've only had Dura-Ace for about 6 mths. How old are your shifters?

[unelite]

they are 8 speed dura ace, model 7400. mid 90's i think?

i was told they were only used for two seasons.

[531Aussie]

Old bike shop guys around here say they were the best ever made, and they'll never make 'em that good again

[Bike_13]

Old bike shop guys around here say they were the best ever made, and they'll never make 'em that good again

Yep, I (old bike shop guy) agree - simplest, least moving parts, least plastic, but heaviest (and compatible only with DA)!

Another tip is (now that they are working) is to get some spray grease (I only know of one product, but there may be others - Motorex - but it seems similar to many of the Motorcycle chain lubes out there).

This aerosal stuff sprays in like an oil, but the propellant evaporates and leaves a light grease in it's place. Certainly better than oil.

This stuff works a treat after the WD-40 clean, and really lubes impossible to dissassemble ShimaNO shifters or all types and ages.

I have a pair of 8s XTR shifter pods that have had daily use for 6 years with this as their only maintenance. They feel as good as new!

If only ShimaNO built their shifters to be 100% rebuildable (like Campag)!