Repairing a Vintage Huret Rear Derailleur: Spring Tension
Repairing a vintage Huret rear derailleur, I have to admit, wasn’t a job I was sure of. I really believed that this 1978 Huret Eco rear derailleur was broken, after taking it off an old French bike. It had no spring tension and it seemed lifeless, the jockey wheels were seized and it had basically given up doing its job. I put it in a box and didn’t think it could be repaired, or at least I thought couldn’t do the job. These derailleurs, however, are incredibly resilient, and with patience and lots of experimentation, ( including some smacks from the spring ) it’s possible to repair them. I got this derailleur working again and it’s now functioning pretty well on my bike.
The two threaded holes
Taking it Apart
The Huret Eco has two threaded holes in its main body, which connects to the pulley cages which the chain wraps around. You will find a nut securing the jockey cages in one of these holes. Cleverly, Huret made two options for setting up the derailleur depending on your freewheel: a hole for a 28 tooth and one above for a 24 tooth freewheel, which is quite a clever idea for adapting to different gear ratios. In other words, your short cage derailleur can become a medium cage one by using the other hole, essentially extending your derailleur cage length, if and when you need it. You can see in the picture that Huret stamped the two numbers, 24 and 28, on the body next to the holes.
The nut securing the jockey cages
The Woes Of Springs
It’s quite simple to take the two sections apart; you unscrew the nut that threads onto the bolt, which connects the main body to the pulley cages, and once that is off, you just need to unscrew the bolt out with a screwdriver, as this same bolt passes though the top jockey wheel. Once you loosen it, the two parts come apart and you have access to the spring. It will most likely need a good clean, as this part of the derailleur will probably never have been accessed before. After removing some 30 year old grease, I came to the problem of the spring. I hate springs. As a rule, when a spring flies out of a part, whether it be it bike part, car part, or any other mechanical device, I consider the task of repair now a nightmare. Getting those things back in properly can cause terrible stress and hours of self-loathing. So first of all, I secured the nut back on the bolt, in the 28mm hole.
The nut secured in the 28mm hole
The Difficult Part
As expected, things got tricky with trying to work out how to set the fiddly spring. There are three holes to choose from to attach the spring into the main body, and these holes sit close to the two threaded holes. One of them will be out of reach when you chose either the 24 or 28 hole you’re going to use. This part takes the most experimentation. I found that with the spring just sitting in either hole, there was very little tension in the derailleur. The picture above shows this, as the jockey cages are sitting loose, straight down from the main body and not sprung back. There are also two notches for the spring to sit on the upper jockey cage, giving you the further option of regulating spring tension. Unfortunately, placing the spring end on either of these notches didn’t increase spring tension.
Too slack
First Attempt
I had a feeling that this setup wouldn’t work; there just wasn’t enough tension in the derailleur, and when the chain ran through the gears, the derailleur pulleys just got pulled closer to the freewheel until there was friction between them and everything got stuck. With the derailleur on the hanger, I tried to rotate the pulley cages around the body to increase tension, but then the tension became too great and the pulley cages just jumped back to their default position, as pictured above. I also realised that by using the 28 teeth hole the distance between derailleur and my 25mm freewheel was too great. So I decided to take it apart and start again.
Too much chain gap
The Solution
I secured the pulley cages bolt through the 24mm hole, and then decided to try to work on the spring itself. By turning the spring independently of the derailleur, trying to manipulate some tension in it myself, I could see that this is where the solution would be found for this limp derailleur. By putting tension on the spring by holding it in different positions, adding more pressure as you are going along, I found the the right setup in the end. Now, the jockey cages didn’t just sit limp as before beneath the main body ( as in picture 3 ), but rested parallel to the body, having rotated 180 degrees from the extra spring tension. I installed the derailleur back on the bike, and hey presto, the spring did the work this time, holding the tension of the chain better and coping with all the gear ratios, from 11 to 24, from a 52/42 crankset.
The better position
Vintage Quality
I don’t think it will ever be perfect, like it was when new, but it’s given the derailleur a new lease of life. You can see the difference in the shorter clearance between derailleur and freewheel. The derailleur has the right shape of having good tension. I love the way this quality derailleur can be adapted and manipulated to fit my gear ratios, even decades later. It’s a sign of how well these derailleurs were made, and to never underestimate their abilities to come back from the dead.
The final setup
Hi! Can you do a video about that?
I’ve the same derailleur and I’ve some problems with setting the jockey pulley (the one near the spring). There’s an allen bolt which holds the pulley to the parallelogram by the 24/28 holes, same as yours. How can I tighten that bolt in order to let the jockey spins free and to have the plate right fixed to the parallelogram at the same time?
Hi, thanks for the question. What is the exact problem is it that you have? Is your jockey wheel seized? You should be able to secure the allen bolt tightly and have the jockey wheel spinning freely at the same time. Securing it to the plate does not impair the wheel’s ability to spin.
The tightness of the allen bolt determines how freely the jockey wheel can move. I would tighten this only lightly so that the jockey moves freely but has no play side to side. The bolt then acts as a lock bolt and secures everything. This can be tightened down without affecting how the jockey wheel is behaving. With regard to the 24 and 28 holes, each hole offers an option of 2 spring placements and there are also 2 options for the arm of the spring on the outer part of the derailleur. I’ve chosen the tightest option for both and am getting good spring tension.
Thanks for the informative comment, Andrew, it’s very helpful. Getting the right setup can be quite tricky, so cheers for the info!
After some googling I’ve come across your post. I am trying to fix my wife’s old Raleigh that has this rear derailleur. While riding the front shifter stoped working and there is a lot of slack in the gear wire (it won’t hold itself in place) – the derailleur itself looks good and the jockey wheels are in the correct positioning. Any suggestions for getting this shifting cleanly again?
Hi Hugh, it’s difficult to say without seeing it, can you post a picture with your comment? If there is a lot of slack it could just need the cable tightening from shifter to derailleur. A photo would be helpful to see what’s going on. Cheers
Hi Dominic
I have just come across your article searching on google . I have been looking for something like this for over a week after spending many hours trying to do the exact same thing BUT i am struggling big style! I just can’t get the tension to stay put and I am not sure if it’s the spring or the fact the main body of the dérailleur doesn’t stay where I tighten it as soon as i start peddling it moves forward and the chain goes slack and falls off. I am SO frustrated as I looked at the pictures you have and I immediately thought I knew what the problem was but after another 3 hours today ……..I don’t lol. I am confused in as much that the main body is attached the bike( a1990 peugot elan gt) on the frame so to speak and I have tightened it as tight as i can but it still moves I looked at replacing the Allen screw that attaches it but it doesn’t seem possible to get it out. which leaves the spring I think its a case of the more I try the harder it gets and is probably so easy I am just overlooking the obvious. Any help you can offer would be appreciated. I have taken some pictures but won’t send them until you ask me too as I don’t want to appear pushy
I look forward(hopefully) to hearing from you
Regards
paul
Ps sorry for the long essay!
Hi Paul, I totally understand how it feels dealing with this problem. Can you send me some photos? I also made a short video of a very similar problem with a similar derailleur in my last blog, the body of the mech was moving, causing chain slack. Cheers
Hello, I have the same derailleur, same year, and am fettling it as part of getting a 1978 LeJeune mixte back on the road as a gift to my daughter. I too was wrestling with the spring issue…
I have a couple of questions: 1) I have the spring sitting in the lower detente on the pulley cage, while you have it in the upper one. I got it into that position by basically rotating the derailleur body as I mounted the hanger bolt, but I think that’s as far as I could get it. Does putting it in the upper detente increase tension? Cause that would be good!
2) My jockey wheels are shot: Is there a source for equivalent new ones, as NOS is impossible to find?
3)I have set the high/lo screws correctly but the high screw is at its limit, almost flush with the plate. Is that an issue with cable tension? I plan on replacing cables but one thing at a time. Thanks for any help.
4) Source for a replacement chain? Not sure of the right dimensions.
Hi, these are good questions, but I can’t say I am an expert on these issues though I have experienced the same challenges that you face. I did use the upper detente because I did feel it gave the derailleur more tension, it felt like there was less slack and shorter distances to travel so tension was greater, but perhaps an engineer would say I am being unscientific. However, it did work better set up this way.
As for jockey wheels, I don’t know of any NOS source, but I think any NOS jockey wheels of derailleurs of that era should be fine. I don’t think the high/low screws position should be a factor in replacing the cable, these are just for fine tuning your derailleur. As for a chain, you just need to buy a 5/6 speed chain and cut it where you need to, there are videos on Youtube all about finding the right chain length. It depends on the sizing of your freewheel, your chain stay length and chain ring sizes, it’s impossible to know without knowing these things. Cheers, Dominic
^^Thanks Dominic. I may try to get the spring on the upper detente. Honestly I’ve got the derailleur working pretty well, but more tension would change the gears with more alacrity.
The jockey wheel has a 6 mm bolt — sadly 4 is the modern standard — not easy to find NOS for a decent price online…maybe when the pandemic ends we’ll be able to have vintage bike meets again…
And good to know about the 5/6 speed chain — I’ve got a breaker so sizing shouldn’t be an issue.
The derailleur hanger on the LeJeune is a bit odd, in that the derailleur body mounts directly onto the axle bolt, with a retaining bolt on the hanger to keep the derailleur from moving. There’s a fair bit of flex in the system, but the bike’s going to be cruiser… onto the brakes now…
Is there no cable adjuster at the rear derailleur? I looked at one and it felt like it was threaded. Wider diameter than a Shimano one though, big enough to allow a cable in without an end cap.
If not, it would help to have it threaded. I wonder what might fit. (There is an adjuster on the lever, I understand).
Thanks.
I have a Raleigh with a 5 Sp Malliard freewheel and Sachs Huret derailleur. The bike is in superb condition and running gear like new. The problem I have is that it will not upshift from 4th to 5th gear. Downshift 5-1 is fine and we’ll as upshift 1-2-3. I have made all the adjustments I can think off and replaced the chain but to no avail.
I tried fitting a Shimano 6 Sp derailleur and worked fine if you pushed it forward a bit while changing from 4-5 gear. Still not right though.
I believe it’s a short cage derailleur and thinking maybe a long cage would help even though it’s more suitable for a 6-7 Sp freewheel
Your help would be much appreciated
Thanks
Julian Stevenson
A 6 speed derailleur should have no problem with a 5 speed freewheel, and I think too that a basic 5 speed set up should work across all the gears. Have you adjusted the hi lo springs on your rear derailleur? Changed your cable and looked for cable slip? When you push your detailleur cage across by hand, can you see that it reaches the last cog? How’s your chain line, does it look straight? It could be a number of small things but I really don’t believe it is a derailleur problem when you’ve tried both a 5 and a 6 derailleur on the freewheel.
Many thanks for your quick response. The cable looks okay and have tried adjusting the spring tensioner both high and low but it makes no difference. The 6 sp I tried was a Shimano one with a longer cage not Sachs. It was only when I pushed the cage slightly forward it slid into gear 5. The freewheel looks new with the standard notches on the tips. The alignment to the front sprocket looks fine.
Moving the derailleur forward and it working sounds a bit like a tension issue. Have you tried a shorter chain? Is it slack at all?
Thanks again for your response. Yes I have tried a shorter chain and a narrower link chain but it makes no difference. You cannot move the cage any further forward as it is on its stop. Tried filing a bit of the stop, again no joy.
Can you post a few pictures of the derailleur and chain on the freewheel? Thanks