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Thread: TR HD billet cog for V2 pull start problems

  1. #1
    Baja-Forum Maniac biscuits's Avatar
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    Default TR HD billet cog for V2 pull start problems

    I managed to get out this week end with the South Coast Bashers and had a great time. Not the best time to put to the test things that you haven't tried before you go but, hey ho. This was one of them though, the TR, option part, HD billet cog for the V2 pull start and I think that there is something wrong with the design of it. To cut a long story short from the first time I pulled on the pull start handle I had problems with my pull start. I thought at first that it was the engine jamming or something, because everything kept locking up. It wasn't until later that I realised that the spring had bent. Or more to the point had slipped between the pull start cog and pull start spool. Basically the spring is supported by the inside of the cog and the pull start spool and then both of them are designed so that when you tighten the whole thing down the two parts are touching supporting the spring. This gives the spring its strength. I swapped the spring out in the field and also went back to my plastic cog.

    First picture; Inside of spool with spring fitted and inside of cog ready to be fitted on top which will then totally enclose the spring and support it

    Second picture; from left to right; my own HD pull start cog (copied from a plastic cog) that I used for 4 months before TR came out with their own HD one , plastic cog, HD TR cog.

    Any road, what I found out and worked out had happened, is the spring had slipped between the spool and HD cog for what ever reason. When I inspected the pull start when I got home I found out that one of the bearings on the spool had disintegrated which would explain the gap. Now there could be a coincidence that the bearing failed at the exact time that I fitted the HD cog after it had been performing perfectly for a year, or, the cog for some reason was designed wrong allowing the spring to get between the cog and spool damaging the bearing. I am not sure which. But the fact that everything was working fine before and now it's all knackered got me thinking, so I looked at the differences between the cogs.

    Third picture; plastic cog and HD cog. Notice that the inside of the plastic cog extends further than on the HD cog. You can also notice it when you put the plastic cog on top of the spool as it rocks over centre bit, as in the centre bit is touching first. It doesn't on the HD cog. I'm going to mill the bottom of the skirt on the HD cog and try it again. When you stand them upside down and next to each other (as you can see in the pic) you can see that HD cog is bigger. I think that if the bottom side of the skirt is milled down it will be alright. To be continued...

    Now there is a possibility that the bearing failed causing the two parts (HD cog and spool) to separate when done up. Personally, I think that the HD cog that I have, has caused the spring to slip through damaging the pull start bearing as the two parts have been forced apart, given that I have had no problems with this pull start for a year and all of sudden it is completely knackered after fitting the HD cog from the first pull.

    Now this is only my observations, but as soon as I fitted the plastic cog, even with the knackered bearing (as I did out in the field) the pull start worked perfectly leading me to believe that there is design fault on the HD cog that I have. I have since swapped back to the plastic one and won't be using it again.

    On another point, having now used this pull start I think that there is a lot of room for improvement and having now used it, I can't understand why it has been designed the way that it is. I think that there is room to get rid of the spring entirely, have a HD cog and have two huge bearings on the spool that would last a life time. Leaving to little or no maintenance of the pull start what so ever. As well as a system to get the cable out other than cutting it.

    If anyone is interested.... ? and it will work
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    Last edited by biscuits; 11-03-2013 at 19:03.

  2. #2
    Baja-Forum Maniac biscuits's Avatar
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    Update on TR HD cog; This is what happened to my spring. It basically went between the spool and the HD cog smashing the bearings. I put new bearing in and put the plastic cog back on and everything was great. Nice smooth action no jamming. I thought cool and put the HD cog back on and as soon as I pulled the pull start it jammed. It eventually freed itself and pulling on it again it jammed again. This time I couldn't free it. I took the pull starter off and had a look at the spring. Sure enough about half way up the spring there was one of the coils out of line to all the rest where it had tried to go between the two parts. Put the plastic cog back on again and all is good. I am in no doubt that the HD cog that I have is manufactured wrong and leaving too larger gap between itself and the spool. I was lucky that I didn't knacker another spring.

    I wanted to run the pull start with the HD cog so I looked at ways of doing it. Firstly I filed the outside of the cog down a little so the inside was closer to the spool. I tried some milk bottle wrapped around the inside of the spring with the idea that it would bridge the gap between my spool and HD cog if a gap formed. To my surprise it worked fine. No more jamming. The problem with it is, the milk bottle will probably wear out over time because its made of plastic and it also takes up a lot of room inside the spring so you loose a lot of the damping affect. The only other thing that I could think of was something metal, spring steel if I could get it. I tried a piece of spring steel which was an off cut from metal strapping/banding used around boxes, but it was also too thick really and I lost all the damping affect. I then used the bottom of an old soup tin which I fetched out of the bin and it worked a treat. I still have some damping, but not much, but I can run the pull start with HD cog no problems at all. Thinking about this TR could have engineered a sleeve in to the pull start system no problems at all and having now taken it apart thats what I would have done if I'd made it, still keeping the damping affect.

    Also, having now taken the thing apart I noticed in the bottom of the pull start housing there is a step. This step is designed to press on the inner bearing in the spool when you put the spool on, so the spool and everything else can spin around the outside of the bearing. Except it doesn't just press on the inner bearing it also presses on the rubber sealing of the bearing as its too big. The step should only be the size of the inner bearing. Because thats all it needs to be. I'm not even an engineer and I don't think that people like me should be spotting things like this. What this lead to, is the rubber sealing being rubbed away and also unwanted movement in the seal as it slides around because it is dragging on the step, eventually destroying the seal and letting in dirt and muck leading to premature failure of the bearing. Well thats what I think anyway. I could be wrong... If you look at the pic and have a look at the step you can see around the outside of the step is polished, shiny. This is because the bearing seal is rubbing on it and inside of the step is dark where the inner bearing touches it.

    Overall, happy now that I have the HD cog on there. Not happy that I have had to loose quite a lot of the damping affect of the spring to get it to work. Not happy about having to make it work either. Time will tell how much extra wear this puts on the pawls and pawl plate because of lack of damping. Incidentally I have been reading about people having problems with their pawls jamming with dirt so a mod has been put out where the pawls have bearings. Has this honestly been tested to death I ask? I mean, really? The bearings are not very big and there is an enormous amount of force on them. I think, like my pull start, if you use it a bit the pawls actually start to wear and the tolerances aren't as fine and they then don't jam with dirt. I really don't know on this one, but personally, I don't think that they will last that long and I won't be investing in one and I hope TR still produce the old one as well. If not I'm going to buy a whole load of spare old ones to keep me going for a few years. I want something that is going to keep going i.e. when I put it on there, its on there and it lasts and I don't have to keep messing with it or fixing it and I am hoping that this last mod now lets the pull start work for a long time without me having to mess around with it again except for maybe cleaning the dust of it and cleaning the return spring.

    I actually have about 4 spare plastic cogs and about 3 springs now and believe it or not there are differences between all 3 cogs in manufacturing tolerances. The best plastic cog that I have and the one which works the best is the one in the previous pics and it is different to the other two. The other two and nearly identical and more like the HD cog.
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    Last edited by biscuits; 12-03-2013 at 23:06.

  3. #3
    Baja-Forum Maniac bajabilly's Avatar
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    when the tr pullstart works without fault its a great bit of kit, the best pawl i found was the hd nylon one by tr, saying that i've gone back to the standard pullstart and got spares for it.
    going back to standard also sheds 40 odd grams of excess weight from the flywheel assy by not using the tr dog drive piece, which helps the engine performance
    Last edited by bajabilly; 13-03-2013 at 20:20.

  4. #4
    Baja-Forum Maniac biscuits's Avatar
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    Just threw the HD cog in the bin. Mod worked for a bit then the pull start started jamming again. Fitted my original plastic cog and the thing works fine. Waste of 13

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