DJ.

I have had a chance to try disassembling the Sigma tensioner. I practiced on an old one first to check that the dimensions were the same after modification. I am pretty sure I have it right, but there are people on here much more knowledgable than me. If you see something I have done wrong, please tell me, I won't have a chance to fit it to the car for a few weeks The first task is to take the new tensioner apart. I released the spring tension using a vise to grip the arms before removing the pin, and I marked the spring and bearing unit to ensure the spring went back the same way (this may well not be imortant). The centre boss is peened over the top washer shown below, I protected the bearing from dust by putting tape over the top face and cling film under. Holding the unit in the drill press is a pain, I made a small block of wood to support it. In the photo, I have already started drilling into the top of the boss: Here is a picture of the replacement parts supplied by Caterham. Here are pictures of the tensioner bearing after the base plate is removed: And these are the parts to be discarded: The next stage is to carefully enlarge the hole in the base plate so the Caterham supplied aluminium boss is a snug fit. This was my first attempt on the old tensioner, the second one was much neater, but I forgot to take a photo and couldn't be bothered to dismantle the tensioner again Here is a photo of the boss fitted into the new base plate: And here with the Caterham washer fitted: The bearing assembly and spring are then put over this. Here is a view from underneath, you can see the spring pushes the back plate away from the bearing: Here from the top you can see the Caterham tensioner collar in place on the top of the bearing. The raised portion appears to be designed to locate in the large hole in the bearing centre. The last stage is to re-tension the spring and replace the pin. As the caterham boss doesn't hold the unit together, I found a nut to fit the retaining bolt supplied with the tensioner and used this finger tight to hold the unit together. I then used the vise to pull the arms together carefully and replace the pin. Obviously when it is fitted, I will remove the nut and have to carefully hold the unit together as I attach it. The design of the modification is very clever, on assembly the correct belt tension is applied by the spring and then as the mounting bolt is torqued up, it clamps the bearing into a fixed position. I hope this is useful to fellow Sigma owners. Duncan

I've had a couple of very useful messages from members that should mean I'm on the right track now, thanks I will post up as soon as I find time to get on and do it. Duncan

Hopefully it is just the horn itself as that's an easy fix. I would take the horn off and just run two a short cables from the battery to the horn to test it. If you want a better horn the PIAA sports horns are a straight swap and very loud: https://www.amazon.co.uk/PIAA-85110-115db-400HZ-Sports/dp/B00067BWBI/ref=sr_1_2?ie=UTF8&qid=1541333422&sr=8-2&keywords=piaa+horns If it isn't the switch or the horn, it's unfortunately a case of checking the power feed and earth with a multi meter.

I've looked on Caterham's site and three items seem to be needed: Tensioner boss: https://caterhamparts.co.uk/other/2763-tensioner-boss-sigma-150hp.html?search_query=sigma+150+tensioner&results=240 Tensioner washer: https://caterhamparts.co.uk/other/2764-tensioner-washer-sigma-150hp.html?search_query=sigma+150+tensioner&results=240 And Tensioner collar: https://caterhamparts.co.uk/other/2765-tensioner-collar-sigma-150hp.html?search_query=sigma+150+tensioner&results=240 I've also found a thread on Pistonheads that describes fitting, but the guy did it incorrectly. Apparently it is possible to modify the tensioner so the spring can be used to tension the belt correctly and then the Caterham parts are used to nip the eccentric part of the bearing as the mount bolt is tightened so the tensioner can't move any more. I think I'll take some photos as I do it in case anyone else wants to try this.

Thanks, I'll have a look on their site. I know the 150 and 140 don't use the standard spring tensioner, so it makes sense to change I think.

5 years ago I had to change the timing belt on my Sigma 125 after the original water pump failed at 13,000 miles. Fortunately, the one I fitted has survived 24,000, but I think it's time to change the belt/pump again. In the meantime, I have heard that racers don't use the standard sprung tensioner as the belt can jump if the engine turns backwards during a spin (my Seven has been spun a few times by myself and my daughter ) Can anyone tell me how to do the suggested modification? Thanks Duncan

BGH won't be cheap. I phoned BGH when I had my gearbox out when the clutch failed. All I wanted was a check over as I'd driven 250 miles without the clutch. I was told "Caterham gearboxes are cr*p, all the bearings will need changing, it'll never last 10,000 miles................what you want is a reconditioned one for £750", so I took the top plate off, didn't find any chunks of metal, changed the oil and put it back in and it's still going strong at 37,000 miles

I have found a small bolt tighted through a rubber grommet placed in the slot just behind the grill works well. The factory springs went missing from my car one at a time.

I fitted PIAA sports horns. Lighter than the original horns, much louder and no need for a relay. Duncan

It is tight but I managed to find a suitable grommet in Halfords. I did have to use some of the rubber lubricant to get the wire through. I thought the grommet on the wing stay hole was worse! Duncan

I did this on my new Tillets 7 years ago as I didn't like the carpet. I used lighter fluid as a solvent and a plastic scraper after tearing off the carpet. The gel coat underneath was fine. It was a horrible job! Duncan

I set my car to maximum castor and have never regretted it, the steering isn't heavy and has been great on road and track. Duncan

Where you buy it is more important than the brand. There are lots of fakes out there. I try to make sure I buy from a reputable shop, for example on Amazon I only buy memory cards actually supplied by Amazon.co.uk. Duncan

Beware of using copper grease on exhaust components close to the cylinder head. My brother has an Esprit and used copper grease on the nuts holding the manifold to the head. When he tried to remove the cracked manifold the nuts were irreversibly fused to the studs with melted copper- it worked like brazing. Result engine out and cutting the manifold into small pieces with an angle grinder............

I wouldn't replace an alternator starter or battery unless it started to give signs of trouble. There's no point throwing money away, and with electrical items, newer doesn't always mean more reliable.

I have found loosening the primaries makes it easier to wiggle the collector off, but it is the standard stainless system. One man job for me each time I have done it Good luck getting your car going! Duncan

DIY is ok as long as you make a note of exactly how many turns the idle screws are set to. Assuming they're going back on the same engine of course

Yes, you've run it in nicely for the next owner. It's a great looking car, I like the 160, but I'm attached to the Seven I built in 2011, only 37000 miles so far Good luck with the sale. Duncan

I made a block of wood with triangles that stick up either side of the cruciform so it can't slide off, and tge cut angled slots so it can rotate slightly as the car is raised. To my mind the biggest risk jacking here is that the jack slips off the round tube.

That is a pain to say the least I don't suppose it is one of the front bolts? If so you might be able to wedge some long nose pliers in far enough to get someone to grip the rivnut inside the alumnium box section. Otherwise, I think grinding the head off will be least likely to damage anything, at least the washer should protect the floor. When refitting, I use plenty of copper grease and a spring washer with low torque and have never had one come loose. Duncan

I suspect it is the master cylinder too. There was no air before your track day and then the pedal didn't feel right. Something must have happened to the system to cause that. If the calliper seals go, you will get brake fluid escaping. I think the master cylinder seal that pumps the front circuit has failed, but I am only an amateur mechanic. You're definitely correct not driving your car. Duncan

I strongly suspect the driveshaft is the problem. When building my Seven in 2011, the offside driveshaft fitted beautifully into the diff from both sides, but the nearside shaft wouldn't go in more than a quarter of the way. A replacement was just like the offside shaft so there was definitely a problem with the splined end of the original nearside shaft. I am so glad I didn't just force it in, because goodness only knows how I'd have got it out again! Duncan

The half hood with full doors gives very good protection ,but in very heavy rain you'll get wet putting it up. The only other option option is to stop an put up a big (Seven club :) ) umbrella.

I got fed up with loosening the handbrake adjuster. I cut the stitching under the handbrake cover and found if I pulled the brake on hard, I could just get it off. Before refiting it I put a couple of press stud fasteners on to make it easy to remove in future.I Duncan

Roadsport06 said: I haven't tried R888 tyres, the only specialist tyres I have used were three sets of Yokohama a021r. They had a very soft compound, so were extremely grippy in the dry, were good in damp/wet and enough channels to be Ok in deeper water. I have to say they were probably the ideal tyre for a Seven in my opinion, but they did wear out very quickly. Of course now they are unavailable. Compared to the Rain Expert, there was definitely more grip in the dry, and I suspect more in damp conditions. However, when I swapped to the Uniroyals, I took it very easy to start and then kept pushing a little harder, I have to say that after one spirited wet autumn drive, I was amazed how good the Uniroyals were. Bricol said: This sums it up well for me