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Mike R

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Mike R last won the day on March 3 2019

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    GT6 Mk3

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  1. How to fit plastic trim to front windshield rubber on spitfire 1500

  2. Thanks all, interesting discussion. Totally agree the only way to really know is the rolling road. The only thing that doesn’t quite make sense to me is why would the throttle be less restriction than the air valve? At full throttle the throttle is a thin disc parallel to flow obscuring maybe 5% of the bore, whereas the air valve is a fat piece of metal slap bang in the middle of the air flow obscuring maybe 40% of the bore. The only thing is the air valve has smooth transition in and out so you get pressure recovery (as per Bernoulli) which you don’t get with the throttle butterfly. So, yes it may give very little, but it can only help, and was more about me tinkering than anything else! cheers, Mike
  3. Dear Triumphants, Like many I like the idea of a little more oomph in my GT6, but then I rarely go over 3000rpm and never over 4000rpm. So this is a little improvement I made a few years ago to hopefully increase power in the lower rev range. The concept was to fit the weaker stromberg dashpot springs combined with richer needles. Before anyone rushes to condemn, read on, and see what you think. The thinking is that at peak power 5500 to 6000 rpm, 105bhp the carb air valve will be right at the top of its stroke and give little or no obstruction to induction air flow. However, at 3000rpm, power is more like 60bhp. With power around 60% of peak, induction air flow will also be significantly lower and so the air valve will sit significantly lower in the carb. The air valve therefore becomes a restriction when at full throttle at lower revs. See sketch below. The air valve is lifted by suction from the air as it flows over the carb bridge, which is balanced by downward force provided by the weight of the valve plus the force of the spring. So weaker spring reduces the downward force, and so the valve sits higher. Now to change the needles and get it right across the rev range needs ability to test under load. This I achieved by installing an exhaust lambda sensor with a gauge in the cabin so that I can measure air fuel ratio as I drive. (See Buckeye triumphs website for excellent description of how to do this ) So I bought and fitted the weaker springs. This made the mixture so weak that the engine would not run. This is good because it shows it’s had the desired effect of the air valve sitting higher. I’ve heard it said that Strombergs have few needles available, but that wasn’t my experience. Burlen produce a little booklet for a few quid that lists about 30 odd needle profiles for CD150 carbs and detail the precise needle diameter profile for each. It took me a couple of trial and error attempts to get the right needles utilising the Lambda sensor and testing on the road, but I got there. It may be a bit of wishful thinking, but she did feel a little more responsive. To sum up .... * The air valve at lower rpm will be a restriction in the induction system to some extent (although not sure how much) * Weaker carb springs has definitely made the air valve sit higher for any given engine load and therefore be less of a restriction (how much less is more debatable) * Changing the needles has increased the fuel flow so that the mixture is correct for the new air valve position across the rev range. * Because the air valve sits higher, the carbs will max out at lower revs that a standard GT6, so my improvement in usable power is at the expense of peak power. As most power improvements are focussed on peak power, I’ve never seen anything like this suggested. I’d be interested in anyones thoughts. Mike
  4. I feel really chuffed .... just completed fitting my new windscreen to the GT6. Thought I’d pass on a few things I learned along the way. Firstly, the spitfire and GT6 magazine has a good set of instructions http://www.triumphspitfire.com/Windshield.html but, there are a few other things as well * Hang the seal for a few days so it takes approx the right shape. * The suggestion to use masking tape to hold the seal on the glass is a good one, otherwise it just pops off as you move to the next part. I had a piece of tape every couple of inches. * Leave the seal taped onto the glass for a few days, it settles into its new shape and the masking tape can then be removed. * Think carefully about the right string / cord for slipping round the seal. Too thin and it can cut the rubber as you try to pull the seal lip over the screen surround. Too large and it will trap between seal and metal and be very difficult to pull. I used 2mm nylon, it did start to cut the rubber at one point, but worked ok if careful. * Heat is your friend. The rubber becomes much more flexible the warmer it is. I had an electric heater sat on the engine and a hairdryer to use as needed. Warm each bit of rubber before trying to pull the seal over the metal rim. * The corners are tricky, the cord doesn’t want to pull. But keep working it, and keep using that hairdryer and it does eventually move. * As you work round the amount of cord left in the seal gets shorter, so when you pull it just pulls through rather than over the metal. Have to keep an eye on this because you don’t want to lose the end. Either work each side alternatively, or hold both ends of the cord. * When finished, some parts didn’t sit fully home. Again judicial use of hairdryer whilst pushing the screen into place made the seal move gradually home. And then there’s the chrome strip.... The reason I needed the new screen was because the old one leaked. It was fitted by one of the mainstream windscreen companies, but I discovered the leak about a year later because of lack of use in the rain. The reason for the leak had 2 parts I believe: 1. The fitter used no sealant 2. The chrome strip fits in the single slot in the outer part of the rubber with the other side of the chrome strip sitting under the rubber seal lip. This means that the seal lip doesn’t seal as well to the surround. I’d be interested in anyone’s thoughts on this? For this reason I’ve decided not to fit the chrome strip.
  5. For info ... I know the issue around ethanol in petrol and R6 vs R9 spec hoses has been discussed at length ... but found this link .... explains the differences very well. http://www.volksbolts.com/faq/fuelhose.htm
  6. Ok, thanks Doug .... gives me somewhere to start I’ve got plastic fuel filter pre mechy pump ... so either filter no good (were cheap off fleabay) or bits from the hoses. I might just change the rubber hoses from filter to carbs as not sure of the provenence ... think I bought R9 last time, but probably fleabay again. Ta, Mike (used to know someone called Dan)
  7. Thanks Pete, I’ll investigate when I get a chance ... or the car forces me too! Hopefully will be ok to get me home Monday ... although nothing too disastrous at the mo. ta, Mike
  8. Dear helpful fellow triumpheers .... This one is stumping me slightly ... I’ve posted in fuel section because the symptoms point me towards fuel ... but see what you think. 3hr journey in GT6 mk3, mostly on dual carriage way / fast A road / some motorway. No problems at all for first hr till came to start stop traffic. Temperature rose a little to not far from the red, but still no issue. Got past the traffic and back on fast road and cruising at 70 got a loss of power for a second or 2. Then normal, and then power loss again. Not total loss, but a definite problem. Then running fine again for another half hour. Until leaving the motorway another section of slow traffic. After joining the next section of fast road got the same symptoms for a minute or 2 again. Then fine for the remaining hour of journey including dual carriageway 70 mph driving. My thoughts were fuel vaporisation from the periods of slow traffic? Although seems odd that didn’t affect until past the slow traffic. Or maybe the infamous rubber slivers? Although, would expect fuel blockage by slivers to affect more often. Being so intermittent very difficult to troubleshoot anything. Thoughts? Mike
  9. My GT6 fuel tank produced lots of rust particles that caused carb issues ... then blocked the filter that I installed to catch the bits ... I used the Frost petrol tank sealer kit. It’s a multi stage process to degrease, kill rust and then seal. Particularly important is to ensure tank fully dry before adding the sealer... think I used the Mrs hair dryer for a few hours (on the tank not me). Tank has to come out to do it all though. That was 10 years ago ... and no problems since. So my experience good with this product. https://www.frost.co.uk/auto-maintenance/automotive-tanks-products.html Mike
  10. Ahh I see now, didn’t realise there are 2 bearings each side, with the carrier held by inner bearing bolted to front casing. I do find that differential drawing difficult to follow. Well many thanks ... I’ve learnt something today. It did seem to significantly improve noise though, so maybe an acoustic affect as mentioned earlier ... but time will tell. Just wanted motorway driving to be a little less painful on the eardrums. Pete ... thanks for the tips - I’ll keep a note of those for the next time I’m delving around in that area. ta, Mike
  11. Thanks for comments ... As I understand it bearing whine increases with load / throttle, wheras too low pinion pre-load can also cause whine... but are on deceleration / part throttle like mine. If you look at the early comments on this thread its fairly consistent about that. Also, bearings relatively new ... at least in terms of miles. Must admit .... I thought looking at the workshop manual that the pinion is held in the front casing and the crownwheel in the rear via the half shaft bearings, therefore the amount of mesh could vary with tightness of the casing bolts? Sorry have I got this wrong? ta, Mike
  12. A little update on this topic .... a reminder .... I had a whine on the diff when at 70 or more which was worse on part throttle. Opinion is that pinion bearing pre- load is wrong and this agrees with other online research I’ve done. I’ve just had the rear suspension apart to do the rotoflexes. Whilst I was there, thought I’d take a look at the diff. Its a collapsable spacer type with the Nyloc nut under the tamper proof cover. I thought about giving the pinion nut the smallest of tweaks to increase pre-load, but lost my nerve as no way of knowing what is correct. Then I checked the casing bolts, and found every one slightly loose. About a quater of turn brought them to the correct torque (based on my calibrated arm!). It got me thinking ... is it possible that slightly loose casing bolts has meant that the casing gasket isn’t fully squeezed leading to lower bearing pre-load? I.e. the 2 halves of the casing were sitting slightly apart? Well with the casing bolts tightened I took her for a spin on the A180 up to 80 ... and it appears much improved. Although that was a quick 5 minute test .... time will tell on a longer run. what do you think? Mike
  13. Good point Pete .... actually the ratchets jammed against the ground and the car rotated around the jammed driveshaft. Luckily it landed back on its wheels and I could continue on my way. 😳
  14. Well I got the old donuts off the car and they were worse than I thought. Split Virtually all the way through on one side, only took a little pull from me to split. Has anyone had a rotoflex donut fail whilst driving? Will it do damage? I’d forgotten what a b****r of a job fitting the couplings is. Getting the bolt holes aligned by adjusting the spring lifter tool height, jacking the vertical link up and down a few times. Crow bar to try and force it .... and eventually magically it works. Maybe that CV conversion might be on my Xmas list.
  15. Hmmm CV conversion .... must admit I am tempted. But then I try to keep any modernisation to minor bits that are easily reversed. So for now its donut’s for me. If ever the Metalastik’s become unavailable that’ll be the time to jump. For now I’m hoping for 10 more years of trouble free donuts. I’m sure there’s a Homer Simpson moment in there somewhere .... mmmmm ... donuts!
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