Rangi246 Posted September 30, 2013 Share Posted September 30, 2013 Hi everyoneThe overdrive box is now in the car and running well, thanks to the advice from on here. However the diff has developed a rather constant, loud growl and my guess is that its fairly well stuffed. The car is currently running a 4.11 HB prefix diff (the rather weak original one I think) and I reckon i'd better replace it with another one before it goes bang. I know there are several trains of thought on which ratio is best, with the 4.11 being better for acceleration and lower ratio's better for top speed but from what I can see most of the discussion applies to either 1300/1500 Herald/Spitfires or 2 litre GT6's/Vitesse's. Anyone have any ideas as to what's a good ratio for the 1600 engine with a dolomite 4 speed and J type overdrive? What are you other 1600 owners running?Mark Quote Link to comment Share on other sites More sharing options...
69vitesse Posted October 1, 2013 Share Posted October 1, 2013 4.11 is crazy low for modern roads.A 3.89 at least, or better yet, a 3.63 from a Spitfire. Quote Link to comment Share on other sites More sharing options...
Rangi246 Posted October 1, 2013 Author Share Posted October 1, 2013 Will the 1600 motor pull a 3.63? Any idea how much of an effect it would have on acceleration? Quote Link to comment Share on other sites More sharing options...
Clive Posted October 1, 2013 Share Posted October 1, 2013 It will make the car a little slower off the line, but you can stay in gear longer. If you do a fair bit of top gear driving, you may well benefit from a 3.63. Remember they come from a 1500 spitfire, with broadly similar power etc to the 1600.If you do more town and slower roads, a 3.89 or 4.11 would be my choice. Quote Link to comment Share on other sites More sharing options...
69vitesse Posted October 1, 2013 Share Posted October 1, 2013 7902 wrote:Will the 1600 motor pull a 3.63? Any idea how much of an effect it would have on acceleration?How often on todays road can you take off from the line and redline the car in each gear up to speed?There ya go. Occasionally, you might be a second quicker to 60 with a 4.11 diff, but 99% of the time, you won't notice anything except you are using a lot less petrol with a 3.63 diff. Quote Link to comment Share on other sites More sharing options...
Pete Lewis Posted October 1, 2013 Share Posted October 1, 2013 I run a 3.89 with OD and and 2ltr 3 rail + dtype and she pulls around 3100 at 70 the 2 ltr box has a higher 1st gear and if you run 4 up and a boot full you can extend clutch slip times a little no experience of 1600 + 3.63 the 1600 has good revability but less torque , if you overgear it wont perform so well mid range if she's on strombergs you stand more chance as you gain around 11 bhp over the early down draft solex set up.Pete Quote Link to comment Share on other sites More sharing options...
GT6 M Posted October 1, 2013 Share Posted October 1, 2013 I run a 3.89 with OD and and 2ltr 3 rail + dtype and she pulls around 3100 at 70 that cant be reet, moer like 3350 at 70 in OD topif on 155s as standard GT / VitM Quote Link to comment Share on other sites More sharing options...
Nick Jones Posted October 1, 2013 Share Posted October 1, 2013 Agree. Mine pretty much 3000/70 on the nose and that's with 175/70 tyres, 3.63 diff and 0.79 5th. It would pull taller gearing but it is a 2L......Nick Quote Link to comment Share on other sites More sharing options...
Rangi246 Posted October 1, 2013 Author Share Posted October 1, 2013 Our car does have the strombergs so has a bit more power than the earlier 1600's. The 1500 Spits have similar power but they're also a much lighter engine so i'm a bit torn between a 3.63 and a 3.89. 3.63 would give longer legs for the motorway of which the car is on quite a bit but am I right in guessing that in 4th OD it might be a bit sluggish? So maybe a 3.89 would be a better option giving good acceleration and slightly longer legs?I've had a look at the Minty Lamb site and noted the various speeds/revs etc, very useful, but it doesn't give you some good old practical experience as to how the car feels when the various ratio's are in......Would love to hear from anyone running a 1600 with a 3.63 diff.Mark Quote Link to comment Share on other sites More sharing options...
Bainzy Posted October 2, 2013 Share Posted October 2, 2013 7902 wrote:3.63 would give longer legs for the motorway of which the car is on quite a bit but am I right in guessing that in 4th OD it might be a bit sluggish? Guess it depends what state of tune the engine is in and in particular how well it breathes, cam etc. With my 1500 engine (admittedly on EFI) and 3.63 diff, I can now quite comfortably overtake people at 70-80mph in OD top by putting my foot down a little harder. Quote Link to comment Share on other sites More sharing options...
Rangi246 Posted October 2, 2013 Author Share Posted October 2, 2013 Its a stock engine, no mods other than the carb air intakes. Engine was rebuilt 25k miles ago and its just had a full service and tune up so is going pretty well - apart from the diff. Quote Link to comment Share on other sites More sharing options...
marktheherald Posted October 2, 2013 Share Posted October 2, 2013 I would go with a 3.89. My estate runs out of puff a bit on a long uphill drag. (1500 with 3-rail D-type o/d and 3.63 diff) Quote Link to comment Share on other sites More sharing options...
Freebird Posted October 2, 2013 Share Posted October 2, 2013 3.63s are more expensive that 3.89s too, people want them for all sorts of reasons with bigger engined cars. Quote Link to comment Share on other sites More sharing options...
Pete Lewis Posted October 2, 2013 Share Posted October 2, 2013 welcome to try mine if youre ever Luton way Pete Quote Link to comment Share on other sites More sharing options...
Ridgetone Triumph Posted October 2, 2013 Share Posted October 2, 2013 I used to race a 1600 Vitesse way back and used the 4:11 diff, well that was if I managed to get to the track before snapping the half shafts. Common occurrence and regular, one time on the night before a meet I was waiting at the traffic lights, I took my foot off the clutch after a short while and forgot it was in first gear, snapped the damn halfshaft. I guess it didn't help that I had my other foot on the brake pedal. Go Subaru or Bemmer ;) Or Jag 8) Quote Link to comment Share on other sites More sharing options...
Rangi246 Posted October 2, 2013 Author Share Posted October 2, 2013 Strangely enough I haven't had any trouble with the halfshafts on the diff. Is there any easy way of telling if it has the stronger halfshafts just by looking at the diff? Or would it have to be pulled apart?I think i'll go with a 3.89 ratio for the new diff. I'm hoping it'll give a good compromise between acceleration and open road driving. Mark Quote Link to comment Share on other sites More sharing options...
Freebird Posted October 3, 2013 Share Posted October 3, 2013 7902 wrote:I think i'll go with a 3.89 ratio for the new diff. I'm hoping it'll give a good compromise between acceleration and open road driving. MarkSound plan. Quote Link to comment Share on other sites More sharing options...
Pete Lewis Posted October 3, 2013 Share Posted October 3, 2013 as for the half shafts ,, my 64 1600 HB 4;11 diff had the larger shafts, have no idea if they were upgraded in production or some retro fit at a point in its life .to check whats in you do need to remove the 4 brg housing screws and withdraw the shaft and bearing assy, it wont upset any internal settings.and measure the shaft and spline diameters way back in history, my second car in 1966 was a rusty 59 948 herald and we sheared the shafts with 37bhp. I had no trouble with the 4.11 and there are many still running ...for better or worsePete Quote Link to comment Share on other sites More sharing options...
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