greybeard Posted October 1, 2007 Share Posted October 1, 2007 Hi all,Another new guy, and guess what, yes more questions than answers.A couple of years ago, I was given the differential, axles, drums, and leaf springs, from a Spitfire, my question is , how can I determine " what Spitfire" it all came from?,At the back of the differential I have two sets of numbers [ hope this helps] they are 22m7 and v2734, and just maybe the letter B or symbol in a circle,[ it is rather indistinct ], I live in hopes that someone just might have the answer.Cheers :) Link to comment Share on other sites More sharing options...
GT6Steve Posted October 1, 2007 Share Posted October 1, 2007 Couple of questions come to mind. What do you intend to do with it? If it's a replacement than you'll want to know the ratio. Count input turns to output turns. Is a swing spring or solid spring? What size are the axle shafts? I think flange size changed as well but not sure. What size are the brake drums (could it be a GT6 diff?)There were model changes but I think the basic cast iron lumps stayed the same thruough out the run. Not positive though...Steve Link to comment Share on other sites More sharing options...
Deleted User Posted October 1, 2007 Share Posted October 1, 2007 There should be a no stamped on the bottom of the diff...may be covered in crap and need scrapping a bit to seeif it starts with FC then from an early spit and a 4 .11Fh from a mk4 and a 3.89 FR from a 1500 and a 3.63 Link to comment Share on other sites More sharing options...
Clive Posted October 1, 2007 Share Posted October 1, 2007 Also the input flange is a bit of a giveaway. If it is square it is an early spit (1 2 or 3) if round 4 or 1500. But doug is correct. Under the diff (the spring is on top with the 4 or 6 holes) there should be a number stamped, prefixes as above.If all else fails, or you want to be sure, mark all 3 flanges. Turn the 2 output ones together, and see how many turns it takes for the input flange to do exactly one full rotation. Just over 4=4.11, just under 4=3.89, just over 3 1/2=3.63 etc. Link to comment Share on other sites More sharing options...
Deleted User Posted October 1, 2007 Share Posted October 1, 2007 That's if it's a spit diff at all Link to comment Share on other sites More sharing options...
greybeard Posted October 1, 2007 Author Share Posted October 1, 2007 I must say you guys are quick, and on the ball, I have just had a quick look, and the input flange is a round one with 4 bolts, and as it is chucking it down at the moment I can't check for numbers on the bottom.The use to which it has been put, I have built a trike using the afore mentioned parts, I had the shaft ends re built, and the guy in South London who did Triumph restoration, put [heavy duty] ends and bearings on them, but he is now out of business, he also did the math, and said that 15''wheels were fine.As for doing the rotation of all three flanges, that will have to wait until tomorrow.The initial question was prompted by the inevitable quest to [ go faster ]. and my thoughts were that it might be simpler to work on the diff...rather than the engine.and the problem was, I had no idea what the diff I had.Many thanks for the replies so, far I will try and get more information tomorrow if it's dry and I can jack it up for a look. Link to comment Share on other sites More sharing options...
Clive Posted October 1, 2007 Share Posted October 1, 2007 At least it should be fairly strong, for a triumph diff. Link to comment Share on other sites More sharing options...
greybeard Posted October 2, 2007 Author Share Posted October 2, 2007 Hi guys,As the day was slightly better, still got wet though, the number on the bottom of the diff, reads FC 3200, as for the input and output flanges, I get 3.5 turns on the outers, to 1 full turn on the input flange.So if I want to gain more top end speed??? [ any and all suggestions welcome ].There is a Triumph breakers I think somewhere in South London, who from memory supply second hand parts, or new if required, Ill find them if I need to. Link to comment Share on other sites More sharing options...
mk2vitesses Posted October 2, 2007 Share Posted October 2, 2007 Bigger wheels, more engine revs, fit a overdrive!! Fit 3.27 C/wheel & pinnion Link to comment Share on other sites More sharing options...
greybeard Posted October 2, 2007 Author Share Posted October 2, 2007 mk2vitesses wrote:Bigger wheels, more engine revs, fit a overdrive!! Fit 3.27 C/wheel & pinnionHi,It's a motorcycle trike, my friend, utilizing a triumph spitfire rear end, I already have 15'' wheels, I had hopes of perhaps upgrading or modifying the diff, rather than having to resort to an engine rebuild.That's why I hang my head, and put the question to my peers on this board. :-/ Link to comment Share on other sites More sharing options...
Clive Posted October 2, 2007 Share Posted October 2, 2007 FC should be 4.11 to 1 ration, not the 3.5 you have.It may be worth rechecking, it can be tricky as the 2 outputs can easily rotate at different speeds when testing.It could be a rebuilt diff in the wrong casing, but that is not common.If it is a 3.63 (nearest to 3.5) then the only other ratio is a 3.27:1 but it is weak (I have broken several) and rare/expensive.Sorry but no other diffs are straight swaps.Taller 15" tyres could help. Link to comment Share on other sites More sharing options...
gravelrash Posted October 2, 2007 Share Posted October 2, 2007 Need to consider what bike engine you are going to use. My bike being quite new pulls about 7500rpm at 80 mph! But then again it does rev to 14500.With a real screamer of a bike it will struggle a bit ith a 3.27.Ade Link to comment Share on other sites More sharing options...
greybeard Posted October 2, 2007 Author Share Posted October 2, 2007 cliftyhanger wrote:FC should be 4.11 to 1 ration, not the 3.5 you have.It may be worth rechecking, it can be tricky as the 2 outputs can easily rotate at different speeds when testing.It could be a rebuilt diff in the wrong casing, but that is not common.If it is a 3.63 (nearest to 3.5) then the only other ratio is a 3.27:1 but it is weak (I have broken several) and rare/expensive.Sorry but no other diffs are straight swaps.Taller 15" tyres could help.Hi, now I am a little confused, when I did the rotation test, I chalked all three flanges and pushed the bike in a straight line, it looked to me to be as close to 3.5 as could be, certainly not 4 revolutions , but I will try it again tomorrow,and I am assuming that the 4.11 is the best diff to have??? Link to comment Share on other sites More sharing options...
CharlieB Posted October 2, 2007 Share Posted October 2, 2007 4.11 (or even 4.55) is best for acceleration, do you want better acceleration or top speed? Link to comment Share on other sites More sharing options...
Clive Posted October 2, 2007 Share Posted October 2, 2007 Top speed seems to be the idea here!Trouble is some of the 4.11 are pretty weak, some are OK. Need the fogures...BUT all 4.11 came out with square input flanges. Some cars have had bits swapped though. Its never easy..................... Link to comment Share on other sites More sharing options...
greybeard Posted October 2, 2007 Author Share Posted October 2, 2007 Top end is whats required, and the input flange is round will double check the bottom of the diff and rotation tomorrow,square end round end on the input flange,does it really matter as long as the internals are correct,might consider getting a rebuilt diff to the 4.11 configuration if they are not to expensive. Link to comment Share on other sites More sharing options...
CharlieB Posted October 2, 2007 Share Posted October 2, 2007 If its top end you want ie higher speed for given engine revs then you want the 3.27. Link to comment Share on other sites More sharing options...
mk2vitesses Posted October 2, 2007 Share Posted October 2, 2007 The 3.27 will not break even in a mildly tuned GT6. They DO break in a Vitesse! It's all down to weight, I suspect the Trike is lighter than a GT6 which has got to be around 18CWT. Find a 3.27 diff and stick it in!! Use the right oil, GL4 spec I believe due to the copper thrust washers.Simon Link to comment Share on other sites More sharing options...
greybeard Posted October 3, 2007 Author Share Posted October 3, 2007 Oh Dear,The brain must have gone on holiday when I did the rotation test, and totally confused one and all,Only this time I might be causing even more confusion.Did the test again this morning, only this time the results are: 1 full rotation of the input shaft = 1 quarter turn on both outers, which if understand things correctly, is the exact opposite to what it should be doing. I even got the wife out to double what was going on in case I had developed a mental deficiency problem in the night.To answer another query re weight the trike weighs about 390 kg a little under 8 cwt.Don't yell at me please, i am embarrassed enough as it is. Link to comment Share on other sites More sharing options...
Richard B Posted October 3, 2007 Share Posted October 3, 2007 Quote:The 3.27 will not break even in a mildly tuned GT6Ummm the 3.27 will break if you put 132bhp through it .............. :B Link to comment Share on other sites More sharing options...
Clive Posted October 3, 2007 Share Posted October 3, 2007 look athttp://www.canleyclassics.com/catalog.asp?category=200208032225063385780837the writing is difficult, but explains all!Best diff for you would "probably" be 3.63 for strength and gearing. From a spitfire 1500. Link to comment Share on other sites More sharing options...
CharlieB Posted October 3, 2007 Share Posted October 3, 2007 greybeard wrote:1 full rotation of the input shaft = 1 quarter turn on both outers, which if understand things correctly, is the exact opposite to what it should be doing.No, that makes sense sounds like you have a 4.11To make sure do one full turn of both output shafts, should give you 4.1 turns of the input shaft. Link to comment Share on other sites More sharing options...
JohnD Posted October 3, 2007 Share Posted October 3, 2007 Gb,Do it the other way around.Turn BOTH output shafts together, and count the revs of the input shaft.One complete rev of the outputs, and - How many of the input?It's much easier to tell that way.Just over 4=4.11just under 4=3.89just over 3.5=3.68etc.John Link to comment Share on other sites More sharing options...
Sam Russell Posted October 3, 2007 Share Posted October 3, 2007 Lock one output shaft, turn the other five revolutions, and count the input shaft. Divide the number of turns by 10. This will give a more accurate number. Link to comment Share on other sites More sharing options...
CharlieB Posted October 3, 2007 Share Posted October 3, 2007 Sam_Russell wrote:Lock one output shaft, turn the other five revolutions, and count the input shaft. Divide the number of turns by 10. This will give a more accurate number.I think the diff is still in the trike ;D Link to comment Share on other sites More sharing options...
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