Darron Posted November 7, 2019 Report Share Posted November 7, 2019 Hi new to the forum, looking for some advice on my gearbox rebuild ,I have a three rail four synchro gearbox that I have removed from my vitesse 6 ,I am rebuilding it due to the reverse idle gear constantly trying to engage the first and second gear synchro while in first gear, the problem I have is that after I stripped it all down the springs in the synchro hubs 1st and 2nd and 3rd and 4th are the same ,! and the rebuild kit I have as two different types one trio looks stronger than the other any advise or help would be much appreciated, I have read somewhere that they should be different but which goes where ? Link to comment Share on other sites More sharing options...
johny Posted November 7, 2019 Report Share Posted November 7, 2019 wow they didnt come labelled up? If so Rimmers diagram shows which go where while in my w/shop manual it looks like the longer springs fit in the 3/4th hub and I think you'll find those holes deeper.... Link to comment Share on other sites More sharing options...
68vitesse Posted November 7, 2019 Report Share Posted November 7, 2019 Four syncro box 1st/2nd hub spring 106388 other 104445 but do not know how to differentiate, axial release load for both 19/21 pounds. Regards Paul Link to comment Share on other sites More sharing options...
Darron Posted November 7, 2019 Author Report Share Posted November 7, 2019 Thanks for the quick reply guys the kit came from Autogearstransmissions used these as they source better bearings and seals than Chinese ones but not labled up ! Will check rimmers diagram later regards Darron Link to comment Share on other sites More sharing options...
Pete Lewis Posted November 7, 2019 Report Share Posted November 7, 2019 the spring length gives enough ball protrusion to work in its sleeve groove if you geta short sprint in a deep hole its too easy to pop together , conversly get a long spring in a shallow hole you can fight the flying balls . simple idea to reassembly is pop the hub and sleeve into a poly bag, work through the open end and with light pressure on the sleeve pop each ball down with a small screwdriver , when all 3 are just nudged in press the sleeve down, easy to check the axial release load just press on some bathroom scales etc. keep the units bagged and when ready to assemble tie them up with fine wire cut it odd when man handling has finished to stop the 2nd gear collet thrusts from continually jumping out assemble the box in a vertical position , make a dummy mainshaft support (lump of hard wood with a spigot bore in it ) in a vice and lower with 6 pairs of hands the mainshaft/lay cluster and case down over the support so when you tap the rear bearing down the shaft and into the case and gravity stops the split collets jumping out with every mallet strike make sure the gear dog teeth and the sleeve have un chimbled well defined tooth chamfers /\ not /~\ as this is a integral part of what makes syncho work Pete Link to comment Share on other sites More sharing options...
Pete Lewis Posted November 7, 2019 Report Share Posted November 7, 2019 ok the from a bit of a search 104445 has aprox 6 coils the 106388 has 5 dont quote me on that if that works out i will write it in my manuals Pete Link to comment Share on other sites More sharing options...
Darron Posted November 7, 2019 Author Report Share Posted November 7, 2019 Pete thanks for all the information chap I have already made a dummy shaft for reassembly and the testing of them on bathroom scale is spot on Regards Darron Link to comment Share on other sites More sharing options...
Darron Posted November 9, 2019 Author Report Share Posted November 9, 2019 Hi all thanks again for the post earlier in the week, going on from what Pete Lewis has Enlightened me with checking the release load of the synchros on a set of bathroom scales ,the 1st and 2nd is about 15 kg (33lbs) and 3rd and 4th is 14kg (31lbs) I will add there are no shims in either synchros, my question is this too high or except-able as the manual I have says 10 to 21lbs regards Darron Link to comment Share on other sites More sharing options...
johny Posted November 9, 2019 Report Share Posted November 9, 2019 my manual says 19/21lbs for both. I know that if its too low you run the risk of gear changes where the engagement starts too soon before the synchro ring has fully matched the speeds so giving a crunch. Too high and obviously youll need more pressure on the lever although yours will probably easy up once immersed in oil.... Link to comment Share on other sites More sharing options...
Darron Posted November 9, 2019 Author Report Share Posted November 9, 2019 Thanks for the quick reply Johnny ,funny thing is that before I took the gearbox out when driving it I always thought it was very stiff to put into each gear it never crunched or anything but wasn’t as slick as I thought it ought to be ! regard Darron Link to comment Share on other sites More sharing options...
Pete Lewis Posted November 9, 2019 Report Share Posted November 9, 2019 the clutch has to clear of the baulk will take for ever . was the test on the scales a progressive or click clack fast push, try being a bit slow and gentle up the load till the sleeve de latches may prove better at least they are both the same . Pete Link to comment Share on other sites More sharing options...
Darron Posted November 9, 2019 Author Report Share Posted November 9, 2019 hi Pete the test was slow and progressive and done several times to check, also the synchos were all lubricated up! Darron Link to comment Share on other sites More sharing options...
johny Posted November 9, 2019 Report Share Posted November 9, 2019 I take it the packers are down in the holes under the springs so are you 100% there's none in there? Id imagine they could be difficult to get out.... Link to comment Share on other sites More sharing options...
Darron Posted November 9, 2019 Author Report Share Posted November 9, 2019 HI Johny i had a good look and also probed at them with a pick but could not make any thing move will have to try again tomorrow and get in with a lighted magnifing glass but would of thought that one or two would have come out while i was washing and cleaning the hubs and gears Darron Link to comment Share on other sites More sharing options...
johny Posted November 9, 2019 Report Share Posted November 9, 2019 yes it could just be that the pattern part springs (which I wouldnt have thought are easy to replicate accurately due to the tempering of the steel wire etc) are stronger than they should be. Hopefully they'll soften up with use or you'll have to have more weetabix..... Link to comment Share on other sites More sharing options...
Pete Lewis Posted November 9, 2019 Report Share Posted November 9, 2019 face a small amount off the spring or just use it and let us know pete Link to comment Share on other sites More sharing options...
Darron Posted November 9, 2019 Author Report Share Posted November 9, 2019 Ahh well Pete I would love to just use it and let you guys know but that’s a awful lot of work to put back in and then to take all out again ☹️ Bit of a stickler for things right ,that’s why I am on here with you gurus ,Going to strip them down again and really check for the allusive shims if I can’t find them then perhaps see if I can measure the old spring rates ,and use them mix and match but with the right amount of coils , even face a bit off the old ones as Johnny as suggested some how try to get the release loads lighter fingers crossed 👍 Darron Link to comment Share on other sites More sharing options...
Darron Posted November 9, 2019 Author Report Share Posted November 9, 2019 Sorry Pete as you suggested not Johnny about facing some off the springs Regards Darron Link to comment Share on other sites More sharing options...
rogerguzzi Posted November 10, 2019 Report Share Posted November 10, 2019 Hello Darron I rebuilt my single rail gearbox last winter and there are different springs(fogot which way) but i think if you check the holes in the hubs one deeper than the other and if you put the long springs in there it will not go together but short ones would not give the 19/21 lbs needed Roger Link to comment Share on other sites More sharing options...
Pete Lewis Posted November 10, 2019 Report Share Posted November 10, 2019 i fought the loads on my 2000 box could get anywhere near the spec but it works ok ie they were lighter than spec'd this is from a Rootes WSM ( they dont hide useful clues) often written by a uncle) its one of the best explanations of how syncro works ive been into truck gearboxes for life i wouldnt worry too much if its a tad high or low, even is the king the idea is to give a snap movement at the ring , not a soft squiggy the tooth chamfers on sleeve ring and dog teeth do all the work the balls and springs make sure you really want to engage and not let selection load drop off halfway through a change Pete Link to comment Share on other sites More sharing options...
Darron Posted November 10, 2019 Author Report Share Posted November 10, 2019 Well gents decided to go with the loads that the new springs give after Pete’s previous comments ,as the loads are the same . will be putting the 1st and 2nd synchro back into the box though there is some damage to the reverse gearing On this but I have had trouble sourcing another with 29 teeth I will attach a photo to see what you guys think Darron Link to comment Share on other sites More sharing options...
johny Posted November 10, 2019 Report Share Posted November 10, 2019 it can have a hard life if the driver tends to put the car into reverse while its still rolling forwards and also a high tickover can worsen the crunch. However I think that gear is good for a few more miles yet just treat it gently (as you should do with the whole box). Are you replacing the synchro rings themselves or are they still ok? Link to comment Share on other sites More sharing options...
Darron Posted November 10, 2019 Author Report Share Posted November 10, 2019 Hi johny i am replacing the synchro rings with very good second hand ones after reading about the pattern replacements sourced a set off eBay £9.70 including postage from a 1500 gearbox but in very good nick 👍 Darron Link to comment Share on other sites More sharing options...
johny Posted November 10, 2019 Report Share Posted November 10, 2019 Not from a 1500 Spitfire I hope as the single rail box uses different rings? Link to comment Share on other sites More sharing options...
Darron Posted November 10, 2019 Author Report Share Posted November 10, 2019 Don’t know to be honest but they are exactly the same as the ones I have in mine but the gearbox in mine is not the original it’s from a mk 4 spitfire I think with a j type overdrive Darron Link to comment Share on other sites More sharing options...
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