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Reverse Spacer Sleeve 137687 dimensions

Peter Truman

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Ref the Spit 1500 gearbox internals into a 3 Rail 4 Syncro Vitesse Mk2 or Spit Mk4 306468 gearbox case. Well I got it all in BUT when I tried to fit the selector cover I had to push too hard it fitted but reverse wasn't right.

I summise that I've used the single rail reverse spacer 22G1435 which goes towards the rear of the reverse idler gear and box case, whereas the 3 rail Vitesse/Mk4 Spit uses a 137687 spacer on the opposite side of the idler ie towards the front of the case closest to where the idler shaft is anchored into the case. 

As 137687 is no longer available can anyone provide its dimensions, hopefully I can modify 2G1435. I think it might be just a length issue.

I hope someone understands the issue and can help.


Peter T

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As far as I know three rail reverse spacer tube goes to the rear of the gear up against the tail hsg or od adaptor plate


its one part that always wants to fall out throuhg the hole in rear of the case when re assembling


I have found single rail 1st 2nd sleeves fitted to 3 rail boxes and this wont work as they have different numbers of teeth, and the hubs a loose fit on the mainshaft

i must have some in the shed , but you could remove the tail hsg. Swap the bush to the rear

engage reverse and measure the depth from rear face to gear and cut you long spacer to suit

just an idea



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Have an old gearbox I took apart years ago case number HC121 no guarantee dimensions are correct for your application. The plain tube I believe to be the reverse spacer has the following dimensions.


External diameter 1inch 25.38mm

Length 0.934inch 23.71 mm

Int. Diameter 0.675inch 17.16mm

The length and external diameter I measured with a micrometer and digital caliper (Aldi's finest).


Hope this is what you are looking for.





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Pete I believe your correct re location that's where the single rail box shows it, but the Rimmers drawing for the Spit Mk4 3 rail has it before the idler gear ie closer to the shaft anchor point of the box, so does my Triumph Vitesse Parts Catalogue maybe I'm taking the drawings too literally. All the internal components of the box are transferred from a single rail box, I've replaced some bearings and thrust washers, , oh and the reverse idler gear as it was chipped (21teeth)


Paul my spacer 22G1435 ex single rail box is, 1.072in long, 0,696in ID, & 0.994in OD measured with my Bunnings Hardware elcheapo ($25) digital caliper been OK for 20yrs. I'll modify mine to 0.934in long (1/8in+ less) this should let the reverse lever move forwards at the top more letting it engage the reverse selector notch easier (hopefully) Luckily my friend has just got a small lathe so we'll do it professionally!


Thanks will let you know the outcome


Peter T

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Just for information the three rail box with j type overdrive in my Vitesse has the fine, single rail, input shaft so is a mixture of three and single rail components. Reverse is up by first and just a single rail Dolomite 1850 clutch plate needed.

Best of luck with your build.





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Whilst yer at it, there a good chance that the rev lever, is  also wrong,

yes I no all the books say the same thing,,or nowt at all aboot this prob,!!!

butt, the thing needs adjusting in most boxes ive done, even OE ones. no chopped aboot


the ..rev idler,.. sits too far forads, and on owa run, and esp in 1st gear,

it,ll rattle against the gear infront of it.

can , and does rattle in 4,th gear, as the oil flow oft gears, ...shuvs it foradsonto ger infrunt even moer

due to play / slackness in lever an idler groove

there is play int pins that rev idler fits into., this dont help either., as it can become flattened on 2 sides


wot ye gotta doo, is bend the rev arm back a wee bit.

which means tek,n it oot, { just one lang bolt, its ont oot side oft casing }

put lever int vice an nok / bend back a wee bit, just bottm aif needs bent

or bend top aif forads, either way works


Butt, first, put on rear adaptor plate,

fit yer  idler gear in place,   can leave spacer oot, nee need for this


and with top gear selecter on, and in a forads  gear, 1,st will suffice

{ as first is the worst for noise on overun, rattling away }

push the rev idler forads a wee bit,


If it touches the gear in frunt, then it needs lever adjusted backwards

it,ll all become quite obvious wen yer looking into it ,thru the back plate  just wots going on.

a torch may help too t,see better into box


Ive had boxes in frae so called specialists that have this gear touching the others

most likely cos they no no wots going on.,or actually drive em,

as its at least an 1/8th away frae the other gear at rest and in gears

on a v v olde used box,it dont doo it as much, as its worn away, so no meks a noise,!!!



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Paul I ended up cutting an 1/8in off the Spacer length with the hacksaw, quite chuffed I was vey straight & accurate now the Spacer is btwn 0.930 & 0.933in with a spare 1/8in annulas free.

Pete your right the Spacer MUST fit at the rear of the box

GT6M (M) thanks for that info I think your right, whilst now the reverse idler sits free of the other gears when not in reverse the reverse lever looks too far back still, can you remove the lever without dismantling/removing the geartrain again!

I cannot find a mention anywhere of what gear the selectors and gear train should be in to replace the selector cover/forks back on the box


Thanks all again for your help


Peter T

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Most triumphs are in neutral .... and fiddle a little

generally the reverse pivot wont remove enough without a mainshaft out

dont you just luv it .


this just confirms my hate of the factory manuals, divisive bit of info is always ommited.


last time I did any single rail work was on a Marina in the 70s



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Peter asks

can you remove the lever without dismantling/removing the gear train again!


Ye need t, assemble the gears t,fin oot where its gonna touch.

as can be seen, the rev idler is just sit,n on a stub on the rev lever

wid top cover on, fit  it into first, then gently push the idler forads

if it touches gear hub, then adjust it backrads,


hold int vice, and a good wack will shift it a wee bit, NOT too much at a time

then re check, still touching, another tap backwards, re test

ye,ll soon get the nak of it


when the rev lever bolt is took oot, then the lever can come up oot the top of the box

IT has t,be assemble t,see where its gonna touch., which can be seen thru  the back OD adaptor plate


It wont doo ye ne harm to have a few pre run builds either,!!!


Another few  wee tips for ye,


the thrusts, if worn doon a bit, then some shim steel fitted to the backs will mek the free play up

saves ye buying new ones, IF they can be got to yer size of  extra thickness


the thrust at back, is small, this teks all the thrust,

can get a frunt thrust, CUT the top bit away, { or it,ll touch the first gear } butt, leave a tang there,

then bend tang owa,like original, so it will lock into casing, this way, ye got a bigger thrust where its needed

its no much,maybe an 1/8th  but it helps

yer limited to size oft laygear ends


Check laygear end is smoothe, or it,ll soon eat into a new thrust, an mek gaps bigger

so back t,square one. bigg  thrust gaps


whenst fitting the layshaft, thrusts can, an doo drop doon, a real pain in the butt

solutionee, a few drops of supa glue ont backs, then fit em onto layshaf, insert into casing, and odd till set

layshaft centers em,  wait till set, and then yer thrust will no dropp oot

{ ye really need an olde layshaft cut doon, or a bit of bar, even some wood dowel will suffice

and slightly chamfer the ends, so it finds its way past thrust into casing easier }


fill yer lay gear rollers wid SLD { Shirt lifters Delight }, an as cold as ye can get it

this will hold the needles in spot, an then melt away wid heat

Grease dont, so could,mek yer needles run dry

nowt wuss when a needle has dropped oot, and ye gotta tek the whole thing t,bits agen, t,get the needles back in, grrrrr


THIS, is also needed on 3 rd gear split collets. really smother the area wid SLD, then they wont part,an drop oot


Be very wary fitting mainshaft onto rear bearing, as tapping it in, can shift the tolerances up onto the gear thrusts

then it seizes solid whenst its running

after fitting, mek sure the gear to thrusts  moves, if it dont, tap / adjust till it does

Note, it dont say owt aboot this int book, so beware of it, or yer box will seeze in nee time


Dont forget the bottom bolt int bell housing needs a copper wesher,  as this goes to inside oft casing

an loctitie for piece of mind


Same too for 2 top OD bolts on OD {  if its been stripped or took oot } thee,s go into OD insides


Dont use gaskets, use a silicon sealant, or LT 574,  never ever any leaks


Dont put bolt an nyloc nut into bottom of gear lever the wrong way round

or ye wont can get 3rd or 4th gears,!!!

bolt heed towards casing side, { Pass side }


If ye got clutch oot, an put,n in a new,n,  then use the First motion shaft to line the clutch up

whilst GB is in bits


Dont let GB drop / hang  onto clutch, it,ll bend the plate, then it,ll all ev t,come ott agen,                                                              as yer car will be hopping along the road,, or hopping aboot yer garage,   whenst revs are up,!!!!

and it,ll also bugger yer first bearing up too. and also,if really bad, yer bearing inside the 4th gear,


Read an digest a few time what ive said, it,ll save some heartache,!!

good luk



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Theres some good clues from marcus,

another way to assemble case and rear bearing without the split collets leaping out when you tap the bearing in is

Bit of hard wood in a vice with hole for mainshaft spigot or old input shaft, protect the spigot


with case and mainshaft held vertically lower onto support

you can then tap the bearing down the mainshaft and into the case without the gears jumping up as you tap , gravity holds the gear ontop of the collet thrusts ,


sounds a bit of a hand full but this works ,

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Thanks for all that good info Gents,

I'm still having trouble getting the rear selsctor (wide one 1st/2nd) o clear the reverse lever so as to get the cover in place.

from the top cover side bolts is 48mm to notch in reverse selector and 46mm to the lever boss/pin so that should clear and there's one full thread protruding past the lever. 

The rear wide selector is a in VGC but is probably a very early Herald version, I don't think Triumph changed them during the 3 rail gearbox run not be Rimmer's listings anyway.

I'm contemplating removing the input & main shaft  then screwing the reverse lever on one more thread, then I can try Pete's vertical method.


Thanks all for the great amount of info, and Marcus I'll save your expansive advice for future ref and use by our local Triumph Stalwarts.

Peter T

aka Grumpy

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  • 2 weeks later...

Well I finally got the earlier Herald (with reverse spacer washer fitted in the selector for the 4 syncro box)) style 3 rail cover onto the GT6 style 3 rail gearbox case.

As Marcus correctly advised the reverse lever had to be bent sideways further. Initially I couldn't move it enough as around 5mm reqd, even with MAP gas getting it red hot, so I drilled a 1/8 hole in the centre of the lever just below the bend and above the welded nut then hacksawed down to the hole and the belted the top of the lever until the slot opened to 2mm trial fitted it then removed AGAIN, then off t0 a mate who is a very competent welder (rebuilt to concour 4 big Healeys, plus Twin Cam Escort, and Mk1 Sprite) and welded the slot, it hardly needed any filing.

Fitted it back in the box and viola cover fitted and I can select all gears TOO. I reckon I moved the pin over around 6mm.

I'm an expert now at dismantling the internals of a 3 rail box, some think I found to daunting in the past! I got so good at it I didn't have to drop the gear cluster.

Now to fit the J type Overdrive.

Interestingly Re the Healeys John is on No.5 a BN1 4 potter, ALL the chassis and body superstructure panels are made locally here in Oz at Ballarat to a very high standard and they ship worldwide. The chassis has been repaired with new parts, rejigged with any damage and panel distortion removed. He's now repairing the super-structure again all new parts where necessary, It is fantastic to see the quality of his work, this BN1 will sell for $150k not a bad pastime for a retired plumber & it gets him out of his wife's hair! Like everyone he needs more garage space to work.

Thanks everyone


Peter T

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