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when i orginally got my 4 speed 1983 ST90 suzuki van last year first attempt at a the 5 speed seemed a little daunting and in needed to get it on the road so i just popped in the 4 speed and got everything going

bought a cheap 1985 sk410 carry a few weeks back which was a 1ltr 5 speed. so it was time again to go at the conversion. its actually surprisingly easy to do assuming you have ALL the bits and only a little bit of customizing to do. which i'm not sure actually needed to happen but circumstance reared its ugly head.

the bits that need modifying are:
spacer between seats - two different van models have different shifting mechanism's, 4 speed solid linkages 5 speed cable linkages with the shifter its self in a different position. the hole in the middle where the original shafter comes out of needs to be cut into the new spacer to allow it to sit low enough to get seats to close. i just traced around the original spacer and cut at it with a grinder and it fits fine. using the SK410 center console to hide everything. and a couple of extra tek screws to hold everything in place.


the circle in green needs to be cut out of the SK410 spacer, there is also a "tab" at the back which needs to be cut off, this is for mounting the center console, which is also to long and needs the end chopped off to fit the seat belts (red), the rear mounting holes line up fine just need some bolts or tek screws at the front to really pull everything snugly down





Drive shaft the 5 speed is a longer box and so the original 4speed shaft becomes to long to use, a place in newy wanted $178 to shorten my original shaft. but my conversion came with a 5speed shaft which is shorter and can be used. THE DIFF's however are slightly different between models, with the pinion flange being slightly smaller and so the bolt holes on the 5speed shaft done match up to 4speed diff.

i had the original idea of maybe trying to get pinion flange from a SK410 van as i had gotten rid of my wreck by the time i found this out :cry: with my time frame getting shorter i decided to lathe up an adapter plate at work. this would allow me to use the shaft and get the length right as well. so far it seems to be working well i noticed a bit of a vibration at some higher speeds (not revs just speeds) but not sure if thats just the tyres i swapped or engine mounts.


shat phone photo but you can kinda see what i had to lathe up with the counter sinking of the bolts that go all the way through to allow saddle to sit flush.


better photo but with shaft installed. i need to replace the bolts with high tensile one's and put some spring washers in there as well so i can take some better photo's of the whole thing and write up a bit of a "how to" spool if people want.





rear gearbox mount the mounts between the 4 speed and 5 speed are different as well. the do line up rather close though and width between holes are the same. this was an easy fix. i just made a mixture of the two mounts and now fits perfect and engine angle seems dead on or near enough as well.

so with the cutting off of 1 stud and locating pin and a tiny bit of welding i have a fully working engine mount. which even if the welds snapped due to the way the engine mounts "cradle" the other the gear box can't actually fall or move very far.


so originally the 4speed box had rubber mount that bolted in to the holes where the green arrow is. the original 5 speed mount mounted up slightly differently to a stud drawn in red. this needed to be cut off and ground flat. theres another stud on top (blue arrow) which is how it connects to the gear box.

to get the alingment of where to weld the mount was easy, i just screwed it to the car in its original and proper location. and raised the gear box up with a jack and hooked it into the mount, it was pretty much supported like this, only reason i welded it was to stop vibation and movement. so just a couple of tack welds to hold it in place then removed it and welded it properly.

the reason its bright grey is just the anti rust paint. i'll just spray it black to keep it all low key.


you can see how its hung in the original mount





quick little splurt around the bock is promising doing 80kph at 3000rpm instad of 4000rpm with 4 speed so might be able to go that little bit faster. or just cruise along and save even more fuel.
 
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