hi ive just got my self a 73 d/c kombi with a 1600 sp and a 1600 gear box would like to know what mods if any are needed to fit a 1800 gear box eg clutch fly wheel mounts just want to lower the revs on the hwy thanks guys

1. I can't answer your question; plenty of others on this forum will chime in with the proper answer.

2. Also consider tye and wheel sizes; for example a 215/70R15 would reduce RPM about 5% over stock (using Mercedes 15" rims); using aftermarket mags, a 215/60R17 tyre reduces RPM by about 5.5%.

hth

1800 nothing , same starter and bellhousing , unless its an early 1600 box fitted with early throw out bearing

1800cc input shaft will need to be turned down for type1 donk. I think its 12mm by memory do research to confirm.

hi any one know for sure if the input shaft needs turning down like bone said im hearing conflicting storys any help would be great

Smiley on here will tel you exactly... hes running a 1800 kombi box with 1600 bug engine. Send him a PM.

Yes he did have to mod the input shaft.

Yep, input shaft will be able to be swapped from one to the other

yeah and that , haha use a 2ltr box better ratios

ive already got the 1800 box came with the ute so do i need to change the input shaft ive been told i dont only the through out bearing may be different but the clutch splines are the same ? any one done the mod them self that knows for sure thanks

yep have changed input shaft from 1600 to 1800 box and just used the throw out bearing etc from the original 1600 box

Yes. You will certainly have to changed the input shaft. The 1800 one is around half an inch longer than the 1600 one. The splined section is the same it's just that the tip of the shaft that sticks into the engine is longer. This is due to the 1800 being a Type 4 engine and having the input shaft support bearing further in.

When I did mine I removed it and turned it down in a lathe to the correct length, alternatively you can swap your old 1600 one in to the 1800 box, they are interchangeable.

Removal is a reasonably straight forward procedure also if you have mechanical abilities.
- Drain all the oil from the gearbox
- Remove all of the M8 bolts that hold the bellhousing to the gearbox main housing
- Remove the bellhousing, you will now have exposed the differential section of your transaxle
- If you look down along the input shaft you will see a small external circlip on the shaft. Remove this.
- This will allow you to slide the collar off the splined section of the input shaft.
- Then you simply unwind the threaded end of the input shaft out of the gear end of the gearbox shaft and it is free.
- Install is a reverse of the removal. Make sure that you don't lose the circlip and that when you refit it, that it is seated down correctly in its groove.
- I also found it a good idea to replace the input shaft seal in the bellhousing while it was off. As they are a lot easier to remove when you can just tap them out from the inside.

I hope this help. let me know if you need a better explanation. I might even have some pictures floating around somewhere from when I did mine.



Smiley

hi just done the change did not have to swap the input shaft or the through out bearing everything is the same even the starter motor car runs a lot better out on the road does not rev as hard not sure what every one is talking about needing to swap the input shaft they must be talking about a 2lt g/box as this has a different shaft ?

The 1800 box should have a longer shaft as well as the 2L.

This is because they both have the Type 4 engine which requires the longer input shaft.



Smiley

Actually, I believe the 1800 has a longer input shaft as it should have a type 4 engine, a 2 litre tranny has an even longer input shaft as the bell housing is deeper for the 228mm clutch which also warrants a different (longer) starter.

If your input shaft was an 1800 one, you'll probably find out, with potential engine or transmission damage, otherwise it may have already been changed to a 1600 version.

OR it could have been a 1700 box.....but the 1600 donk woulda not fitted right...

the g/box was the origanal 1800 out of the d/c just that the motor died and the owner had a 1600 and box from a rusted out bus he had so changed the lot i messured the input shaft length and diameter and all were the same checked a mate that had a 2 lt and a 1800 box his 1800 was the same as mine just the 2 lt was different this is because of the fly wheel size for the 2 lt

The 1600 box likely has a 5.375 diff and 0.821 -4th gear = 4.413 final drive.
The 1800 box will likely be 4.857 diff and 0.889 -4th gear = 4.317 final drive.
...so about 80 rpm different.
If your 1600 uses the later replacement 5.4286 diff then you are better off by about 115 rpm.

The input shafts on all of the boxes that suit type 4 motors are all the same length.
The 2 lt bell is deeper for the larger clutch, but the shaft is the same as the 1800.
The 1600 shaft is shorter, but only on the end that fits inside the pilot bearing.
I think it is about 12mm different, but I will measure one later today.

If you have small hands you can change the shaft over once the bell is removed.