948cc gearbox into 803cc conversion update

[martin418]

i have just started my 948 to 803 gearbox conversion and it is as most thought very straight forward , apart from gear ratios and gear sizes the 2 boxes appear identical inside so i am going to fit the 948 gear clusters into my original casing ,i am waiting for a few new parts and hopefully by thursday it should be done

[katy]

Suggest you check the length of the input shaft to make sure it's the same. IIRC there are some differences, but not sure on what boxes.

[bmcecosse]

Novel idea! Not heard of it being done before - although it probably has. Keep us up to date on how it goes - take some pictures if you can, please!

[martin418]

update input and main shaft are the same , the reverse and 3/4 th selector rods are different , i have just had a test run with just the 803 selector rods and gear lever and it looks ok , the main casing , front cover and side cover are the same ,as are the selector forks and lay shafts , hopefully i will get the parts tomorrow and have a test assembly

[Declan_Burns]

Martin,
Read through this.
Regards
Declan[frame][/frame]

[martin418]

thank you very helpful

[brucek]

In all honesty, you can save yourself a HUGE amount of time and work if you marry the 803 tailshaft segment of your 803 box to the main gearbox casing of your 948 box having first removed the remote gear lever extension portion from your 948 box. It is a very simple job and has been done many times already. It allows you to use all the internals of the 948 box (which, as far as the case is concerned, is identical, I think, to the 803) whilst retaining the long original style gear lever. Given all the various detent springs, ball bearings and other gearbox paraphernalia, taking the internals out of a working and perfectly sound 948 and putting them into an 803 having first removed those internals, is a nice project but gets you exactly what you already seem to have. Or have I misread the original post?? Good luck anyway

[martin418]

HI I AM FITTING THE WHOLE 948 GEARBOX INTERNALS I JUST STRIPPED IT TO CHECK IT OVER

[bmcecosse]

The suggestion is to use the complete 948 gearbox - less remote control......which is the 'normal' conversion. Your way is novel and if you are able and willing - good luck! It will keep the original gearbox casing (and ID number) with the car - if that is important to you.

[ampwhu]

on the 803 you need to lift the gearstick 'up and over' to engage reverse. this isn't the case on a 948.

this may cause an issue if selecting 4th in a hurry. a crunch may suggest you have selected reverse!

I think the way around it is on the web somewhere.........

[liammonty]

He's already changed the selector rods ;-)

[bmcecosse]

Exactly - keep going... However -if anything has to be retained from the old 803 parts - it may be the selector rods - particularly the reverse....

[martin418]

update the 3/4 th gear selector rod is also different the fork is thinner , the 948 one works ok but it makes the reverse rod work slightly out of line , i can't finish final assembly due to only ordering one layshaft bearing !!!!