Topic: Need help with a five speed gearbox

[manamer]

Hi, I'm asking for help building a five speed gearbox, someone can help me with this project, I need drafts or pictures of the gearbox inside.
Thanks

[biketesting]

Hi I took one apart once and they are not too complicated. Just take it apart and have a look! Really!

BTW I just made mine a short ratio 4 speed and this works great. I am not sure what you would do with the other gear. Do you use it for the road, or track?

[DaveA]

How does the Panda 5 speed conversion work out ,

Does it fit in the chassis with stock 600 rear trailing arms ?

I would like something with an overdrive  5th for driving down the freeway and not having the  the engine scream (wear out)

it will be hooked up to a A112 motor with sidedraft DCOE weber

any photos of the conversion   or the gearbox installed on the web /

thanks for your help

[biketesting]

Someone in the TC/Radiale area has a really nice 5 spd conversion and excellent pictures. I noticed it was a short tranny style too. Just run a search on this site and you'll find it.

Sorry i don't think the Panda will work, the 600 swing arms leave almost no room. The best conversion I have seen is the Porsche 914 box with adapter made by PBS but I think this car I saw had a Ford Cortina motor. I wonder f you could use the Panda gear set inside the 600 Box?

[DaveA]

It would be nice to keep it in the Fiat Family ,
as those gearboxes were made for smaller tires than the 914 so the gear ratios would be better with the Fiat and 13 inch tires.

The 914 box has a weird shift pattern,
1st  and  reverse are  above each other, then 2nd-5th is in the regular "H" pattern,
great for high speed driving , but bad to drive on the street,


Anyway I will look for those  pics in the TC/Radiale area  , but I  really need to do it on the cheap with available parts that can be machined etc to work

thanks for your help

Dave

[Paul vander Heyden]

Hello Dave

I did a conversion of a Fiat 600 transaxle to a 5 speed and then a 6 speed using a Punto gearbox.  There are five important issues.

1.  Finding a way to maintain preload on the pinion bearing.
2. Mating the two items (Fiat 600 diff case and Punto transmission) by externally splining the 600 pinion shaft and internally splining the Punto shaft.
3. Relocating and pinning the Fiat bellhousing (punto shafts are about 1mm further apart than the 600)
4. Relocating one of the chassis rails to make room for the shift assembly.
5. Re-engineering the Punto shift lever assembly to work in the 600 chassis.  (otherwise the shift pattern comes out backwards/upside down)

I have done two of these now and I know of another European racer that has done one along the same lines as well.

The gear ratios are as follows - 1st- 3.909, 2nd - 2.157, 3rd - 1.480, 4th - 1.121, 5th - 0.903, 6th - 0.780  I run this with a 5.34 diff gear from the Fiat Multipla.  If you wanted a really short gearbox you could put in the early Multipla diff ratio (6.35).

I have also concluded that it is WAAAAY too much work for most people.  So, I have just done the design on a close ratio 4 speed gearset with synchros and straight cut gears.  I am having 20 sets made of these and they fit inside the standard gearbox.  Ratios are 1st 4.33, 2nd - 1.75, 3rd - 1.20, 4th - 1.00  I recommend running these with a 4.33 diff gear (9/39).

Hope this helps

Paul Vanderheijden
www.scuderiatopolino.com