On the B/S page we were talking about taking 850's to high speeds 
and Lalo, I think, mentioned that he thought it was not wise 
unless you had an 850 SEDAN tansaxle.  

So what I'd like to find out is what's different about one of 
these and how much does it affect top end, and where can I find 
one?  Or can I have one built?  

And no, I don't really care to much about bottom end, at least 
not that one.

Gregory Smith, Lime Green '72 Fiat 850 Sport Spider
Fiat Enthusiasts Northwest, Seattle, Washington

Gregory Smith, Seattle, wrote:
:  ...850 SEDAN transaxle. So what I'd like to find 
out is what's different about one of these and how much does it 
affect top end, and where can I find one? Or can I have one 
built? And no, I don't really care to much about bottom end, at 
least not that one.

 Greg, the difference between the Sedan & the Spider/Coupe 
transaxles is the ring & pinion (ratio). The Sedan has a 4.63 
(8/37) unit, while the Spider/Coupe have a 4.88 (8/39) unit. Like 
Lalo, I also have a Sedan R&P installed in my car (69 Spider), 
because I wanted a little longer gearing than stock (I drive on 
the freeway a lot). This can increase top-end speed (depending on 
tire selection), or looking at it another way, it also lowers the 
RPMs needed to obtain a certain MPH (vs. the stock 4.88 unit). 
This helps ease the strain on the engine of prolonged, high-speed 
driving.

 Where to find one? Dunno. Try junkyards, parts cars, swap meets, 
want ads, Fiat parts dealers, Fiat Clubs (newsletters!), other 
Fiat/850 owners... hard part is, the only way to tell the 
difference is to remove the bellhousing & look for the "8/37" 
stamp on the ring gear.


Jeff Stich
Yorba Linda, Ca.
http://home.earthlink.net/~fiat850/

1969 Fiat 850 Spider (daily driver/beater)
1969 Fiat 850 Coupe  (Euro. specs & RHD)
1969 Fiat 850 Sedan  (my very first car!)
Rear Engine Fiat Club member

Jeff Stich wrote:
The Sedan has a 4.63 
: (8/37)unit
Do both sedans (850 (Normale ??) and the 850 Special) have the 
same final ratio ?
Olav Rypdal, Norway
'71 850 Sport Coupe (A112 Abarth powered)
'74 124 Sport Coupe (2x40 IDFs)
'73 130 Coupe
'83 125 Polski Pick up (132 TC power)

Good question, and the answer is no. In fact, only early sedans 
(which used 12" wheels) had the taller final drive. Later cars 
with 13" wheels, and the berlina "Special" used the 4.88 as on 
the spider and coupe models.

Matt Ruiz wrote:
:  ...only early sedans (which used 12" wheels) had the 
: taller final drive. Later cars with 13" wheels, and the berlina 
: "Special" used the 4.88 as on the spider and coupe models.

...but the "850 Special" Sedan had a 5.13 (8/41) r&p, not the 
4.88 (8/39). (Can you say "Autocross"? If you think first gear is 
near-useless with the 4.88 r&p, imagine the 5.13!! Zing!)

 Although the books/manuals list the 12"-wheeled Sedans (1964-8) 
as using the 4.63, my 1969 Sedan had the 13" wheels & the 4.63 
unit. Same thing with my 1970 & 1971 Sedans. I've never seen it 
noted as using the 4.88 in any of my books either, so I have 
always assumed ALL 850 Sedans ("Special" excluded) had the 4.63 
r&p in them. (I don't know WHAT the "Idroconvert" used??) Do you 
have a book that states otherwise? Just curious...


Jeff Stich
Yorba Linda, Ca.
http://home.earthlink.net/~fiat850/

1969 Fiat 850 Spider (daily driver/beater)
1969 Fiat 850 Coupe  (Euro. specs & RHD)
1969 Fiat 850 Sedan  (my very first car!)
Rear Engine Fiat Club member

Jeff Stich wrote:
:  Greg, the difference between the Sedan & the Spider/Coupe 
: transaxles is the ring & pinion (ratio). The Sedan has a 4.63 
: (8/37) unit, while the Spider/Coupe have a 4.88 (8/39) unit. 
:  Where to find one? Dunno. Try junkyards, parts cars, swap 
meets, 
: want ads, Fiat parts dealers, Fiat Clubs (newsletters!), other 
: Fiat/850 owners... 

I've got three of 'em.  AND a 4.11 r&p :P hehehehehe

: hard part is, the only way to tell the 
: difference is to remove the bellhousing & look for the "8/37" 
: stamp on the ring gear.

Uh, that's not entirely true.  The sedan gearboxes were marked 
at the factory with a green "Z" on the top of the bellhousing.

-Lalo
Vice-President, Fiat America
'74 X1/9       1500cc FI, 5-spd, PBS Big Valve Head,
               cam, etc...
'81 Brava      FI, 5-spd
'69 850 Coupe  "Big Block" sporting dual Dellortos,
               30/65 cam and Abarth exhaust...
'68 850 Coupe  Chassis donor
'67 850 Spider Waiting it's turn at having $$ and time
               thrown at it...

Thanks for everyone's information.  I've submitted this as a 
last-minute update/superceding to all previous xmas wish 
listings.  I've posted a "wanted", as well.  I'll keep my eyes 
open and ask y'all to do the same!

One last question.  Is it possible to change the part that's 
different only?  And therefore just convert mine to the 4.63
r&p?  
I just want to know if it's possible in case I find just the ring 
gear (?) .

Gregory Smith, Lime Green '72 Fiat 850 Sport Spider
Fiat Enthusiasts Northwest, Seattle, Washington

In fact, I have an original, unaltered car that states otherwise, 
as did Randy Bent until recently. 13" wheels, 4.88 rear ends, 
etc. 

There may have historically been some mixing and matching of 
components on Fiat's part, which could account for an occasional 
anomaly, but i have yet to see a later 850 sedan that had a 4.63 
ring and pinion fitted. If Greg (Schmidt) were here, I think he'd 
concur.

You may be right about the "Special" final drive, but I'll have 
to take your word for it since I've never seen one in anything 
but a picture.

Who knew it was all so complicated ;-)

You can have the ring and pinion (and speedo gear) changed 
without too much trouble, to either a sedan r&p or (if you want 
to and can find one) a Simca 1000 r&p (4.38). 

As someone else mentioned, there are several other ratios 
floating around as well, including Simca (4.11) and Abarth (4.11 
or 3.89), but they're only appropriate for something with a lot 
more grunt than a stock-ish 850.

Lalo wrote:
: Uh, that's not entirely true.  The sedan gearboxes were marked 
: at the factory with a green "Z" on the top of the bellhousing.

May be true, but all 5 of my Sedan bellhousings were NOT marked. 
I have seen different colors on others from Coupes & Spiders, 
though (red, yellow or orange).

Jeff Stich
Yorba Linda, Ca.
http://home.earthlink.net/~fiat850/

1969 Fiat 850 Spider (daily driver/beater)
1969 Fiat 850 Coupe  (Euro. specs & RHD)
1969 Fiat 850 Sedan  (my very first car!)
Rear Engine Fiat Club member

Matt Ruiz wrote:
: You can have the ring and pinion (and speedo gear) changed 
: without too much trouble, to either a sedan r&p or (if you want 
: to and can find one) a Simca 1000 r&p (4.38). 
: As someone else mentioned, there are several other ratios 
: floating around as well, including Simca (4.11) and Abarth 
(4.11 
: or 3.89), but they're only appropriate for something with a lot 
: more grunt than a stock-ish 850.
Jeff Stich
Yorba Linda, Ca.
http://home.earthlink.net/~fiat850/

1969 Fiat 850 Spider (daily driver/beater)
1969 Fiat 850 Coupe  (Euro. specs & RHD)
1969 Fiat 850 Sedan  (my very first car!)
Rear Engine Fiat Club member

Jeff Stich wrote:
: May be true, but all 5 of my Sedan bellhousings were NOT 
marked. 
: I have seen different colors on others from Coupes & Spiders, 
: though (red, yellow or orange).

Interesting, my transaxles and my friends other 3 ARE marked 
with a green 'Z'.  All other I've seen are also marked.  Hmmmm, 
the plot thickens...

-Lalo
Vice-President, Fiat America
'74 X1/9       1500cc FI, 5-spd, PBS Big Valve Head,
               cam, etc...
'81 Brava      FI, 5-spd
'69 850 Coupe  "Big Block" sporting dual Dellortos,
               30/65 cam and Abarth exhaust...
'68 850 Coupe  Chassis donor
'67 850 Spider Waiting it's turn at having $$ and time
               thrown at it...

Matt Ruiz wrote:
: You may be right about the "Special" final drive, but I'll have 
: to take your word for it since I've never seen one in anything 
: but a picture.

I'll try to scan the "Special" info from one of my factory books. 
Check your email. :o)

Jeff Stich
Yorba Linda, Ca.
http://home.earthlink.net/~fiat850/

1969 Fiat 850 Spider (daily driver/beater)
1969 Fiat 850 Coupe  (Euro. specs & RHD)
1969 Fiat 850 Sedan  (my very first car!)
Rear Engine Fiat Club member

Lalo wrote:
: Hmmmm, the plot thickens...

Perhaps we've come upon another 850 conundrum, like the strange 
mix/swapping of early/late trim items on the "cross-over year" 
1968 850 Spiders?

 I wouldn't put it past Fiat to do something similar with the 
Sedans (after all, look at the '69 Sedan front bumper & body- 
mounted turn signals?)... "Hey Luigi, we got these leftover 
"early" parts, what should we do with them?"... "Ah, just use 
'em. No-one will ever notice!". 

(Yeah, right) ;^)

Jeff Stich
Yorba Linda, Ca.
http://home.earthlink.net/~fiat850/

1969 Fiat 850 Spider (daily driver/beater)
1969 Fiat 850 Coupe  (Euro. specs & RHD)
1969 Fiat 850 Sedan  (my very first car!)
Rear Engine Fiat Club member

On the subject of changing the transaxle to get more favorable 
high speed performance, here's a snippet from something I posted 
in early 1999.  You may or may not find it useful.

---

Anyone have an opinion on using an alternate final drive ratio 
for an 850 Spider? 

Since tire size affects rpm (and performance, of course), I'm 
also intersted in hearing opinions on appropriate tire size. 

[snip]

My car is not currently on the road, so I must calculate my 
highway rpms. Using Bruce Bowling's RPM and MPH calculator 
(http://sura1.jlab.org/~grippo/auto.html) is very handy for 
this.  All you need is final drive ratio, ratio for top gear, 
and tire size. So:

(This table should look OK if your browser is set to a monospace 
font)

Final Drive Ratio   Tire size   RPM @65mph  Comments
.................   .........   ..........  ........
4.88                165/85-13   4556        Current setup
                    175/70-13   4718        Smaller tires
                    185/60-13   4913        Smallest tires
...........................................................
4.63                175/70-13   4476
                    185/60-13   4662

[snip]

Bob (rjl@sei.cmu.edu) | Pittsburgh, Pa. | '67 Fiat 850 Spider