131 transmission/rear end

[babu2001]

What is the max HP the 124 transmission can handle? Is there an upgrade kit to make it more robust? Like the syncro made from steel, not from brass. Where can we get a Fiat 131/132 transmission and rear axle in NA (transmission WITH the remote of course...)? I've checked eBay and CraigList without success. Don't like the idea to install RX7 read end or something similar if I'm not able to find what I need.

[vandor]

Rule of thumb is 150 HP, but really it's more about torque than HP, and of course driving style! Not aware of any upgraded parts being available. Synchros have nothing to do with how much power the engine makes anyways.
SPcoupe has ~160 Hp and the tranny seems fine, but he never floors it in first gear and is generally careful not to shock the drivetrain.

You have to hunt for a 131 gearbox, but sometimes they turn up. The remote shifter was never available in NA, so you have to look on foreign sites for that.

[So Cal Mark]

and the 131 rear end is drum brake with a higher ratio

[djape1977]

gearbox

124 transmission is very old colotti type gearbox designed way back when fiats had 50-60hp at most from their 1100ccm-1500ccm engines. 5th gear is just an afterthought, added way back at the end of gearbox. only model that came to US with this gearbox is 124, most of them spiders, but those were rarely used as only car. in europe, where 124 sedans made a bulk of 124s on the roads, and later fiat 125 sedans (4sp and 5sp), gearbox problems were well known issue. stronger the engine, shorter was a lifespan of gearbox. in twincam models, such as 124special and 125, as soon as odometer turned to zero, at 100k kms, gearbox would start making problems. you could prolong the life of a gearbox by carefull use but average user will encounter problems sooner rather than later.
in last model that used colotti type gearbox, 1972 and 1973 fiat 132 sedan, gearboxes lasted no more than 70.000km.

second series of 132 and first generation of 131 got a brand new gearbox designed by ZF of Germany, intended to be used with new generation of engines, 1800, 2000 and 2 and 2,5l diesels and turbodiesels with 2 or 3 times larger torque. these gearboxes also sometimes fail, but not below 300.000kms in a diesel and no less than 500.000km in a petrol powered cars. therefore, they're pretty much maintanance free. even position of output shaft places rear o-ring seal higher than on colotti type gearbox, so when it fails most of the oil can't leak out.
remote shifter on 131/132 gearbox was first introduced in 131 abarth and many of these shifters have ABARTH cast on top but don't be fooled in paying silly money for it. ALL remote shifters that came out of about half a million of 131 supermirafioris made has abarth cast on it! later, fiat argenta, a sucsessor of 132 also got the remote shifter. unlike ones from supermirafiori, these had no outside markings apart from part number but are otherwise exactly the same as "abarth" shifters.
also, unlike 124's gearbox remote shifter, 131/132 remote shifter is a bolt on modification for gearboxes that had ordinary shifter. only 4 bolts on top of gearbox to undo.
installing this gearbox into spider requires a bit of cutting, welding and hammer bashing around gearbox tunnel and driveshaft.


differential

again, same as for gearboxes, 124's diff was made when fiats typically had 50-60bhp. they usually outlast the car itself, having at least double the life expectancy of a gearbox, but in very old cars that aren't used everyday, usually the o-rings dry rot, leaving diff dry and than it all goes down south fast.
131 diff is in europe well known for "chocolate diff syndrome" (google it), meaning that insides were made of brown stuff. it seems to have been transitional solution untill real thing came into being in 1975 when new rear axle was introduced in fiat 132 and later used in fiat argenta. these are bulletproof! only time when these fail is when cars that weren't used for more than 20 years are put back into service and o-rings are dry rotted, but even than it takes several tens of thousands of kilometers to kill it.
as i've said in other topic you've started, both these diffs require cutting and welding on upper trailing mounts on a rear axle to install into 124spider.


do you really need these mods?

probably not.
if you can find someone to do a proper job rebuilding your gearbox and rear axle, even highly tuned 2 liter angine won't be able to destroy them in less than 20k kms or so. big question is how many miles do you make in your spider per year? if it will take you 10 years to make 20kms, than 124 transmission will do just fine.

[fiat218]

Got to ask!
How do u know all this! I'm asking in a good way

[djape1977]

and the 131 rear end is drum brake with a higher ratio

this is easy to solve, since most RWD fiats use same halfshaft bearings, anchor plates are interchangable, or to be more precise, bolt holes are equaly spaced. therefore, you can use 124 rear anchor plate with 124 discs and calipers on a 131 and 132 rear end.

Got to ask!
How do u know all this! I'm asking in a good way

because i live in europe and i currently own
124BC
125
131
132 x3
850sport
ritmo (strada) x2
lada 2103
and i've had couple more 125s, 131, 132 and argentas over the years, and i'm working on a restoration project 1970 124 spider for a customer. my fiddling with old fiats started as necessity, turned into hoby and in past 3-4 years it turned into a business

pic of my workshop these days


and in front...
http://img585.imageshack.us/img585/9675/photo0358oh.jpg
http://imageshack.us/photo/my-images/21/photo0357t.jpg/

[babu2001]

Wow! Thanks A LOT for all this information. Will be really helpful. My target in HP is anything between 150 to 175 but more on the 175 side. And I do about 5 to 10 000 KM per year with my summer car (which is now my Spider). I want it to accelerate fast, don't really care about speed. As long as I can go to 130 KM/H, that's enough for me. So torque I need and torque will kill my transmission... BTW, how it will breakdown? Will it worn faster or a shaft will give up? Both I presume... If somebody have or know where I may find these parts, PM please. Gonna be costly getting them from Europe or Australia.

PS Thanks again!

[djape1977]

front gearbox bearing and synchros will be first to go. more agressive driving style, faster it will happen. second and third gear will suffer most because of hard acceleration and quick shifting between gears.

buy a 131 5sp gearbox in US, you should be able to source one.
buy a remote shifter from europe, it's only 1.5 kilos or so.
now i don't know what type of rear end you got in spiders in US, the later models definately had 131 or 132 rear end. if it was 132 rear axle than that's the way to go. if it's the 131 rear end, i'd pass and go for 132 diff from europe and gulp down transport costs for 50 kilos of iron.
look for 4.1/1 ratio, 132 1600 and 1800 will have that, along with rear discs.
get a propshaft too. you'll need a front section off a 131 or 132 since 131/132 gearbox is longer than 124.
i guess you'd be using 2 liter engine, but i'd go for 1756cc ( 1.8 ) because of shorter stroke.
use 225mm clutch (2L spiders should have it) and a clutch plate for fiat argenta turbodiesel or fiat croma turbodiesel. 8springs instead of 4 and heavy duty construction.

expect to pay, at least in europe:
gearbox - around 250$. with or without remote shifter, depending on luck
remote shifter - 50-100$
propshaft - 50$
rear axle - 100-200$

greasy gearbox or rear axle is a sure sign of oil leaks and those are to be avoided. nice looking, cleaned, polished, painted parts are a bit iffy, unless they come from reputable seller. they could have been leaking and just got a salesman's spit and polish treatment.

if you do all of this, your drivetrain will be pretty much bulletproof. depending on width and compound of tyres you will use in the back, you'll either eat'em up in no time, or rubber donut will fail ocassionally.
also, rear upper trailing arms bushings will suffer and need to be changed about every 20k kms or so. i've had polyurethane bushings installed there on my car and it ended up causing damage to the chasis, so there's a lesson to learn. just replace them once in two years.

[greenspider81]

Hey Babu2001,,,I got your message about the alternator conversion. I found it online and made the change on mine about 2 years ago. I got the Ford Temp 90Amp alternator on Ebay and took it down to a local alternator repair shop. They quickly put a pulley on it for $5 bucks,,they had a lot of pulleys that would fit.. The one thing that I had to do was drill out the large bolt hole on the alternator. It fits a little tight but works really good. I had already upgrade the lights (added relays) and the size of the battery cable,,As for the electrical plug,,,it came with the alternator...you can also find the wiring online...I don't remember the problem but whatever it was,,,was easy to fix. Let me know if ya need anything. There are some good pics online and maybe even in this Forum....

[vandor]

>i don't know what type of rear end you got in spiders in US

After 1978 they all looked alike externally (cover on the rear), but over the years they changed the thickness of the gears inside (even tho the ratio stayed 3.90:1 for the 5 speed Spiders). 1978-80 was one size, 80-82ish was another, and the last years was the strongest one. The last one used axle shafts with larger diameter (26mm) splines, I assume this is from the 132/Argenta rear end.

[djape1977]

i guess than that spiders have gone tru all three types of diffs. makes sense that last series got the 132/argenta diff because argenta remained in production after all other models were discontinued, so production of other types of rear ends was phased out. 124 was never a big part of fiat's sales (globally) so they stuck on what they had at hand.
i'll measure diameter of splines to see if that's the case, i have a couple of these diffs around my workshop

[TX82FIAT]

I'm not sure how well it works but Vicks is selling a Lada transmission that is supposed to have a number of components strengthened to withstand Russian roads that is still produced today. This is said to be the transmission that is used in the Niva SUV. Saw the Niva on Top gear and looked pretty durable? I can only imagine the 5th gear would be more like modern day gear ratios saving some fuel on the highway. Again, this is supposed to fit into the 124 with a slightly shorter throw on the shifter.

Anyne have any actual use knowledge on this transmission?

[djape1977]

lada transmission is .... how shall i put it... mostly made of brown stuff.
ladas are far more common in my neck of the woods than fiats so i dare say that i do know quite a bit about them.

first and foremost, anything made in USSR, up to about 1985 is very good quality. after that, newer the date of production, worse is the quality. checked that myself for about 500 times so far.

there's a little tale in that claim:
i've had an opportunity to talk to several russians who worked in lada factory over the years. when asked about the quality diference between soviet and post soviet era, they all told me same story
when a worker was caught slacking on the job, drinking alcohol during lunch break, being late for work often etc, he would be re-assigned to a lada service somewhere beyond Ural mountains, to the far north near finnish border or way down south to one of middle-eastern republics, to one of places god said goodnight a long time ago. new appartment was provided, job for the wife, school for the kids, everything needed but in a place where camels or polar bears would be the only possible pets.


gearbox:

lada gearboxes are colotti type gearboxes, same as fiat 124/125 gearboxes. many parts are interchangable with fiat but not all.

4 speed is exactly the same as on fiat 124 sedan and early 131. i guess early 124 spider is the same. almost indestructable. usually lasts 2-3 hundred thousand miles, as long as the car itself. if you happen to change oil fine, if not, no problem.

5 speed gearbox is still made, but since production started after 1985 or 86, quality is pretty much disasterous. i rebuild about 15 of these each year and sell 15-20 used or rebuilt units. first thing to fail are o-rings, than oil leaks out, next to go is front bearing closely followed by 5th gear. usual lifespan in a sedan is about 100k miles, while in Lada Niva (4x4) it usually lasts around 60k miles.
5 speed used for sedan and for 4x4 is exactly the same and it has not been reinforced or strenghtened in any meaningfull way.
lada 5sp is a russian design based on fiat gearbox. 5th gear assembly is different to fiat 124/125 and is not interchangable.
fifth gear ratio is the same as on fiat though - 0.82
lada 5sp shifter is a marvel of ingeneering, great piece of work, perfectly smooth gear change, comparable to best gearboxes out there.

using lada 5sp gearbox in a spider would put shifter exactly where your radio is now, and remote shifter from fiat can't be installed on ladas gearbox without serious machining. simply said - no go.

all this said, when selling rebuilt units, i always change the bearings and o-rings with quality parts, regardless if they're ok or not. instead of recomended 1.2liters of oil always use 1.8 and regularly check for leaks.


differential

rear axle is simmilar to fiat early fiat 124 spider, apart from shock absorbers mounting points which are placed outside the springs, like on 124 familiare.
BIG drum brakes instead of discs.
halfshaft bearings are bigger than on 124, meaning thex can take a bit more abuse.

diff is the same as on 124. parts are interchangable. several diferent ratios are available, ranging from 3.9/1 to 4.44/1 stock and 3.7/1 to 5.3/1 in aftermarket versions.
LSD of all three main types are available as aftermarket option. torsen included.

unlike gearboxes, diferentials are decent quality regardless of date of production. pretty much the same if not a bit better than fiat's

[vandor]

> This is said to be the transmission that is used in the Niva SUV.

If you read up on the Niva you will see that it's transmission is considered a weak point. They had the same tranny as the Lada sedans.

[djape1977]

to be honest, if people were following factory recomended service procedures and intervals, most of lada and fiat transmissions would last indefinately. from my experience, most transmissions that end up at my shop get their first oil change EVER when i rebuild them.