transmision strength

[cyclecyko]

Was wondering at what horsepower level I should start worrying about the trans in a 124 ? From my experiance with aftermarket tranny's there is both a horsepower and an RPM limit.

[mdrburchette]

Some people say the tranny is a weak link in the drivetrain but I've never had a problem. Some of the SCCA guys are running 180 bhp engines mated with the original trannies and aren't witnessing any failures.

[Hjulenx]

In my engineering opinion I would say that the rubber guibos and the differential would be more cause for concern. A transmission from a Fiat 131 is a bolt in replacement and is more robust; except for the fact that the shifter comes out in the wrong location. This of course isn't a problem for a race car, but for a street car you would have to modify the interior trim significantly.

[mdrburchette]

James, some of these racers are running a guibo from a BMW if I'm not mistaken. They're supposed to be more "robust".

[msrmd]

What's a guibo?

[perthling]

guibo = donut

[rlux4]

guibo=donut=flex disc.
The hexagonal rubber connector between the drive line and the rear of the transmission.
Ron

[msrmd]

Thanks, I had always heard it called a flex donut.

[Hjulenx]

A more robust guibo would certianly help a lot. Guy Croft in his book says that the DOHC Transmissions for the most part are very robust, but then again he could have been refering mostly to the 131 trannys.

We need some of the race guys to chime in and see what they are using.

[manoa matt]

I've followed that thread on flex discs in the mirafiori forum, apparently the BMW disk is more robust however some versions do not have the "keyed in" metal flanges like the fiat disc. Its around $50 if you can find it in the 12mm bolt hole version. If you replace your Fiat flex disc every two years, like you are supposed to, then you shouldn't have a problem with it.

The rear diff is the weak link, considering the limited parts avilability vs the trans. Worn driveshaft universal joints and worn trailing arm bushings will put more strain on the differential components. Burn outs and squeeling the tires will also dramatically shorten its life.

[Curly]

A more robust guibo would certianly help a lot. Guy Croft in his book says that the DOHC Transmissions for the most part are very robust, but then again he could have been refering mostly to the 131 trannys.

We need some of the race guys to chime in and see what they are using.

It's increased torque that places extra loads on gearboxes. Over here most of our high performance 2-litre or turbo cars opt for the stronger 131 box. I fitted such a box to SPYDUH to be on the safe side with about 100bhp at the wheels and loads of torque. The AC coupe on the other hand with a 1600 develops about the same power but nowhere near the torque and it's had the same 124 box box behind it for a decade of tarmac rallying and other competition events. I change the oil regularly and always drop in a tube of Nulon gearbox additive as well. The shifter forks are prone to wear in the 124 box and that leads to them jumping out of gear, so train yourself not to rest your hand on the gearlever.
I've just fitted a finned alloy sump to my coupe's gearbox to increase the oil capacity and assist with cooling during extended competiton use. It will be interesting to see if it makes any difference.

[vwdmc16]

that is very nice where did you get an aluminum pan?

[Curly]

that is very nice where did you get an aluminum pan?

How's your German?
The GRÖßERE ALUMINIUM-GETRIEBEÖLWANNE MIT KÜHLRIPPEN is available from GB Motortechnik in Germany for 146,22 Euro. They don't correspond in English, but were great to deal with, being patient and good-humoured at my High-School German assisted (or more likely scrambled) by Babel Fish.
Stefhahn (FS.com forum member from Stuttgart) was also helpful in translating the fitting instructions for me.
Their website is at:
http://www.gb-motorentechnik.de/
Scroll down the left side of the page to "Getriebe" and then select "Getriebeolwannen" from the sub menu.

[stefhahn]

...if you need a helping hand (e.g. a german template for ordering) then pls let me know.
ciao,
Stefan