Reinforce /make stronger a car gearbox

[Memmeddu]

Hi everyone , hope you are all doing well.
As the title what would you do?
I'd go custom building intake and takeoff shafts to fit stronger gears that's the most intelligent things my brain developed
Any idea?

The problems with this type of gearbox are
Not enough strong (it would see almost 6 times the amount of power it's born for)
First gear is not synchronized
Just 4 gears .
Unfortunately it's almost impossible to fit anything else .
If there's not a way to change the output axis on a "normal" FW gearbox
More I try to just imagine this project more problems I find.

 

[tom2207]

look for a stronger box to start with , then work out how to fit the two together , making a box stronger unless it has one well known weak spot is a very costly and complex thing to try.

 

[Popcorn]

You could always get yourself a Hewland Box, bit expensive though

 

[Memmeddu]

look for a stronger box to start with , then work out how to fit the two together , making a box stronger unless it has one well known weak spot is a very costly and complex thing to try.

The main problem is the car itself, want to use the specific model
Unfortunately FIA doesn't allow me to cut half car to fit the engine how I would .
So I have to use the original gearbox .
I've heard about some sort of compatibility between Skoda rapid and fiat 126 gearboxes but they look completely different and I can't even imagine how they would be compatible

 

[8ob]

Hi everyone , hope you are all doing well.
As the title what would you do?
I'd go custom building intake and takeoff shafts to fit stronger gears that's the most intelligent things my brain developed
Any idea?
View attachment 388728

The problems with this type of gearbox are
Not enough strong (it would see almost 6 times the amount of power it's born for)
First gear is not synchronized
Just 4 gears .
Unfortunately it's almost impossible to fit anything else .
If there's not a way to change the output axis on a "normal" FW gearbox
More I try to just imagine this project more problems I find.

Fit a vw/audi five or six speed transaxle ?

 

[Wildatlanticwelder]

Or subaru impreza 2wd , there are crown wheel and pinon kits available for these so can be used facing the wrong way in air cooled vw to scooby engine conversions

 

[Barking Mat]

What car ? Would help.

If the gearbox isn't strong enough, you need to adapt a bigger stronger gearbox.

More to the point what engine, and what horse power ?

 

[tom2207]

The main problem is the car itself, want to use the specific model
Unfortunately FIA doesn't allow me to cut half car to fit the engine how I would .
So I have to use the original gearbox .
I've heard about some sort of compatibility between Skoda rapid and fiat 126 gearboxes but they look completely different and I can't even imagine how they would be compatible

If a rapids doing 100 horse ,, and you reckon your getting five times that
say 400 hp , allowing for even the wildest pub chat horses ,, even 350
Im not seeing a 26hp fiat 126 box lasting as long as it took to screw it in.

 

[Wildatlanticwelder]

Aircooled vw's and all the porsche 911s and similar layout porsches use a box that suits your needs if you can jam it in there!

 

[Memmeddu]

What car ? Would help.

If the gearbox isn't strong enough, you need to adapt a bigger stronger gearbox.

More to the point what engine, and what horse power ?

FIAT 126
FIAT 1.2 8V Fire turbocharged
10 psi boost
1.5mm decompression plate
Standalone ECU
Around 130 ish BHP
If not found a 1.4 T-Jet which is always around 150 BHP

 

[Memmeddu]

If a rapids doing 100 horse ,, and you reckon your getting five times that
say 400 hp , allowing for even the wildest pub chat horses ,, even 350
Im not seeing a 26hp fiat 126 box lasting as long as it took to screw it in.

Original 126 gb doesn't even last with the original stock engine

 

[Barking Mat]

Means nothing to me, but if you want I can ask the racing company next to me, but I don't think they'll have any experience with those engines.

 

[Barking Mat]

Is it a standard sized gearbox fitting ?

 

[minimutly]

The gearbox you posted is not a transverse engine gearbox - did the 126 engine sit in front of the gearbox? Or behind it like the Renault 4?
If so the VW box would be ideal, even an aircooled one might last with the engine your proposing. For gearbox side by side any suitable box would do surely?
The point about gearboxes is, the shaft sizes and seperation distance will dictate the gear sizes and strengths, then the casing will. Most would struggle with 3 times original torque I would suggest.
Edit: googled it. Air cooled vw box would do it?

 

[Memmeddu]

The gearbox you posted is not a transverse engine gearbox - did the 126 engine sit in front of the gearbox? Or behind it like the Renault 4?
If so the VW box would be ideal, even an aircooled one might last with the engine your proposing. For gearbox side by side any suitable box would do surely?
The point about gearboxes is, the shaft sizes and seperation distance will dictate the gear sizes and strengths, then the casing will. Most would struggle with 3 times original torque I would suggest.
Edit: googled it. Air cooled vw box would do it?

Too big for the car .
If I want to fit it I'd have to cut the frame which translates in cutting for cutting I put an entire front end in the rear of the car

 

[minimutly]

Too big for the car .
If I want to fit it I'd have to cut the frame which translates in cutting for cutting I put an entire front end in the rear of the car

The reliant van gearbox was shorter was it not? What's the smallest modern audi box, the one the driveshaft goes throgh the bellhousing, surely that fits?

 

[CompoSimmonite]

What did Abarth do to the original 500 gearbox ?

 

[hotponyshoes]

I'd just get a stronger box, make it fit.

If you can't do that.. What's the weakness with the original boxes?
Often cars have common problems caused by poor design/function/manufacturing techniques and those are well known about and solvable.

Upgraded bearings might make an 85hp box handle 100hp. Improved lubrication might make it last twice as long at 85hp etc etc..

The problem ones are the ones that have been very well designed, well made and very reliable at 85hp. If everything about it has been carefully chosen to suit 85hp then you are going to have to replace/redesign every component for 100hp.
Obviously an issue if the rules say you can't replace the original housing with one machined from billet and good for 500hp.

If you are allowed to make changes (or internal changes won't be discovered ) iv seen plates put inside housings to hold bigger bearings, welds/chemical around existing housings prone to crack, gears reamed out for larger shafts, gears removed and replaced with bearing plates, grooves cut into the housings for cooling and so on..
Problem is the first upgrade just pushes the issue onto the next weak spot so you tend to spend endless weekends pulling the box back out of the car....

As they say, it's easy to make power, hard to contain it. I don't know what you are racing in but one strategy might be to go for reliability, finish every race and try to win the championship on points!

 

[8ob]

Aside of the strength of the original box there will be compatibility issues,no way in the world would the original gear or diff ratio`s suit or compliment the tuned up engine.

Bob

 

[Memmeddu]

So I've taken in consideration an option .
Custom build one.
To adapt the original gearbox to the engine I'd have to laser cut an adapter plate ,then skimmed to make it perfectly flat and parallel.
Because of the bell housing which requires mods too ,cut parts etc.
Being this project a rally car,it will be always under load,stresses etc
My idea is to build the new housing out of steel ,yes more weight but an initial disadvantage can be considered a bigger advantage.
It's placed right in the center line of the car longitudinally , and at floor level.
This would surely increase weight but , it will make an huge difference in matter of weight distribution and center of gravity of the car itself
Mid rear so it will be less prone to roll over in my head.

This part in the middle is what contain the differential
I believe it would be possible to make it ,line bore for the shaft put .
And drive the diff using the output shaft from a FCA group modern 5 speed transmission (obviously modifying it) .
Also the diff from the same transmission so modern axles can be used "solving" several problems
I should take a modern gearbox, a 126 gearbox dismantle both study both and make it fit "together"
Unfortunately rules Don't allow me to cut the original car frame otherwise engine and gearbox would sit in the car as in a normal FWD car but moved to the rear which would be ideal.
This idea involves custom built input output shafts, gear housing, and modern stronger gear train from OEM.
It's hard to understand I guess but it works in my head