More info about limited slip differential

[PhillipM]

I was surprised to discover that.
Even group A cars like the ford fiesta wrc doesn't go faster than 170km/h
Yaris 240
What I've understood is that in those types of competition what's important is acceleration and how fast you can turn

It takes a shedload of power to drive a car on knobbly tyres in mud at 130kph. What a car runs at on the road on normal tyres isn't comparable. Those cars running 160-170kph are also 300-400-500bhp rally cars to do it.

A standard engine should take very little to cope with rallying, oil and cooling work is generally all, OEM engines go through insane durability trials.
What you need to put in to compete at the top end is very different from what you need to compete.

If you have 50-100k spare and a workshop and don't care about time, sure, build something bespoke with all singing engines and drivetrain. But if you're saying you're on such a budget you're trying to fit springs to the spider gears instead of just a plated LSD, you need to be just doing the basics and go from there. Getting carried away with it will just mean it never goes racing.

 

[Memmeddu]

It takes a shedload of power to drive a car on knobbly tyres in mud at 130kph. What a car runs at on the road on normal tyres isn't comparable. Those cars running 160-170kph are also 300-400-500bhp rally cars to do it.

A standard engine should take very little to cope with rallying, oil and cooling work is generally all, OEM engines go through insane durability trials.
What you need to put in to compete at the top end is very different from what you need to compete.

If you have 50-100k spare and a workshop and don't care about time, sure, build something bespoke with all singing engines and drivetrain. But if you're saying you're on such a budget you're trying to fit springs to the spider gears instead of just a plated LSD, you need to be just doing the basics and go from there. Getting carried away with it will just mean it never goes racing.

You're right about Time.
There are way easier ways to do what I want.
I can easily fit a F.I.R.E. engine on the original transmission (70HP instead of 20) .
It will require just few easy modifications
Or a bike engine connected to a differential via chain drive.
Use a torsen diff as suggested from an Alfa 147 which are pretty common to find and cheap .
Anyway more I get information ,more I can do something.
Now the biggest problems are with the rules.
Because the car has to be street legal .

 

[Memmeddu]

I've seen that those torsen diff are pretty cheap even new units doesn't cost as much as an LSD , and they work even better from what I've understood .

 

[Rkweld]

There are mixed reviews on them, I remember watching the youtube video on the principle of how it works years ago. I would probably try one but are other people doing what you want to do with it?

 

[minimutly]

They are a mixed bag tbh. I had a Quaife on 30 years ago on my 2l autograss racing FWD metro. I couldn't work out why it zigzagged around corners (loose dirt/mud surface). What happens is that the diff only locks if it has drive - when the inside wheel lifts it releases - like a normal diff, bit pointless really. So I'd be on quarter lock into the bend, drifting nicely, bit of a hop over a bump, inside wheel lifts, the outside wheel suddenly changes from power down, drifting to steering. Suddenly I'm changing line, so a correction outwards brings the inside wheel down, and were ready to do it all again. Still with me?
The fix was to left foot brake, so keeping both wheels loaded - no zigzagging no more, and I learned to left foot brake.
On smooth tarmac the torsen is fine....

 

[nickk]

Can you weld the sun and planetary gears,so it’s solid,or does it become impossible to steer?

 

[8ob]

Just to bore you sh1tless educate you, many moons ago Merc had an interesting form of TC, the bil had a twin turbo Brabus Merc ( about 600hp) and it started to tear the diff mounts off. Got it on the ramp to remove the diff and noticed there were a series of hydraulic pipes going to the diff output flanges, long story short the hydraulic pulses were mechanically sensed at a valve block and a driveshaft running faster than the other initiated a brake grab on the loose wheel until they were the same again. It was a truly amazing bit of kit off the line.

Bob

 

[minimutly]

Just to bore you sh1tless educate you, many moons ago Merc had an interesting form of TC, the bil had a twin turbo Brabus Merc ( about 600hp) and it started to tear the diff mounts off. Got it on the ramp to remove the diff and noticed there were a series of hydraulic pipes going to the diff output flanges, long story short the hydraulic pulses were mechanically sensed at a valve block and a driveshaft running faster than the other initiated a brake grab on the loose wheel until they were the same again. It was a truly amazing bit of kit off the line.

Bob

Honda CRV.....
Truly a masterpiece of design logic, 4 generations of it.

 

[Memmeddu]

I've got stuck once with my car wheel right was spinning .
I've used the brakes to get out

 

[Hopefuldave]

Honda CRV.....
Truly a masterpiece of design logic, 4 generations of it.

Standard on the full-fat 2.4 Accord, too, uses the ABS sensors and pump, dynamically brakes the inside wheels if you overcook it into bends, too - had to switch it all off when I was teaching my daughter to drive on a moss-covered runway, just to make it more "educational". No ABS defeat, unfortunately...

Dave H. (the other one)

 

[bricol]

Standard on the full-fat 2.4 Accord, too, uses the ABS sensors and pump, dynamically brakes the inside wheels if you overcook it into bends, too - had to switch it all off when I was teaching my daughter to drive on a moss-covered runway, just to make it more "educational". No ABS defeat, unfortunately...

Dave H. (the other one)

Pull the ABS fuse?

I wasn't aware of my Challenger having the ability to brake individual rear wheels to try to pull it back into line - I'd be happily applying opposite lock, there'd be a sudden noise of tyres shrieking, and I was now heading in the wrong direction.

Luckily it can be reduced and turned off completely

 

[Memmeddu]

There are mixed reviews on them, I remember watching the youtube video on the principle of how it works years ago. I would probably try one but are other people doing what you want to do with it?

Tbh yes
There are lots of 126's ,500's,A112, and other smaller Cars which are modified to mount motorcycle engine and their sequential transmissions to do hill climbing races .
Not many people have made AWD proto cars

 

[Turbo]

I should think there will be track days in Italy, build yourself a basic track car, do a few track days, see if you like it & go from there.

A standard car will be adequate for track days with a few basic mods.
Make sure the engine is fully serviced & running well, likewise the gearbox, brakes & suspension.
Decent tyres, I use second hand rally/race tyres.
Fit competition brake pads & dot 5.1 brake fluid, the brakes really get a hammering on track. Decent vented discs are a good idea.
A bucket seat to stop you sliding out of it on corners. Doesn't have to be a proper race seat.
A helmet.

That's it, apart from removing as much unnecessary weight from the car.

That's the way my sprint/track car started - a standard 205gti. Bit by bit I added modifications as & when I could afford it, with each one making the car more fun to drive.

 

[PhillipM]

I've seen that those torsen diff are pretty cheap even new units doesn't cost as much as an LSD , and they work even better from what I've understood .

They won't on a rally. You want a plate diff.

 

[northwest]

Try to do everything to start with and you'll be wondering where 20k and 3 years has gone.

As little as that?
I gave up rallying in the 90's as the panel damage was becoming too expensive. I can't believe what I sold all the kit for.

 

[PhillipM]

If you're making stuff yourself yes. And never add your labour.
If you're buying parts........5x that.

 

[northwest]

If you're making stuff yourself yes. And never add your labour.
If you're buying parts........5x that.

I think a few people on here would be shocked to find out what it costs to run a go-kart competitively in the Junior class.

 

[dobbslc]

I agree with that ^ It cost me all I had to race a TZR 250 for a year when I came back to racing! A high side, another massive crash and finally some monkey on a 400 ramming me from behind on the slowdown lap of practice at Brands finished me off!
It costs ££££££££££

 

[bricol]

All of which is why I do trialling these days