LSD for Fiat 124 CC Coupe

Non-engine, eg: aerodynamics, gearboxes, brakes, suspension
Steve H
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LSD for Fiat 124 CC Coupe

Post by Steve H » Mon Feb 18, 2013 8:13 pm

Hi Guy's

Can anyone tell me if a Lada LSD will fit into my Fiat 124 Coupe, if so what model/name and where would I source one from.

I have no knowledge in this area at all so any help would be appreciated.

Many thanks Steve.
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Guy Croft
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Re: LSD for Fiat 124 CC Coupe

Post by Guy Croft » Tue Feb 19, 2013 12:35 pm

If anyone can guide Steve on his - would they please?

There are a number of folk here who have expertise with LS units.

If you are one but do not know about the Fiat 124 Coupe CC series (1974 -) please just say so here,

thanks,

G
Guy Croft, owner

GaryR
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Re: LSD for Fiat 124 CC Coupe

Post by GaryR » Tue Feb 19, 2013 6:14 pm

Hello Steve.

I had a LSD for my 124 cc Coupe rear axle some 20 years ago now. I purchased it from Avanti Motorsport in Somerset. They are still going and have a website. Not sure if I'm allowed to post their website link here so won't, but it's easy enough to Google.

Unfortunately I can't remember anything about the make or any details of the unit, but I enjoyed having it.

All the best!

Kind regards.

Gary.
GaryR. Book #104/500

Guy Croft
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Re: LSD for Fiat 124 CC Coupe

Post by Guy Croft » Tue Feb 19, 2013 6:59 pm

Thanks Gary

Steve - look them up privately if you fancy,

G
Guy Croft, owner

Steve H
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Re: LSD for Fiat 124 CC Coupe

Post by Steve H » Tue Feb 19, 2013 7:58 pm

Will do, thanks Gary.

Am still interested in Lada LSD if anyone has any info.

Many thanks Steve.
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Urbancamo
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Re: LSD for Fiat 124 CC Coupe

Post by Urbancamo » Tue Feb 19, 2013 8:07 pm

What kind of info you need? I've worked with Lada LSD's for years, both Torsen and clutch-pack ones and I have first hand knowledge how they will perform in rally/motorsport use..

Ordinary Fiat 124 has pretty much same rear axle than Lada (except Fiat has disk brakes) and the rear 3rd is the same and fully interchangeable with Lada.

T
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Steve H
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Re: LSD for Fiat 124 CC Coupe

Post by Steve H » Tue Feb 19, 2013 10:22 pm

Hi,
GC has put the idea in my head that my 124 CC restoration would be better with a LSD bearing in mind it will have a stage 3 GC engine, but as I know absolutely nothing about LSD's I wouldn't know where to start, so any help information would be great.

Steve H
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Guy Croft
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Re: LSD for Fiat 124 CC Coupe

Post by Guy Croft » Tue Feb 19, 2013 10:50 pm

LSD - often referred to as 'limited slip differential' but actually an acronym for 'limited spin differential'

this link explains the benefit quite well:

http://www.drivingfast.net/technology/d ... SQBIlxFDIU

Someone who has a car fitted with one might care to explain the benefit 1st hand..

Steve's 124 CC Coupe new GC 2 liter engine - in my opinion - will deserve one of these if it can 'be got'...

G
Guy Croft, owner

badlyworntoy

Re: LSD for Fiat 124 CC Coupe

Post by badlyworntoy » Tue Feb 19, 2013 11:12 pm

My advice would be to take up this conversation with Tommi (Urbancamo) he's really good with anything Lada/Fiat/Diff related

Nix

Urbancamo
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Re: LSD for Fiat 124 CC Coupe

Post by Urbancamo » Wed Feb 20, 2013 4:05 pm

As this subject is often asked, I will gather small info package for these specific diff's I know like my own pockets.
There are two types of Lada diff's around today:

- Torsen ATB
- traditional clutch-pack LSD

I don't go to details how these work, internet is full of info and the link Guy posted contains good info too.

I reckon clutch pack one for competition and fast road use. It has to have at least 50 Nm or 5 kg's of preload. In rally use the preload is usually higher, like 8-10 kg's. Loosish LSD is hopeless. It won't work as supposed.
5-8 kg's is good amount for road use. It's stiff, but not too stiff, it still allows rear wheel to spin independently in tight turning situations in grippy surface like tarmac. If it's too tight, inner wheel will resist tight turnin really badly.

Torsen ATB is more suited to ordinary driving to give nice aid for standing starts in slippery conditions and more accuracy and drivabilty over stock open differential. It's really good for this purpose. I have driven over 30.000 km's with my russian made Torsen ATB and it's one of the best investments so far.
When there is no power applied to rear 3rd, it acts almost like an open differential. This is really good for ordinary driving, but in competition use it's a downside in RWD car.

Benefits of using any LSD:

- No more inside wheel spinning in hard cornering
- Driver has 100% control of his RWD car. Behaviour of car is always similar especially in slippery surfaces. No more russian roulette whether 1 or 2 wheels will spin without any logical sense.

Negative sides of LSD:

- There isnt any?


COMPETITION oriented (gravel, ice/snow, tarmac) tips for Fiat 124-based cars

- Lada has these gears available: 3.9, 4.1, 4.3, 4.44 (civilian gears) and 4.77 and 5.1 and 5.3 (for racing)
These are durable gears even they pretty small (crown wheel only 8")
I have never heard of chipped teeth when properly adjusted and driven with proper oil like Redline Heavy Shockproof or similar.
I know cars with over 200 bhp with a turbocharger and they hold up too.
There is no way any usual N/A engine will demolish these rear 3rds.

- I've never heard of broken Lada clutch-pack diffs. They are very durable and they have been in competition use many decades.

- Forget using bolts to secure rear 3rd. They have nasty habit of loosening in competition use. Fit proper M8 studs to banjo with Loctite and use nyloc nuts, Nord-Locks or again Loctite and tight them real good. That way your rear 3rd stays in place forever and you won't generate massive oil leak between the banjo and rear 3rd if the bolts cannot hold up.
No paper gaskets needed, just use gasket making sealant like Permatex Ultra Black or similar...
Trust me, this is the correct way to do this to avoid future problems.

- Fiat/Lada axles are pretty robust but they can bend in competition use, especially after hard jumps. The solution is simply reinforce the axle by adding RHS tubing under the axle with welding.

- Drive shafts are pretty robust too, but avoid a situation when car is in the air and lands with sticky tires and high rpms. Drive shaft can snap sometimes in this situation. If it snaps, you always get a drive shaft wich has no spline end anymore. it's inside the spider gear...

T
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Steve H
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Re: LSD for Fiat 124 CC Coupe

Post by Steve H » Wed Feb 20, 2013 6:46 pm

Hi Tommi
Many thanks for that information very informative, looks like a Torsen ATB would suit me best, where would I source one of these units?

Steve
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ace124
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Re: LSD for Fiat 124 CC Coupe

Post by ace124 » Wed Feb 20, 2013 7:43 pm

I too have done many miles with the torsen/ quaife type lsd in my coupe. The differential transforms the car and is maintenance free other than oil changes. Traction is definitely improved in a straight line and so is exit corner drive. It can catch you unaware if you power too early out of a corner on a slippery surface though, if you have never driven a car with an lsd before.
The only drawback with the torsen type over the clutch pack type is that the torsen type will not transmit drive if one wheel is off the ground like a clutch type will, hence the use of clutch type in race cars. The torsen is a better on road proposition though, especially if you do a lot of tight turning.
A tip on car setup if using the torsen on a 124, keep the back end soft. Dont use a rear sway / antiroll bar or it will lift the inside wheel, loose drive and defeat the purpose of the whole exercise.

Urbancamo
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Re: LSD for Fiat 124 CC Coupe

Post by Urbancamo » Thu Feb 21, 2013 7:42 pm

Don't be afraid to use proper clutch pack diffs in fast road use. I have done countless miles with various clutch LSD's in various conditions (tarmac, ice/snow, gravel) and I have nothing bad to say. They only improve RWD handling, not make it worse.
They will fit nicely both competition or fast road use. In the old days there was nothing but cluth LSD's and they were terribly expensive compared to todays prices!

If the diff has not excessive preload, you won't notice anything negative. Of course the car is more tail happy under throttle in slippery conditions, but if you are an experienced RWD driver it's only a plus.

T
Last edited by Urbancamo on Sun Mar 24, 2013 10:19 pm, edited 1 time in total.
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Rallyroller
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Re: LSD for Fiat 124 CC Coupe

Post by Rallyroller » Tue Feb 26, 2013 12:50 pm

Hi Steve

When I bought my original Rally Spider back in 83, ( 73 BS with live rear axle) it already had a clutch type LSD. It was a Borg Warner unit. After much searching , I discovered it was nolonger available and the rights had been sold to Italy. The unit was repaierd a few times, and eventually , when it was fitted to my Rally ST a lot of new parts had to be made and fitted. However- it was worth it. The difference an LSD makes is huge. OK , on loose stages it is a must, but even driving on the road, the difference going through tight bends or hairpins is noticable. As stated by others, it makes the car more consistant, and to be honest fun.

I have a Lada Sport diff to fit to the new car. I note with interest from Tommi that the pre load should be around 8kg for a competiton car. I tried my diff last night and noted only 3 kg. ( and I asked for it to be supplied stiffer for competiton use). I have had a look at it and suspect it is only a matter of spacers/disc spring mods to increase the preload. ( Tommi if you read this perhaps you could advise? ) If I mod it I can take a few pictures so you can see how it all goes together.

Nigel.
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Guy Croft
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Re: LSD for Fiat 124 CC Coupe

Post by Guy Croft » Tue Feb 26, 2013 2:22 pm

Tommi

MODEL POST!

The breadth of your techincal expertise on this subject is mighty impressive.

You are widely admired here.

Thank you for sharing your expert knowedge.

G
Guy Croft, owner

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