Torque with LSD in X1/9 5 speed

LSD for X1/9 1500 5 speed. Just for interest I will update my post from a few weeks ago. Despite my best efforts I still haven't found the maker of my Torsen type helical gear lsd.
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But I did find 2 manufacturers of this type for our 5 speeds.

RSX Racing Solutions in Spain, their post re X1/9, Strada T105, Uno Turbo mk1 C506/C507 type gearbox LSD; Yes, we still make the Torsen LSD for Fiat Uno Turbo MK1 and it costs 595€ + transport.

https://rsxracingsolutions.com/…/210600220-autoblocante-fia… and the photos.

Also one sold by Classicperformance, made by IngranaggiPrina.it , but it is more expensive at 1500 E, they also sell the Bacci Romano plate type, shown on their web site, at the same price.
https://classicperformance-parts.com/…/fiat-x1-9-5-speed-g…/
http://www.ingranaggiprina.it/differenziali_autobloccanti.p… I sent them a photo of mine but theirs is different.
Gripper LSDs in the UK can also make a plate type one if you ask them.
So I am in the process of fitting mine in to my track X 5 speed with Strada/Regata 100S close ratio gear set and will see how it performs. I guess I will never find out who or where it was made.
 
My mystery helical gear torque biasing lsd is in the car and I have finally had a chance to drive it, only 100km on the road for brake pad bedding etc, no track use yet.
As expected, you don't even notice this type of lsd in normal driving, but it does launch quickly with both wheels spinning on a loose surface. I drained the synthetic 75W85 gear oil after 100km and there is quite a bit of very fine metallic particles in the pan, I have fitted all new bearings, but original gears, except the lsd. Now filled with Redline MTL.
One interesting aspect is that these ATB helical torsen type lsd's don't put any power to the ground if one wheel is in the air, from everything I have read. I was curious about this as I had noticed if you hold one axle still, it takes about 20 ft lbs to turn the other axle. (Edit, after 2 years of use the torque to rotate 1 axle has reduced to 12 ft lbs). After I fitted it, with both back wheels off the ground and turning with the car idling in first gear I put my boot firmly against a tyre and I couldn't stop it turning. I also tested it with one wheel on the ground and the other in the air so it could spin freely, with that sides suspension on blocks with my greased alignment plates between them. Started the engine and eased the clutch out with a few revs and there was enough torque transmitted thru that one wheel to drag the car off the blocks. Admittedly it wouldn't take a lot to move the car off the greased plates, but still some torque was transmitted. I repeated that test without the greased plates and it wouldn't drive off the blocks.
Not having any experience with these lsd's I don't know if this would be normal, or have I got one with some kind of friction plates between the two side gears? There is a Torsen T-2R Racemaster like this for Mustangs, and a Wavetrac lsd with clutch plates, but I'm pretty sure I don't have either of those.
Anyone here with experience with ATB type diffs?
As a reminder, here's a pic of my diff.
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Greg, the ATB diff function is "torque biasing". So what you are not able to test, in that manner, is the torque flow through the diff. There is a significant difference in function when you apply torque across the axle (hole one wheel and turn the other) and direct torque through the ring gear to the diff.

The ATB will direct torque away from a wheel with less traction but it does require some load on each wheel for the action to work as designed. (The clutches in the Wavetrac are there to prevent the torque biasing function from opening up were one wheel in the air. ) Its important to note that the diff is designed to work with torque applied through the normal path; that is applied to the ring gear (or diff housing) and not across the axle. The difference in torque path changes the diff's function. Thus I wouldn't put any relevance on the tests you performed other than driving.

To properly test the diff's function put one rear tire on tarmac and one on gravel, dirt or grass. Then perform the hard launch. The car should accelerate at near normal rates, although you might have to physically steer the car back toward the tarmac as the torque applied to the wheel with traction will attempt to steer the car away from it.
 
Are the "ATB" type diffs usually available in different percentages of torque biasing? Or can the bias percentage somehow be changed inside one?
 
Two good reads on diffs:

ATB:

We use a open diff on the LeMons racer. On that 1700 pound car with 200+ Bhp, wheel spin on corner exit never a problem.
This is due to the way this chassis is set up, but this chassis set up not gonna work for a road-street car. No Stability bars
(aka sway bars) on the LeMons racer. Roll stiffness is set up by spring rate.

~"A number of years ago, famed race car designer David Bruns explained to this writer that “springs put the power down, anti roll bars tend to lift the inside wheel.” Therefore if wheel spin is a problem with low powered cars, increase rear spring rate, and reduce swaybar stiffness at the rear."


Bernice
 
Thanks for all the feedback.
I didn't realise that the regular Quaife lsd has a belleville preload pack in it, I don't know if all ATB lsd's have that. Steve, that preload friction would explain why my test with one wheel in the air, the other wheel still transmitted enough torque to drive the car forward. So not quite like an open diff with one wheel lifted then.
Not that I have a problem with wheel spin, I don't, my interest in having a lsd is really just the extra strength over the standard X1/9 5 speed open diff. I did think it may have some handling advantages, like in trail braking into a corner, but apparently the ATB ones don't work under decelerating. The diff came as a bonus in a spare gearbox I bought.
It will be interesting to see what difference it makes, if any, when I get on the track in 4 weeks time.
 
I'll be curious to learn how this diff works out for you. In the Miata world, LSD (Torsen-ATB) diff are sought after even after the spec-Miata folks who have driven both open diff and ATB states the lap time advantage is iffy if much at all.

Bernice
 
I have finally got to drive my X on a track with the Torsen-ATB type lsd. To be honest I can't say it made much difference in the driving, it can be balanced on the throttle quite easily by lifting slightly to correct any understeer. No wheel spin, but it's not a track that I got wheel spin on anyway. Unfortunately the track layout has been changed slightly by placing bollards to tighten corner entry for one corner, so I can't compare lap times accurately to previous times. And I have added the boot lid spoiler since then also, but I would guess the times are within a tenth or two. I was a bit concerned that this type of lsd might increase any power on understeer but it is fine, and trail braking into corners was good too. I really need to try it on a tighter track or hill climb.
I also checked the gearbox temp with Redline MTL in it and it's only getting to 60 deg C on a 23 deg C day.
Here is a lap of incar on youtube
 

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Greg, nice lap. Car looks like fun.

I should note that an ATB diff shouldn't cause throttle understeer. A clutch type can.

What track is that?
 
Steve, Greg‘s car is right hand drive...

But there was another red one, with a K-Series swap I think?
Wasn‘t that one built from the yellow one built by Steve and Maureen Soar, painted by Mike Middlestead?
That one went to AUS and was made even faster there.
I forgot the details and who owns it.
 
Sounds like you are talking about the X in these picks imported here about 5 years ago, Honda engine, LH drive. Russell supercharged it and fitted a sequential box, hasn't been seen for a couple of years after experiencing some major mechanical problem. It was very quick.
X1-9 Russells.jpg
 

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Nope, not the same car.

I remember the Soar's car. I actually drove it at a National Tour in Bremmerton, Washington.

The car I was thinking of I helped build about 20 years ago. It was raced as a Prod Car in with SCCA in the South East Division for a few years. Then the owner decided he wanted a Formula Ford and sold it to a buyer in Australia. I corresponded with the buyer a few times. He did a great deal of additional work on the car, including a complete driveline swap. I forget what the swap was now.

That was about the time I changed careers (to Pro Racing) and lost track of the car. I have tried to find it a few times but no one seems to know what became of it. As often happens to old racecars, they disappear never to be heard from again. Perhaps it will turn up on ebay when somebody cleans out an old garage somewhere.
 
Steve Hoelscher said:
Nope, not the same car.

I remember the Soar's car. I actually drove it at a National Tour in Bremmerton, Washington.

The car I was thinking of I helped build about 20 years ago. It was raced as a Prod Car in with SCCA in the South East Division for a few years. Then the owner decided he wanted a Formula Ford and sold it to a buyer in Australia. I corresponded with the buyer a few times. He did a great deal of additional work on the car, including a complete driveline swap. I forget what the swap was now.

That was about the time I changed careers (to Pro Racing) and lost track of the car. I have tried to find it a few times but no one seems to know what became of it. As often happens to old racecars, they disappear never to be heard from again. Perhaps it will turn up on ebay when somebody cleans out an old garage somewhere.
Click to expand...

was the owner of the car you're thinking of in the USA a guy called Dave Boling? (it was light blue)

If it was, then that's the car I gave my friend Gordon a hand to re build / engine swap with a turbocharged 2 litre lancia engine / trans.

SteveC
 
fiatfactory said:
was the owner of the car you're thinking of in the USA a guy called Dave Boling? (it was light blue)

If it was, then that's the car I gave my friend Gordon a hand to re build / engine swap with a turbocharged 2 litre lancia engine / trans.

SteveC
Click to expand...

Well, I didn't see this at the time but glad I finally did.

Yes, David was the owner of that car. It was one of the first SCCA Production racers I had much involvement with. Didn't know much then as I was still learning.
 
This is what the car ended up looking like, Gordon has sold it on again now, he's retired from racing (he's about 70) ...he's building a montecarlo grp 5 bodied (turbo) kit on it and still likes his Fiat / Lancia cars tho.

gordons x19 a.jpg

SteveC
 
Here is a video of a couple of runs up my local hillclimb at Collingrove last weekend , it's quite short and technical. I was getting some front wheel lockup on 2 tight corners, and the tight RH corner the front was pushing wide and engine bogging down a bit, revs in 2nd gear not high enough, (my 1st gear is very low). Last time here was 6 years ago with no LSD, and I was getting the inside wheel spinning, and that meant it wasn't bogging down. Run times are no faster, but still good fun.
 
I love narrow tracks. Makes it feel like you are going much faster than on a wide track. 😀
So how does the car feel better? With or without LSD?
 
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