5 Spd Lsd possible option

Maxmod

Maxmod

Lachlan (aus)
Hey Guys,

I thought I would post this up and maybe someone else can follow it through

I have a Punto GT gearbox and an x19 5 speed on my bench stripped at the moment.

The punto GT gearbox is a C510 which uses the QDH2K-10 Quaife LSD unit. https://shop.quaife.co.uk/alfa-romeo-145-quaife-atb-helical-lsd-differential-2176

I was looking at the Diffs and taking some measurements they are nearly identical even down to the outside diameter of the speedo spline whether or not that's the same ratio I don't know. The diff spins around in the x19 casing without an issue. The inside diameter on the x19 speedo gear is smaller than the Punto GT so if the ratios aren't the same you could remove both have the x19 one machined to the right side and fit it to the Punto Gt diff.
039.JPG

036.JPG

X19 Left Punto GT right

The overall height bearing to bearing is identical, they use the same bearings, the x19 input shafts fit and lock into the Diff.
037.JPG


038.JPG

There are two major differences
1 the bolt pattern is different the x19 has two less bolts
2 the crown wheel internal diameter on the x19 crown wheel is a lot larger. This means you can't just redrill the 19 crown wheel and run it if only it was that simple.

Now there is a 4.07 final drive C510 gearbox well apparently there is anyway you would need to find one and count the teeth on it. It's possible that it could mesh up with the x19 4.07 5 spd pinion and your off and running. I doubt this will work but you never know the gears for the punto gt are a 57/17 I happen to have a 17 tooth x19 shaft it is 4mm smaller in diameter than the x19 17 tooth.
IMG_0565.JPG




It's probably easier for someone to organise with someone like Bacci to get a set of x19 crown wheels made with the smaller internal diameter of the Quaife diff and the right bolt pattern. That guarantees the correct fitment.

IMG_0566.JPG


Punto GT diff sitting in with the punto GT cluster in the x19 casing. Now the cluster won't swap over it's far too different before anyone asks that.


Here's a real quick video of the diff spinning in the x19 casing with the Punto Gt cluster again.

Now don't take this as the gospel it may not work but it does look damn close to me. Certainly close enough for someone to possibly take it a step further. I haven't done this because I intend on taking it further it's just information for someone who may. I'm converting to run the Punto GT box which has newer synchro designs, top shift cable etc.

If anyone is keen on taking it further and would like some more measurements let me know I probably won't have the x19 casing apart for too long so get it quick.

Hopefully this helps someone.
 

Attachments

  • 039.JPG
    039.JPG
    303.8 KB · Views: 248
Wow, I would not thought that it would mesh as well as that. The "problem" with automotive gears is that no one uses standard modules or tooth profiles. Sure, standard gear profiles exist but they are mostly so people building low volumes of things don't need to be gear engineers or pay to have tooling made to their designs. Car companies and suppliers DO have gear engineers and are going to make tens of thousands of the same parts so they can design whatever they want to optomize the performance. It isn't like thread sizes where everyone pretty much has agreed that the standard sizes will do. For reference, I work in the feild and our cylindrical gear drawings take two-sheets and reference multipage documents to fully describe them. So two parts appearing to fit together may be misleading. If there was even one of the dozens of parameters off a little bit (gear-world tolerances are microns and micro radians), the experiment of swapping parts would be noisy and short lived. Now, as this is the same company making a gear for the same application, they MAY have decided to carry on with the identical tooth geometry. I mean, it's possible. So if the shaft distances were identical and the tooth counts identical and the helix angles identical....who knows? You could paint the teeth of the ring and pinion gears with grease paint (gear marking compound), button-up the unit and turn the input in both directions with some drag on the outputs and see what the contact pattern looks like to get an idea of how well they really mesh. I'd argue that some of the patterns shown below as acceptable aren't (you don't want the pattern running off of the tooth for example) but you get the idea.

1299_1L.jpg
 
Hey,

That meshing is actually because it's the punto gt diff and the correct punto gt counter shaft it's just in the x19 casing.

They didn't change the centreline of the countershaft to the centreline of the diff measurement. The punto gt box even runs the same shaft bearings.

Yeah I'd certainly agree with you though the cuts on all the gears are very different to the x19 cuts.

It's unlikely you'll be able to find the correct counter shaft for a 5spd x box that meshes with the desired crown wheel of the punto gt diff. More than likely you'll need to either get a custom countershaft/pinion or get a custom crown wheel. I suspect the crownwheel will be a lot easier to make custom than the pinion. I'm just guessing on that one.
 
That's alright Paul easy done.

Mkmini I'm not aware of any that did you would have to get the quaife. The current Abarth 500 also runs the C510 gearbox although be careful there are ones that don't. I'm not sure if they ran a factory lsd? I haven't worked out which ones do and don't yet. I do know that I bought a different final drive for my punto gt box and they List the same part number for the 500 and the punto gt.

Bacci may even already have done this potentially if you contact them. It could be as easy as asking them to make the x19 4.07 crown wheel with the punto gt pattern and inside diameter. I assume they would have cad drawings of both.
 
Maxmod said:
make the x19 crown wheel with the punto gt pattern and inside diameter
Click to expand...
IF the 'new' 500 has a LSD available with the same compatibility of fitment (into the X's gear box) as you found with the Punto GT Quaife diff, and IF a new ring gear (crown wheel) could be made to mate the two (without need for more radical modifications), then that would seem like the most affordable way to get a LSD into the 5-speed X (eg. a used LSD from a totaled 500 Abarth combined with the 'custom' ring gear). Especially here in the US where things like Punto's don't really exist. Interesting possibility. As Paul alludes to, large manufacturers like Fiat often utilize existing designs on subsequent models to help keep costs manageable (Paul, hope I haven't extrapolated too much from your comments), so it might be a compatible pairing. I seem to recall* in older threads on the topic of LSD's for X's where Paul had a lot of very useful information. Unfortunately I've been away from the forum for quite awhile so I'm not current on related discussions. Paul, any more insight on this concept? Could it be a viable potential?

Anyone know what LSD options are in the new 500's? And are they holding up well? The Abarth 500 has enough power that a diff from it should easily manage a modified 1500 SOHC.

On a related note, as far as I remember* the only option for any type of diff 'upgrade' on 5-speed applications was the "Phantom Gripper" type kit? Not saying it is a good option, but is is that even still around?

[*never trust my memory]
 
Last edited:
O.K., partially answered one of my own questions. A look on their web site shows two Fiat applications for the "Phantom Grip"; 124 (which might have been the Fiat application I was remembering*...going back to my earlier 124 days) and the one linked below:

https://phantomgrip.com/product/1971-1983-fiat-127-fiat-130-fiat-140-fiat-uno-fiat-stella/

I'm pretty sure this is not compatible with the X's box?

[*see the note in my previous post about trusting my memory]
 
Last edited:
Just took a look at Bacci's site (bacciromano.com). In addition to (and separate from) a listing for the 4-speed X, they also have this listing for 1500 X's:

http://www.bacciromano.com/?p=prodotti&l=eng&cat1=25&cat2=84&mar=4&pcd=4234#4234

I don't remember them having this option in the past. Sounds like "DAE23" is compatible with the 5-speed box? Although at over $1800 USD (plus shipping from Italy) it does not seem like a good purchase. But the same P/N also fits Ritmo's. Does that open up other possibilities for swapping diff's? Not that we (USA) have access to Ritmo diff's, but it might give thought to another 'work around'? I'm just not well versed in Fiat tranny's...need some qualified insight here.
 
Jeff I'm not sure about the ritmo but I wouldn't be surprised. The Alfa 147 runs the same box the Alfa 147 gta doesn't that uses the larger m32.

https://t124.com/forum/filedata/fetch?id=293797

Here's a list of the fiats using the c510.

I wouldn't rule out the possibility of finding a fiat 5spd counter shaft that works with the punto diff but I'd say it's unlikely. I've got a 17tooth counter shaft for the x box which is the correct tooth count for the puntos crown wheel but it's 4mm smaller in diameter. It does mesh but it would definitely strip it's just running on the top of the teeth.

Other than the shifter design and newer synchro design the main difference is the cut of the teeth. They have gone to slightly wider gears but a much courser cut than the fine cut x stuff.
 
That is a fair bit cheaper than the quaife but by the time you find a c510 diff to fit it in will you be much better off than the quaife. The quaife being a proven Torsen vs just a clutch plate design which likely won't last.

You could probably have someone build one of those clutch pack LSD's a guy in AUS did it didn't last an event.

Finding any information about the punto gt anywheres really hard. Punto specialists often don't seem to even deal with them.
 
Maxmod - the link did not work for me, but I Googled the C510 trans and found a couple interesting things. Looks like the 500 Abarth and 500 Turbo both use it in the USA, other 500 models have the C514. I read a discussion with USA Fiat Abarth engineers about the ratings for the C510 box. The technical specs for the current C510 show max torque at 206Nm, but the Abarth 500 engine is rated at 230Nm. The engineers could only speculate the listed ratings refer to different aspects (rather vague). Makes me wonder if perhaps Fiat has different versions of the C510...especially compared to the older units in X's. So far I've not found much on the C510 diffs specifically...particularly LSD versions. But this all got me to thinking, IF the C510 currently in use (for certain USA 500 models) has interchangeable diffs with the 5-speed X (this may be a big 'if'), then how about the aftermarket LSD units available for those 500 models. Look at one example here:
https://www.vividracing.com/catalog...h-c510-5mt-transmission-0913-p-150757798.html

Could it be possible something like that could work directly in the 5-speed X box, without having to transplant a Punto, Ritmo, or other diff first? Keep in mind that we (USA) do not have ready access to those models and their bits, but we do have the new 500...along with the after-market support for them. I believe the WaveTrac (linked) is a Torsen design like the Quaife, but considerably less expensive (at least here in the US). I know they are popular with the water-cooled VW crowd. Not sure if any X owners have approached companies like WaveTrac about fitting their existing units into the older C510 boxes, might be worth a look.

MkMini - the "Traction Concepts" unit you refer to is the same as the "Phantom Grip" (US version I guess) I mentioned above. It looks like the diff would need to be swapped first, then this unit added. So like Maxmod said it could be close in total cost to buying the Quaife unit outright. Maybe better to get a new unit specifically made as a LSD than taking a used item and adding a pseudo-LSD kit? But I like the way you are thinking for other options, same as me.
 
Just saw the following on the "Fiat Chrysler Automobile" official site, regarding the new 500 Abarth trans. The traction control system is involved via brakes, but not totally clear if the diff itself is a LSD type as well? However the aftermarket unit I referenced above is LSD:

High-performance transmission and driveline
Developed by Fiat Powertrain Technologies (FPT) for high-output applications, the Fiat 500 Abarth is equipped with the heavy-duty C510 five-speed manual transmission. Proven on the European 500 Abarth models, this transmission features a 3.35 final-drive ratio for quick acceleration and faster top speed, while maintaining fuel efficiency.

Designed to handle the increased torque loads, the Fiat 500 Abarth’s C510 transmission includes an intermediate shaft with equal-length half shafts to mitigate torque steer. Compared with the Fiat 500, the 500 Abarth features 23 percent larger half shafts (28.1 mm diameter vs. 22.8 mm diameter in the Fiat 500) for increased strength and to reduce torsional stress in the driveline during performance driving on the road or track. To handle the increased power and torque of the new 1.4-liter MultiAir Turbo engine, larger constant velocity (CV) joints with 53 percent greater torsional strength (2600 N•m vs. 1700 N•m in the Fiat 500) deliver added durability and refinement.

Maximum track handling with Torque Transfer Control (TTC) system
Helping the driver to utilize the power of the new 1.4-liter MultiAir Turbo engine is an Abarth-tuned Torque Transfer Control (TTC) system. TTC is designed to control and transfer the engine’s torque to the drive wheels for world-class performance and improved at-the-limit handling.

The TTC system is a differential locking system that uses the mechanical differential as a reactive element in the transmission to control torque via the brake system and electronic stability program (ESP) sensors. Utilizing ESP enables the 500 Abarth to transfer torque from a front wheel that slips, to one that grips.
 
Last edited:
Hey,

Yeah I would believe the wavetrac would be the same as the Quaife option interms of viability.

The one thing to add the gearbox in the X isn't a C510 they were earlier I can't remember the code but that's why you won't be able to ask if it fits.

I think they were the C501 C503 or C507 I can't remember the code and that T124 link isn't working anymore your right i'll have to ask the Admin.

I bought a Final drive for the Punto GT box from Bacci last night so I asked them if they think it would be viable to make a crown wheel to suit the application. I'll let you know if I get a response.

It is interesting about the torque rating of the C510 I've heard that it is improved with the LSD. I know guys with 1.9 Turbo's running the C510 box with good results and a lot more than 210nm. I'm running nearly 260nm at the wheels so I guess we will find out how it goes. Mind you the box i'll be running has been Shot peened, cryo treated and has the quaife diff in it.
 
Ah, that explains it...the X trans is a different code number. I should have realized, it would have been way too easy to find a late model unit with interchangeable parts for the older X trans. Plus I'm sure someone on this forum would have discovered it before.

I found a cross-listing of trans that the Quaife diff fits (its a "txt" link within a web page, so let me know if it works):
https://shop.quaife.co.uk/fileuploader/download/download/?d=0&file=custom/upload/File-1462290259.txt

Note where it states a "modified crown wheel" from a 128 is needed to fit in a Uno Turbo. Be interesting to hear what you learn from Bacci about crown wheels.

I think the torque rating for the C510 is a old spec that has continued to be carried over and actually does not relate to the current design C510. Based on listings for replacement parts, there are different versions of C510. Interestingly I see ads selling complete new C510 Fiat 500 trans units for around $1500 USD...not that much more than the cost of an aftermarket LSD. Also, the more I read, it appears the Abarth 500 does not have a LSD but uses sensors to detect slip and applies the brake on that side to control things. They call it "torque transfer control" and describe it as "a differential locking system", but it is an open diff. Actually sounds more like a "throttle limiter" in practice. But the US spec Abarth seems to be different than the Euro spec one. Isn't there a non-turbo (NA) Abarth 500 over there? So the diff's may be different?
 
Good find, Well that pretty much confirms it is possible then with the modified crown wheel. I wonder if they know someone who's done it then.
 
Dr.Jeff said:
As Paul alludes to, large manufacturers like Fiat often utilize existing designs on subsequent models to help keep costs manageable (Paul, hope I haven't extrapolated too much from your comments)
Click to expand...

Well, I doubt that they would carry-over tooth geometry, but I'm saying it is possible. I can see them wanting to keep the same center distances because they might have machines made to bore holes at that distance that may not be easily converted to a new center distance. The gear geometry is easily changed as it is just a few hundred dollar hob and some CNC code. They probably grind the teeth too, which is just a matter of dressing the wheel differently which is just code.
 
Maxmod said:
Hey Guys,

I thought I would post this up and maybe someone else can follow it through

I have a Punto GT gearbox and an x19 5 speed on my bench stripped at the moment.

The punto GT gearbox is a C510 which uses the QDH2K-10 Quaife LSD unit. Punto GT right

The overall height bearing to bearing is identical, they use the same bearings, the x19 input shafts fit and lock into the Diff.
View attachment 3183
Click to expand...

The ring height offset / height is also different - based on your pic - unless there is significant distortion in the photography?
 
Dr Jeff,
The MK1 Uno turbo used two different gearboxes. Early ones used the " bottom change" box like the strada/ritmo and later ones used the C510 "top change" like the Tipo/Uno turbo MK2/Punto Gt.

From the link..

"Fiat Uno mk1
Fiat Uno Turbo WITHOUT CAT - ONLY with modified crown wheel (fiat 128 style gearbox) 105HP Fiat Uno Turbo WITH CAT 100/101HP
ONLY FITS LATER MK1 WITH C510 GEARBOX. DOES NOT FIT EARLY MK1 WITH C506 GEARBOX"

Note "DOES NOT FIT EARLY MK1 WITH C506 GEARBOX"

From Wiki on Uno Turbo

Cars built from 1985 to late 1987 were fitted with a Ritmo/Strada-derived five-speed gearbox. This was then replaced by a newly developed 'C510' five-speed gearbox, often referred to by owners as the 'Tipo style' gearbox, featuring a more durable differential and improved gearchange linkage. Ratios were unchanged between the two units.

Regards
Andy
 
Ya, I was thinking the X had the same C510 box. So my earlier comments regarding fitment are not relevant. Looks like it's back to the original concept of this thread. Sorry for the diversion.
 
You must log in or register to reply here.
Back
Top