ALFAGTV6.COM

[killaz]

What gear ratio is that box? Maybe is better to look for another crown?

[xrad]

I looked and looked ..but no luck. I have three sets of standard R+P gears..but not the knowledge to set them up for LSD..

[Mats]

I looked and looked ..but no luck. I have three sets of standard R+P gears..but not the knowledge to set them up for LSD..

Well, if that's the only thing standing between you and the frustration of trying to weld the scrap you have... I'll try to write something to share my knowledge.

How does that sound?

[xrad]

Thanks Mats.

just so you know, I dropped the gear off at a specialty welding center (wow HUGE place, like a small stadium) Apparently, they have done this before, ...but that does not of course mean it will work.

I still have three other transaxles with good used 3.54(?) rear ends but no LSD's.

AND, I just bought a rebuilt lightened 4.1 LSD Plat transaxle from richard jemison off alfabb.

Sooooo...I should have one excellent gearbox, 1 lsd box needing R+P, and 3 spares(2 verde and one GTV6). I also have extra shims and friction discs now for the LSD.

But, that does not mean I don;t want to learn from you Mats. Sharing your knowledge would be very much appreciated!

[zar162b4]

Hi
Sorry if I write in your post, I just have a question. Suppose you have 2 cases:
1) Alfetta 4 cylinder, with 2 satellites differential
2) GTV6 with 4 cylinders, with 4 satellites differential

Suppose you want to install an LSD in both cases.

Case 1
Use a shim between the crown and the LSD, (MATS, I think you gave me some hints on that, do you recall?), no setting on the pinion height (if the same casing is mantained), set the LSD differential bearings preload, set the crown pinion teeth backlash. Is this correct?

Case 2
No need to use any shim between the crown and the LSD, no setting on the pinion height (if the same casing is mantained), set the differential bearings preload, set the crown pinion teeth backlash. Is this correct?

Summarising, the difference between fitting an LSD in lieu of a 2 satellites diffferential or in lieu of a 4 satellites open differential is that the modifications on the 2 satellites case a 3mm shim is required.

Can someone, who actually did this, confirm?

[zar162b4]

Sorry, case 2 is GTV6 with 6 cylinders obviously and 4 satellites open differential...

[xrad]

I have no idea....

[zar162b4]

Maybe it is not easy to answer this question. Perhaps I should ask the question in a different way. I believe that the Milano Silver and Gold 4 satellites open differential is the same of the GTV6 or the Alfa 90 2.5. The Milano Silver, Gold and Platinum used the same hypoid gear ratio (41/10) but the Platinum had the LSD. On this side of the pond (Europe), at least in Italy, when the alfa75 turbo was introduced, it was normally offered with LSD, but it was possible to order the same model without LSD (in both case the hypoid gear ratio was 43/11). My question would be: is it reasonable to assume, that the hypoid gears on the Milano Silver or Gold is identical (within the machining tolerances) to the hypoid gear of the Milano Platinum and so the same hypoid gear can be used with the LSD differential or the 4 satellites open diff?
Thank you for your patience
Regards
Oscar

[xrad]

You can't mix and match R+P'S, but you can change out the set.

I think the actual tooth width is different. the LSD r+p's have slightly thicker theeth than non lsd. I can see this by looking at mine and I think MATS posted a link to his trans rebuild which shows same thing.

BUT: you can use non lsd r+p gears with LSD with proper shimming milling?.?

ALSO: the milano and late GTV6 transaxles have bigger rear end bearings...(so I hear)

Also...different pinion shafts for speedo so gtv6 is different than milano.

[Mats]

Maybe it is not easy to answer this question. Perhaps I should ask the question in a different way. I believe that the Milano Silver and Gold 4 satellites open differential is the same of the GTV6 or the Alfa 90 2.5. The Milano Silver, Gold and Platinum used the same hypoid gear ratio (41/10) but the Platinum had the LSD. On this side of the pond (Europe), at least in Italy, when the alfa75 turbo was introduced, it was normally offered with LSD, but it was possible to order the same model without LSD (in both case the hypoid gear ratio was 43/11). My question would be: is it reasonable to assume, that the hypoid gears on the Milano Silver or Gold is identical (within the machining tolerances) to the hypoid gear of the Milano Platinum and so the same hypoid gear can be used with the LSD differential or the 4 satellites open diff?
Thank you for your patience
Regards
Oscar

NO!

Rings/pinions are matched sets, meaning you shoudln't even mix and match between gears of the same type (lite taking one 75 3.0 ring gear and use it in another 75 3.0 gearbox with the pinion that came wuth that box.

[zar162b4]

Sorry,
I probably used the wrong words to express my thoughts.
The car in the picture is my car.
The gearbox of this car needs to be rebuilt (new syncros for the 1st and 2nd gear, use the 5th gear syncro on the 3rd and 4th gear, use the 3rd/4th gear synchro on the 5th gear, check the play between forks and sleeves, replace the oil seal rings, check the pinion's head position, the differential bearings preload and the crown/pinion teeth clearance).
I plan to buy a 75 twin spark gearbox, remove the LSD (detaching it from the crown, which will be kept close to the 75 twin spark pinion) and have it installed in lieu of the GTV6 4 satellites open diff. I won't mix crowns and pinions from different gearboxes (I know very well that crown and pinion are matched at the beginning of their lives and can't be mixed. In Italian, they are called "Coppia Conica", because they are a "fixed couple" that can't be divided). However, I plan to use the original GTV6 "Coppia Conica" and the LSD differential.
I know very well that this implies that the pinion and crown positions will need to be adjusted after this operation, but this is not a problem (a 60 years old Alfa Romeo mechanic will do the job, he has the original Alfa factory tools and has perfectly rebuilt the gearboxes and differentials of my 2 Alfa 75 twin spark, which in fact do not whine at all in any condition).
My question, in more explicit terms is:
is it possible to attach the alfa 75 LSD to the GTV6 crown and then proceed to the bearings preload adjustment and the adjustment of the clearance between the pinion and crown teeth by using the appropriate shims located beside the differential bearings or is it necessary to machine a spacer between the alfa 75 LSD and the GTV6 crown before proceeding to the hypoid gears shimming?
Thank you again for your patience
regards
Oscar

P.s.: I know that it is possible to do the job by simply fitting a ts gearbox and a dakota digital converter, but this would be my last option

[xrad]

soooo much easier to use 75 gearbox and Dakota digital and milano amp and 86 alfa speedo...

spend money rebuilding 75 gearbox(synchros, lightening gears, sliders, dogs. etc...)

I was going to do EXACTLY what you want to do...but is it soooooo much easier just to use 75 gearbox...

[Mats]

I don't know how thick bearing shims are available or how much you would want to move the diff over but if the GTV diff is the same geometrically as the 75 open diff I'd say it's doable.

[xrad]

So you are taking the LSD out of a 75 and putting it into a 1980's? transaxle?

I thought the diff carrier bearings are smaller on the older gearboxes...and will you need the stub axles from the 75?

will the older gearbox stub axles fit the new LSD?

[zar162b4]

Hi,
thanks for your reply.

Xrad, yours is a good point. Getting an alfa 75 10/41 gearbox with an LSD would definitely make things easier. Honestly, if I lived in America, I would buy a Milano Platinum gearbox and would use it. Apart from the LSD, there is a definitely better gear spacing. However, on this side of the Pond, the Alfa 75 2.5 v6 did not come with a LSD. The only one with a 10/41 hypoid gear and LSD was the Alfa 75 twin spark. However, I think that a gearbox from an alfa 75 twin spark might be not safe when used with a V6 engine. Apart from the stub axles that must be replaced (and this is definitely not an issue), there is a bearing which is located next to the pinion's head which is supplied in 2 different dimensions, the smaller one being installed in the gearboxes used on 4 cylinder non turbocharged alfas (like the twin spark, ven if equipped with LSD) and the bigger one being used on v6 and turbo transaxle alfas. To be on the safe side (and get the bigger bearing), I'd need to:
-Find an alfa 75 twin spark gearbox (relatively easy here in Italy)
-Find an alfa 75 turbo (not easy to find, especially now) or v6 gearbox (almost impossible to find)
-uninstall the 10/41 hypoid gear from the twin spark gearbox
-install the 10/41 hypoid gear in lieu of the 11/43 hypoid gear in the alfa 75 turbo gearbox

This would create a gearbox equal to a Milano Platinum gearbox, and safe with v6 alfas (by the way the 75 turbo stub axles are good for the gtv6). However the whole process looks complicated (I'd need to get not just one, but two gearboxes, and hope that the hypoid gear is in good shape, you never know what you get from junked cars until you open what you've bought...). and last but not least, I'd have to buy and then install a Dakota Digital converter...

My plan of action is different and simpler. I have the gtv6 that you can see in the picture. I know that the hypoid gear and the rest is in good shape (no whine, usual synchros problems but these can be fixed duing overhaul). The only new element would be the LSD diff. These diffs can have worn elements, but I have some spare clutches and spacers, so my mechanics is capable to bring it to the original conditions.

There is an update on the questions I was asking in the last posts. I have sent a PM to Tectoteam, which has a big experience in overhauling these gearboxes (he has a 1984GTV6). This afternoon (Central Europe Time) I received his answer (merci encore!!). He told me that he did exactly what I am planning to do:
-Got an alfa 75 turbo gearbox
-Took the LSD from that gearbox
-Installed the LSD in lieu of the gtv6 open diff in his gtv6 gearbox
-Checked bearings preload
-Adjusted the play between the pinion and crown teeth (that are the ones of the GTV6)

To summarise the situation, to fit an LSD:
-On GTV6 gearboxes no spacer is required between the crown and the LSD. The bearings preload and the teeth clearance MUST be adjusted (thanks Tectoteam for the hints!!)
- On gearboxes coming from 4 cylinders non turbocharged alfas (for instance when it is desired to install an hypoid gear coming from a Giulietta 1,3 or an Alfa 75 1,6 to have shorter ratios on a car intended to race on slow circuits) a spacer is required between the crown and the LSD (thanks Mats for the inputs you gave me on this). Furthermore, as always when fitting an hypoid gear in a different casing, the bearings preload and the teeth clearance MUST be adjusted.

I hope that this might help someone (these investigations and the answers I got helped me a lot).
Regards
Oscar