Another 74 Alpina A4 on Bring A Trailer

[markmac]

Quite a bit of information on this particular subject.....

 

 

[jon2002]

sold at $65k.  seems like a deal to me.  tough market.

[2k2tii]

I have a genuine Alpina limited-slip differential (with paperwork to prove authenticity), if anyone is interested.
 

Direct message me. 

[uai]

23 minutes ago, 2k2tii said:

I have a genuine Alpina limited-slip differential (with paperwork to prove authenticity), if anyone is interested.
 

Direct message me. 

So what's the difference between an alpina LSD and a BMW LSD?
none... - or perhaps paperwork.
So it's a BMW LSD manufactured by ZF sold by alpina

Edited November 14, 2023 by uai

[BarrettN]

I had thought that Alpina had higher lockup percentages available, am I wrong?

[JsnPpp]

13 minutes ago, BarrettN said:

I had thought that Alpina had higher lockup percentages available, am I wrong?

 

My understanding as well, like up to 75% (memory only). 

 

Not that a standard LSD couldn't be customized, but just noting a potential difference.

[uai]

22 minutes ago, BarrettN said:

I had thought that Alpina had higher lockup percentages available, am I wrong?

No Standard back then were 40% you could get optionally 75% at BMW too if you wanted to.
It's just the amount of friction pairs - ramp angles were the same.

Edited November 14, 2023 by uai

[Son of Marty]

I have a 75% lsd sourced through BMW parts, IMO anything more would have to be a locker.

[mac]

Back in the day, Miller&Norburn would build you anything you wanted. 

Today, Korman can do it too. 

Racers use locked diffs.  

 

Mac

[markmac]

I was just looking at an Alpina catalogue (1975), as far as differentials go, for 4 cyl cars, they offered the 75% locker and a wide variety of rations from 3.45 to 5.86.  No where to they say 'Alpina Differential'.  As previously stated they were parts that came from BMW and sometimes assembled to the customers requirement by them.

 

Funny enough, my race car had one of those 5.86 75% lock diffs in it, with some special add-ons, oil cooler pump and drive for the alternator.  Alpina definitely wasn't racing the car with a 5.86 gear set in it, no doubt the Italians that bought it and were doing some Hillclimb events and selected that ratio, who knows (or cares where it came from).  I changed that out and have a 3.9 gear set in there now.

 

As far as the 2002 tii with Alpina A4 engine goes, seems to me it did pretty well for what it was (a 2002tii with a documented Alpina A4 engine and some nice parts - cobbled together).

[Preyupy]

I bought three 75% Alpina limited slip units from Miller and Norburn in 1975 for use in Solo II cars.  I still have all three and they work fantastic.  There is no preload/break away torque, on the bench they act like an open differential, but apply a bit of power and drive around a cul-de-sac and it acts like a locker. I have them fitted in 3.45, 3.64, and 4.11 diffs now.  

[Mikesmalaga72]

From my observations I do remember Alpina did add the additional cooler setup on the early BMW race diffs which of course was a cool "pun intended" addition....then continued that concept onto their later bespoke cars into the mid to late 90`s even with diff temp gage in the dash..

[Son of Marty]

53 minutes ago, Preyupy said:

There is no preload/break away torque, on the bench they act like an open differential, but apply a bit of power and drive around a cul-de-sac and it acts like a locker. 

Mine acts the same, any idea why they won't lock up unless there under power? 

[Preyupy]

54 minutes ago, Son of Marty said:

Mine acts the same, any idea why they won't lock up unless there under power? 

They use a different ramp angle and don't rely on spring preload to initiate the locking action.    

[Dudeland]

Why do I think that they had a proportional valve ala the Turbo?