LSDs specs

[Limey]

Hi all, I've posted this on the stock forum as well.

I'm building an SII Alpine in the UK and for a challenge will be taking it to the Stage 3(4) tune as available in period as much as possible. I'll be using the 1960's list of Rootes mods and trying to replicate every one as close as possible.

One item I'd like to replicate is the limited slip diff. I'll be going to Gripper but I could use your advice.

1) What specs would be close to the LSD available from Rootes at the time . See available list below. (E&F ''old ZF spec''?)
2) What spec would be best for fast road and track days in your opinion?
3) Given that Gripper LSDs don't shock the shafts much by virtue of their design, should I bother with hardened drive shafts? If 'yes' do I have my originals hardened or made from scratch? The reason why I am not automatically including this mod is that it neither adds to the drive feel or period appearance)

Below are the specs that Gripper list on their website:-

A - Tarmac Race 40/65 Ramps 120Nm
B - Road/Trackday 40/65 Ramps 60Nm
C - Gravel 30/60 Ramps 120Nm
D - Gravel 30/60 Ramps less plates low preload 60Nm
E - Race (Old ZF Spec) 45/45 Ramps 120Nm
F - Road (Old ZF Spec) 45/45 Ramps 60Nm
G - Race (Soft Locking/Lightweight) 50/80 Ramps 120Nm
H - Road (Soft Locking/Lightweight) 50/80 Ramps 60Nm
J - Race (Open on over-run) 30/80 Ramps 120Nm
K - Road (Less Plates) 30/80 Ramps 60Nm

Thanks

Oliver

 

[jdoclogan]

Limey, I started a thread in Harrington Alpine that shows two LSDs from the time period. One is a Rootes Factory (?) model and the other is a Dana. The basic question here is: Did, in fact, the Rootes Factory produce a LSD? Limey, do you know? It appears that Rootes may have and, if so, I only know of two in existence. The Kimes race car and my Promotional Harrington Le Mans. Ultimately it appears you are just trying to find the right combination for "fast road and track days." If I knew how to find the specs of my existing units I would attempt to do so. The Rootes Factory unit is installed in my PHLM, however, the Dana is on my bench ready to complete my #41 Sebring Alpine rear end.

 

[Limey]

Ok - just received the 'Repro' diff. Looks good. Lovely machining, unused, 25 spline. the only marks are "RB" stamped in and 'ALPINE' in felt tip.

Guess I'm going to have to pay for custom made hybrid axle shafts - SII dimensions but 25 spline inner ends?? I don't suppose later series 25 splines are interchangeable with early series? pardon my ignorance but late Series are a blind spot for me ( no fins...)

Cheers

Oliver

 

[RootesRacer]

Limey, I started a thread in Harrington Alpine that shows two LSDs from the time period. One is a Rootes Factory (?) model and the other is a Dana. The basic question here is: Did, in fact, the Rootes Factory produce a LSD? Limey, do you know? It appears that Rootes may have and, if so, I only know of two in existence. The Kimes race car and my Promotional Harrington Le Mans. Ultimately it appears you are just trying to find the right combination for "fast road and track days." If I knew how to find the specs of my existing units I would attempt to do so. The Rootes Factory unit is installed in my PHLM, however, the Dana is on my bench ready to complete my #41 Sebring Alpine rear end.

The Rootes "Factory" LSD was a modified Dana (Salisbury) 23 Powr-loc which has the same operation as the one above.
Rootes either had to made a 10 spline axle to fit the Powr-loc side gears or made the side gears to fit the Rootes 17 and 25 spline axles. I would bet on the former since I have never seen a complete ready to run setup.

 

[RootesRacer]

View attachment 19094 View attachment 19093 View attachment 19090 View attachment 19089 View attachment 19088 Ok - just received the 'Repro' diff. Looks good. Lovely machining, unused, 25 spline. the only marks are "RB" stamped in and 'ALPINE' in felt tip.

Guess I'm going to have to pay for custom made hybrid axle shafts - SII dimensions but 25 spline inner ends?? I don't suppose later series 25 splines are interchangeable with early series? pardon my ignorance but late Series are a blind spot for me ( no fins...)

Cheers

Oliver

Late SII to SIV were 25 spline so one of those axles should theoretically work.
SV also has 25 spline but the axles wont fit an SI to SIV case.

 

[Limey]

Thanks Rootes Racer.

It's been many years since I last saw my SII axle shafts but I can only remeber having 10 spline ones. I'm relieved to hear that SII 25s fit so I don't have to dig out for custom shafts.

Where 10 spline SI early SII only?

Oliver

 

[RootesRacer]

Thanks Rootes Racer.

It's been many years since I last saw my SII axle shafts but I can only remeber having 10 spline ones. I'm relieved to hear that SII 25s fit so I don't have to dig out for custom shafts.

Where 10 spline SI early SII only?

Oliver

There were NEVER 10 spline (stock) axles. early alpines through mid SII were 17, all later were 25.
10 splines is what the Dana LSD took.

 

[Limey]

Sorry and thanks, I'm conflating my memories of the coarser 17 splines I kind of half remember before the rebuild 6 years ago and with the 10s mentioned above. And I don't have any drive shafts in the spares shed to look at before I made my dozy comment. Time for bed...Thanks for the confirmation tho'