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#41 Sebring Alpine Rear Ends
- Thread starter jdoclogan
- Start date
alpine_64
Donation Time
Dan,
On a short course a 4.22 would be good. On some of the longer more open circuits i can see 3.89 being ok. LeMans def taller the better. I remeber reading thr interview with either Harper or Proctor about the race at LM in the alpine. Apparently at the start of the Mulsane they would light up amd then ash out before the breaking zone at the end of the straight... Those were the days.
Dan was steves replica sebring twin 40dcoes motor aldo a 1725 as opposed to a 1600?
sunbeam74
Silver Level Sponsor
On the Facebook "Rootes Racing" page I posted two pages from 1964. It list all the races Dan and Don ran with the Alpine. Just below the name of the course HJ listed the gear ratio. The car had O.D. and almost all races were using the 4.22 and 4.44. Example, Road America and Mid-Ohio, 4.22.
Lynndale and Watkins Glen, 4.44. I was surprised at Watkins Glen using the 4.44. It seems like the 4.22 would have been better but they might have been anticipating running at Thompson and didn't want to have to change the differential since it was 2 weeks later.
I think I have notes where they used a 4.86 ratio at Lime Rock but that might have been from 1963
Lynndale and Watkins Glen, 4.44. I was surprised at Watkins Glen using the 4.44. It seems like the 4.22 would have been better but they might have been anticipating running at Thompson and didn't want to have to change the differential since it was 2 weeks later.
I think I have notes where they used a 4.86 ratio at Lime Rock but that might have been from 1963
RootesRacer
Donation Time
Dan, I hear what you are saying but I just cant picture a Dana gearset mounting up into the Rootes pumpkin. There are just too many degrees of freedom of the parts for them to line up in the Rootes pumpkin within the range that shims could adjust the ring and pinion for perfect mesh.
The Dana 23/25 is the Powr-lok carrier that was used in the day, the Dana 27 carrier as well as the ring gear is tool large to mount in the rootes pumpkin.
I have a set of each Powr-Lok carriers.
My bet is that Rootes made low qty runs of non standard gearset just like they did with the 10 spline axles.
spmdr
Diamond Level Sponsor
The Dana 27 number was a poor guess, I knew there was another number, 25 just didn't come to mind.
I have only seen one Rootes Pumpkin modified for a Dana/Spicer LS.
I'm not sure what gear set was used, Rootes or Dana.
As I recall, it was disassembled, hard to say what all the parts are, from memory, YEARS ago.
I have only seen one Rootes Pumpkin modified for a Dana/Spicer LS.
I'm not sure what gear set was used, Rootes or Dana.
As I recall, it was disassembled, hard to say what all the parts are, from memory, YEARS ago.
spmdr
Diamond Level Sponsor
As far as Steve's old Green Alpine, he ran several engines, both 1600 and 1725.
The engines were a mix of performance levels. We did run a 1600 with a 1725 cam and oil pump.
The 1600s were mostly place holders between 1725s.
As far as the rear ends with LS, chances are most or all of the parts in the US are likely traceable to Doane Spencer.
And as far as rear end gears, again, you NEED to be able to PULL a gear.
The 3.89 is a bit too tall for the Weekend Racer, with it's current (low) power level/aero drag level, a 4.22 would be better, maybe, 4.09 for sure.
And, of course, the usual Alpine engine on a diet of some steroids usually wants to see more RPM, AND a bigger number rear gear.
There IS a case of TOO tall rear end gearing, at least on the track.
The engines were a mix of performance levels. We did run a 1600 with a 1725 cam and oil pump.
The 1600s were mostly place holders between 1725s.
As far as the rear ends with LS, chances are most or all of the parts in the US are likely traceable to Doane Spencer.
And as far as rear end gears, again, you NEED to be able to PULL a gear.
The 3.89 is a bit too tall for the Weekend Racer, with it's current (low) power level/aero drag level, a 4.22 would be better, maybe, 4.09 for sure.
And, of course, the usual Alpine engine on a diet of some steroids usually wants to see more RPM, AND a bigger number rear gear.
There IS a case of TOO tall rear end gearing, at least on the track.
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sunbeam74
Silver Level Sponsor
I have a drawing created by HJ Meyer of Sports Car Forum which he starts with a Plymouth rear axle and then tapered to fit the Alpine hub. Looking at the drawing I am assuming the axle is a 10 spline at the start. Overall it is beefier than the Alpine axle. I can't recall if Don or Dan ever broke axles when they were racing the Alpine but it is a problem. I am sure they magnafluxed the axles regularly.
Oddly, I have an LSD out of a California Alpine which uses the fine spline axle. I don't think it is a Dana but I'm unsure of the manufacture. The carrier cover isn't the hard sharp shoulder you typically see on Dana LSDs. More of a rounded cast cover. Unfortunately, it is damaged beyond use. (this reminds me of the Kime's LSD if I am recalling correctly)
Oddly, I have an LSD out of a California Alpine which uses the fine spline axle. I don't think it is a Dana but I'm unsure of the manufacture. The carrier cover isn't the hard sharp shoulder you typically see on Dana LSDs. More of a rounded cast cover. Unfortunately, it is damaged beyond use. (this reminds me of the Kime's LSD if I am recalling correctly)
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jdoclogan
Platinum Level Sponsor
I was able to get the two rear ends (standard 3.89 and 4.44 LSD) completely disassembled. The following photos show the axle comparison between the LSD 4.44 ten teeth axle and standard 3.89 17 teeth axle. Interesting the standard axle is longer than the LSD and the LSD has a thicker taper at the tooth
end.
Note: a couple sets of hardened woodruff axle keys from George Coleman on the left. Thanks George.
There was a reason the LSD was not used for the next race. The bearing on one axle went bad and there was actual movement of about 1/4 inch to the outside.
end.
Note: a couple sets of hardened woodruff axle keys from George Coleman on the left. Thanks George.
There was a reason the LSD was not used for the next race. The bearing on one axle went bad and there was actual movement of about 1/4 inch to the outside.
