View Full Version : Rear-end Gear ratios

12-24-2006, 05:23 PM
Ok here is my first post on the technical side of the forum and I have this question to offer the panel of experts on my 1959 Lark. It came from South Bend as a Six-Cylinder Standard, but in the coming months It will be tranformed into a V-8 Automatic. I have two rear-ends, the original still in the car and I have a 1962 Lark automatic rear-end, which one is going to better serve the needs of the Lark, Performance and drive ability, or Drive ability and gas mileage? If you ask me the ratios of the rear ends I will have to say I have no idea.


Mike Van Veghten
12-24-2006, 08:45 PM
Can't answer the question untill you pick an application!

You say - "performance and driveablity".
ThEn you say - "drivablity and gas milage".

For the performance end, the 4.11 would be great. though it will limit your freeway cruising speeds to about 55/60mph.

For the milage end, a 3.23 or 3.55 would be good, but will limit the performance side of things.

Before just jumping in to swapping axles....you NEED to remove the covers and find out exactly what the two ratios are! Don't make a blind guess, you'll not know "exactly" what you currently have, then later, if you decide to try another ratio....you won't have any idea what to change it to!

Again...don't guess, open'em up and find out what each is, thEn make a decision.


12-24-2006, 09:18 PM
If the v8,trans, and rearend are a matched set you will probably be better off to go that route. Those Studebaker engineers were pretty sharp. NT

Neil Thornton
Hazlehurst, GA
'57 Silver Hawk
'56 Sky Hawk
'51 2R16 dump truck
Many others.

12-25-2006, 05:07 PM

There were 3 different rear axles used amongst the Stude cars and those 3 axles had various gear ratios available amongst them. All of them were built by Dana.
The Type 23 RA(rear axle) is a light duty unit used in 6cylinder applications. The Type 27 was used in HD 6cyl apps to some degree and used behind 259 V8s as well. The Type 44 is the heaviest duty axle and was used in fleet/HD apps.- behind most 289-equipped cars as well as all the Jet Thrust/R-series engines.
They would have had ratio tags affixed under one cover bolt when new. Thru the years, some of these tags have "taken flight". But you can take the cover off and READ the ratio off the shoulder of the ring gear OR you can make a chalk mark on the backing plate/drum edge of one brake and then see how many turns of the driveshaft input yoke it takes to turn the drum one full revolution. If it's got (for instance) 3.31 gears in it, it's gonna require 3 & 1/3rd turns of the yoke to make the drum do one full rev. If it's got 3.54 gears, it'll take roughly 3& 1/2 turns of the yoke. Make a mark on the yoke and the axle case to determine the number of times you have to turn it to get one rev at the drum.
Stude used (primarily) these gear ratios amongst the 3 type rears I've detailed above: 3:07 - 3.31 - 3.54 - 3.73 - 4.10 - 4.27 - 4.55
I've heard tell of 2.93 & 3.92 as well but these aren't listed in the Stude parts manuals and are probably from someone lifting gears from Dana rear axles of BrandX makes. These same rears showed up in many other make cars - some foreign types even - and as long as they're the same family (23, 27 or 44), the gears will fit given the carrier that the gears mounts to is the right size.
The 3.07 is the "leggiest" - affording the best economy if you live on relatively flat terrain. 3.31 is what's most common behind V8 automatics with 3.54 working as well and affording a bit more ZIP and of course, a bit less economy. 3.73 and higher will be more fun to stick your foot in but you'll be revvin' while crusin' down the highway![}:)] Ted Harbit tears up the 1/4-mile with 4.55 gears but they're not that practical for cruzin'.[:I]
There's a thread of late about the TT (twin traction) rear axles and these can be identified by an extra tag under one of the rear cover bolts OR by taking out the oil fill plug and looking into the hole. If you see the metal housing of the TT clutch pack less than an inch from the fill hole, well, it's a TT.:D If there's nothing right there, close to the hole, it's not.
In short - you don't want either 6cyl rear if you're gonna use a V8. You'll want at least a 27 and best - a 44. BTW, these ID numbers (23,27,44) are cast into the webbing of the axle housing - near where the axle tubes meet the housing.
Don't forget to upgrade to V8 brakes too![^]

Miscreant adrift in
the BerStuda Triangle

1957 Transtar 1/2ton
1960 Larkvertible V8
1958 Provincial wagon
1953 Commander coupe

12-27-2006, 07:05 AM
I have a complete 1962 rolling chassis, 259 - Automatic and drive shaft and rear-end just waiting to move over in the lark, From what Gib told me the rear-end is a 3.31, So am going to be changing a few more parts this spring :D Thanks for the help.


12-27-2006, 11:05 AM
Mr Biggs,
My 59v Lark with the 259 has a Model 23 rear axle with the 3.31 ratio.

59 Lark