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Transfer Case Chains - Specs

AgitatedPancake

AgitatedPancake

Frobot
Joined
Nov 28, 2020
Member Number
3093
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1,174
Loc
Sacramento, CA
So I've had an interest in learning more about transfer case components for a while, seeing what you can mix and match between various tcases to make interesting combinations. I just found a pretty useful catalog from BorgWarner/Morse that I think is worth its own post, just for handy future reference. It has pitch, width, and length (number of pitches) for most of the common chain drive tcases out there.



Morse Chain Catalog - 1.png


Morse Chain Catalog - 2.png


Morse Chain Catalog - 3.png


Morse Chain Catalog - 4.png
 
On our old 7S ranger, Culhane had removed low range from the case and put in a smaller drive gear for something like a 30% underdrive. Allowed for the use of 4.10's in the front diff and 6.0's in the rear. I always wondered where he got the shorter chain and gear.
 
bdkw1 said:
On our old 7S ranger, Culhane had removed low range from the case and put in a smaller drive gear for something like a 30% underdrive. Allowed for the use of 4.10's in the front diff and 6.0's in the rear. I always wondered where he got the shorter chain and gear.
Click to expand...

That could be cool:smokin:
 
So after reading that interchange table it seems to me like there could potentially be options for speeding up or slowing down the front output of a case by using a smaller sprocket on one side (I don't think any cases have enough room in them to go substantially bigger). Unless you get massively lucky on splines (who do we have to pay off at Sonnax to get that info?) you'd probably have to modify the sprockets to make them work.

Honestly, this info seems like it'd be far more useful to the people building buggys using FWD car drive-trains because they're usually lacking for top end speed and in my experience chain driven transmissions have a little more wiggle room for sprocket size changing than transfer cases do.
 
bdkw1 said:
On our old 7S ranger, Culhane had removed low range from the case and put in a smaller drive gear for something like a 30% underdrive. Allowed for the use of 4.10's in the front diff and 6.0's in the rear. I always wondered where he got the shorter chain and gear.
Click to expand...

Very interesting, just to clarify they undersized the drive sprocket and ran a shorter chain? That's exactly the kind of crazy stuff I like to hear about.

arse_sidewards said:
So after reading that interchange table it seems to me like there could potentially be options for speeding up or slowing down the front output of a case by using a smaller sprocket on one side (I don't think any cases have enough room in them to go substantially bigger). Unless you get massively lucky on splines (who do we have to pay off at Sonnax to get that info?) you'd probably have to modify the sprockets to make them work.

Honestly, this info seems like it'd be far more useful to the people building buggys using FWD car drive-trains because they're usually lacking for top end speed and in my experience chain driven transmissions have a little more wiggle room for sprocket size changing than transfer cases do.
Click to expand...

I've got a handful of sprockets in the garage, and as you note unfortunately splines seem somewhat arbitrary from one case generation to another. Some are even relatively close in shape and diameter, but the count is different for whatever reason the engineers decided.

For the specific application of changing the drive ratio, yeah FWD transaxles would be an interesting application. But just in general, just learning more about these oil bath power transfer chains makes the creative gears churn :stirthepot:
 
AgitatedPancake said:
Very interesting, just to clarify they undersized the drive sprocket and ran a shorter chain? That's exactly the kind of crazy stuff I like to hear about.
Click to expand...

Yes, made the front output under driven to match the gearing front to rear. I think the lowest gearset you could get for the front diff was 4.56 and they were weak. 4.10's were much stronger, so that's what was used. With 6.0's in the rear and a C4, top speed was about 85 with that poor little 2.9.
 
Left to right (and bottom to top)

Np231 1” wide chain

Np242 1.25” wide chain

Np271 1.5” wide chain

The 1” and 1.25” sprocket are same size (pitch, diameter, tooth count), the 1.5” is actually a smaller sprocket. Power transfer splines on the ID are larger than the other two

IMG_9945.jpeg


IMG_9947.jpeg


IMG_9948.jpeg
 
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