18 spline vs 23 spline 4 speed

[John Milner]

I have an extra 23 spline 4 speed that I am going to rebuild for my '68 Charger.  I am going to tear the whole transmission down and install new bearings, synchronizers and gaskets.  Since I am doing this, it got me to thinking about installing an 18 spline gear set while I am in there.  From what I can see, that will be a pretty significant investment.  What makes the 18 spline transmission a better and stronger transmission?  Are the gears cut at a different angle, similar to the M22 Muncie GM transmission?  It seems like every complete 18 spline 4 speed that I see has a price ranging from $1,500 to $2,500. 

[Birdflu]

From an engineering standpoint, Chrysler was fearful that the 23 spline input was going to be a problem with the capabilities of the Hemi. The larger diameter 18 spline input was used to accept the additional torque. In later years, it was also added to all 440 4-speed applications. As far as strength is concerned, outside of the input shaft, the input bearing, the retainer and some special gear sets, there were no other measures added to the A-833 for Hemi's. Compared to the Muncie you mentioned, a stock 23 spline A-833 will out perform ANY aluminum cased Muncie behind a modified big block whether it be Mopar or GM. Though an 18 spline input would be preferred, I know of many applications in which customers are running mid 500hp RB motors in 'sticky tired' B and E body cars with no issues. If you did decide to swap to an 18 spline gear set, it would be best to use an A-833 that has a 4.80" input bearing retainer. That way, you will reap all of the engineered benefits of going to the 18 spline gear set. PM if you'd like, I believe I may have a couple of complete 18 spline gear sets on the shelf.     

[John Milner]

Thanks for your detailed response. I am not sure what bearing retainer that my transmission currently has.  I will look into that and see.  It was out of a 383 4 speed 69 Charger. I have ran the 23 spline units and have never had an issue other than mine right now that I am running has a rough bearing noise under deceleration.  I have not been very nice to them either and they have handled anything that I wanted to put them through. However, I've always just been curious about the 18 spline transmissions and wouldn't mind giving one a try. 

One more question, what was special about the gear sets?  Were they made out of a stronger metal or maybe the teeth on the gears cut at a different angle when compared to the 23 spline gears?  If they are cut at a different angle and are a little more "straight cut" I would imagine that they might be a bit noisier.  If that is the case, I happen to like that. 

[Cooter]

I've sold more 4spds(833) to chevy and Ford guys than Mopar.

[John_Kunkel]

Keep in mind that some of the most powerful engines (Max Wedge/Race Hemi) came with the 23-spline trans and there was no epidemic of failures.

[c00nhunterjoe]

Keep in mind that some of the most powerful engines (Max Wedge/Race Hemi) came with the 23-spline trans and there was no epidemic of failures.

[astjp2]

One question I have is the 10 spline input from the MY6 transmission seems to have the same number of splines and helical angle as a 3.09 gear set. Is it possible to us the Chevy OD input with a Mopar gearset?

[Cooter]

One question I have is the 10 spline input from the MY6 transmission seems to have the same number of splines and helical angle as a 3.09 gear set. Is it possible to us the Chevy OD input with a Mopar gearset?

"10spline" doesn't man ness. that the physical size of the input in mm or inches will bee the same. I stuck a 10 spline disc on a Ford input and was "Sloppy" lose.

[astjp2]

One question I have is the 10 spline input from the MY6 transmission seems to have the same number of splines and helical angle as a 3.09 gear set. Is it possible to us the Chevy OD input with a Mopar gearset?

"10spline" doesn't man ness. that the physical size of the input in mm or inches will bee the same. I stuck a 10 spline disc on a Ford input and was "Sloppy" lose.

so is that a NO it wont work? or no you didn't like it?