What are the benefits of an 18 spline over a 23 spline behind a 700 hp engine? Worth the extra $$?

The input shaft and the gears inside are a little bigger and made out of better metal according to some of the Mopar drag engineers at there old seminars.
All the gears have bronze bushing inside them also instead of steel on steel like the 23 spline have which is better also
There have three different ratio also so make sure you get the one you like

I am not an expert but after reading multiple threads here, either one might work with hard compound street tires but real traction and 700 HP is going to test even a modified 18 spline. I recall that the 2/3 gear change is what blows them apart with real power and slicks. I am sure there are really good stick guys who get them to live a bit longer with good clutches but for the average street rat with a traditional clutch, it better not hook too well regardless of 18 or 23 spline.

Been running an 18 spline, slick shifted for many years. Heavy B body running low 11's. I pull the front tires at launch with 1.5 short times. I also run the same set up on the street, except for the slicks! Never broke anything in the tranny. From what I've researched, a 23 spline is good for around 550 ft/lbs, where the 18 spline is good for 650 ft/lbs. Both transmissions are very strong for a production unit. There are better ones out there, but that's another consideration.

"All the gears have bronze bushing inside them also instead of steel on steel like the 23 spline have which is better also"


So What...Why does that matter?


The thing with that is you can actually weld a speed gear to the main shaft. When that happens...The rear wheels lock up. When it happened to me I was in high gear at over 120mph. So you say step on the clutch... no no It doesn't work like that. The transmission is welded together, disconnecting it from the engine means nothing to your rear tires. 23 splines (for me) no longer go behind anything with some smoke

18 splines are barely adequate... I've busted so many I almost cant take it anymore. I have a shelf with clusters and speed gears all tore up and I race on polyglas tires. 3rd gear is the week link.

I will say this... A soft lock is your friend

I ran an A833, pro shifted, vertical gate shifter 23 spline, many years ago, ran low 10's with a 340. Never broke the transmission. Ran a three puck metallic type clutch. I found that if the clutched slipped a tiny bit, on the launch, the car ran faster, and was pretty easy on parts. I used to run an aluminum flywheel, and the riveted in heat shield would start to warp about every 150 runs or so, I could feel a little chatter driving around in the pits, I simply went home and replaced the heat shield, that was the sacrificial wear component. I know a guy with a fast Pontiac stick car, he runs low 9's and he said the same thing, clutch setup is what determines the life of the transmission. On a automatic, the fluid in the converter absorbs some of the shock off the line, a stick car uses the springs in the clutch hub and some slippage to do the same thing.