To help you here, lets say it this way:

all slants that had an a833 behind them with a 122 tooth flywheel,
gets you a great tranny with no known good off the shelf performance clutch options

all slants that have the large flywheel, 143 tooth have the NP 435 tranny
that gets you a flywheel that has some performance clutch options, but with
all respect due to America's farmers, is a farm truck tranny, real low granny gear,
no fast shifters,,

maybe an adapter the fits an a833 to a NP435 flywheel housing would be the ticket seems that DI is working on that,,,,
maybe join forces on that project?

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It's a typo...

All 1975-1987 A-833OD equipped vehicles use the 122 tooth flywheel and either the 9 1/4" car clutch or the 10" truck/ HD car clutch... neither of these are suited for high performance use,
luckily the 9 1/4" will just wither and fade, unlike the 10" that will explode if pushed to the limit. With some judicious fitting you may be able to use the 273 9.5" clutch... the bellhousing is identified by the starter being up toward the manifold stack.

1975-1976 flywheels are lighter than the cast crank engine 1977-1987 flywheels and can be noted as having a ring of metal on the backside of the flywheel... the extra weight will help launch a heavy vehicle, but will cause some loss of quick shift time in getting into the next gear as the extra weight takes a little longer to get the syncros to line up...

Going back to the early 60's slant six powered trucks could be opted with a 143 tooth flywheel that uses the 11" clutch common to the economy big blocks... the 60's models had 10 wide spline teeth and somewhere in the late 60's early 70's they went to the more common 23 spline. This bellhousing is identified by the starter being low to the ground like a small or big block.

If you are Rick (that's an awesome thread on what is this clutch setup?!!?!), you might get lucky and get a 130T small block set up that bolts to a slant six from a forklift... which would allow the use of small block clutches.

McCleod made the best setup but no longer available. I ran a Spec 2+ as a daily driver in my duster with a warmed up base engine and lasted the longest, I tried a stage 3 behind a 196hp build and it eventually withered.. I thought it was the hub and went with stage 4 solid hub puck clutch and that to failed to hold behind a 200+ hp engine after about 3-4 passes at the track...

After seeing Dave M knock down an 11 sec 1/4 in his car with an 11" clutch and a lenco planetary transmission, I thought I'd try to make it translate.

I have made one plate, and have a spare "blank" with and IBR hole bores in it as a spare/future development (maybe future tremec cobra box...)

If you decide that you want to go that route you will need to have a machinist make up a plate to go between the bellhousing and the A-833OD box... then there will need to be holes drilled and counter sunk for the 11" clutch bell then holes for the A-833 pattern to bolt the tranny to the plate.

So far I have all of it installed in my car with a 12:1 NA engine... because cars have less room than trucks and I used the mechanical linkage, exhaust and the starter clearance to the centerlink is problematic... here's the rub (and not trying to hijack the thread):

NP bellhousing typically uses a big clunky 9 tooth starter (I have seen some that used the standard 10 tooth starter but not sure if the flywheel tooth pitch changed, I'm using a matched set from a 1983 D-150). A denso mini starter can be made to work for this low starter combination by pulling a standard Dakota starter and a starter from a 1992 V-6 Dodge Minvan... you will need the nose cone, contacts, plunger, and body from the dakota starter, you will need the 11 tooth gear (and or the end assembly depending on compatibility). Luckily denso starters are like Holley 4 barrels and everything can swap back and forth if needed as long as the end result fits together... this will get a lighter starter for the HD truck crowd with the granny 4 speed transmission.

Current jackstand testing of this set up started well, but after a few runs up to high rpm the OD transmission failed to want to shift from 3-OD back to 1-2 or Rev. everything external checks so I think putting a very heavy flywheel and a lot of power to the input shaft has bent something in the shift levers or the crossover lockout mechanism. Either way it did shift twice in a test run from 1-OD under a no load situation at 4-5000 rpm....

Another item to consider is the issue with the aluminum casing. The A-833 is a fairly good unit in design.. but for the OD unit, when it is under load in 1,2,and OD all the power is going from the input shaft to the countershaft and back to the main/output shaft... so any heavy torque applied here can force the input shaft and mainshaft to bow slightly and put force on the countershaft.. if abused enough the counter shaft will wallow or egg the holes it sits in and then you'll have gear mesh issues... (this doesn't happen in 3rd since the shift locking collar directly ties the input and mainshaft into one unit and anything the engine put out goes to the driveshaft and rear axle...a fair amount of racers using the OD box will just shift to 3rd and leave it until the end of the run).

Two ways to help this situation will be to have the transmission rebuilt and while inspecting have them bore and bush the casing with something better than cast aluminum... or if weight isn't a problem, you can find a 1975 A-body Iron unit and swap the bodies out (an number of big block guys running an A-833OD Truck unit in their E bodies on another board have gone this route)


Hope that gives you what you need to figure out how to tackle the 4000 lb boosted brick trying to clobber a 13-14 sec 5 liter.

If you have your heart set on needing the gearing and an OD and an automatic is a better road for you, Lou can give you the run down on the hard to get adapter and a smallblock A-500, or you can see if the adapters are still available for the GM 200 or 700R4 transmission.

THANK YOU VERY MUCH!
That makes so much more sense laid out like that
I guess cutting the trans tunnel will have to be put on hold until I can de idea what the best option is here, thanks gents

What is a realistic number you think the current market would be interested in, 20-25?

They would build nearly anything if the magic number is 100?

I would bet we could get 20-25 people together. I would buy 2-3 myself if McLeod would make the good 9" again. If they stepped up to a really good 10" diaphragm with high clamping force, I would also be in for that. The 9" is really good, though, at least up to about 300 ft lbs.

Lou

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Home of Slant6-powered fun machines since 1988

I'd buy 2 at this point just to get the numbers up