Need info about the 203 to 4speed t-case. I did a search but couldn't find what i needed for my app. My cruiser runs a 400 sbc to a 32 spline 465 hooked to a 4 speed case stock axles with 4.10 gears and kockers, i have plenty of power but i need lower gears. It just doesn't crawl. I dont want to regear the axles because it see's the freeway once and a while, and a toy box or orion are just out of the question because of cost. So what do i need to do the 203 range box? Any info would be great.
203 to 4 speed t-case? (1 Viewer)
- Thread starter fjsomething
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Doubler
I don't know what 4 speed transfer case you are talking about.
But I think you are talking about using the front half of the 203 and another transfer case, effectively doubling your low range.
Problem is that GM didn't make many 465/203 combos. It wasn't a very desirable combination.
I wanted to do the same thing, but could not find a 465 to 203 adapter.
I'm sure someone else will have more info/facts.
JR
I don't know what 4 speed transfer case you are talking about.
But I think you are talking about using the front half of the 203 and another transfer case, effectively doubling your low range.
Problem is that GM didn't make many 465/203 combos. It wasn't a very desirable combination.
I wanted to do the same thing, but could not find a 465 to 203 adapter.
I'm sure someone else will have more info/facts.
JR
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- #3
Its the stock case that came behind the 4 speed trans.
Np205
Probably a NP205.
If so, it will be difficult to find the adapter to bolt up the 203 to the 465. And I think there is some difference in spline count in the 465 output to the 203 input. Hell, I don't know.
Does you xfr look like this one?
JR
Probably a NP205.
If so, it will be difficult to find the adapter to bolt up the 203 to the 465. And I think there is some difference in spline count in the 465 output to the 203 input. Hell, I don't know.
Does you xfr look like this one?
JR
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Agree with JR. Your challange will be finding an adaptor from your tranny to the np203. I got my adapter plate and shaft from Advanced Adaptor when I did my 203 to 3 speed case. Give them a call and see they can help you.
Let us know what you find out. IMHO, this is a cheap way to get some lower gears.
Let us know what you find out. IMHO, this is a cheap way to get some lower gears.
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- #7
sorry mine is the stock t-case that came behind a 4 speed cruiser trans. also did they ever put a 203 behind a 32 spline 465?
Tigerstripe40
SILVER Star
fjsomething said:
They do make the adapter.
I think you will need to use one of the transitional gears for the 4spd t-case that has 10 splines for the input. But you will have to double check that.
If you are using this in an FJ40 you will have a VERY long drivetrain, and a VERY short rear driveshaft.
Honestly, I think you'd probably be better off getting an Orion 4:1 t-case rather than runnign the NP203 reduction box.
If you had more wheel base, then that's another story.
465/203 adapter is easy. Call advance adapters. And the 203/4 speed tcase Colorado Cruisers/Mudrack etc Can hook you up.
A lot of if this is gonna work or not will depend on where the V8 was placed. If it is fairly far forward you will probably be fine. If not, you might need to flip your rear springs around a bit.
A lot of if this is gonna work or not will depend on where the V8 was placed. If it is fairly far forward you will probably be fine. If not, you might need to flip your rear springs around a bit.
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- #10
I dont think wheel base should be a prob. im sittin at about 102 right now and i hope to go longer then that. Mace do you know about what they charge for the 203/4 speed case adapter or can you give me some info on how to reach them. as for the orion, its just out of the price range and plus i still want the 2 to 1 low range or i guess it would be mid range.
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- #12
thanks mace. i'll give them a call.
You can change the output shaft in the 465 from 10 spline to 32 spline, then the gear reduction box from the NP203 would be readily available (like behind a Turbo 400). That saves the length of another adapter.
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- #14
So LukeZero, my trans is already the 32 spline, so what else do i need? well i know i need a 32 spline 203, but where can i find an adapter besides from AA.? Will a th400 adapter work?, I wouldn't think so but its worth a shot.
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They're hard to find but there is a factory GM piece from the 465 to the 203. Like vintage 1969 or something.
Just for reference I recalled that Jack Rice did what you are looking to do
Here is his write up from the tech links
http://medusa.ih8mud.com/NP205/Doubler.html
"The frustrating aspect of NP203 gear boxes is that they utilize a female input shaft that connects directly (no spud shaft or coupler) to the transmission to which they were originally mated. This means that each original transmission-NP203 combination used a different input gear, varying in both length of the input shaft and the spline count (e.g., 10-spline for the SM465, 27-spline for the TH350, and all other combinations used on Dodge and Ford transmissions). Even more frustrating is the fact that perhaps the most popular combination for today's conversions, namely the SM465-NP203, was the most rarely used OEM combination. The 465-203 combination was only used in 1974 and rare '75 Chevy Blazers. Consequently these 203 cases and their adapters are very difficult to find."
Here is his write up from the tech links
http://medusa.ih8mud.com/NP205/Doubler.html
"The frustrating aspect of NP203 gear boxes is that they utilize a female input shaft that connects directly (no spud shaft or coupler) to the transmission to which they were originally mated. This means that each original transmission-NP203 combination used a different input gear, varying in both length of the input shaft and the spline count (e.g., 10-spline for the SM465, 27-spline for the TH350, and all other combinations used on Dodge and Ford transmissions). Even more frustrating is the fact that perhaps the most popular combination for today's conversions, namely the SM465-NP203, was the most rarely used OEM combination. The 465-203 combination was only used in 1974 and rare '75 Chevy Blazers. Consequently these 203 cases and their adapters are very difficult to find."
fyi!
if you're going to bye an adapter i would bye the setup to go into the split case (fj60) and grab one of them. the cost of the adapter is the same and they are a stronger design. I have broken three outer cases on the 3 and 4 speed fj40 cases. and two front out put shafts for the frond drive(one fine,one corse). I'm planning an fj60 build like bob bellafounte" with the 350,th350,203, splitcase. should be hella stout. Right now i'm running a 40 with a helthy 350,sm420,rockbox,4speedcase/3speedgears,,,,, which is what i keep breaking cases/outputs in. I built a transfer case saver though and have been ok for the bast year and a half though, knock on wood.. anyway just an idea
if you're going to bye an adapter i would bye the setup to go into the split case (fj60) and grab one of them. the cost of the adapter is the same and they are a stronger design. I have broken three outer cases on the 3 and 4 speed fj40 cases. and two front out put shafts for the frond drive(one fine,one corse). I'm planning an fj60 build like bob bellafounte" with the 350,th350,203, splitcase. should be hella stout. Right now i'm running a 40 with a helthy 350,sm420,rockbox,4speedcase/3speedgears,,,,, which is what i keep breaking cases/outputs in. I built a transfer case saver though and have been ok for the bast year and a half though, knock on wood.. anyway just an idea
spendy but they must look like this
http://cgi.ebay.com/ebaymotors/CHEV...004QQitemZ140007081524QQrdZ1QQsspagenameZWDVW
http://cgi.ebay.com/ebaymotors/CHEV...004QQitemZ140007081524QQrdZ1QQsspagenameZWDVW
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- #20
kegwilliams said:
How much more would it cost me to convert the split case input to the 32 spline? I Ithink if I have to buy a new input for the t-case, a 203 adapter then the adapter for the 203 to split speed case, if you start to add up the money a rock box or toy box starts to look good and thats way out of the price range. I want to get low gears in the t-case but im kinda on a budget.
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