Adapt 4x4 Th350 in Place of 700r4

[HotRodPC]

i found a spacer kit with no shaft you can view the instuctions on pdf it said to get a shaft out of a car tranny with a 6in tail and measure from the center of the speedo gear clip hole out to 31/4in and wrap tape, and cut off 13/8in including the saw blade. now is the T/C bolt pattern the same for the 350 and 700r ?

That sounds right to me. You see the chunk I cut off, it's about that long. I know it's between 1in and 1.5 inch, so 1 3/8 is probably good and it can be off by 1/8 too. yes, the Th350 and 700r4 are the same bolt pattern so they share the same Tcase adapter. All you need to worry about is getting the output shaft the correct length and use that spacer and you're good to go. It's very easy.

 

[TIC]

That sounds right to me. You see the chunk I cut off, it's about that long. I know it's between 1in and 1.5 inch, so 1 3/8 is probably good and it can be off by 1/8 too. yes, the Th350 and 700r4 are the same bolt pattern so they share the same Tcase adapter. All you need to worry about is getting the output shaft the correct length and use that spacer and you're good to go. It's very easy.

i guess Tcase and torque converter share the same initials, i ment the torque converter bolt pattern. and do ya measure from the center of the bolt hole to the center of the Tconv. and double that to get the hole pattern # ?

 

[HotRodPC]

yes, the torque converters are all the same, 2wd and 4wd. Same bolt patterns. Same part #'s even.

 

[Roy gibson]

I'm thinking about doing the switch from a 700r to a 350 turbo in a 84 4x4 with the spacer and a 2 wheel drive trans.Was wondering if everything else will work in same place cross member linkage mounts and Speedo thanks for your help

 

[mcpaddleboat]

Hey guys. I’ve been reading this thread for about three days now and it has helped a lot. I still have just a few question. I have an 89 gmc 4x4 with a 350 tbi. It came stock with a 700r4 and a 241c tcase but I lost third and fourth gear. I just had a th350 already mounted, with an adapter, to a 241c tcase given to me. I want to put the th350 in my truck until I have time to rebuilt the 700 for the overdrive feature. But in the mean time I just need to know if the kickdown cable still hooks on to the throttle. What do I hook the vacuum modulator on the th350 too? And there is a 4prong plug on the 700 that is behind the shift linkage goin into the valvebody that is not in the th350, do I need to bypass the pig tail or just leave it be? I can upload any pictures if need be. Thanks in an advance for any help that can be shared.

 

[HotRodPC]

Simple simon here for you. BTW, your 700r4 burnt up the 3/4 clutch pack. I suggest a commercial Alto 3/4 clutch pack in the rebuild or equivalent, not the Z pack.

Yes, just bolt it in. If it has the adpater already, same driveshafts and all. Detent cable will hook to the same place the TV cable on your 700r4 went, and just run a vac line from the modulater to any engine vacuum soure. You can T off the carb, T off the intake, wherever doesn't really matter so long as your getting vacuum to it.

 

[mcpaddleboat]

Thanks bud. I still need to get a torque converter but I don’t know if it’s a lock up trans or even if it’s a th350c. Any obvious way to tell the two apart?

 

[Swims350]

square plugin on the driver's side dead giveaway of a th350c lockup

 

[mcpaddleboat]

No square plug on the th350.

I do have a square plug on my 700r4 that I pulled out of my truck tho. So do I just need to leave that plug alone or should I jump it.

 

[Swims350]

leave it alone that's the lockup when you put in the th350 you can leave it hanging. Maybe tape the end to keep out dirt, then if you ever do a lockup th350 or another 700r4 you can reuse it.

 

[HotRodPC]

Swims is correct. Just tape that 4 prong square out of the way to keep it clean and from getting ripped on something while you're wheeling. So if your Th350 does not have the square plug, this is a Th350, not a Th350C, C designating Converter Clutch. You're going to lose some mpg, but you certainly have the more reliable transmission in a Th350 without the Converter Lock Up. Let us know if you have any more questions. It's straight forward install provided it's done right.

 

[mcpaddleboat]

Thanks a lot guys. You really answered a lot of questions for me

 

[hatzie]

Swims is correct. Just tape that 4 prong square out of the way to keep it clean and from getting ripped on something while you're wheeling. So if your Th350 does not have the square plug, this is a Th350, not a Th350C, C designating Converter Clutch. You're going to lose some mpg, but you certainly have the more reliable transmission in a Th350 without the Converter Lock Up. Let us know if you have any more questions. It's straight forward install provided it's done right.

I'd get the mating half and four cavity plugs to cover the connector. It's less than $5 in parts. It'll keep out the dirt and weather far better than any other solution.
One Weatherpak 12015024 connector and four Delphi Packard 12010300 cavity seals.

If you get a TH350C you'll need the lockup control.

 

[Dub11]

And since this is the thread that brought me here. Here is this.
http://www.advanceadapters.com/products/50-8506-adapter-to-replace-gm-700r4-with-gm-2wd-th350/

 

[84 M1008]

As most of us know already, Tranfer Case adapters for 700r4 usually fit Th350 also, and vice versa. This is because the tailshaft housing bolt pattern is the same and so is the output splines meaning, they'll share the same driveshaft yoke.

Here is where the 2 differ and why you simply can't swap a Th350 in place of a 700r4 and vice versa. The reason is, because the 700r4 is longer in the main case before it gets to the tailshaft. So what happens, is the crossmember needs to come forward if your using a Th350 instead, and also you'd need a new driveshaft since it would be short.

Today I happen to be at Pull a Part and seen a 4x4 Burb. It was gutted, except I could see the trans and tranfer case hanging down from a distance. I looked inside the Burb and seen the gear shift indicator was D 321 telling me it was originally a 700r4 which is correct for an 85. Just happened to look under it and seen a Turbo 350 and NP241C. Walked off and then all of a sudden it him me. I bet there is an adapter for Th350 to 700r4. There sure was. Its an expensive adapter. I've been told about $225. It took me about 15 minutes total to get it and I bought it for $5. I also got the hardware that goes with it.

I had to get this adapter when Monster sent me a super duty R4 transmission for a C30 not a K30. I was pissed, but it worked out.

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