6.2 TH400/Np208 To SM465/NP205 Swap Questions? Opinions?

[campfire]

Thankyou for the sources I will check them out.
I'm pretty set on swaping in the sm465 since it will be less of a hassle, and I've already found a decent donor truck Just gotta get the parts together and make sure I don't screw up.

To clairfy
-I'll bolt up the clutch pedals and mechanisms either mechanical, or a hydrallic one if I can find a donor after 85. that should bolt on directly
-I will order a Single mass Flywheel for a 6.2 manual
?-will I be able to use the same clutch disc/cover and other components?
-Then bolt the bellhousing/tranny/transfercase as a single unit.
?- then the only issues I need to face is the crossmember for the tranny, and drive shaft lenghts correct?

Thankyou for all the helpful information

Yes, all the parts will bolt on directly from the donor truck. All you will need to buy is a flywheel (though I would replace the wearing parts like the pilot bearing). The pedals (hydraulic or manual) will bolt in with minimal modifications. You will need to modify them to accept hydroboost, but that's not a big deal (read the thread). You'll hafta attach the mechanical linkage brackets to the relevant frame/body locations, but that's just copy & paste from one truck to the other.

If you go with the hydraulic clutch , you will need to round up pedals, M/C, S/C, the hydraulic line, and also a bell housing with the mounting boss for the slave cylinder. This is worthwhile if you're going to run the NV4500 in the future, but if you're happy with your current gearing, you may never want O/D. Maybe you're better off just running the setup from the donor instead of finding a 1986+ donor.

Clutch disc will be the same, cross member can be moved if need be. Like I said before, redoing the shafts can add another level of cost vs. running one of the later transmissions (GM eventually standardized tranny lengths, but not until later). The good news is that your donor truck will come with a front driveshaft that should be the right length, so you should just hafta modify the rear shaft.

 

[KSSIII]

M1009 crossmember is the same as the 79. May need to move it to a forward set of holes that are probably there. Shifter holes are not the same. Swap trans humps. Then shafts need built.

Just thought you will be swapping vacuum boost brake pedals to a hydro boost system. You'll need to look into the differences at the pedals between the two. Vac pedals can be made to work on hydroboost. Don't know what it takes though.

Great! shafts wont be an issue either I know a place where they can lengthen or shorten mine.
I didn't take the brake pedal assembly into the equation, but thanks for the heads up, I'd like to keep the current brake assembly I have now, I'm sure I should have the parts available in the donor truck if i have to convert.

Thankyou

 

[campfire]

M1009 crossmember is the same as the 79. May need to move it to a forward set of holes that are probably there. Shifter holes are not the same. Swap trans humps. Then shafts need built.

Yes, if both trucks have removable trans humps, definitely swap them. That is such a nice feature, I wish GM had done so on all of their trucks.

Just thought you will be swapping vacuum boost brake pedals to a hydro boost system. You'll need to look into the differences at the pedals between the two. Vac pedals can be made to work on hydroboost. Don't know what it takes though.

Yes, the pedals are different. There are at least 3 solutions to this. As I said before, read through my M1009 thread, the procedure and various solutions are detailed with pictures.

 

[campfire]

Great! shafts wont be an issue either I know a place where they can lengthen or shorten mine.
I didn't take the brake pedal assembly into the equation, but thanks for the heads up, I'd like to keep the current brake assembly I have now, I'm sure I should have the parts available in the donor truck if i have to convert.

Thankyou

You do, it just will require removing 2 studs from the new pedal bracket and then modifying the brake pedal to match the hydrobooster. You can take your old automatic pedal and cut it down to size and then bolt it into the new bracket (which is what I opted to do on both of my rigs). Installing the bracket (above the steering column) requires taking a bunch of the under-dash area apart, but it's not a big deal. It's just a headache.

 

[campfire]

Awesome! thats great to hear Hopefully I'll get the donor by the end of this next week. but I cant see any pictures youve posted, I click them and they bring me to an error page

You hafta be a paying member to see pictures uploaded to the forum. For you, I think it is definitely worth the $25 cost because you will benefit a bunch from seeing pictures of how all this can work out in other real-life trucks. The 3 pictures that I posted in this thread are engine speed vs. wheel speed charts, to predict cruising RPM values for a given gear/tire/tranny combination. Not required, but kinda nice, and they are the reference data behind my statement that your combination will be happy on the street.

 

[KSSIII]

Yes, all the parts will bolt on directly from the donor truck. All you will need to buy is a flywheel (though I would replace the wearing parts like the pilot bearing). The pedals (hydraulic or manual) will bolt in with minimal modifications. You will need to modify them to accept hydroboost, but that's not a big deal (read the thread). You'll hafta attach the mechanical linkage brackets to the relevant frame/body locations, but that's just copy & paste from one truck to the other.

If you go with the hydraulic clutch , you will need to round up pedals, M/C, S/C, the hydraulic line, and also a bell housing with the mounting boss for the slave cylinder. This is worthwhile if you're going to run the NV4500 in the future, but if you're happy with your current gearing, you may never want O/D. Maybe you're better off just running the setup from the donor instead of finding a 1986+ donor.

Clutch disc will be the same, cross member can be moved if need be. Like I said before, redoing the shafts can add another level of cost vs. running one of the later transmissions (GM eventually standardized tranny lengths, but not until later). The good news is that your donor truck will come with a front driveshaft that should be the right length, so you should just hafta modify the rear shaft.

Awesome! thankyou very much Campfire and every who has contributed, this was my most daunting expedition with my M1009 but now Its almost laid out like a map

 

[campfire]

Awesome! thankyou very much Campfire and every who has contributed, this was my most daunting expedition with my M1009 but now Its almost laid out like a map

Exactly. Other folks have already done this conversion, so you can be pretty confident of completing it without hitting any major snags.

 

[campfire]

@obijuank5 pointed out that not everyone can see sig lines (they're turned off by default if you're on a mobile screen), so here is an explicit link to my M1009 build.

https://ck5.com/forums/threads/322496/

 

[wallerus]

Thankyou for the sources I will check them out.
I'm pretty set on swaping in the sm465 since it will be less of a hassle, and I've already found a decent donor truck Just gotta get the parts together and make sure I don't screw up.

To clairfy
-I'll bolt up the clutch pedals and mechanisms either mechanical, or a hydrallic one if I can find a donor after 85. that should bolt on directly
-I will order a Single mass Flywheel for a 6.2 manual
?-will I be able to use the same clutch disc/cover and other components?
-Then bolt the bellhousing/tranny/transfercase as a single unit.
?- then the only issues I need to face is the crossmember for the tranny, and drive shaft lenghts correct?

Thank you for all the helpful information

You might want to think about buying a leg exorcise machine, 2 months of rowing that thing in traffic (nv4500 is worse) and you left leg will be as big an Oak tree. Unless you have daily driven a truck manual you won't understand. Good luck and have fun.

 

[dyeager535]

Not a big fan of the 205 anymore. A 241 is a better option for most people, IMO. There are always variables, but the 241 is a lot easier to manhandle and has far better low range. Also, you'll have to butcher your floor to fit the 205 shifter stuff in it, and it won't line up with the reinforced ring in the floor where the boot/trim ring is supposed to bolt to. It will leak mud/water if not bolted down tight. 208 really nothing terrible about it either, I just like the 241 better.

Finding an '85+ 465 isn't easy, but its doable. Note that the 10 spline 465/205 setup is notorious for stripping the coupling between the two (almost guaranteed to need replaced immediately if you don't want failure later on) and breaking the adapter, which is expensive to replace. Not only that, the front driveshaft connection on the pre-'85 units absolutely sucks to disassemble once it's in the truck. The '85+ units are not a lot of fun either, but a whole lot less hassle screwing 4 bolts in from the front.

You've got a 208, I don't deal with automatics, but the '85+ 465 will be 32 spline output, your 208 will be 32 spline input, they might even bolt together.

I used to think the 465/205 combo was the ultimate, but I've changed my mind. For sheer longevity, it probably is. The 205 is "stronger" than the 208/241. But many people don't need that added strength. Coupled with the downsides, for a truck that isn't purpose-built to take serious abuse, I don't think the 205 is the answer. Don't forget (even though I'm ignoring the upside of a fixed yoke 205) the slip yoke 208/241 don't require driveshafts that wear out. The splined section of the fixed yoke driveshafts wear out, and if you haven't priced out driveshafts lately, they are expensive.

I've been running a 465/205 for ~16 years now, and I have the 241 to replace the 205 sitting on my floor ready to swap.

 

[campfire]

You've got a 208, I don't deal with automatics, but the '85+ 465 will be 32 spline output, your 208 will be 32 spline input, they might even bolt together.

Yes, the 208 Tcase will bolt to any 32-spline round-pattern GM transmission. And if you change the input shaft, it will bolt to any round-pattern 27-spline transmission, also. It's nice having the swapability of the later equipment. But if the donor truck drivetrain is in good shape it can be swapped in as a matching set (yes, replacing the coupler is a good idea). The harder part, as mentioned above, is finding a later SM465 when you already have the donor truck lined up.

 

[KSSIII]

Thankyou everyone, the donor sold before I could get to it, so now im on the search for another one

 

[KSSIII]

I tried getting in contact with that guy in maryland about his 6.2/ manual trans for like 200$ but he never replied, I appreciate it though

 

[KSSIII]

http://www.oreillyauto.com/site/c/d...Search_flywheel_5002264_2074&keyword=flywheel
Would this be the correct flywheel? casting #14050525

 

[campfire]

http://www.oreillyauto.com/site/c/detail/PTQ5/NFW1049/02271.oap?year=1983&make=Chevrolet&model=K20+Pickup+4WD&vi=5002264&ck=Search_flywheel_5002264_2074&keyword=flywheel
Would this be the correct flywheel? casting #14050525

That is the correct casting number. It's the same form factor as a sbc flywheel but noticeably heavier and is intentionally off-balance to externally balance the engine (which is why the 7th hole is drilled to index the flywheel correctly to the crankshaft).

 

[sreidmx]

I'll jump in regarding the gearing, depending on where you live if it's flat go for the taller gearing, if it's not you are gonna want the lower gears, I have 33/3.73 and even at 65 it feels like the motor is spinning decent rpm.. it'll do it, trust me I've made it do it, I've also kept it wound up to 70 and it'll do that too but it kills the mileage. I think it got 14 mpg on that trip. So I stick to 60-63 mph and that keeps it happy enough and gets 16-17 mpg around here with all the hills.

 

[KSSIII]

I'll jump in regarding the gearing, depending on where you live if it's flat go for the taller gearing, if it's not you are gonna want the lower gears, I have 33/3.73 and even at 65 it feels like the motor is spinning decent rpm.. it'll do it, trust me I've made it do it, I've also kept it wound up to 70 and it'll do that too but it kills the mileage. I think it got 14 mpg on that trip. So I stick to 60-63 mph and that keeps it happy enough and gets 16-17 mpg around here with all the hills.

Awesome! thankyou

 

[campfire]

Awesome! thankyou

I know you said that you couldn't see them, but the charts that I posted before will give you a graphical comparison of engine speed with different gearing options. I could email them to you if you aren't willing to spring for a paid membership.

Or you could fiddle around with excel and make your own.