700r4 swap

[TXVeteran898]

Looking for some help i currently have a sm465 in my 85 c20 and i love the truck and recently has become my daily driver. Im looking for overdrive and want to swap to a 700r4 rather than do the nv4500 swap. Little help with a parts list I need to get me going to do the swap.
Thanks

 

[Jims86]

Looking for some help i currently have a sm465 in my 85 c20 and i love the truck and recently has become my daily driver. Im looking for overdrive and want to swap to a 700r4 rather than do the nv4500 swap. Little help with a parts list I need to get me going to do the swap.
Thanks

What rear gears do you have in it now?

 

[TXVeteran898]

3.42 get around 60 and the rpm's are about 2500, really would like overdrive to drop it to around 2000 at 70. Contemplating a gear vendor cause I like the 4spd and for the price I imagine cost around the same to do the conversion.

 

[Jims86]

3.42 get around 60 and the rpm's are about 2500, really would like overdrive to drop it to around 2000 at 70. Contemplating a gear vendor cause I like the 4spd and for the price I imagine cost around the same to do the conversion.

Would cost even less to change the rear end ratio, unless you use 1st gear for stump pulling all the time.
Assuming you have 215/85-16 tires, a 3.08 rear gear would yeild 2043rpm at 60 mph...for a fraction of the cost and work of a 700r4 swap, and keep a stronger transmission meant for a 3/4 ton truck.

 

[TXVeteran898]

Would cost even less to change the rear end ratio, unless you use 1st gear for stump pulling all the time.
Assuming you have 215/85-16 tires, a 3.08 rear gear would yeild 2043rpm at 60 mph...for a fraction of the cost and work of a 700r4 swap, and keep a stronger transmission meant for a 3/4 ton truck.

I thought about that but the engine in her is a little on the old side and im slowly building a small block for her but in the mean time she runs good but is already slow off the line with the 3.42 gears and the wide gap between 1 and 2. i can only imagine how slow off the line she would be with 3.08 gears.

Anyone on here hooked up a gear vendor to their sm465 that you know of? And i am leary about the 700r4 as i do tow a boat few times a month so would like to keep the set up i got but with od.

 

[HotRodPC]

You won't get a 3.08 gear for a 14b Full Float anyway. 3.21 is the highway gear for 14b FF if that's what you have.....and now that I think of it, he has the 14b SF. How do I know? 3.42 is available for 14b SF, but not 14b FF. Honestly, that set up you have now is not bad at all, and you're not going to save but maybe 1 mpg or so. All things considered, I'd keep what you have, for the strength and I'd run the other optional tire size that is OEM. 235 85R16. That's what I have on my 84 C20. It's just over 31 inches tall, actually to be 31.7 inches, and it's a narrow tire which is great for highway driving. With the 4 speed, you have an actual 1 to 1 ratio in 4th. 1 to 1 with 3.42 gears and a 31 in tires is just a hair over 2200 rpm @ 60 and is just under 2600 rpm @ 70 which puts you well under the 3000 max crusing rpm for long distance drives.

Also, if you're seriously thinking about going 700r4, I'd damn sure consider dropping down to a 4.10 rear gear too, cuz the 700r4 is gonna need all the strain taken off it that it can. I'd actually say 4.56, but I know 4.10 ratios are common and can be had for $125-$150 or so in a 14B SF and a direct swap in. 4.10 with 700r4 Locked up in OD and a 31in tire will give you just under 2200 rpm @ 70mph, and under 1700 @ 60

Gear Vendor? I'd get that idea out of my head. The cost of the unit alone is a deal killer. Then ad the fact of driveshaft mods, crossmembers mods, it would take you 20 years or more to recover the cost.

But, if you're deadset on it, you're 8 hours away, I'd trade you out of all your SM465 stuff, pedals, steering column, flywheel/flexplate, bellhousing blah blah for everything you need automatic including a trans and converter cores. Giving thought to it, might even just be easier to swap trucks.

 

[Jims86]

I thought about that but the engine in her is a little on the old side and im slowly building a small block for her but in the mean time she runs good but is already slow off the line with the 3.42 gears and the wide gap between 1 and 2. i can only imagine how slow off the line she would be with 3.08 gears.

Anyone on here hooked up a gear vendor to their sm465 that you know of? And i am leary about the 700r4 as i do tow a boat few times a month so would like to keep the set up i got but with od.

if its slow off the line now, it would be worse with a 700r4, as 1st gear is about 1/2 the ratio of the sm465.

 

[HotRodPC]

if its slow off the line now, it would be worse with a 700r4, as 1st gear is about 1/2 the ratio of the sm465.

Uhh not likley. I much doubt he's taking off in 1st gear. Most who drive a SM465 as a DD, drive it like L 1 2 and 3rd. Basically drive it like a 3 speed. I drove my SM420's that way too, my Dad drives his NV4500 like a 4 speed, starting off in 2nd too. No need to start off in granny low.

 

[Jims86]

Uhh not likley. I much doubt he's taking off in 1st gear. Most who drive a SM465 as a DD, drive it like L 1 2 and 3rd. Basically drive it like a 3 speed. I drove my SM420's that way too, my Dad drives his NV4500 like a 4 speed, starting off in 2nd too. No need to start off in granny low.

Right, but I was assuming for the sake of conversation, that he goes through all the gears. I know some people that think its bad to drive them that way, even though you show them proof to the contrary.
You suggestion of upping the tire size, or moving the gears up the ladder with the highest rear ratio would probably satisfy his needs, rather than swapping in a transmission that wont take much 3/4 ton style abuse, without a very pricy rebuild.
Ifit was me, and I was dead set on the auto, I would find a 4l80e and use the 94-95 TBI PCM to control it.

 

[HotRodPC]

Right, but I was assuming for the sake of conversation, that he goes through all the gears. I know some people that think its bad to drive them that way, even though you show them proof to the contrary.
You suggestion of upping the tire size, or moving the gears up the ladder with the highest rear ratio would probably satisfy his needs, rather than swapping in a transmission that wont take much 3/4 ton style abuse, without a very pricy rebuild.
Ifit was me, and I was dead set on the auto, I would find a 4l80e and use the 94-95 TBI PCM to control it.

Yep, the 4L80-E is the best choice by far if he's willing to fork out the funds and go electronics. He can get that done for about half the cost of a gear vendor unit provided he could locate a used 4L80-E at a fair price. But yep, I'd say tire size change with the 3.42's should be sufficient. Doesn't sound like he does alot of towing, to need lower rear gears, but you're right, I've never liked the idea of a 700r4 in a 3/4 ton truck and I can even build my own when I break one.

 

[Jims86]

Yep, the 4L80-E is the best choice by far if he's willing to fork out the funds and go electronics. He can get that done for about half the cost of a gear vendor unit provided he could locate a used 4L80-E at a fair price. But yep, I'd say tire size change with the 3.42's should be sufficient. Doesn't sound like he does alot of towing, to need lower rear gears, but you're right, I've never liked the idea of a 700r4 in a 3/4 ton truck and I can even build my own when I break one.

Millions of dollars in engineering cant be wrong.

 

[TXVeteran898]

Well im running 265 tire and i just threw a tac on there about a week ago just to find out what im running rpm wise and at 60 im right around 2400 with that tire size. I really dislike the 700r4 been through 3 in my k5 blazer but i really want overdrive as i commute alot on the highway and i dont like cruising at 60 to try to keep the rpm below 2500.
And yes i use the tranny like a 3 spd L gear is to small to even bother and 1st isnt much better. If i had the coin i would do the NV4500 but the tranny alone is pricey plus the AA bellhousing and all the other little things you need to do the conversion. Guess i will just stick it out as is to put away some money so i can do the lq9 4l80 swap i really want to do.