Where to go from here (Motor and Trans)

[mr_blasto]

Been a while since I posted in here because my truck has been in storage since the motor went bad almost a year ago. I have the funds to do something about it now, I am just not totally sure what I want to do.

I am almost certain I am gonna put a 383 in, but I get stuck after that. The key points I am stuck on are heads (Vortec or 180cc Dart Iron Eagle), carb v. TBI, and most recently transmission--if the motor is out and you want to make the truck fun to drive, might as well get a different tranny.

This may sound backwards but I think if I can decide on a transmission that will help me decide everything else--just because it is all a budget game. The truck will be running 37's with 4.56 gears and the th350 just doesn't seem ideal. After playing with an online calculator the th350 just isn't impressive from a crawling or hwy cruising point of view, but it is impressive from a budget and simplicity point of view (it was working just fine when the motor died). Then I started eyeing the 700r4 and the nice hwy rpm's as well as slightly better crawl ratios--but these are pricey to have built right and even so, I don't know if my mind would be at ease (and it would need a doubler for awesome crawl ratios). Then I plugged in the numbers for the sm465 and I started getting excited.

The 465 seems to be liveable at hwy speeds, but not ideal. The crawl ratio should be pretty respectable, and if I add a doubler down the road it should be awesome. I also trust a stick a lot more than an auto, and I enjoy driving a stick more than an auto. I have one of these lined up with a np205 and 32 spline output for $200, so I would be all set for the doubler down the road. I have almost totally talked myself into this setup, the only problem is that I currently have an auto and I am worried about doing the conversion to a stick. Is this that big of a conversion or pretty simple and straight forward? Yes I read the write-up in the technical articles section.

What would you guys do? My budget for this whole motor rebuild tranny thing is $5k total, but my motor has already been rebuilt at least once before, so I will likely be starting from scratch with the motor.

 

[Greg72]

The SM465 and TH350 should both be identical on the highway.

Neither one has an OD gear so the final ratio is going to be 1:1 on either one.

Sounds like you might also be forgetting to calculate for the stall converter "effect" when calculating crawl ratios for the auto trannies. They aren't that far behind the SM465 in terms of 1st Gear "real world" ratio.

Either way, it DOES sound like you're going about it backwards. Deep crawl gearing will never come from the transmission....if you want a dual-purpose rig, the only place to add deep crawl is the transfer case. Otherwise, you'll be running way too much RPM on the highway.....

OD trannies aren't really an option either....too long when combined with a Doubler (especially in a 104" 1st Gen). Maybe with an aftermarket box like an Atlas or STaK....but those will never fit in the budget anyway.

 

[mr_blasto]

You didn't vote. You are just adding to the uncertainty... so cruel.

 

[4X4HIGH]

If i were in your shoes i would buy a crate engine and swap the cam to a more torque friendly version then do a doubler with triple stick using the 700R4 trans after a quality build of HD parts. This will net you everything you're wanting within your budget.

 

[mr_blasto]

If i were in your shoes i would buy a crate engine and swap the cam to a more torque friendly version then do a doubler with triple stick using the 700R4 trans after a quality build of HD parts. This will net you everything you're wanting within your budget.

Show me how? The crate engines I have been looking at look like they would take up about my whole budget after shipping and adding whatever they need to be turnkey. If I could seriously do this setup within my budget with HD parts, I might just name my first born after you.

Links...

 

[bigblock72]

700r4 all the way!!! It's just slightly longer than a t350 has a lower first gear and is plenty sturdy for a 383. The 465 is ok but crawling with a 4 speed is tough unless you have a lot of gear ratio, meaning a doubler is going to be mandatory if you plan on doing anything very serious in the rocks.
4.56s are a little high for 37" tires so make sure the motor makes plenty of torque below 3,000 RPM. With that in mind I'd suggest a set of Vortec heads (I really like the Bowtie Vortecs) and a short duration hydraulic roller. Keep the duration @ .050 under 215* on the intake and the lobe center in the 112-114* range. Also make sure you use dished pistons to keep the compression under 9.5, that big, heavy high geared beast will want to ping. Step up to fuel injection (even TBI) if you can.
If you do use the 700r4 make sure the converter lock up works properly so you don't cook the trans on highway cruising. Your gearing is going to put the converter just above the stall speed in OD at 65 mph, so without lockup the converter will slip like crazy unless the lockup is wired correctly. Make sure the trans cooler is at least 12" x 12" stacked plate mounted in front of the radiator and run a temp gauge.

 

[mr_blasto]

Bigblock thanks for your recommendations. You aren't too far away from me, would you mind me coming over and checking out your toys sometime?

I know that 700r4's can be built stong enough, but they are usually very expensive at that point. Interesting perspective on wheeling with a manual vs. an auto.

I am definitely going for torque early in the powerband, which is why i would use 180cc runners in the heads instead of 200cc or more (vortecs are really close to 180cc too). I think other heads might flow better than vortecs, plus there is something to be said for not being religated to vortec specific parts. I know that they are a lot of bang for the buck though and produce great low end torque. Also, I was under the impression that roller cams aren't worth the expense because they aren't all that beneficial unless you are using really high horsepower high winding motors, but maybe this is off (or maybe my memory is way off). And yes I would like TBI, but I am on a budget and TBI means something else would have to give somewhere--it's all give and take.

 

[mr_blasto]

Greg if I remember right you were working on some pretty trick drivetrain setups using really unconventional parts where ever inch counted. Aren't plenty of people running a 700r4 with a doubler on blazers? Is length as big of a deal with this setup?

 

[bp71k5]

You forgot one option here:

http://coloradok5.com/forums/showthread.php?t=212062

Greg's right. I almost made the same choice in using the sm465, but the highway gear would not have been any different than my th350. If you really want a manual AND a good freeway gear, the best option is the nv4500.

On the money side of it, I don't know what a good 700r4 costs now but when I priced them out the tranny cost was basically the same as a nv4500 after factoring in core charges for both of them. (~$1500)

Of course there's lot of other stuff you need which drives up the cost.

If you're converting from auto to manual, that's by far the biggest amount of effort no matter which tranny you use. I'm just about finished doing this exact thing so feel free to pick my small brain if you need some tips.

If you want a doubler, that might be the only thing I would do different. The atlas is an equivalent cost to a doubler, but you have less drivetrain issues to deal with. Although it is pretty fun to drool over such a huge hunk of drivetrain in such a small vehicle.

 

[Greg72]

Greg if I remember right you were working on some pretty trick drivetrain setups using really unconventional parts where ever inch counted. Aren't plenty of people running a 700r4 with a doubler on blazers? Is length as big of a deal with this setup?

Initially, my setup was using a 4L80E/203/205 setup in my '72K5. Talk about a LOOOOONG setup! (see pic below)

This is set in the frame 5" further forward than stock. Even then the rear driveshaft was only going to be 30"....the front was going to be longer than the rear!!

The problem with the 1st Gens is two-fold. First of all, we have a shorter wheelbase than the later K5s (104" vs. 106.5") and the factory driveline was about the most compact you could get (TH350/NP205). The later trucks using NP241s and such can throw in a Doubler and don't really end up with a longer driveline because they are replacing a really long transfercase with two short ones.

As for my "other" setups....yes, I've got a rather unconventional strategy in place for Stomper v2, and an even wilder one for Stomper v3.

v2 is using a TH400 and an Atlas4 with a 5.44 low range, and 4.10 axle gears. This is what I was hinting at earlier for you. The axle gears allow for decent highway RPMs without buying an expensive OD transmission, and putting REALLY deep ratios in the Atlas box allows me to still crawl with the best of them. The only caveat to a setup like this is that the motor needs to have some low-end balls for street driving, because there isn't much reduction available to get the truck moving when it's in 2WD.

v3 is an even weirder setup using a 6-speed manual transmission (T56) and another Atlas 5.44 transfercase. This one is designed to tame really DEEP axle gearing of some Unimog axles I'm using (7.56:1 ratio). The only way to drive them on the highway at a reasonable speed is to get about 50% overdrive somehow. A conventional OD tranny with a 25 - 30% overdrive won't be enough to get the job done.


In any case, if I were you I'd focus on the highway speed you want to drive FIRST, then calculate the RPMs it will take to accomplish that...... from there you can work backwards and figure out what transfercase and tranny will suit you best.

I could throw some options into CrawlCAD for you... it makes things pretty clear in a hurry.

 

[mr_blasto]

BP--the nv4500 would be awesome, but I don't think it is within my budget right now. The part about the manual conversion that worries me is getting all the little odds and ends to make it work might end up costing me a lot more money and time than I budget.

Greg--how does the 4L80E compare in length to a 700r4? Also is that the first gen doubler from ORD? Isn't their updated version a little shorter? I am planning to use 56" springs in the rear turned around backwards with a zero rate to bring them back forward 1.5"... which is a long way of sayng my rear axle might end up 2.5" further back from stock. I probably won't do a doubler now (but I haven't ruled it out), but I want to have the flexibility to add one in the future without the need to replace everything in my drivetrain.

Right now I am leaning towards the 700r4, but I fear the price of getting a built one might make things tough. As far as hwy RPM's go, I will be using 37's, but who knows what I'm going to be using in the future (Most likely 37-39). I don't do a ton of hwy driving, and it came stock with 3.73 gears so with 37's and 4.56 gears even without an overdrive it would still be an improvement over the stock setup. The 700r4 is nice cause of the lower 1st and 2nd gears in addition to the overdrive. If I can drive at some speed between 65 and 75 with the RPM's somewhere betwee 1700 and 2900, I should be ok. So I guess the extremes would be gears that give me 2900 rpm at 65 v. 1700 at 75 and everything in between. Both these numbers might be a bit extreme, but I think you get my point.

 

[Bent77]

I'll try not to steer you wrong here.

THe 4l60e is a 700r4, only computer controlled shifty. All other parts for these, and length, should be the same.
Unless you plan you plan to add the computer components to run the 4l60, there is nothing wrong with properly built 700. You already have it as a bonus

I use a 465, but you already have a tork conv and linkage correct for the 700? I wish I had OD, my only complaint.

In ref to the ORD Doubler, the 2nd gens are shorter, visit their site off the home page tech article on the doubler, they have a write up there.

 

[RGV72BLAZER]

if the wife wouldn't have slipped in that she wouldn't mind driving my rig every once in a while, i woulda run the 465 hands down. nothing like a stick shifter. oh well the 700R4 will have to do.

 

[Bent77]

Correction, that is in the product reviews for the double write up.

 

[mr_blasto]

I'll try not to steer you wrong here.

THe 4l60e is a 700r4, only computer controlled shifty. All other parts for these, and length, should be the same.
Unless you plan you plan to add the computer components to run the 4l60, there is nothing wrong with properly built 700. You already have it as a bonus

I use a 465, but you already have a tork conv and linkage correct for the 700? I wish I had OD, my only complaint.

In ref to the ORD Doubler, the 2nd gens are shorter, visit their site off the home page tech article on the doubler, they have a write up there.

I know the 4l60e is a computer controlled 700r4. My question to greg was in reference to the 4l80e, which is essentially a computer controlled th400 with overdrive (IIRC), so I figured the length might be a bit different. No I don't want to add any computer crap that isn't necessary (FI might be an exception), so the 4l60e is out. For clarification, I have a th350 already, not a 700r4.

The only parts I already have are the ones currently used in the 350/th350/np205 setup. Yeah the 2nd gen doublers from ord are a bit shorter, I was just trying to use greg's setup as a bench mark to see if I could get some setup to work.

So Greg's rear driveshaft length is 30". If my motor is in the stock location my driveshaft with an identical setup would be 25". Move my axle back 2.5" gives me 27.5". The 2nd gen double vs. the first gen would give me 3 inches putting me at 30.5". I have read that the case length of a 4l80e is 26" and the case length of a 700r4 is 22 3/8" (but I don't have much faith in these numbers), so this would put me at about 34" for rear driveshaft length. Any idea what the stock length is? Just trying to see if a doubler setup down the road would work.

 

[bp71k5]

I'm sure a doubler would "work" if you go with a CV shaft. I don't think you can do it any other way. the 700r4 is shorter than the 4500 which is what I got installed with ORD's gen2 doubler. I can measure the rear shaft length, but it's around 30-ish inches long.

Here's a pic

 

[4X4HIGH]

Just for reference, Greg's doubler in that pic is a Gen II doubler (shortest version). Also you cannot figure out how long the driveshaft will be without knowing exactly where the axle is going to be positioned and also how much lift you have. Obviously the more lift you have the longer the shaft is going to be and also the further back the axle is makes the shaft longer once again.

 

[mr_blasto]

Good point about the CV shaft, and 4x4high thanks for clarifying which doubler was pictured.

One thing I was just remembering from back when I was more active on these boards and thought about this stuff a lot more, isn't the standard clutch system mechanical on the sm465 and brutally stiff? Wouldn't you need to use a hydraulic system to do it right? Aren't those more expensive to get a hold of and more complicated to install?

Also, bigblock72 was saying crawling with a manaul is really tough unless you have really deep gears. Anyone else want to share their perspective regarding manual v. auto without a doubler?

The stiff clutch thing and difficulty in ther rocks are all... um... concerns for when... uh... my wife... er ya... drives. No sissies here.

 

[Greg72]

Alright.....time to put some ideas to the test.

The whole comparison of Auto vs Manual is pointless. From a pure crawl ratio perspective, the change in ratio is minimal. Here's the data from CrawlCAD.

You're trading a crappy 45:1 ratio for a slightly-less-crappy 58:1. Plus, you have to spend more money, add a clutch pedal, probably a hydraulic setup...and will likely need to move crossmembers too.

There is NO benefit on the highway either.....you're turning 2692 RPMs at 65MPH either way.

Again, I will repeat my comment: Changing the transmission type is NOT how you are going to improve your crawl ratio in a meaningful way.


Theory #2: Overdrive transmission - With 37" tires and 4.56 gears, a 700R4 will only be turning 1884 RPMs. I don't think a small block will be very happy trying to push your truck down the highway without some more RPMs. Odds are it's going to hunt in and out of overdrive unless you plan on driving a lot faster than 65. Adding larger diameter tires later will only make this worse. It doesn't sound like adding the expense and trouble of an OD tranny is going to really work for you either.

The "REAL" option:

You want opinions? Here's mine.... Keep the free TH350, and apply the money you were willing to spend for transmission swaps on a better transfercase. A Doubler is a safe choice (though certainly more expensive that people initially believe) but I like the deeper reduction of a custom box. (Atlas or STaK)

With your axle gears, the Doubler gets you to 90:1. That's not bad, but not quite slow enough for a 37" tire.....

On the other hand, going from a gearbox reduction of 3.94 (Doubler) to something deeper like 5.44 (Atlas or STaK) you suddenly find yourself in the "sweet spot" with a crawl ratio of 125:1. As a side benefit, you don't have crazy short driveshafts out back to deal with (like you will with double cases), or potentially high u-joint angularity. And your highway RPMs are the same as they are now....not perfect, but certainly acceptable.

 

[vtblazer]

Anyone else want to share their perspective regarding manual v. auto without a doubler?

An auto will be smoother, that's about it really.

For rocks, I'd go auto everytime.