The Stovebolt Site Forums The Shop Area Driveline Need Some Help Ref T5 Choices

I'm editing my original post, as I've come to the conclusion that the T5 is going to be the way to go. Now, I need to know which out of the many different transmissions that were made will work best in the truck, with the least modifications. From what I know (what little it is), I think I should try to find a unit from the '82-'87 or so model years, with the mechanical speedo. What model number transmission should I look for? They all begin with 1352~ with 3 more numbers. I have no idea what the differences are between them, maybe based on which vehicle they were originally installed in? I've just had the engine rebuilt and right now its still revving pretty high at 50mph, so Id like to get this truck more driveable in modern traffic and have less strain on the newly built engine.
Any information is welcome and appreciated, since I know this is a popular swap and these units are 'disappearing' quickly!

I'm running a 1352-146 (1985 S10) 4.03:1 1st gear, 0.76:1 5th.
As far as I know, 1986 was the last year for mechanical speedo drive.
I've got a sheet I printed off years ago from inlinersinternational.org. Can't bring up that info on their sight anymore, maybe someone else can post the link. I've got another one stashed (not wanting or trying to sell), 1352-145 that is '85 - '86 S10, has 3.76:1 1st & 0.72:0 5th. I like the 4.03 1st, but I'm an area with terrain. If you find one & have a tag # I'll see if it's among my listing.

GKE,

Just found this today as I was searching for a T5 myself. I think this is what your looking for.

http://www.mongosgarage.com/tech/t5/T5Numbers.PDF

https://lugnutz65chevystepside.weebly.com/t5-info-page.html

Big Ed

Make sure to chose your rear axle ratio to do what you want the T5 transmission and inline to accomplish.
Some think that 2,000-ish RPM at 60 MPH is a smart thing to do because it keeps the engine from screaming.
That is a mistake in my opinion (as well as others who have done it that way). These engines perform best and get the best gas mileage at 60 MPH at 2,400-2800 RPM. A vacuum gauge will confirm this.

Thanks for the info! So, anything with the mechanical speedometer is '86 or prior, which is what I've been looking for. The truck has the inline 6, but I'm not exactly sure what rear end it has, probably somewhere around 3:91 or maybe even 4:11 judging by how it quickly slows up when I let off the gas at 50mph, which is about all I'll get it up to. There are a couple on ebay right now that I'm looking into. The more info you folks provide, the more I'll know what questions I need to ask the seller. Thanks, again, for your help!

Thanks, Ed, great info in those 2 websites you listed! Will definitely use as a reference!

Probably a good idea to figure out your rear end ratio to start with. Would be a shame to have to change it later on?

Ed

Since I’m still haven’t bought the transmission yet, do you know approximately what gear ratios I would need it to have to run with the rear gearing it has now, which like I said I’m guessing it to be 3:90 or 4:11. Is it the 5th gear ratio that has to “match up” as close as possible to the axle ratio?

Example, 31" tires, 4.11 gears, no overdrive @ 65mph engine turns 2896 rpm.

31" tires, 4.11 gears, 5th gear with .83 ratio @ 65 mph engine turns 2403 rpm. About perfect for a stovebolt 6 cyl.

You need to consider tire diameter along with final transmission ratio along with rear end ratio to calculate rpm at a given speed. Also decide what your target cruise speed and preferred rpm is.

This is one of many online calculators. Once you've ran the numbers then it's time to look for the perfect T5.

Optional 5th gear ratios: .83, .76, .72 are the common ones.

Gke59stpside,
I mostly agree with what others have said here already.
I know for a fact that the S10 T5 used a mechanical cable speedo connection through 1988. I have owned several. I have a T5 in both of my trucks and both have an inline six. I also rebuild them. I’m in Columbia, SC and not that far from you.
Others don’t always share my opinions. You do need to figure out what your rear axle gear is before you buy a T5. The easiest swap for your truck will be an S10 T5 from 1983-92, but only the 1983-88 years have the mechanical speedo connection. The 14 spline input shaft can be swapped out for a 10 spline shaft so you can continue to use a factory clutch kit. Swapping the shaft isn’t the only way to go, but it’s the most logical and the cheapest.
Please consider calling me so we can talk. I may have what you’re looking for. I’ll send you a PM with my contact info.

The standard rear end ratio for 3100/3200 TF trucks without overdrive would have been a 3.90:1. If it came originally with an OD it would have a 4.11:1 ratio. If you have a 3600 series the stock ratio would be 4.57:1. In my opinion, trucks having any of the above ratio's need an overdrive of some variety to function well.
Fred

For one more opinion, I chose to use a 3.07 Chevy rear end 12 bolt from 1969. It wasn't an accidental choice. A lot of work and study went in to that selection. My T-5 begins with a 4.03 first gear and ends up with a .86 fifth speed. If you do the calculations, you'll see the final gear ratios in my first 3 speeds match the original final gear ratios within a hair or so. This means the truck performs in town exactly the same as it did. In my opinion that's important (especially if you live anywhere with hills) unless you enjoy replacing clutches and don't want to haul anything heavier than a 6 pack in a styrofoam cooler. Bottom line is I can still load 800~1000 pounds in the bed and drive off without any problems. Then fourth gear is a 25% reduction in rpm from the original 4.11 rear end and 5th gear takes it down another 14% from that. With the tire size I have at 55 it will be about 2000 rpm and at 60, around 2200. With 5th being so close in ratio to 4th, if I'm driving on the highway in an area with rolling hills and I want higher rpm, I can simply leave it in 4th until things level out more. Honestly I think that is pretty much ideal, especially if you have a well-running engine. It is a fine line. Above 2500 rpm certain inefficiencies start appearing which have been discussed here numerous times.

Everyone has different needs and wants as far as how to modify their drivetrains. If you are happy with your setup, I am happy for you as well.
But (there is always one of those, since everyone has one), if I had your 3.07 rear axle on my truck, I would still be stranded at the boat ramp since
Wednesday. You can read my story about that episode in the HiPo Forum.
Carl

One more thing.
To my thinking, if the rear axle gear is numerically higher than 4.11, I would start with a rear axle gear swap to 3.73 or 3.42.
For normal driving, 1st gear X the rear axle should ideally be between 9 and 12.
My factory 3 speed has a 2.94 first gear and a 3.73 diff. That’s 10.96 and right where it should be.
The S10 T5 being considered has a first gear of 3.75 X 4.11 = 15.41. That’s essentially a granny gear and makes first gear rather annoying unless you are pulling something heavy at a slow speed. With a 3.73 diff you get 13.98. It’s a bit out of range but not too low to be useful. I know because I’ve driven one.
The T5 has a 2.18 second gear. So 2.18 X 4.11 = 8.95. So if the 4.11 diff remains, the owner will use 2nd gear to start moving, but will need to use 1st gear on a hill.
A T5 5th gear of 0.72 matched with 4.11 = 3.00. That will be a bit too low for cruising gear for highway speeds. At 65 MPH with a 29” diameter tire the RPMs would be 2260. These inline 6 engines are more efficient at higher RPMs as has already been stated.
A T5 with a 0.86 5th gear and 4.11 diff would be at 2662 RPMs at 65 MPH and seems to be a better choice.

BUT WAIT! I said earlier that I would START with a diff change! That’s because you really MIGHT be completely satisfied with how it drives with a 3.73 diff.
If you currently have a 4.11 diff your RPMs will be around 3095 at 65 MPH. Changing to 3.73 would get 2809. So you see, a diff change to 3.73 is a lot less trouble and really only 147 RPMs more than the whole T5 swap. A whole lot cheaper too.

Finally, what if you’re not happy with the 3.73 and still want a T5? Well, with a T5 plus a 3.73 you would still be able to make good use of 1st gear. For 5th gear the 0.86 OD X 3.73 = 3.20 which means at 65 MPH the RPMs would be 2416. That’s a pretty nice combo IMO.

OK, will do! Like I’ve mentioned, this is a totally new area for me, and really appreciate your response as well as the input from all the other folks who have responded to my request for any information that will help me make the right choices and assisting me to not waste my money on something that I cannot use.
This is a great site, filed with great people who are really interested in helping others. I’ll be in touch and look forward to any suggestions you have in helping me get this truck on the road and getting to enjoy driving it!

Going from 28" high tires to 30.5" helped me dial in my setup, making 1st gear very useful for starting from a stop, but still make it possible to crawl out of a steep, nasty bout ramp with a heavy jon boat behind it. Before that change was made, 1st gear was granny and I would normally start in second.
As a reminder, I have a 4.64 rear axle ratio and a T-5 with .72 overdrive (I don't know what my 1st gear ratio is).

Lugnutz--I have a 94-95 T5 in my truck, how do you convert speedometer??

Only 1988 and earlier S10 T5s have a cable speedo connection. As you can imagine, they are becoming scarce.
So if you want a cable speedo connection you will have only 4 options. Links included.
1. Buy an expensive VSS to cable conversion box.
https://www.dakotadigital.com/index...id=886&category_id=287&mode=prod

http://www.abbott-tach.com/cablex.htm

2. Send your tail housing to a specialty shop to have them fabricate the cable style connection.

https://www.ebay.com/itm/221620352568

3. Change to a Camaro tail housing and case cover with shift linkage. This will result in the shifter moving back about 9” and under a bench seat. Switching to bucket seats might be required.

4. Find a rare 1988 or earlier S10 tail housing.

So what actual rear end will hold the best gears for a T5 swap? I have a 1948 Suburban with 3 on the tree. My goal is to go 65 to 70 comfortable and still have the stock width if the rear axle. I live in a relatively flat area with some rolling hills. Of Madison Wisconsin. I may even swap in a larger chevy 6 cylinder like a 292. Any suggestions on a T5 with a 292 and which rear axle?

Not sure what my rear end is now. I assume 3.90

First thing to do is confirm what your rear axle is. A 3.90 rear axle is a good one for an OD tranny.
Here’s a video I made showing a simple way to calculate the rear axle gear for an open diff. You don’t even need to take off the back cover. Rear axle calculation video.

Next thing to do is calculate your rear tire diameter. Here’s a nice website to do that. It’s the third section. Tire diameter link

The S10 T5 came with either a 0.73, 0.76, or 0.86 overdrive. The Camaro T5 usually had a 0.73 or 0.63 OD gear.

You’ll probably be better off with an S10 T5 from 1993 or earlier because it will have the correct Muncie bolt pattern for the bell.

If your burb isn’t too heavy, then the inline 6 will be able to handle the 0.73 OD gear on the flat and might need to downshift on the hills. Don’t expect a huge improvement on MPG. There’s lots more to say on the subject. Post your info about tire diameter and rear axle gear when you have it.

I got My 'T5'Trans with Mech Speedo out of a 93' S-10,extended Cab.... Factory installed

If knowing your speed is your main goal you might want to check out a GPS speedometer. The are dead accurate no matter what tires, transmission, or rear end and run about $60. Very easy to install. The largest in dash one is 85mm ( about 3 3/8") so a reducer ring is needed to mount in the factory 5" dash hole.

This has been my exact experience. I've had a .70 overdrive transmission installed for twenty years. I installed a MOTORMINDER VACUUM GAUGE about eight years ago because it was a lighted gauge that I thought looked cool and it was colorful, indicating: 0-5 vacuum inches=Red=Poor, 5-10=Orange=Fair, 10-17=Green=Good, 17-21=Blue=Idle, and 21-30=Yellow=Decelerate. What I discovered to my astonishment is that to keep the engine happy in the GREEN Zone, THE MOST EFFICIENT ZONE, in many situations the engine LIKED MORE RPM's. I just did a search and the model very similar to my STEWART WARNER Gauge is selling for $81.14. After radial tires and the overdrive transmission this is easily the best purchase I have made for my truck as it has EASILY PAID FOR ITSELF IN FUEL SAVINGS.