The Stovebolt Site Forums The Shop Area Driveline My 59 3100 and T5 Swap

The T5 trans is a popular topic these days. I’m going down this path myself and thought I’d post my choice of parts, problems and successes as I go to help others that might have some questions.

My truck has the original, stock 6 cyl engine and bell housing, and the 3.90 rear ratio.
Some parts showed up today. I think these will work, we’ll see in time.

Per fellow forum member Lugnutz referral, I ordered the shifter parts from Core Shifters. The shifter arm is #0085 from the site.
The shifter mechanism that bolts to the trans itself is their T5 base with the “Option D” pivot arm having an angle biased towards the driver.
Then an accordion boot for the interior.
I want to keep my bench seat so I sourced a S10 based T5.
My trans is coming in this week, I’ll post an update and pics when I get it.
Adventure begun!

Sounds good so far. That shifter...is it built for a more narrow shift pattern? I raised mine 1.25" higher with an aluminum spacer. I had to make/add some shim pieces under it to get the shifting smoother, but it certainly made shifting nicer. Which 1st and 5th gear ratios did you get?

Yes, the shifter is a short throw arrangement as I understand it.
The spacer on the shifter measures 2-7/8” tall.
The ratios are 3.78 for 1st and 0.72 for 5th per the vendor.

That will help your shift pattern notably. Fifth gear will be ideal.

I’ve been wondering about these t5 swaps. How much does a guy have to hack up the floorboard to make it work?

I have it in my head that the shifter moves rearward and almost into the seat but not sure where I got that idea.

If you get the T5 with the shifter toward the front of the tail section (where the tail section connects to the main transmission body), then you'll have the shifter in the right place for the bench seat and you will only have to cut about a 3 inch by 4 inch hole for the shifter...which can easily be done with a sabre saw in a minute or two. The S10 transmissions (and the van transmissions) work ok for the bench seat in the AD trucks. The transmission bolt holes are metric and miss being the right diameter for the 235 bell housing by just a hair or two. Run a drill bit through and you'll be done. Easy work. Some have an input shaft which is a bit too long, however some (like the one I got) require no trimming of that. And you must either find a Jeep input section (10 spline) or use a clutch disc with the right number of splines for what you have. In my case, I had an 11 inch flywheel and I used an 11 inch pressure plate and clutch disc which had been designed for use in some GM product which I don't offhand recall--14 spline. All in all, it was one of the easiest transmission swaps I've done. As for the speedometer, you can use a manual (cable driven) one or you can do what I did and convert an electronic (even a GPS type) to fit in the original housing and look pretty much like the original one. I've posted stuff about that here.

The 10 spline Jeep input shaft will open up different pressure plate/clutch plate combinations for you and as I recall those input shafts are $100 or less.

[img]https://media.fotki.com/2v2aUsTPpxDubp.jpg[/img]

This is where the shifter is in my 50. S10 T5 behind a 216, with no adapter spacer (T5 bolted directly to the 216 bell housing). As Jon mentioned, I also cut a small rectangular hole in the floor panel, and a smaller round hole in my rubber mat. I need to find a boot to install. Mine uses the stock S10 shifter with an ND GMC 4 speed stick welded to the S10 shift mechanism.

Thanks. Not nearly as far rearward as I thought. That’s a good looking original interior BTW.

Some will put the shifter pretty far back...the Camaro transmissions for one example.

OK, here are the goods. Casting indicates vintage 1987.
The supplier (Competition Transmissions on eBay) had done the conversion to the 10 spline input shaft, bearing retainer and a general rebuild. It looks really nice and should install with minimal drama. Fingers crossed.
Thanks to Lugnutz, I checked the speedo driven gear and see that it will need to change to a blue gear per his suggestion, a different tooth count I presume.
The trans output shaft is 27 teeth, I have my local Napa counter guy checking on a slip yoke to fit 27T and my 59 driveshaft on the U joint side. I’ll post later part numbers for the yoke. Cheers.

Wait!
Look inside the tranny tail housing at the DRIVE gear. Is it RED or BLUE?

Survey says ... Red.

My tires are 235/75R-15, an eyeball measurement is give or take 29” in diameter, 3:90 rear gears as previously mentioned.
I’m not quite following your page on this topic Lugnutz, to get an accurate speedo and odometer readings do I swap out the driven gear that came with my T5 for a blue (22 teeth?) version?

Thanks for your help.

Yes, your tire diameter is 28.9”.
I use THIS TIRE SIZE CALCULATOR which makes it simple to plan ahead.

To pick the correct DRIVE gear and DRIVEN gear combination, I use THIS CALCULATOR. . Part way down that page is the SPEEDOMETER GEAR CALCULATOR section. A Chevy T5 can use a blue 7 tooth or a red 9 tooth DRIVE gear.
Since DRIVEN gears only come with limited choices of tooth count, you might need to use a blue 7 tooth DRIVE gear in order to find a matching DRIVEN gear.

Example:
Your current red 9 tooth DRIVE gear with a 3.90 axle and 28.9” tire will require a 24.47 tooth DRIVEN gear. (So either a 24 or 25 tooth.) Unfortunately, there is no DRIVEN gear available for a T5 with that tooth count. Top tooth count is 23 teeth.

Recalculate using a blue 7 tooth DRIVE gear. Result is 19 teeth for the DRIVEN gear, which IS available.

DRIVE gears and DRIVEN gears are available from LA SPEEDOMETER GEAR.

Get a speedo app for your phone. Drive 50 MPH by gps, the dash speedometer reading either + or - X2 will give you the ratio you need , then find a ratio adapter to speed up or slow down the speedo cable by that much.

Interesting solution. So if I drive 50 based on my phone GPS, and my truck speedo says 60 . . . Then I should multiply 60 X 2 and would get 120? Or should I multiply the error of 10mph X 2? That seems more logical since 10 X 2 = 20 and the MPH is 20% off. Then I’d need to order a speedo reduction adapter for 20%.

That is how I finally found that the electronic speedo on my 54 was off and the fabulous MPG I was getting was all wrong. In Indiana, the roads are in a grid pattern marked as mile roads. I use those to calibrate the odometer. well, a mile crossroad could only be 8 tenths or 9 so the calibration sequence would be off.

Lugz, I played with those calculators and see where you are coming from.
But I’m too chicken and lazy to take the tail housing off and change to the 7 tooth drive.
I located a 23 tooth driven gear from www.allstategear.com, so a little closer to 24.5 than 22. It’s ordered and on it’s way. I’ll try it out and if it bugs me too much maybe I’ll seek out one of those correction boxes.

I think you have a typo in your post where it reads “24.47 tooth Drive gear”, shouldn’t that be “Driven” gear?

Some universal joint measurements indicate my drive shaft has the #1330 joint.
So off to a local driveline shop tomorrow to see if they can source a slip yoke for the T5 and #1330.

Moonlight,
Yes, you caught a typo in my prior post. DRIVEN is the correct term. I’ve edited that post.
Nice research. I’ve not found a 23 tooth DRIVEN gear from other vendors.

Your speedo will work fine with a 23 tooth but will be a little inaccurate on the high side. Probably not much to worry about and the % difference will be minimal.

You might need a longer speedo cable. Your drive shaft will need to be shortened by about 3”. I used a worksheet from Denny’s Driveshaft on the internet. Worked perfect and gave my drive shaft shop all the info needed.

Lugz - My speedo cable will be ok I think. It’s likely not the stock length one, there looks to be plenty of slack to move 6”+ rearward.
Dang! on the drive shaft length. I was hoping I wouldn’t have to mess with that.
I went out and got my tape measure and eyeballed things: existing 3 sp with OD - 21 3/4” to the end of the tail housing. The T5 is 24 1/4”, both measurements from the bell housing face that the trans mates to. That 24 1/4” lands halfway into the 1st part of the u joint. I thought it would be plug and play. Oh well, too much in this to back out now, the plan evolves.

Quote:
Interesting solution. So if I drive 50 based on my phone GPS, and my truck speedo says 60 . . . Then I should multiply 60 X 2 and would get 120? Or should I multiply the error of 10mph X 2? That seems more logical since 10 X 2 = 20 and the MPH is 20% off. Then I’d need to order a speedo reduction adapter for 20%.[/quote]


Yes, need to slow down the cable rotation by 20%. If you think in terms of 100 MPH being 120 MPH indicated it make it simpler for the math but harder to get away with the road test!

Ratio adapter needs to be 1: 0.80

The 23 tooth speedo driven gear arrived today. I was a little skeptical the larger diameter would engage with the drive gear, but some wiggling and twisting on the output shaft got everything in place and seated.
The slip yoke for 27 tooth output shaft and 1330 universal should be in this week. I’ll post up some pics when I have that in hand.
Getting closer...

Picked up the slip yoke today. A little pricey at $115, but ya gotta pay to play.
Spicer PN 2-3-12081X. I test fit the shifter to the tranny this weekend, it was all good.

I knocked out the last jobs before I start the swap; to drill out the top mounting holes for the 1/2-13 bolts to fit thru. Then I tapped the lower holes for 1/2-13 Helicoils as the lower bolts insert from inside the bell housing into tapped holes on the trans.

Then drove to a friends place, he’ll be helping me out. I should be digging into it tomorrow night after work.

An update, good progress on the trans swap in the truck today. Old one pulled out, new 5 speed in place.
It all went very smooth. The input shaft fit was perfect, no shortening needed on the tip. Splines fit the clutch correctly, clutch movement and feel were normal. All the mounting bolt holes in the bell housing lined up with the T5. Existing speedo cable fit right up.

I dropped off the driveshaft at local shop for shortening. Have to cut the floor for the shifter, install the shifter interior boot, remove some overdrive wiring and the 3 speed linkage and shift lever. Will knock that out tomorrow. Should be all back together and driving by next weekend. Crossing my fingers the job will wrap up as smoothly as it went today.

With the flat tines on the pressure plate, did you use the taller style release bearing?

I don’t know. I used what was in place already. That bearing isn’t very old, I had all that stuff replaced 3-4 years ago so it doesn’t need changing. I guess a tall one is in there, pedal travel and feel seem normal.

You have the correct one in there.

I worked on interior tasks today. I figured the floor access panel had never been removed before so the clutch head screws would fight me the whole way. I gave them a couple shots of penetrating oil leading up to removal so that helped. There were only 2 that were a bit troublesome but they gave in with some hammer persuasion. I wish I had the forethought to have ordered a new gasket for between the panel and floor ahead of time. LMC has them, but I’ll try my local NAPA tomorrow and see if they can bring one in this week.

Using the magic marker lines scribbled around the shifter box from underneath, I drilled some starter holes on the corners and saber sawed the opening for the shifter. Then wire brushed the panel and put down some paint, and did a test fit after it had dried enough to handle and it looks good.

Also test fit the shifter handle and worked the gears a little. Maybe I should have gone with a straight shifter handle, we’ll see if the bend at the top will send the knob into the bench seat. It feels nice and precise, and will probably improve with ATF in it and some miles.

It’s back to work tomorrow so progress will take a breather, more to come though.

Installed the drive shaft tonight, it was shortened 3-1/8” to 50-3/8” universal center to center. My local shop charged $240 for shortening, installed new universals front and rear and balancing. Seems pretty fair to me and they gave it a fresh coat of paint to boot.

I then poured in not quite 3 quarts of ATF in the T5, started the engine and let it idle. Listening for any squeals or grumbling, I didn’t pick up anything so I’m encouraged.

So far, so good. We are watching your progress. I’d like a picture of the smile on your face when you drive it for the first time.

I sure have enjoyed mine since I installed it!!!

Sorry to miss that pic for you Lugz, my selfie skills are way down the scale, :-)

Late Friday I did a 10 mile test drive, then Saturday just about finished the swap, more on that later.

I’ve driven a little under 100 miles so far, and really, really like the results. The shifting is nice and smooth, great feel when changing gears, very quiet too. The throw is compact, there are no worries about contact with the dash or seat when shifting. I find myself putting my foot in it more, taking the rpm out a little more going thru the gears. It has brought back and increased the fun of driving it. If you are thinking of doing this swap, I vote two thumbs up.

Comparing a GPS app to the speedo, the truck speedo is reading 3 to 5 mph above the GPS reading. It’s closer to the GPS reading say at 40 and lower, then seems a bit more optimistic above that. Of course a little needle waver and paying attention to traffic is good for a couple mph miss read too. I’m running 60 at 2K rpm give or take which is what I had with the previous 3 speed and OD. In the end I’m quite happy with how it turned out. I’ll get to a stretch of road with some mile markers and see how the odo side of it looks.

The last thing to do is make a collar or base let’s say for the shift boot to rest on. The boot I got is little short to reach the floor comfortably. You’ll see in the pictures below. I could stretch it enough to reach the floor but I don’t like how that would look. I have access to a 3D printer and design parts often so I have something in mind.

The one fly in the ointment comes from the shifter I picked having an angled tab that directs the shift arm towards the driver. It ends up sending it a bit too far left. The height is good, it’s just when making the 1-2 shift I am grazing my leg. It doesn’t bug me too much, I’ll give it more time and see. Once you are doing 3-4-5 it is fine. If I did it over I’d go with the straight version, option “C” on the vendors web site.

Yeah, overall I’m really pleased with the outcome, I have about $2,500 in the job, a little more maybe. When I get the boot collar done I’ll post a couple pics. Cheers.

Unscrew the knob and remove the boot. Get your torch out and heat to red in the area covered by the boot and bend away from your leg to wherever you want it. Let cool, reinstall the boot. Easy fix.

Last update I think, and that is the shift boot spacer.
Since the shifter lifts the boot up too far to reach the floor without excessive stretch I modeled a spacer to take up a bit of the distance.
It was 3D printed, it took a couple of iterations to get the curves right, but it worked out pretty nice in the end. A couple of screws to hold it to the floor and its ready to go.
I might paint it later but for now the green works.
I’m still really enjoying the T5, if you are thinking of doing it, go for it.

First class job! Looks great!