Inliners International Forums General Discussion Drive Train T5 install

Gentlemen

I want to give you folks my T-5 install info. I have included a lot of detail. This may seem like info overload, but it all mattered in the big picture. Hopefully this will keep you from hitting any “gumption traps”.

The truck I installed it in is a 1979 Chevy C10 step side, inline 250, with a Muncie SM 465 transmission. The aluminum bell housing is GM part # 460486, and has a boss on the driver’s side for the clutch bell-crank. Drive shaft is two pieces.

The transplant T-5 is serial number 1352-145 from an 85-86 S10. Input shaft is 14 splines, 1.0” diameter, input shaft tip is 0.590” dia. Output shaft is 27 splines.

I tore down my T5 completely and replaced worn components. This was a good learning experience. I had not previously even opened a transmission. Works great!

T5 modifications:
Remove the shifter and tape over the rectangular hole. This allows you to install your tunnel pan to be marked for the new hole for the T5 shifter.
Drill out to ½” diameter, the 4 holes in the T5 mount “ears” that bolt to the bell housing.
Trim 3/8” length from the end of the T5 input shaft. I did this with an angle grinder with a cut off wheel. Bevel the end with a file or Dremel so the tip slides into the pilot bushing easily.
Remove the input bearing retainers from the SM465 and the T5 and had Columbia Machine Works trim the T5 retainer off to the same length as the SM465 retainer. You can do this in your shop with a cut off wheel but a lathe does a nicer job.
Reinstall your trimmed bearing retainer on the T5 tranny.
This next operation is a must do. Lengthen the splines on the T5 input shaft. Tape up the gap between the bearing retainer and the input shaft to keep metal particles out. Use a dremel with a cutoff wheel and just “massage” the splines with the tool to lengthen them approx 3/8”. Use your new clutch disc to check that the disc moves freely across the lengthened sections of the splines.

Truck disassembly:
Disconnect the battery ground cable.
Raise the truck and secure with jack stands.
Support the rear of the engine with a jack stand or blocks to maintain the correct “angle” of the motor, tranny, driveshaft relationship.
Pull the tunnel cover from inside the cab.
Remove the shift lever from the SM465.
Pull the drive shafts and bearing support for the two piece shaft.
Disconnect the clutch linkage, speedo cable, loosen parking brake cables.
Pull the cross member that is also the rear tranny mount. There are no rear motor mounts with the GM 460486 bell housing so the tranny mount point on the cross member needs tobe modified to accommodate the T5’s rear mount. This is described later.
Drain the oil from the SM465.
Pull the SM 465 tranny. Be careful. Way heavy!
Pull the starter and clutch dust shield.
Pull the bell housing.
Pull the pressure plate and clutch disc.
Clean the face of the flywheel with denatured alcohol.

Bell housing and clutch pack details:
The hole in the bell housing for the SM465 bearing retainer is 5-1/8” i.d.. The bearing retainer on the T-5 is 4-5/8” o.d. The folks at Advanced Adapters have a reducing ring, part # 716041, $51.22 including freight. This was secured in the bell housing hole with blue threadlocker, according to Advance’s instructions.
The stock pilot bushing has the correct i.d. for the T5. Advance adapters confirmed this.
The stock SM465 pressure plate works.
I had to replace the stock clutch disc with a 1” dia hub, 14 spline, 11” diameter disc, Autozone part # CP 31078.
The stock clutch release (throw out) bearing works and so does the stock clutch fork. I replaced both of these with new stock ones. Cheap insurance.

Next align the pressure plate and clutch disc and secure them onto your flywheel. Tighten to spec. This should be the last time you will have to do this for this project.
Install the throwout bearing into the fork.
Install the T5 with its stock neoprene mount bolted on. You can bench press the T5 up and slide in by yourself, but a second pair of hands is much better. Use a jack stand to support the T5 away from the rear mount so you can mark the cross member for the cut out for the new mount.

Bolt in the cross member. I reinstalled all the bolts for the cross member to ensure alignment at final assembly. You will see where to mark the cross member so the cross member can be notched to begin modification for the new mount point.
After I marked the cross member and made some notes, I pulled the cross member and did the notching on the bench with an angle grinder and cutoff wheel.
It is a simple process to make a mount plate for the T5 that will slide into your notch in the cross member. I used a short length of 2” x 2” x 3/16” angle iron and drilled an oversized hole for bolt clearance. Take your time and bolt in and pull out the cross member as many times as is necessary. Any errors you make in notching can be corrected, so don't get gun shy. Use an angle grinder with a cutoff disc and save the pieces until your project is done. Just try not to get carried away notching it.
When you have your new piece drilled, bolt it to the tranny. This is a metric bolt.
Install your cross member. Be sure that the motor-to-trans-to-rear end alignment is maintained.
Tack weld the newly fabbed mount angle or plate into the cross member. I pulled the cross member for final weld up at the bench. If your fit is good you can weld it in place in the truck. Just be careful not to set fire to the neoprene transmission mount.
Clean and paint your newly fabbed mounting area.
On this truck there is a muffler heat-shield brace. You will need to drill a new hole in the cross member to bolt this on as you probably cut out the existing hole when you notched the cross member.

Drive Shaft details:
The front (short) drive shaft will have to be shortened.
The yoke has to be replaced with one with a 14 spline count.
This is a good time to replace all the U-joints.
I contacted Drive Line Service in San Leandro and told them what I was doing. They had me measure from the face of the transmission tail shaft seal to the center line of the drive shaft bearing support on the frame. I took this measurement and both shafts to them. They selected and installed a new yoke, replaced the U joints and cut the front shaft and balanced the drive shafts as an assembly.
Put some grease into the yoke so it will slide onto the tranny tailshaft.
Install the drive shafts and bearing supports and do final tightening.

You can now reattach your clutch bell crank, dust shield, starter, and heat muffler heat shield support.

This is a good point to fill your T5 with new fluid. It is very easy fill from the top with the shifter not installed, and with the tunnel cover off.

Now you can set the tunnel cover into place inside the cab and secure it with a couple of bolts. Before I reinstalled mine I thoroughly cleaned the underside and painted it with silver paint. This makes marking the area to be cut out for the shifter hole much more visible and reflects light in the area so you can see what you’re doing. Also looks cool.
Mark the underside of the cover by tracing the approximate outside of the rectangular area of the shift mount boss. Pull the cover and cut the hole. Be sure you have your “new” shift boot and shift boot retainer plate on hand so you can check to make sure the opening you cut does not get bigger than the inside hole of the retainer ring.
Install your shifter without the shift handle. This makes it easier to replace and remove the tunnel cover until the hole is cut with the proper clearance. You may need to install and remove the cover, and open the hole more than once.
I found I wanted to heat and bend the arm on the shifter so that when my shift lever (stock S-10) was installed it did not hit the bench seat. Mine shifted fine into first and reverse without bending, but it looked funky.

Adjust your clutch and drive.

Hope all this helps. Fantastic upgrade.
EV

Even if somebody is not installing a T5 into a C10,you've provided great tips for any T5 install. If you took any pics, this would make a great article for 12PN.

I was wondering if you could have used an earlier bellhousing from a setup that was using a 3 speed trans instead of the SM465 and then I don't think you would have to use the adapter plate. I installed the T5 in my '65 Pickup a few years back and I don't recall any problem with the retainer dimension but the '65 bell is a cast iron unit with the mounts on it. Excellent article and detail on how you did the install. Will be of help to somebody looking to do it. Are you happy with the new trans? I really like mine behind a stock 292.

GM Dad,
Regarding the bell housing, I did not (still don't) have enough knowledge about the different bell housings. The one I used has a boss on it for the bell crank for the mechanical clutch. So I knew that had to be on it. I wasn't sure I could find the perfect bell housing for less than the adapter. Since then I have done some research and have found one that may work on my next engine (another 250). If it does, I will post the casting number to save others some hassle and dinero.

The tranny is great! I had a 4 speed SM 465 with granny low. It needed a higher gear for cruising. On my engine, I am going to swap out for an earlier (non intergrated) head. I have an offy intake manifold and the head but I need some advise on the carb (2bbl) and headers. I am condsidering T. Langdon's cast iron headers and his holley/weber 2 bbl. I am not sure how a "progressive" 2 bbl works. Any thoughts on the setup?
Thanks.
Regards,
Ken

Congrats on the install.

A couple tips for installing a tranny by yourself would be to cut (4) 6-8" long pieces of threaded rod to help guide the tranny into the bellhousing, and put the tranny in gear so that you can wiggle the output shaft in case the input splines don't quite line up with the disc splines.