The Stovebolt Site Forums The Shop Area Engine Shop Stabbing in a transmission

Any tips for a first-time transmission installer?

I have the transmission (SM420 4-speed) on a transmission jack doohickey that lets you tilt it. The input shaft is bumping around somewhere in the vicinity of the pilot bushing, but damned if I can get it aligned properly to go in. Frustrating!

If the answer is just "play with combinations of height adjustment and tilt adjustment until it goes in," that's OK, just let me know, but if there's some magical alignment trick to guide the process, man, that would help tremendously.

First make sure the pressure plate is in alignment (you can use an old input shaft or buy an inexpensive alignment tool at your auto parts store. Take a long bolt the same diameter as the transmission mounting bolt and put it in one of the transmissions "ears" and use it to help align the transmission.
Just gotta hold your mouth right.

M. Rhoten,

Someone must have told you about an alignment tool..right! No! You must not have installed a new clutch and pressure plate otherwise this issue would have come up.

Without a dummy input shaft or a wooden alignment tool it can still be done. Using the cool doohickey to level the tranny, run the snout into the bellhousing and put it through the throwout bearing and into the clutch splines.

Have the transmission in gear (low) so you can turn the output shaft which will turn the input shaft and make it easier to engage the clutch splines.

You have to have a helper in the cab to depress the clutch which allows you to wiggle it around and find the pilot bearing...hold your breath, wiggle and twist and it will go right in.

Stuart

Sorry, I should have mentioned - I used an alignment tool when putting the pressure plate and clutch disc on. I am a rookie, but not that bad of a rookie I do have the splines engaged - I'm just less than an inch away from the transmission being flush to the bell housing.

It feels like the input shaft is bumping the side of the pilot, or perhaps the flywheel, so I figure I'm just needing the alignment to get that front part of the input shaft to hit the hole in the pilot.

I will get a helper and fish around some more. Thanks for the words of encouragement!

Get yourself a couple of 3/4 x 4 in bolts and cut the head off of them and taper the ends where you cut the heads off. Then cut a slot in the bolt for a screw driver at the tapered end. Screw these bolts into the top holes of the bell housing for alignment bolts. Inastall the transmission on the upper bolts and use them for a guide. Works every time. These alignment screws can also be used when installing a 6 cyl head to keep your gasket in place when installing the head.
Hope this helps it worked for me and saved me from having a couple of sore arms.

Tom

Rhoten,

Did you replace the pilot bushing? If yes, are you sure it's sized correctly?

Did this transmission come out from where you are trying to put it?

Paul

You might try the alignment tool again to make sure no one accidently depressed the clutch and allowed the clutch disc to fall while you were installing the transmission.

alignments pilot guides are about $2.80 at FLAPS southern auto/ carquest etc...

Yeah, it's a new pilot. I checked it against the old one and it looked identical. This trans came out of the same truck, so I figure it's just skill (or lack thereof) on my part, rather than parts fitment.

I will try the trick with the bolts - that's a good idea. I notice the shop manual specifies using alignment pins in those upper holes, so trying to emulate that is probably not a bad idea.

Guess I'll head out with my two year old son to Tacoma Screw!

I could have wrote this original post word for word last weekend. My first attempt at a transmission install and it just wouldn't go in all the way. the output shaft of the tranny turned as I turned the crankshaft pulley up front so I knew the splines were engauged, but the sm420 mounting flange just wouldn't meet the bellhousing, it was 1" away :hammering: . I did a stovebolt search, found this thread with these words of Automarc, which were golden Once I depressed clutch pedal, tranny slipped in like a hot knife thru butter, thanks again fellow stovebolters for sharing some knowledge.

Truckstein

Truckstein,

Mama Atomarc didn't raise no dummies...if only the doctor hadn't dropped me on my head! :whistle:

Stuart

To go the final distance, I used my feet on the back of the tranny and moved it in. I also used the guide bolts in the top.

i have also had problems with the plastic install tool not being as good as a old shaft i cut off. there was more slop with the plastic tool causing it to not be aligned perfect. i have always had to do it by myself so i have never had to push in on the clutch, you could ptob put a block on it to hold it in.