The Stovebolt Site Forums The Shop Area Engine Shop Giant Box-O-Rocks sounds in second and third gears

Hello all,

I will post my pics and greetings, too, but this just happened today.

I have a 48 chev 3100 1/2 ton, with a 1960 235 6 cyl and a floor shift four speed.

I've just had the truck for a couple of months, and just recently discovered this forum.

On a few recent occaisions, I've noticed a rumbly gravel sound in third gear, just when shifting into third.

Today the sound changed to big rumbly sounds in second and third, but then 4th gear sounds and feels just fine.

So, I don't think its the U-joints, but I am feeling like it's transmission.

Will I be learning trans rebuilding soon?

Or should I swap in another trans?

Or is there anything else I should look at or check before tearing into it?

thanks,

Fourth is direct so no power is transmitted through gears or other shafts. Because you have no noise in 4th but do in 2nd and 3rd I suspect you've got a gear or counter shaft problem. These transmissions aren't hard to find I'd advertise in the swap meet for a replacement and just swap.

is there oil in the tranny?

I'll check for oil. the PO said he changed it. I'll look for a used one to swap in, too.

Crack that thing open chance is that you will see the problem right away and can probably repair it yourself,Then you will know exactly what you have in your trans. JMO

Thanks

Novak sells a very nice rebuild kit for that transmission. picture

The rebuilt kit looks like fun. but will I need special tools like pullers, etc? I have wrenches and sockets, like the usual stuff.

Or, what if it is just low on oil? the PO said he changed the oil, but what if he didn't put enough in. How and where do i check the oil level? Or are the bearings ruined if I am hearing big noises?

And I need to positively identify this transmission before ordering a rebuild kit.
I am not sure if it is the original. Are there numbers or marks for identification?

thanks all for your help,

If you go to the NOVAK site I believe you will find all the info you need to ID your transmission.

From what I understand these are very easy to work on but not being a mechanic I had mine rebuilt by someone who does such things... it wasn't expensive.

There is a section of the REPAIR MANUAL that covers this if you want to tackle it.

Good luck.

thanks Woody, I'll check the Novak site

I clicked the repair manual link, and i already Have that book.

It has pictures of how it all comes apart with gear puller tools, etc.

the Novak site says it's simple to rebuild, and all that is needed is a small arbor press, snap ring pliers, and a bearing puller.

I have snap ring pliers!

Maybe this is more than I want to get into.

Can I do this? Or should I take it out and get someone else to do the rebuild?

I should just check the oil level first.
Is there a fill plug up high to check how full it is?

yes Scot, there's a plug in the side that the oil should be up to, but if it's that noisey it needs to be opened up and inspected, so you should quit waffling and pull it out and see what condition it's in, the answer as to 'what next' will reveal itself

Bill

ok, you're right. sometimes I just need to get slapped around a little..

Getting that monster out of there isn't going to be easy, it weighs a ton! Here's a PICTURE of a contraption I made to deal with the mine.

It's pretty simple with a boat hoist thingie to provide the muscle.

The only mistake I made was the 2x4 that you see placed front to back should run side to side to allow the movement you'll need to get it away from the engine.

Ask around and see what it would cost to have it done. I think my guy charged me $100, but I delivered it and picked it up. Any good mechanic should be able to knock it out in a couple hours.

I like your puller idea. I can make something like that. And I will check around locally and see about help to rebuild.

I got the floor out today, and yes, it is an SM420.

The only bolt that looked like an oil fill hole was on the passenger side about half way up and angled slightly to the rear. There was plenty of new clean oil in there up to that bolt. It was dripping out when I loosened it. I guess the problem was not lack of oil.

So, now what's next?

Should I take the top off and look in there while it's still in the truck?

Or take it out? If taking it out, how many bolts attach the trans to the bell housing? I see two at the top, and maybe one other on the driver side lower, but any more?

I noticed in another post to make guide pins with long bolts replacing the two top bolts for removal and installation.

How long should those bolts be? I can go get some before attempting this removal.

Should I drain the oil first before removal? So it might be less messy?

Most likely at that year, you have four bolts in a square hooking it up to the bellhousing. It may have metal shavings running around in the oil, or ground-out synchros or gears?

There should be a cover bolted to the left side of the box which I believe is where the power take-off would be if so equipped. Remove this and look inside to see if you can see anything. If you can get your finger into the bottom of the case you can poke around for loose bits of metal.

Regardless, your trans is going to have to come out to be repaired. It's supposed to turn smooth and free, anything else is bad news. Transmissions have this bad habit of not fixing themselves.

The two bottom mounting bolts are coming through the bellhousing from the front. there is a big bump part on the trans on the passenger side and no bolt head. Do I have a special overdrive trans?

I'm gonna go take out those two bolts.

Not likely.

A few quick pictures would help.