No tranny mount on my TH400? 70' c10

[Mrturner1]

I'm in the middle of an engine rebuild and currently have the engine out but transmission is still in, sitting on a block of wood and still has the driveline hooked up. When I pulled the motor I was very surprised to see that there is no transmission mount. It's bolted to the motor, and then hooked up to the driveline. I always wondered why it felt weird when I would jump on the gas at higher RPM's, and I think this is the issue. Truck is a 1970 C10, with a th400 and 350 SBC.

Should there be a trans mount?

And could this be an issue IF the truck was previously a manual transmission?

[Grumpy old man]

Yes, Your truck was manual at one time evidenced by the cut out cross member . Yes you need a automatic trans cross member to keep it from "winding up" behind your new rebuilt engine . Check with member DLtruck he has been listing a lot of cross members in the classified section lately . Do a vin check on your truck and it will give you some interesting facts .

[kehstr]

I'm surprised you are still alive!! When you pulled the motor where the motor mounts trashed? And yes you DEFINITELY need a crossmember

[Mrturner1]

Originally Posted by kehstr

I'm surprised you are still alive!! When you pulled the motor where the motor mounts trashed? And yes you DEFINITELY need a crossmember

Surprised I'm still alive? Is it that dangerous?

[kehstr]

Originally Posted by Mrturner1

Surprised I'm still alive? Is it that dangerous?

Well a t400 transmission is not exactly light, so all of that weight on the driveline, is not good, it could brake and then there's just something flipping around that can hit anything in it's path destroying pretty much anything it comes into contact with. Then not to mention the extra weight it has on the motor mounts that really are not made to have that sort of load on it.

[Mrturner1]

Originally Posted by Grumpy old man

Yes, Your truck was manual at one time evidenced by the cut out cross member . Yes you need a automatic trans cross member to keep it from "winding up" behind your new rebuilt engine . Check with member DLtruck he has been listing a lot of cross members in the classified section lately . Do a vin check on your truck and it will give you some interesting facts .

Thanks Grumpy! Jeez one more thing to buy lol

[firedemon]

Originally Posted by Mrturner1

Thanks Grumpy! Jeez one more thing to buy lol

if you can weld you can build one for about 10 bucks in scrap I got the measurements for one I built I would be glad to post for you . its based on one of those $120 dollar aftermarket ones

[Possmguts]

wow... I mean.. WOW... how was it even still under there?? I mean... WOW!!

[Grumpy old man]

This is when he finds the 12 inch long crack thats already in the trans bellhousing , And the worn out universals along with the slightly tweaked drive shaft ....

[Mrturner1]

Hoping that once I put a trans mount I'll get more power to the ground and a firmer shift too. Seems like a flopping tranny would rob you of some performance

[Grumpy old man]

So... Now that your going to have all the power from the new rebuild and after you install a new trans cross member . Whats the plan for the rear differential ? Because 100' burnouts with a one drive wheel wonder can be done with a 6 cyl with a 3 ott . Are you thinking POSI yet ? Yes ,I know what your thinking "does it ever end "? The answer is NOPE always one more thing to tweak to get it just right .


P.S. climb under your truck with a 4 inch grinder and grind the rivits off whats left of the old cut cross member (SAFETY GLASSES) You'll need the room to install the new cross member .

[Mrturner1]

Originally Posted by Grumpy old man

So... Now that your going to have all the power from the new rebuild and after you install a new trans cross member . Whats the plan for the rear differential ? Because 100' burnouts with a one drive wheel wonder can be done with a 6 cyl with a 3 ott . Are you thinking POSI yet ? Yes ,I know what your thinking "does it ever end "? The answer is NOPE always one more thing to tweak to get it just right .


P.S. climb under your truck with a 4 inch grinder and grind the rivits off whats left of the old cut cross member (SAFETY GLASSES) You'll need the room to install the new cross member .

100' burnouts with one tire would be such a shame after all this time and work haha The differential is next on the list after stall converter and external trans cooler. I definitely want to put a posi in it, but I'm not sure about gear ratio yet. I am going to have plenty of power, so I don't have to go extreme like 4:10's or anything. But I would really like to be able to cruise on the freeway now and then without winding it up to 3000 rpm ya know?

[truckdude239]

show us pictures so we know what exactly you have

[Mrturner1]

Originally Posted by truckdude239

show us pictures so we know what exactly you have

The pics are in another thread. We've got it figured out, now just need to get a crossmember bolted up

[tcrist]

That could be the reason for the "no power at take off" issue that you were having. Everything that was supposed to allow you to hook up was moving around instead.



Guess it really does not matter at this point but, hate to think that you are going through the engine for no reason now.

Well, at least now you will know what you have. Time to start checking everything, and I mean everything. Now you don't know what else could have been Mickey Mouse'd.

[Mrturner1]

Originally Posted by tcrist

That could be the reason for the "no power at take off" issue that you were having. Everything that was supposed to allow you to hook up was moving around instead.



Guess it really does not matter at this point but, hate to think that you are going through the engine for no reason now.

Well, at least now you will know what you have. Time to start checking everything, and I mean everything. Now you don't know what else could have been Mickey Mouse'd.

I think that can be attributed to the big cam with no stall, and the stock gear ratio. But I think you're right, that definitely robbed some power. This engine build has been so fun I wouldn't take it back anyway

[Mrturner1]

Do any of you guys have pictures of your crossmember and transmission mounts? I'm a little confused about mine. There IS a crossmember, but the transmission isn't bolted to it and doesn't even come close to touching the trans

[Gmc.guy]

I don't see a pic. But the one you have that seems cut. That's a manual trans Trimmed to fit auto That bolts to bell housing and trans hangs off the back. Look near the tailshaft. Should be 2 bolts there near the back on bottom. The crossmember bolts there and on the lip of frame on each side. You should have a couple sets of holes there. I don't have any pics but pretty common setup and you should be able to find one

[Gmc.guy]

I'm surprised you didn't have clacky noise with fan tapping shroud or cracked distributor cap.

[Mrturner1]

From what I gather reading and looking at Google images, the transmission should have a mount at the crossmember and the tail shaft. Does it matter when I'm getting parts that I have a TH400 instead of TH350

[kehstr]

That is the correct mount, and i am not sure, but i believe it does not matter if you have a t350 or t400. I do recommend, however, that you buy a polyurethane mount, like one from energy-suspension, they last longer, and in my opinion are much better.

[gvnick]

So was the engine leaning back against the firewall? This is wild!

[Mrturner1]

Originally Posted by gvnick

So was the engine leaning back against the firewall? This is wild!

Oddly enough no lol there is a crossmember there but it's not bolted to the transmission.

[tcrist]

Is the trans mount broken or just missing the bolts?

When you were getting on it before you tore it down, did it vibrate or make a thumping noise like the trans was hitting the body underneath?

Were there vibrations on acceleration or deceleration?

For me, as far as the trans mount, I would not go to a urethane mount unless you go with the same urethane type motor mounts. The engine and trans needs to be able to move with each other. If you have a urethane trans mount (stiff) and rubber motor mounts (not as stiff) you take a chance on cracking the trans tail shaft housing.

[kehstr]

Originally Posted by tcrist

For me, as far as the trans mount, I would not go to a urethane mount unless you go with the same urethane type motor mounts. The engine and trans needs to be able to move with each other. If you have a urethane trans mount (stiff) and rubber motor mounts (not as stiff) you take a chance on cracking the trans tail shaft housing.

You are exactly correct, i was just assuming that he would change the motor mounts, sense they had all of that unstrung weight on them