What is the purpose of the engine mount to tranmsission strut rods?

[vandelay industries]

What i'm trying to do is swap a STOCK 4.3 in where a v-8 small block was. The truck is 2WD and my TH-350 not only has the thin tin dust cover, but i have left if off for about 7 years. Thus, i would have no place to attach them to irregardless. The 4.3 came with these strut support rods with the mounts.

Are these strut support rods really necessary especially in a stock 2WD application? Also, considering the truck has run v-8 small block with no support rods all this time with no problems?

 

[rebelgregory]

Can't be that necessary. I haven't had mine in about 8 yrs. I'm sure they help in certain conditions, but not vital. Mine is a 4x4.

 

[vandelay industries]

Yeah, that's my gut feeling as well; After all, i've been running cast iron v-8 small blocks in there without the strut rods with no problems, no cracked bellhousings all this time.

Just wanted to get more opinions.

 

[beags86]

I took mine off and proceeded to break my transmission case. In an off road, off camber situation. I wouldn't run without them. In a 4wd.

Seems that they help with the transfer case loads and forces.
2wd stuff doesn't use them. And I wouldn't worry about it.

 

[76zimmer]

It seems the way its mounted it would only help with forward/aft movement
Like if the t/c was to hit an object that rod would keep it from breaking the tailhousing of the trans

 

[diesel4me]

My '82 K2500 has a 2wd cased TH400 in it behind a 6.2 diesel,has the tin flywheel dust cover,so no place to bolt those 2 support rods too any more,they are there but just tied up out of the way.....been beating the snot out of it plowing with it since 2003 when I got it,haven't noticed any cracks yet,and it hasn't fallen out of the truck yet so---I dont think they do much in my application,but I'd feel better if they were able to be bolted up none the less...

 

[ktmoutfront]

They are there to be in the way when you need to work on anything. Both of mine still have them.

 

[beags86]

My '82 K2500 has a 2wd cased TH400 in it behind a 6.2 diesel,has the tin flywheel dust cover,so no place to bolt those 2 support rods too any more,they are there but just tied up out of the way.....been beating the snot out of it plowing with it since 2003 when I got it,haven't noticed any cracks yet,and it hasn't fallen out of the truck yet so---I dont think they do much in my application,but I'd feel better if they were able to be bolted up none the less...

You plow with a 2wd? Or you run a divorced t- case?

The truck that I have that broke is a plow truck that I converted from a 6.2 to a 454, when I did the conversion I took them off thinking I didn't need them. Then I took it off road one day deer hunting got into a twisty and cracked my whole bell housing off the T400. After I got it fixed I put them back on, and never ad a problem since.

People may think you don't need them. And that's fine, but I'll continue to run them. My cost of tuition was 1 turbo 400. That was enough for me.

 

[K85 Octane]

I think all 3 rods are important. Simply to keep everything aligned and tight when things get twisted up. The joint between the block and tranny is right in the middle of the frame mounts, putting it stress on those bolts. Considering the tranny hangs lower than that bell bolts, the additional rods even the load. The long T-case rod is important all the time, even on the street, cause that driveshaft is constantly beating on the T-case whether it's spinning or not.

 

[79rustyk10]

Aren't those rods for use with the K cases that use the cast aluminum cover? I never put them back on on my 89 LD K2500 and never had an issue, but that was a stock truck and never really wheeled.

I'd give them the axe in a 2wd. All they would do is get in the way.

 

[diesel4me]

You plow with a 2wd? Or you run a divorced t- case?

The truck that I have that broke is a plow truck that I converted from a 6.2 to a 454, when I did the conversion I took them off thinking I didn't need them. Then I took it off road one day deer hunting got into a twisty and cracked my whole bell housing off the T400. After I got it fixed I put them back on, and never ad a problem since.

People may think you don't need them. And that's fine, but I'll continue to run them. My cost of tuition was 1 turbo 400. That was enough for me.

My truck has a 2wd cased TH400 that someone evidently either swapped in a 4x4 output shaft into,or it is some version that happened to have the same output shaft length as a 4x4 one...it has a NP-208 transfer case...it does have the truss rod from the T-case to the bellhousing bolt,but not the other 2 short rods that went from the motor mount frame pad to the dust cover..

I'd prefer to have all the proper truss rods bolted up as GM intended,but so far it hasn't seemed to bother my bellhousing...(subject to change without warning I suppose!)..I dont go off road,but I have had to slam into snowbanks at 15 mph a million times in the past 12 years with it plowing..hard enough to feel like the cab is coming off the frame..

 

[89yimmiJ]

Not trying to stir the pot or anything but...the manufacturers typically don't spend money designing structural parts, manufacturing parts, installing parts, etc. that aren't needed. I would have to assume that GM saw some occasional breakage during R&D that necessitated the strut/ truss rods. I would leave them in whenever possible.

 

[vandelay industries]

Not trying to stir the pot or anything but...the manufacturers typically don't spend money designing structural parts, manufacturing parts, installing parts, etc. that aren't needed. I would have to assume that GM saw some occasional breakage during R&D that necessitated the strut/ truss rods. I would leave them in whenever possible.

That's what i'm afraid of. However:

1) i'm running a th-350 and there's no place to attach these rods ( i will try to locate a pic or diagram asap of the rods)

2) Truck has run small block chevy v-8s (all iron i might add) for 30 years with the original transmission and the trans bellhousing has never cracked.

3) i would think a v-8 would put more stress on the bellhousing than a 4.3 v-6?
v-8 weight = approx 575 lbs.
v-6 weight = approx 425, 450 ish lbs.

 

[Bowtie85]

I have a 2wd case swapped in my k10. I drilled holes and bolted the k series inspection plate on. drilled all but 1 I think. Bolted it from the backside and called it a day.

 

[89yimmiJ]

That's what i'm afraid of. However:

1) i'm running a th-350 and there's no place to attach these rods ( i will try to locate a pic or diagram asap of the rods)

2) Truck has run small block chevy v-8s (all iron i might add) for 30 years with the original transmission and the trans bellhousing has never cracked.

3) i would think a v-8 would put more stress on the bellhousing than a 4.3 v-6?
v-8 weight = approx 575 lbs.
v-6 weight = approx 425, 450 ish lbs.

I don't think you will ever have a problem, I just wouldn't remove them if you had a provision for them. Like I said, probably only a small percentage had a problem during R&D and that's why they added them. I believe their intended purpose was to hold the mating surfaces tighter together to keep the entire driveline more inline. As more gears where added and transmissions and transfer cases increased in length the problem probably compounded. Slightly off topic but I believe still relevant, I remember in the 90's when we started installing ZF 6 speeds in our cars in place of the 4speeds a few guys started having problems as the run out on the mating surfaces wasn't always equal side to side. Not a problem with a relatively short 4speed but with a long ZF it caused multiple issues. The blocks from the 80's and later seem to be nice and true where the old blocks can be off. Now whenever I build a car that is getting a 6 speed, I check.

I wish you good luck and I wouldn't worry.

 

[diesel4me]

I think the weight of the transfer case is the main concern,not so much the engine...it "hangs" off the rear of the transmission,and can put enough stress on the bellhousing to break it during a hard landing off road,or if it bottomed out on it...a heavy cast iron NP-205 or NP-203 will put a lot more strain on one than an aluminum cased one like a NP-208 or NP-241 will...