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Strut rods.....

4x4blaze

4x4blaze

That's not going to work
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Hey guys, feel like I'm taking 1 step forward and 2 steps back with my 75 blazer.. The truck is running a sbc with a 700r4/208 combo.. I am also running Off Road Designs competition style motor mounts. And of course, they will not work with the original strut rods that 700r4 trucks used.

I know this has been asked before, but how necessary are these struts? My competition style motor mounts have absolutely 0 play along with my poly crossmember mount.. would this make the driveline rigid enough to not cause concern? Or should I modify them to work? I will be making around 500 hp..

Any input or personal experiences would be great.. I'm at the point of my build where I can see the light, but am also really getting burnt out from stupid issues like this..

HELP ME:1zhelp:

Thanks guys!
 
Hey lol, I’m the guy that posted the pic on FB. Cool to see you here.
 
I believe the reason the strut rods are there is because of the extra stress of 4x4 and the aluminum case of the automatic transmission combined. I would weld something up if the factory strut rods don't work out although everything will still work without the rods, just my preference as I have seen a tranny case Crack and have owned a few square body's with welded bellhousings in 4x4s...I wouldn't run 500 horse on a 700r4 without major upgrades and even then I'd still be concerned.
 
Well, I spent about 5 hours tonight cursing & modifying just to find out that all of my time spent was wasted....:doah:I have a Moroso oil pan with a slight kickout on either side.... Which perfectly blocks the routing of the rods..... Honestly unbelievable.. So running without the braces it is! I may eventually try to fab something, but we'll see... Concerning, but I'm kinda screwed.

& This 700r4 is a performabuilt that's rated for way more than I'll be making, so I'm not too worried about it.. I want this thing to be a driver, so O/D was a must. The only thing truly 700r4 about it is the case..
 
Engine should be right around 500 give or take with a 9 inch converter and 3200 stall speed.. This truck will be good at nothing. But I assure you it will be fun:rotfl:

& If it grenades the tranny, I'll change it up and put something even beefier in it! But I've heard lots of good about performabuilt, so we shall see!
 
4x4blaze said:
Well, I spent about 5 hours tonight cursing & modifying just to find out that all of my time spent was wasted....:doah:I have a Moroso oil pan with a slight kickout on either side.... Which perfectly blocks the routing of the rods..... Honestly unbelievable.. So running without the braces it is! I may eventually try to fab something, but we'll see... Concerning, but I'm kinda screwed.

& This 700r4 is a performabuilt that's rated for way more than I'll be making, so I'm not too worried about it.. I want this thing to be a driver, so O/D was a must. The only thing truly 700r4 about it is the case..
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Sounds like you have the same Moroso pan that I got. If you want to go with a larger oil filter you end up having to go with a remote mount which leads to a whole nother rabbit trail. I still have to have my 77 Jimmy smogged so I couldn't go completely psycho with it, but I am putting out 415 to 425hp with my 400. Next rebuild I will probably go with a full roller, I just didn't have the extra grand to spend this time around. Do you have a build thread of your engine? Always looking for new ideas for longevity and power upgrades.
 
Joel Wilson said:
Sounds like you have the same Moroso pan that I got. If you want to go with a larger oil filter you end up having to go with a remote mount which leads to a whole nother rabbit trail. I still have to have my 77 Jimmy smogged so I couldn't go completely psycho with it, but I am putting out 415 to 425hp with my 400. Next rebuild I will probably go with a full roller, I just didn't have the extra grand to spend this time around. Do you have a build thread of your engine? Always looking for new ideas for longevity and power upgrades.
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I always though the strut rods plus the big rod that goes from bellhousing to the output side of the transfer case was a good idea, if not a must have for any of the aluminum drivetrain options. with that much HP, I would cut/weld modify them or come up with something to do the same job- gotta protect that bellhousing and tail housing! -and maybe transfer case!
 
If it wasn't needed GM wouldn't have spent the money on them because car companies are notorious penny pinchers. I have all the braces in mine for just this reason. It doesn't take much to break these trans and transfer cases.
 
scottsdale86 said:
If it wasn't needed GM wouldn't have spent the money on them because car companies are notorious penny pinchers. I have all the braces in mine for just this reason. It doesn't take much to break these trans and transfer cases.
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This ^^

They might only be $100 worth of material but there was a reason GM spent LOTS of money on R&D and tooling for them, manufacturers don't WANT to spend money.
 
Well guys, I'm back! Truck has been all over it seems, but I just picked it up and brought it home this weekend. I haven't been able to work on it, but at least it is completely wired now! So one step closer to running..

But, as I stared at it in the garage, I remembered these annoying strut rods. With my pan setup and some other things, I don't believe I would be able to make them work the way they originally did going from the motor mounts to the dust cover..

So I came up with an idea and I wanted to get some input from you guys.. What if I went from the frame rails to the dust cover with heim joints and an adjust link? They would still be doing relatively the same job, but instead of pulling, pushing.. And since they would be both pushing forwards and at roughly a 45° angle, they would probably do a good job at locating and securing the trans.. Possibly better than gm's original idea.. And considering my engine is mounted with ORD's competition style motor mounts, and the transfer case has a poly mount, I really don't imagine that the driveline will have any play compared to the frame.. So what do you guys think?

It's these late night thoughts that will kill ya.......:surepal:

20220424_233733.jpg

& I know this isn't the greatest picture, but gives an idea of what I'm talking about.. The rods look like the would be able to fit right underneath my exhaust also.. & If not, I could fab up a little spacer..
 
The strut rods are not there to hold the engine to anything. They are there to transfer transfer case weight to the engine mounts. Tying to the frame with rigid anything will be detrimental when the frame flexes.

Cross member and a flexible mount for the transfer case. Or just leave them off. I would bet more trucks do not them than do.
 
4x4blaze said:
I will be making around 500 hp..
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Can you share specs on the engine? This should require something like 6400RPM to achieve. The transmission cares more about the torque, which may be closer to 450. Also, not trying to call you out, but there are lots of transmission builders claiming to make bulletproof 700s that just don't hold up. Maybe you can share details on the trans.
ktmoutfront said:
A cross member at the transfer case would take the load off of the bell housing.
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Are you proposing making a sort of L-bracket that ties the strut mount holes to a cross member directly underneath (between the two frame rails)? Obviously this provides more support to the 208, but is it doing the same thing that long rod did? The rod should provide resistance to twisting (in one direction) due to being in tension. What the added flexible cross-member mount does depends a lot on the execution.
 
ktmoutfront said:
The strut rods are not there to hold the engine to anything. They are there to transfer transfer case weight to the engine mounts. Tying to the frame with rigid anything will be detrimental when the frame flexes.

Cross member and a flexible mount for the transfer case. Or just leave them off. I would bet more trucks do not them than do.
Click to expand...

Hmmm... I see what you're saying. I would like to somehow someway add reinforcement, but man, this is turning out to be quite the task.. I could leave them off, but my biggest concern is horsepower. This truck is primarily a cruiser, so don't expect to see me doing any hardcore crawling where I'm really binding everything.. But it is going to be a pretty hot little engine with a big stall, soooo... It will be pretty fun to line up next to a raptor or TRX:whistle2:

I guess I'll just be the guinea pig... Will he crack the housing or not... Stay tuned!:burnout:
 
Blue85 said:
Can you share specs on the engine? This should require something like 6400RPM to achieve.
Click to expand...
385 sbc, forged eagle crank, forged h beam rods, forged pistons, Dart heads & intake, 202 valves, hydraulic roller, 550/555 lift cam, fuel injected, 10.8:1 compression.. Hydraulic roller will be the limiting factor on rpm, we'll see what she spins here shortly.. First sbc I've built in a while, have a 509 bbc in a camaro, and a 540 in a boat.. All are built to be way overkill..

& Trans is a performabuilt 700r4.. I have lots of friends that run them in some pretty ignorant street cars, and have always had good service.. So, we shall see.. Because I assure you I'll test it!
 
Back to work, so I'll reply more in depth later.. The big rod that goes from the transfercase is installed, the two little ones from the trans are not just so we're on the same page
 
If you really want the strut rods what about building a bar that runs across the cover mounting holes to extend the rod's lower mounting points further out? You'd probably only need to go 2"-3" per side so I doubt you'd get too close to the headers.
 
I always believed the rods are to keep the bell housing from ripping open, when in low range, lots of skinny pedal and good traction with heavy vehicles.

Is the 700r4 a k case ?
 
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