77K5. The IronMaiden...9/2 headed for Blazer Bash 20!

[76zimmer]

I will try to find some pics of it, if I can't I will go take some tomorrow. My setup needs some changing as I am using rubber motor mounts and rubber mounts on the first xmember, but poly on the rear xmember.

Nope no pics I will take some tomorrow

More pics is always helpful to me Eric....I like to see, not think

I don't have a doubler but when I made my custom crossmember I kept the factory style mounts. Which isn't necessary but if you are going to use poly fab bushings I would keep them inboard more. You have a big block, and it will break your TH400 case if it is not supported correctly. Keep in mind you are already doubling the number of mounts, which doubles the resistance. If you spread the mounts out more it will multiply both of the mounts. You want the engine mounts to absorb the torque, the trans/tcase mounts should just hold the weight of those components up, not absorb torque.

I have read about that too Heath, I think my structure will be pretty stout, with full boxing and cage too, but I would still like to err on the conservative side and keep the actual t/c mounting close to center instead of at the frame rail.


Here is a pic of the frame as it sits right now with drivetrain in, obviously no body.

Frame is 2* angled up at the rear..

Here is the ujoint angle 5* down with the trans pan level to the frame, which if the frame was level, would make this 7* down towards the rear.

A shot across the bottoms of the frame rails. The trans pan is level with the frame rails, and the front t/c mount is about level to where the factory crossmember mount is. I think that is where I need to be, keeping the trans pan level with the frame rails?

The t/c at its lowest point is 3.5" below the bottom of the frame rails.

 

[folkenheath]

I have read about that too Heath, I think my structure will be pretty stout, with full boxing and cage too, but I would still like to err on the conservative side and keep the actual t/c mounting close to center instead of at the frame rail.


Here is a pic of the frame as it sits right now with drivetrain in, obviously no body.

Frame is 2* angled up at the rear..

Dave, I am not worried as much about your frame twisting, I am more worried about the engine torque. The engine will torque around a lot more than you think, even with poly mounts. And if too much of that torque is resisted through the transmission, you will brake the case. I've seen it happen. But it sounds like you have it covered either way.

Also, FYI, my stock t-case output angle is 4 degrees. However, I did not measure if the frame is level. The truck sits pretty level.

 

[76zimmer]

Been reviewing the doubler crossmember thread, and got some more ideas. I like the idea of keeping it low profile. Here's what I'm thinking: bolt some 1/4" plate big enough to bolt to all 4 mounting holes of the two adapters, and maybe to the back of the 205 with a few bolts going to the rear output, then make the sides of that bottom plate rise up immediately as it extends outward to the framerails, then make the bushing mounting above the bottom of the 1/4" plate, then run it out to the framerails, and also triangulate to the top and bottom of each frame rail. The triagulation would help distribute the shock of a hard smack on a rock throughout the frame, not just at the t/c plate. Also make a support for the heavy end of the 205 that hangs out there, and bring that back to the area of the rear 205 support too. That would help control torque as the t/c tried to rotate from driveshaft resistance.
The flat plate on the bottom would be reinforced between the two t/c's to provide rigidity out to the point of where the rise up to the framerails would intersect.

Any of this make sense to anybody?

 

[sixb]

I am more worried about the engine torque. The engine will torque around a lot more than you think, even with poly mounts. And if too much of that torque is resisted through the transmission, you will brake the case. I've seen it happenl.

I'm living proof of this
You can see mine in my cucv truggy build thread, I plan on switchining the engine to poly and building another mount for the t-case.

 

[76zimmer]

I'm living proof of this
You can see mine in my cucv truggy build thread, I plan on switchining the engine to poly and building another mount for the t-case.

What are your plans David?

Got a pic of your setup as is?

 

[sixb]

Yeah there's pictures in my Truggy build thread. Basically the soft worn out motor mounts plus the newly built poly mounts for the rear of the doubler were no match for the beating I gave it at the Idaho top truck challenge
You'll have to look at the pictures to see what I'm talking about but I plan on building another set of mounts to go in the traditional spots for the doubler and switching out the motor mounts for poly also.

 

[76zimmer]

I see top suspended...and with the rubber? engine mounts that did it in you think?

Are you planning on a bottom mount in addition to the top mounting?

 

[sixb]

I see top suspended...and with the rubber? engine mounts that did it in you think?

Are you planning on a bottom mount in addition to the top mounting?

Yes the 205 is suspended from the top and that will not change. Also the engine mounts are stock. I do believe especially after some research that I was destined to fail eventually.

I will build similar poly mounts for the t-case adapters. and I bought some diy4x engine poly motor mounts that I'll install.

When done I believe it will be bullet proof

 

[76zimmer]

I have Kerts engine mounts too David, nice stuff, you'll like em.

I think I'll get some steel tomorrow, and start throwing my ideas together for this cradle, and see what you all think.

 

[folkenheath]

That would help control torque as the t/c tried to rotate from driveshaft resistance.

This sounds like a bad idea, you don't want to control any torque through the tranny. If you want to install poly bushings on the outside of your crossmember for shock absrorption, then you still need to put some in the center where the tcase bolts to it as well.

If you want a rod to support it front to back, you can fab up something similar to the factory one that links the tcase to the engine block. But if your driveshaft has enough compression travel, you should be OK.

 

[76zimmer]

actually Heath, that outer support would be bolted to the rear cover, or perhaps those two holes for the factory side support, but would then come back to the bottom plate where it is bolted to the t/c's. This would put all of the support in the area just underneath the t/c's. The poly bushings will be outboard of the bottom plate, but as close as possible to the sides of the t/c's/

This pic, shows kinda what I'm thinking by having the poly mounts up on the side of the t/c's to help keep the bottom as low profile as possible.

 

[folkenheath]

actually Heath, that outer support would be bolted to the rear cover, or perhaps those two holes for the factory side support, but would then come back to the bottom plate where it is bolted to the t/c's. This would put all of the support in the area just underneath the t/c's. The poly bushings will be outboard of the bottom plate, but as close as possible to the sides of the t/c's/

This pic, shows kinda what I'm thinking by having the poly mounts up on the side of the t/c's to help keep the bottom as low profile as possible.

You know I was going to try and make a sketch of something similar, but I don't have time, busy at work, but that picture shows it all, that's a great idea. Who's is that?

 

[76zimmer]

Heath, I can't remember now, but it came from the doubler crossmember thread.
Going to go get some steel now before going to work, so I can hash this over more tonight at work...something else came up the bottom of the 203 has areas that hang about 1" below the bottom of the adapters, so may have to space down the bottom plate. Also the front output side, looking at it, it I support the rear of the 205 where the rear output is, that cast iron case is strong enough I'm sure it don't really need the support, and by tying in the two cases, the rear support, and the cradle to weld to the bottom plate...that as a unit I think will be plenty stout to resist any twist between units.



Also got the engine buttoned back up today, and tuned better.
This is more what I had in mind:

 

[crawdaddy]

Man that looks and sounds sweet. Now you just need to box it up and send it to me..

 

[76zimmer]

bottle up exhuast fumes?

because racing gas smells so good!

So BBC guys what are you running for mechanical and vacume advance curves? @ idle I got 15* mechanical as it is right now, no vacume hooked up because it throws about another 20* when I hook that up. I'm thinking I'd like to keep 10-12* mechanical at idle, then maybe 32-34 max by 2500. Add vacume to get to about 45-50 total by 2500.

 

[folkenheath]

bottle up exhuast fumes?

because racing gas smells so good!

So BBC guys what are you running for mechanical and vacume advance curves? @ idle I got 15* mechanical as it is right now, no vacume hooked up because it throws about another 20* when I hook that up. I'm thinking I'd like to keep 10-12* mechanical at idle, then maybe 32-34 max by 2500. Add vacume to get to about 45-50 total by 2500.

Are you trying to tune a whimpy engine for a Jeepster or what Dave? Hook that vacuum advance up to full manifold vacuum, yes it throws more advance at it, but it will like it most often, especially with performance cams. You can check by doing it and seeing if idle increases(don't count during the vacuum leak obviously). Also, throttle response will increase, and it will idle more consistent when you put it in gear with that extra timing at idle. It will idle cooler too sometimes. And don't worry, under load the vacuum falls off and goes toward inital anyway, that's what it's for.

With that said, while the vacuum advance is disconnected, I would set it up for 15-20 initial, then 34 - 38 in by 3000 RPM. Then plug the vacuum advance back in, and try it and set it for 50 - 52 total at cruise RPM.

Obviously if it pings you know to back it off a couple degrees till it quits.

If you want a good read on that, check this out...(go to the drivetrain technical, and then timing/mech good read post)


http://www.maliburacing.com/forum/

I have my 388 regal locked at 38, (not enough vacuum for advance), real snappy. (has digital start retard)

My truck BBC I have setup like I stated above, at 36 degrees total at WOT, plus vacuum advance to 51.

 

[76zimmer]

come on Heath, quit busting my balls here.....

I'll try the vacuum again, when I tried it before the one rocker was off, so idling was tough to achieve anyway. I need to open a port for direct manifold vac. source, right now all I have is ported vac source.

I'll try to map those out tomorrow.

Just bought 88$ worth of steel for the doubler cradle, and maybe some extra's for the shop too.

 

[acewilson]

When you get your new crossmember built and you think you might want to part with that flat bottom one keep me in mind. I am in the search for something stock like that.

 

[76zimmer]

When you get your new crossmember built and you think you might want to part with that flat bottom one keep me in mind. I am in the search for something stock like that.

I did take the upper brace portion off that crossmember as you can see it in this pic, it had a riveted on brace that triangulated the pass side of that crossmember....

 

[acewilson]

I see that now. I was looking for something stout and flat that would also allow me to run true dual exhaust. Guess im back to the drawing board and fab table.