Suby cradle, rethinking all conversion cradles. Options

[ruby914]

When I started my WRX914 ,I didn't want to modify the car to fit the WRX.
Before long I found myself cutting and welding quite a bit. Looking back, it will never be a stock 914 again.
So why did I use the stock 914 X bar mounts? Like most, I am sure, because they are there. I was basing my decisions off a model for a kit (IMG:style_emoticons/default/confused24.gif)
They are great for plug and play but I have a welder.

Seems they are not in the best location for the WRX motor. It seems to me that the rear suspension inboard ears (Inner console) are just about the best location to tie into.

The Inner console would no longer be indirectly supporting the motor but directly supporting it reducing the load transferred to the tub.
It seems this would stiffen the Inner console as well.
When I originally did my "cradle" I did add a little extra tie-in to the ear but it is not taking the bulk of the load.
I am thinking, if I reinforce the Inner console and tap my x member 100% into the Inner console, I can remove all other "cradle" tubing.

Has any one else taken this route? Any thoughts why not? (IMG:style_emoticons/default/confused24.gif)

[ruby914]

Tangerine has a kit that is a good start for this.
What I have a hard time grasping, is hanging the motor from the Inner console going to reduce stress loads from the Inner console to the body or create a new stress points?
http://www.tangerineracing.com/chassis.htm...inforcing%20Kit

[d914]

others have created a u "cradle" connected tp the rear firewall//??

Tony w I think and some of the early ones....

[ruby914]

others have created a u "cradle" connected tp the rear firewall//??

Tony w I think and some of the early ones....

The way I had it set up, the X member was resting on top of the "L" member, seen in the photo. The "L" member is connected to the rear firewall and the OEM 914 X bar mounts. The connection to the rear fire wall is through DOM tube welded to both walls of the rear firewall and bolted through. My "X" member runs directly under the motor mounts. To remove the motor, I supported the motor and trans, removed the "L" members and pulled the motor out.
I don't like the cradle only because it prevents me from only pulling the transaxle if I want. The OEM trans mount is preventing the motor from FWD and AFT movement.
Interesting note: the motor and 914 trans are almost equally balanced under the suby motor mounts.
I am wondering why I even have the "L" members?

[ruby914]

(IMG:style_emoticons/default/locust.gif)

Not just Suby conversions , any conversion.
I am looking for a little validation before I start cutting.

Any race car builders have any thoughts on this? (IMG:style_emoticons/default/confused24.gif)

[Mike Bellis]

I would worry about the structural integrity. Porsche designed the mounts to hold the engine where it is. If you beef up the suspension console, it might be OK. But you are transferring the load to an area not designed to hold it.

The suspension pushes up. the engine and tranny push down...

[a914622]

You pic is a little hard to see what you have going on.

I have been staring at a svx 6 design cradle. I was looking at a way to tie the rear suspension ears into the cradle with a front mount like the factory 6 or a version along those lines. I want to use the subaru engine mounts and have the frame tied into the front,ear,engine in a triangle and a cross bar under and around the oil pan to the back /or/ tie in at the factory subaru bottom trany mounts? But the ears are the bastard in the mix. I will probably end up boxing them in all on there own, the last thing i want to do is pull one ear out of place with the tork and flex of the engine/cradle?

The newer subarus have had the engine mounts moved to the trany, and in front center like the 914-6. I have aslo toyed with the idea of hanging a big U from the rear firewall with a 6 style front.

good luck

jcl

[ruby914]

I would worry about the structural integrity. Porsche designed the mounts to hold the engine where it is. If you beef up the suspension console, it might be OK. But you are transferring the load to an area not designed to hold it.

The suspension pushes up. the engine and tranny push down...

These were all my thoughts as well but if you move the engine and trans directly to the beefed up console, wouldn't you be taking the load off the console to frame connection. At that point the console would only be carrying the frame with out the motor.

You pic is a little hard to see what you have going on.

I have been staring at a svx 6 design cradle. I was looking at a way to tie the rear suspension ears into the cradle with a front mount like the factory 6 or a version along those lines. I want to use the subaru engine mounts and have the frame tied into the front,ear,engine in a triangle and a cross bar under and around the oil pan to the back /or/ tie in at the factory subaru bottom trany mounts? But the ears are the bastard in the mix. I will probably end up boxing them in all on there own, the last thing i want to do is pull one ear out of place with the tork and flex of the engine/cradle?

The newer subarus have had the engine mounts moved to the trany, and in front center like the 914-6. I have aslo toyed with the idea of hanging a big U from the rear firewall with a 6 style front.

good luck

jcl

Good point guys. I don't know about the SVX but if the newer Subys moved the mount to the front that would be better for the 914 X bar location.

If I am not mistaken the torque would be all up and down equally on both of the
suspension console ears.

I made a fast SketchUp drawing of what I have now. I didn't show the motor mounts on the X bar. I am using the Suby rubber mounts. I think others are solid mounting at the motor and rubber mount at the frame. (IMG:style_emoticons/default/confused24.gif)

[DBCooper]

My son broke the mounting ears off a 901 transmission at a drag strip almost as soon as we mated the WRX engine. It's not relevant to this because I know that engine's motor mounts weren't rigid enough and let the motor vibrate, which was the cause, but it's one reason I like the cradle that provides support for the full drive train, independent of the car's chassis. It provides rigidity to the drive train while also triangulating the whole rear of the car, though not the suspension attachment points themselves. It seems to work pretty well. So far, anyway. Oh, and now we use the Subaru mounts too, and they're perfect.

[ruby914]

My son broke the mounting ears off a 901 transmission at a drag strip almost as soon as we mated the WRX engine. It's not relevant to this because I know that engine's motor mounts weren't rigid enough and let the motor vibrate, which was the cause, but it's one reason I like the cradle that provides support for the full drive train, independent of the car's chassis. It provides rigidity to the drive train while also triangulating the whole rear of the car, though not the suspension attachment points themselves. It seems to work pretty well. So far, anyway. Oh, and now we use the Subaru mohnts too, and they're perfect.

BDC,
I have to go back and look at your build. Many guys were adapting the Small car engine mount to the 914 X bar. Seems this would put all the load FWD of the motor and on the trans mounting ears. I found that my CG of the WRX and 901 together is at the Suby motor mounts. This puts a lot less stress on the trans mounting ears and more at the console ears if I go this way. When your son broke the mounting ear was he using, in any way, a combo of solid and rubber mounts?

[DBCooper]

BDC,
I have to go back and look at your build. Many guys were adapting the Small car engine mount to the 914 X bar. Seems this would put all the load FWD of the motor and on the trans mounting ears. I found that my CG of the WRX and 901 together is at the Suby motor mounts. This puts a lot less stress on the trans mounting ears and more at the console ears if I go this way. When your son broke the mounting ear was he using, in any way, a combo of solid and rubber mounts?

I bought the Small Car mount but didn't use it because it obstructs the area in front of the engine where the stock WRX exhaust has to pass through. It's OK for a N/A car where the exhaust can go back, but if you use that mount that goes forward with a turbo engine you also need custom exhaust... not worth the trade. The SC mount bolts all along the oil pan though, and I can see that being supported there, and for such a distance, could stabilize the engine more than just being attached at the "waistline" of the engine/transmission assembly. I don't know, really, we didn't go that way.

We had all rubber mounts, front and rear, but breaking the transmission was because of compliant (non-OEM) motor mounts, not the mix or the location. It's really not germane to your build. I know it's illogical, but after seeing that broken tranny ear and what was holding the other side I kind of like the idea of a "cradle" under the whole drive train. Makes me feel comfortable knowing I'll never drop any of it on the highway. Again, that's totally illogical, entirely my psychological problem and not in any way a build consideration. But it works for me, so what the hell.

[d914]

I also have a full cradle engine mount to tranny mount.. cradle bolts to car. engine bolts to cradle.. Fairly easy to drop as a unit and it just makes me feel all warm and fuzzy!!
I aslo have a suby tranny..

[charliew]

One thing the stock suby has is the pitch mount or dogbone support on the top front of the tranny. You see them on all the tranverse motors also. I will be using one I'm pretty sure. I actually like the u shaped motor supports. I think they look cleaner but I am not sure if they prevent the front to back motion that 400ft lbs and fat tires will cause. Also the u shape might hinder turbo applications. My son's sti uses a external waste gate and it's crammed right up in that area. My application will try to use a lot of aftermarket suby motor stuff cause we have lots of left over parts and used performance parts for subys are pretty cheap.