The front and middle sections of my car are already semi-tube framed. Now its time to do the rear section. I pulled the engine and started cutting. I decided to fabricate a rear tranny/engine mount using tubing and tie it to the shock towers and the rear side of the swing arm "ear". I 'm going to do one side at a time so I don't loose the alinement and location of the trany. Here is a shot of it cut away...

another

Oh NO what have I done???

The inner fender piece that is rear of the shock will be cut away also.

The tape in this shot shows how the bars are going to be installed. I'll also connect each side with a cross bar running over the top of the tranny.

I'll be using 1" tubing.

I'm also running bars from the shock tower forward to the main hoop.

Have I lost my friggin' mind?

Paul

Wowsers, not much left!!! I need to start cutting my car up now also

Paul, your either brave or....nevermind.

Really, how do you cut the tubing? Do you use a notch cutter at the ends?

One day I wanna hack my car up too.

David,
I use this tubing notcher I bought at Wholesale Tool. You chuck your 1/2 drill motor to the shaft, and install a hole saw on the end of the shaft. Clamp the tubing in the the left and you can adjust the angle of the cut.

Its not for pro quality but it works for a home workshop.

This is my new favorite tool. Porter Cable "Porta-Band". A bandsaw with handles.
Ajustable speeds. Cuts sheetmetal like it was paper..

Paul

P.S. Don't cut up your car. Your car is way too nice. Mine had rust issues.

Paul,
I would use something a bit sturdier than 1" tube to carry the tranny.

Paul, maybe add some additional braces (see pic below)
Try to get the brace from the tranny mount down to the susp. ear as low on the ear as possible (check clearance of the drive shaft)

This is what I'm aiming for (I'm leaving the stock dogbone in place though)

Chris, I'm using 1 1/4" from the shock towers down to the tranny and 1" running to the ear. Plus a bar on top of the tranny to connect each side.


Jeroen, It's not good pratice to run bars to the center of another bar without having more bars on the other side of it. Which is what you're doing with the bar between the shock towers. I'm going to try to get the bars as low as possible on the ear.

I'll also be running 1" bars over the top of the engine to the main hoop. I rough cut the bars today and I'll post the pics as soon as the camara battery charges.

Paul

...................

I see it but I don't like it.

That bar between the shock towers is stressed right there in the middle.
The whole thing could fold up on the center line of the car.

Oh well... it's not the first time we disagreed on cage designs

Keep them pics flowing!

interesting how he braced the inner ears though. Went back with them as well as going to the firewall.

Does anyone actually study up on this stuff or do we just wing it? Like going with your gut.

Alot of the time the best engineered and tested systems don't seem to make sense on first sight.

I've been looking at, taking pictures and studying semi-tube framed 914's for years.
Everybody's just a little different. And they all think thier way is the best way.

For my purpose which is autox only, I think my design will be fine. If I was building a 3.6 road race monster, I would need more structure. I'm not entering a corner at 120 mph and holding +1 g's for 10 seconds.

Simple layout, easy to fabricate and lightweight is what I'm going for. The idea behind lightweight tubing space frames is, if you see a problem developing, you can add some more bars or gussets to stiffen it up. I could run 2" bars everywhere but I never know where I was over designed.

Call be Colin Chapman....

Paul

Also many engineering solutions to problems are the simplest!

I have forgotten the word, but there is a word or phrase, that describes, the first most apparent thought being the correct solution... and its not KISS ( keep it simple stupid)

Paul, Jeroens illustration looks like it would work just fine..

Also ever wonder why the floor of you home is made from 2x8 or 2x10 or 2x12wood or glue lams?... and yet the wall is made up of 2x4 ( or 2x6)

Slenderness isnt bad in engineering circles..

You need large section members where bedning is a consideration..

small section works well in tension and compression

I think the four tubes (two forward and two rearward) that meet in the middle of the crossbar are somewhat useless.

I like the one in Chris' pic. It gets rid of the oddball 914 shocks....when you've gone that far, why keep the towers..., strong ( to a boilermakers eye) and elegant in it's simplicity....but WTF do I know

J P, I thought about cutting out the shock mounts but tieing back into the frame rails would be a bitch of a connection to fabricate.

What I'm trying to acheive is:
1. Larger bars with smaller diagonals.
2. All bars begin and end at a connection of other bars or back to the car tub.
3. Bars can't "dead-end" into the middle of another bar.


When I'm done the rear shock tower will have four tubes tied to it. The front has three bars tied to it.

Keep the comments coming..

Paul

this rig looks good

This pic shows better on what I'm planning. I just spent 1 hour fitting one tube in. Some fun.

The bars over the engine clear the filter just enough.

The bars over the engine will be 1".

Here is the connection at the shock tower to the bar running to the main hoop.

You probably thought of it already,but...

Make sure you have clearance for movement of the motor from torque. Even with rigid mount, mine move a little. Also, gotta be able to service, tune, etc the carbs.

And what's the deal with your firewall? Are you going to cut it more or leave it like that?

I *really* like what you did with this last pic in front of the shock tower.

As far as the rear tranny mounts.... most of the 914 owners here with 3.0+ engines would SHIT a brick if they knew that their stock tranny mounts where held on with ears that are spot welded in 4-5 places. You dont need a TON of bracing in the rear for the tranny.

In my tube frame car shot... 90% of what you are seeing is CRASH protection Not tranny mount.


B

I want to be able to reach around and adjust the fuel pressure and timing while I drive.

OK maybe not, I'll replace it with a piece of sheetmetal (or cardboard )

I'll have about 3/4" over the a/c top.

Paul

It was a PITA fitting that bar in front of the tower but it should be a lot stronger.

Vic Elford (i think) told about how he had to work the throttle on his 917 (i think again) directly when the cable broke during a race.

See, you and Vic have alot in common.

Thank you, I thought that was the case.

Paul

I thought that was your car so I didn't say anything.

The only place I need crash protection is in the front when I hit those damn cones.

Paul

Careful there, I think Vic lives in South Florida. Down in the Grove if I remember right.

I've heard that story too.

Paul

The brace your adding in this pic... is that going up to the pass.side of the main hoop or is it going across the engine to the center of the firewall / mainhoop x-brace ?

Pass. side of main hoop.

P

You should get rid of the Weltmeister tranny mounts and bolt the ear up directly to a metal plate.
I would prefer to see your bottom braces go forward to the underside of the longitudinal instead of to the inner suspension ear. IMO, the trailing arm pickups shouldn't be used to support the mass of the car.
Normally the only major loads the inner console sees are in a forward direction, during cornering (draw an arrow from where the rubber meets the road to the hole in the inner console). Any rearward forces are somewhat less since they only occur to the unloaded, inside wheel.

I'll do that. I was undecided on bolting the tranny right up to the mounting plate. But if you think its OK I'll do it. It will be cleaner.

Thanks

Paul

Let me look to see where I can tie it in under the frame rail. One of the reasons I was tieing to the ear was that it was an easy connection. I could pull the location of the tie in point up to the inside of the frame rail if that is better.

Thanks again,
Paul

I fitted the tranny support bars in this afternoon. Also cut away some more sheetmetal to get better access. Have a look...

I removed the Weltmister solid mounting block and will mount the tranny ear right up to the support base plate, per Chris' recommendation.

In the picture above you can see the black line that goes from the rear of the shock tower to the outside toward the fender. That is the cut line to wack off the rest of the inter fender sheet metal.

I used the tubing notcher, the porta-band saw (both shown in a earlier post above)and a 4" angle grinder. You need to be very careful when fitting the bars in. You have to work slow to fit one end of the bar and than notch the other end to get it to fit. When you change the angle on one end you're changing the other end as well. Sounds basic, I know but you really fit both ends of a bar at the same time.

Paul

are your welt tranny mounts for sale now?

im interested

Just PM'd ya.

Paul

You have a strange way of fighting rust.


M

soon it won't be a 914 if you keep cutting

I looked at that last pic and I thought "well where is the car?"

All that's left are the sail panels and of course, the motor.

Paul is building a full tube frame car within the silouhette of an orignal 914

instead of building a tube frame chassis, and hanging a body on it..


I think LOL

that's why it is taking 25 years

I have learned tons of stuff from guys like Paul...

someday my car will be less than his LOL

Look, if it is behind the rear wheels- it coming off!!!

I just went out and cut off what was left of the right side behind the shock. The fender is hanging out there by itself.

You guys just wish you were as sick as me, HAHAHAHAHAHA

I have a friend that lives down the street. He couldn't change a light bulb. He works at credit union, drives a Civic, you get the picture. He looks at my car and is completly lost. If it wasn't for the seat facing the steering wheel, he wouldn't know the back from the front.

I'm MAD, I tell you, MAD. HaHaHaHAHAHAHA...