porsche powered mid-engine double cab

[67dubcab]

Here is my version of a truck, not a what you would normally see on this forum but I visit here often to check out all the great car builds.
It is built as a daily driver shop truck. Built to handle ,haul materials, and keep up with most modern cars. A euro version of a Pro-Touring Truck.

[k9kevin81]

Nice, thats pretty sweet.

[keithq69]

Very nice. Love it.
Should handle great as a mid engine.

[Thephranc]

Thats cool.

[Guyt699]

I love these things. Rutledge Wood has a '66 that is pretty sick too. Very cool!

[rjsjea]

Heck yeah, that's cool

[astroracer]

Hey! I was following the build on that on The Fab Forums.... Wondered what happened with it. Now I know! Thanks for posting it up!
http://thefabforums.com/main/index.php?topic=141.0
Mark

[rustomatic]

That is awesome, no qualifiers needed! This is just the kind of car/truck that makes this forum what it is!

[72D100]

thats awesome.

[67dubcab]

Thanks for the positive response guys.
The truck is in the driving/crap! not driving phase.
I am working through some faulty components but can say with the limited wheel time I have had that the truck will handle very well once sorted.
I had the reverse problem that most of you are addressing with too much rear weight bias when driving without a load. The mid engine solves that and the rear transaxle keeps it with what I think will be about a 55/45 weight split. I will get it corner balanced when all the rough tuning is completed to get true figures, I think my finished wet weight should be about #2900.

I read some posts here about using late model Corvette drive trains which should really help rear bias with the torque tube and transaxle aft in a "normal" truck.
The fabricator who worked on my rig is now building a Ranchero with a aluminum v6 in front and a Porsche 944 torque tube and transaxle in the back, should balance nicely.

[67dubcab]

Took the d.c. to a autox test day at Sonoma raceway.
I have not done any tuning to the chassis/suspension since I got it running, so this was a chance to find a baseline before I start optimizing.
The truck ran well and put up with being flogged for over six runs and some figure eight skidpad laps.
In it's present form it has heavy understeer and the rear is too stiff in comparison to the front and just spins the inside tire.
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The big track shot is some low speed laps during lunch break.

[ChevelleNV]

Very nice...

[Bryce]

very cool, thanks for sharing!

[wfo guy]

I like it! Plus you have a trailer hitch. All toys should be useful. :)

[Kenova]

Cool !
It is mid-engined, can carry a load, and has a trailer hitch. What's not to like?
Keep us updated with your chassis tuning. This should be interesting.

Ken

[BMR Sales]

Buses are bringing Huge Money these Days! If you Google Charles Slater's Bus - it is a FabCar Built with a 993 Twin Turbo Motor. Also Check out racetaxi.com

[Tig]

Wow, that is awesome.
Do you have a build thread?

Isn't there a Porsche powered bus that is racing around nurburgring?

[67dubcab]

Thanks all for the kind words.

I will start my chassis tuning by swapping out my front springs from #220 to around #275, I am still running torsion springs with the coil-over shocks and my calculation that the front and rear were close at around #300 effective wheel spring rate each may be off. I will still need a higher rate for the rear as I carry loads (and will tow a trailer) just need to get them closer (I think).
Once I am happy with the spring rates I will get it corner balanced and aligned. I need to get the front roll cage fabbed in first as it will add some weight, and stiffen the front up a bit as I had both doors pop open during the autox run (at different times, when one of the staff mentioned it I told him I thought I hit a cone and wanted to get a better look!).

I have a few build threads, one on The Samba V.W. site and one on Pelican Parts, a Porsche site, if you search "Porsche Powered mid engine double cab" it will get you there for those interested and I will keep posting up here further refinements and modifications.

The "race taxi" mentioned by BMR Sales is a full on racing bus built in Germany, with lots of good video online.

Split window buses are going up fast in price, and a few people winced when I started cutting this one up, but I to me it is a tool that I use and admire every day, I just wanted to make it a bit sharper.

[67dubcab]

Here is some video from my first autox test session, I still need to change the spring rates to dial out the understeer.
http://youtu.be/_Ks2JAA_9Eg

[2jz_Dime]

I love it!!

[BMR Sales]

I really like the Fab work on your Rear Shocks!

Why did you use a 944 Transaxle vs using a 901 or 915?

If it were me, I would put a piece of 180 Degree bent piece of screen in front of your Front Oil Coller to keep Rocks from Punching through & Debris from Clogging it up.

T.C.

[67dubcab]

Thanks for the kind remarks guys.

T.C. It was my general design to run the pushrod shocks for space and travel reasons but my fabricator Seth Bomar made it all work.

The reason for the 944 transaxle is that with a torque tube layout I could put the engine where I wanted it, in this case under the existing seat pedistal for access.
I could also keep the torsion tube intact in my case I had Seth weld in the 944 torsion tube which locates and carries the rear suspension arms. It also helps that the 944 transaxle is cheap and in the case of the 944s2 version strong enough to handle the 3.2 Porsche engine (and hopefully the dual turbos I will add in the future!)

I am still detailing the front bumper and actually made a screen frame some months ago but have since made the cooler opening smaller so need to re-size it, but your right, it is getting beat daily driving it on country back roads. I am also going to fair in the opening to smooth it out.

here is a shot to show the drive-train layout. Lots more on my build thread.
92761

[BMR Sales]

How are you getting Air to the motor?

[67dubcab]

The air comes from the grills on the side of the truck, 66 and 67 model years had these instead of the grill on the rear sides, because the grill is so far forward v.w. had holes in the bulkhead leading forward and I took out the panels which seperated the rear of the truck to the cargo hold under the seat. The engine runs cool, rarely kicking in the secondary thermostat to the front bumper mounted cooler.
My future plan is to hammer out some aluminum scoops to replace the stock louvers.
92796

[67dubcab]

I found some carbon fiber mirrors used off a race car from a shop at Sears Point Raceway.
They weigh 5 ounces each and replace the stock bus mirrors which weighed in at 24 ounces!
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I went back to the same shop (Auto Spa) and put the d.c. on the corner scales, to get a rough tune , I will need to return after the front cage is fabbed and if I change my spring rates again to fine tune balance.
The first #'s are without driver weight and no adjustments made.
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94679
The cross weights were good and front to rear bias is about 50%, so far so good. Not happy about the overall weight at almost 3000#, this is with 3/4 tank fuel and 18 qt. oil in the dry sump.
Things are about to get worse-driver weight added.
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note to self-refrain from cheese intake.

94677

This is what I ended at, decent cross weights and about a 54% front bias.
We were also able to max out the front camber at -1.1 deg.
This with changing the rear coil-overs from 400# to 550# springs should help the oversteer I had at my last autocross.I am looking to book a session soon to re-test.

Note: those readouts are reversed.

[mikeextrafast]

Yep

[Boatmark]

Very cool build that ticks all the boxes for me - interesting, different, well executed, and being flogged in the real world. Thanks for doing this thread. It's definitely not the norm for this forum, and I hope it will encourage people to post the unusual without fear of being accepted.

And where are the updates !!!!

[67dubcab]

Thanks for the kind words Boatmark.
No big updates to report, I did up my rear spring rates to 650# which pencils out to about 320# effective rate. Ran it at another autox event at Sonoma Raceway, the higher rate did help the double cab's propensity to understeer. Still need to get the front end to stick better, but I think I am running out of tuning options till I build a A-arm front suspension.
105742
Some fancy cars and a old bus/truck
105743
Some more work to the nose oil cooler
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Some detail on how the drivetrain connects
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Working for a living

[Tom Welch]

awesome build, love the whole thing.

[67dubcab]

I am finally working on the front suspension swap, using the front off a Porsche 928s4.
The front end is bolted up, next to do is steering rack and steering column.
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[67dubcab]

I have finished the final iteration of my suspension, mostly just tuning left.

Front suspension specs: wheels O.Z Fittipaldi 8.5” x 17”,tires 235/40/17
928S4 upper and lower arms, spindles, Brembo calipers, Rabbit rack&pinion
Bilstein coil-overs 700# springs, 1.25” hollow splined sway bar .188” wall.

Rear suspension specs: wheels O.Z. Fittipaldi 9”x17”, tires 255/40/17
944S2 torsion housing, stock torsion springs, early offset 944 aluminum arms, S2 Brembo calipers. 1.5 ratio rocker arms connecting to Bilstein coil-overs 600# springs, 16mm 944S2 sway bar.

[Larry Callahan]

Very cool ride. I used to have a '65 van and I miss is so.

[Frank ZX]

I can only imagine the feeling of fun sitting on top of the front axle. You have to optimize this thing. It could be the most fun autocrosser there is!