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Posted by: Montreal914 Feb 1 2025, 06:08 PM

Were the few 916's equipped with the GT stiffening kit?

Other than the obvious rigid roof, were there any chassis stiffening improvement to handle the larger powertrain/gearbox?

Posted by: TMM914 Feb 1 2025, 08:36 PM

Here is a shot of the 916 at Canepa that you can see the reinforcement plates present.
My guess is they were installed by the factory.

Posted by: Maltese Falcon Feb 1 2025, 08:44 PM

For some reason those cup washers /transaxle mountings look out of place with what I usually see ¿¿
But I think that with the 916 hot rod 2.4 mfi, the stiffening kit should be present.

Posted by: Maltese Falcon Feb 1 2025, 09:17 PM

This is how the 916 nose cone transaxle mounting hardware has been running in my biturbo / flatfan car for the last 30+ years. I do use custom made T6 aluminum solid rear mounts though.

Posted by: rgalla9146 Feb 2 2025, 08:09 AM

They're in the wrong place...should be between the casting and the trans mount.
When in the correct place they are often installed wrong side up.
BUT...racers sometimes place them wrong side up to stiffen engine/trans
location.


Attached thumbnail(s)

Posted by: Maltese Falcon Feb 2 2025, 10:08 AM

Good to know Rory...and after all Bruce Canepa IS one hellova fast shoe !
Marty

Posted by: davep Feb 2 2025, 08:21 PM

I do not know the VIN of the 916 at Canepa, but only 3 of the 916 had the 2.4S engine; the other 7 had the 2.7 RS spec engine.

Posted by: Maltese Falcon Feb 2 2025, 11:16 PM

@Montreal if you have a bit of time during your 4 to 6 conversion> you should definitely schedule your chassis reinforcement kit installation. Having to go back and do it once your 6 is converted and running is a lot more work.
Starting in 1976, club racing / time trials in the 914>with a T4 2L boosted at 7psi started a few hairline cracks in the inner ¼ panel/ fender well sheet metal areas. I didn't even know about the gt stiffening kit, and just left as is. In 1978, I converted to a 2.7L 6 and raced at same tracks RIR and Willow, still left the weak rear inner fender areas as is.
In 1985, when I installed 3L biturbo, and GT steel flares, 916 trans, 8 point cage; I located the stiffening kit + welded that as well. When we sanded away all of the undercoat and paint the sheet metal damage was seriously worse than just a few cracks.

Posted by: Maltese Falcon Feb 2 2025, 11:21 PM

Master exhaust header fabricator Eujeñio was so proud of his GT stiffening kit skills, he needed this picture taken

Posted by: Maltese Falcon Feb 2 2025, 11:26 PM

Good times at this track, just needed a taller 5th for that Long back straight !
Current times> the track has been gone for decades; hope all the homes + shopping mall makes Riverside citizens happy...

Posted by: burton73 Feb 3 2025, 09:07 AM

Here are several photos of the reinforcement that was done from PMB on my 6. Note the strengthening on the front 914 -6 engine mount as well as reinforcements from the body to the area where the trailing arms mount.
Trailing arms are also reinforced with eric's own style of inside of the arms tubes welded in

Best Bob B

The 30th 914-6 #41 build:
http://www.914world.com/bbs2/index.php?showtopic=307620

Posted by: Montreal914 Feb 3 2025, 09:39 AM

Thank you TMM914, Marty, Rory, Dave, and Bob.

Yes Marty, I now plan on adding the GT kit on my build, and I have been wondering about what else to reinforce. My car will be a naro body street car, therefore no roll cage.

I wanted to start with the basics, i.e. what did the special project crew of engineers at Porsche did on the 916 being some didn't come with roll cage. The GT kit seemed logical, but maybe something else was done?

Reinforcement of the A-pillar maybe, other exclusive 916 reinforcement mods?

Interesting to see that Brutus did not have any visible reinforcement of the trailing arms and suspension ears.

Current plan:
- Inner Maddogs kit
- Outer RD clamshell
- GT kit

Thinking potentially:
- Suspension ears reinforcement
- Inner ear heim joint rod to firewall
- Outer heim joint rod for alignment adjustment and maintain
- Rear trailing arm bulhead plate (Chris Foley's trailing arm reinforcement design)
- Some rear suspension tower seam stich welding

I might be overthinking this, but a 3.2 and a 916 box is a very different setup compared to a VW bus engine.

When I was young I had 3/4" front and rear sways bar on my sleeper hot rod VW Beetle at a little lowered right height (not carzy like we see in SoCal) and with the bad streets of Montreal, I cracked the front pan (the triagular part of the pan under the tie rods area). This was an eye opener on imposing more stress on chassis.

Posted by: 930cabman Feb 3 2025, 10:27 AM

These chassis mods (meant to stiffen) are great, but will the added stresses be sent to another location? and will these areas need additional reinforcement?

From what I can tell most of this work is a function of the forces added, wide tires, increased HP, ...

I do not have any answers, just questions today

Posted by: technicalninja Feb 3 2025, 11:01 AM

Your list is very close to mine...

I'm for more seam welding and further rear mods.

The 914 V8 guy Renegade Hybrids had a simple rear ear mod that I'm going to incorporate with your above list.

Had I been you I'd have kept those front sway bar mount reinforcement plates you sold to Fred. I liked those...

I'll do a little bit of front pan re-enforcement and increase the strength of the top mounts for the front struts.

As I'm planning on keeping the removable top, I'm not planning on working the A-pillars.

I believe a roll bar similar to Tygaboy's V8 car is the way to go on an open top car.

I'll be re-enforcing my car for 300lbs./ft. and 350 rwhp. I will not be using a Porsche 6.

Current candidates are a blown K20 (lightweight) or (more likely) a GM LGX 3.6L V6.

Current tranny choice is Boxster 6 speed (and Tygaboy's steam punk shifter!).

Posted by: Maltese Falcon Feb 3 2025, 11:18 AM

@http://www.914world.com/bbs2/index.php?showuser=12023 you can always come by* + visit the 8gtt proj and peek at the interior, front, and rear unibody upgrades >for your ideas. During welding make Sure to properly brace the unibody, and set the car on very flat tarmac to get Best results !
Door gaps , and other areas will change (for the worse) if you don't use bracing.
*I can have your header set...World <discount> (it's back !) ready for pick-up as well
Marty

Posted by: TMM914 Feb 3 2025, 03:27 PM

Dave here is the vin of the 916 at Canepa.

Posted by: davep Feb 3 2025, 04:03 PM

OH, 9141430195 is Brutus, the prototype, so, close enough I guess. Not sure on the drive train, either when completed or now. I'll bet a lot was done during the various restorations.

Posted by: Cairo94507 Feb 3 2025, 05:21 PM

I really went back and forth on stiffening modifications for my car. It is narrow bodied with deep six wheels running 195x65x15 tires. I finally decided the inner tub stiffening kit from MadDog would be sufficient for me for a street car. Now, if I had flared my car and was running some wide, sticky tires, I would have added more bracing, etc. But my tires will never provide enough "stick" to tweak anything, I believe. To be honest, I do not drive my car hard; it sees redline frequently, but typically on straights.

Posted by: dr914@autoatlanta.com Feb 3 2025, 05:57 PM

funny the transmission round plates are on the wrong side of the ears

916 had the chassis stiffening kit welded in

Posted by: rgalla9146 Feb 3 2025, 08:11 PM

[quote name='dr914@autoatlanta.com' post='3190151' date='Feb 3 2025, 06:57 PM']
funny the transmission round plates are on the wrong side of the ears

... see posts 3,4,5 and 6

Posted by: ClayPerrine Feb 4 2025, 07:12 AM

I was always under the impression the big cupped washers on top of the transmission ears were there to keep the slotted transmission mounts from slipping rearward if the bolt was loose.

I know that has frustrated me in the past when pulling the motor. So I started leaving the mount on the transmission.

Posted by: Montreal914 Feb 4 2025, 09:19 AM

So it looks like the concensus on the 916 is:

- Welded top (obviously)
- GT stiffening kit

That's it. No seam welding, no other structure reinforcement.