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HMeeder's Avatar
 
Join Date: Sep 2000
Location: San Diego, CA, USA
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Porsche Crest Home Made Harness Bar

In response to a few requests for some better shots of my bar here you go.

I had a few reasons for building my own bar:

1. I didn't want to drill into my firewall. My car is my daily driver and I have to live in it. The car is rust free and solid and the backpad is in very good shape. I wasn't willing to mess that up.

2. I'm a cheap SOB and couldn't justify kicking out $200 for the Weltmeister bar. I also felt that the Weltmeister bar wasn't secure enough. In a head-on crash the bar seemed like it could rotate forward and introduce a couple of inches of slack, effectively eliminating some of the advantages of a harness.

3. A good friend had already built one and we had a few hours to kill one night.


When we built mine we purposely built it as close to the top of the backpad as possible to ensure clear a view out the back window. To counteract the rotation factor, we welded a tab to the bar that bolts into place where the take-up reels would go (this would not work for '71 and earlier cars.) This design also allows the use of early-style original belts in addition to the 5-point harness (It's a pain to have to re-train every passenger on the adjustment and fitting of the harness. Easier to just tuck the harness behind the seat and use the 3-point belts.) Additionally, technically, my 5-point harnesses aren't DOT approved (but 30 year old belts are, go figure.)

I also anchored the sub-belt with a forged eyebolts so the force would be perpendicular to the floor (I ended up having to drill 2 holes after all.)


Before doing anything like this, please determine the requirements of the racing organizations you plan on running in. This set-up was built with the intention of running PCA Zone 8 Autocross & Time Trials, and the POC California Short Track Series.


I found G-Force Belts, cost me $60 a set (jegs.com) $12 for the eyebolts and about $10 in materials for the bar and I was out the door for about $160. While safety shouldn't be anything to pinch pennies about, this set-up is safer than the original and complies with all the requirements for the level of driving in which I intend to participate.

Any Questions? Problems that you can see?
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Herb
'72 Tangerine 'Teen
2.4 liter aluminum handgrenade
Old 08-20-2002, 11:55 PM
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Nice job, Herb! What size tubing did you use, and how did you manage to bend that strap iron you used for the anchors?
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Yellow '76 914 3.2
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Old 08-21-2002, 04:06 AM
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Good job Herb, how about a picture of the engine side of the firewall showing the washers, etc.
Old 08-21-2002, 08:10 AM
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He did not put anything on the engine side - he used the factory seat belt reel mount.
Old 08-21-2002, 08:19 AM
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James is right. The tab is bolted directly to the original seatbelt reel mount (with the original bolt, no less)

The tube is 1"x.120" stock and the strapping is 2"x1/8" flat bar stock. And as for the answer as to how we bent the strap: That would be with a vise and a big as$ rubber mallet, sir.

The one thing I was concerned about was the use of phrases in the rule books such as 'must have adequate attachment to sheet metal'. Ambiguous phrases like this just leave too much open to interpretation (what exactly is 'adequate'?), so I consulted our local PCA tech inspection chair. I guess what it boils down to is anything that improves the safety of the driver is allowed. Since I run in stock class and this bar (and other mass produced ones like it) are superior to the stock set-up, they are good to go.
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'72 Tangerine 'Teen
2.4 liter aluminum handgrenade
Old 08-22-2002, 12:46 AM
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I'll have to take a look at the welded boss for the stock retractor since I thought it was in a single thickness of sheetmetal? I would worry about the new direction of force on the rear bulkhead and also the length of the 1/8 inch steel bracket which most likely would bend in a crash? Remember it was bent with a mallet? Check out the website: http://hyperphysics.phy-astr.gsu.edu/hbase/seatb.html for some scarry numbers on what happens in a crash. But since Herb's car is a stock 914 it can't go fast enough to crash very hard???? Hate to see you get injured Herb!
Old 08-22-2002, 08:24 AM
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You are right John.

Actually I mis-typed. The thickness of the bar is 3/16, and yes, I nearly hurt myself smacking it with that mallet. It does bend... eventually. The purpose of the tab is to help minimize the possibility of the bar rotating. Next time you see me, I'll show you what I mean. The primary source of attachment and support are still the original seatbelt bosses on the sail panels.

All the seatbelt bosses I believe are intended to split the forces in the event of a crash (when the reel locks, isn't the full force of the belt tension in the bolt and boss in the firewall?) Though the force would be perpendicular to the firewall, not parallel to it like the reel when locked. My hope was to improve on what I thought was a potential flaw in the Weltmeister design. Truth be told, I have no empirical evidence that supports that contention (nor do I intend to collect any!)

Yeah, I know my car isn't all that fast, but concrete barriers have a way of introducing themselves in a very final way to even the slowest cars (ask Doug!)

Perhaps I'm rationalizing here, but my intention was to improve my own safety, preserve the car to the greatest degree possible and even get away without having to spend full ticket. Too many things on these cars can increase in price simply because the word 'Porsche' appears in the sales literature somewhere. I examined the Weltmeister bar (Don Traver has one) and I just couldn't find $200 worth of steel and workmanship in it.

ps Thanks for the kind thoughts on my safety. I'm not crazy about the idea of me getting hurt either!
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Herb
'72 Tangerine 'Teen
2.4 liter aluminum handgrenade

Last edited by HMeeder; 08-22-2002 at 04:58 PM..
Old 08-22-2002, 04:54 PM
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How did you do the passenger side? I noticed you had the stock seat belt over there. Is it the same as the drivers side and you just put the seat belt reel inbetween the belt and the mount?

~Steven
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Old 08-23-2002, 05:14 PM
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Porsche Crest

Actually, the mount or tab is only on the driver's side. It just didn't seem necessary to have it on both sides, though for the sake of symmetry perhaps I should have.

And re: the belts. The belts that do work with the setup are the older non-reeling type. I tried to put the reels in but the bar interferes with the travel and alignment of the belt as it moves through the upper pivot loop. I just could not get the thing to gather smoothly on the reel. It would either hang up on the reel, or bunch up as it passed through the upper loop. Were I to do it over I would try to compensate for that, It just seems that the bar is exactly where the belt needs to be for the reel to operate correctly. I had a set of the old belts, so I used them instead.
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'72 Tangerine 'Teen
2.4 liter aluminum handgrenade
Old 08-24-2002, 12:09 AM
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So when I was a passeneger and driver in your teen I was using NON-DOT approved seat belts!

Where's my Lawyer.....

James

Opps
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Last edited by red-beard; 08-24-2002 at 07:15 AM..
Old 08-24-2002, 06:58 AM
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