Overrider bumper guard stud types

[Barry Brisco]

I recently noticed that the stud (not sure of the correct terminology) and nut holding my right rear bumper guard and overrider bar together had mysteriously disappeared: the nut must have vibrated off and the stud fell out as well. I'm certain it was there a few weeks ago.

A 356Talk member kindly sent me another acorn nut and a friend offered me another stud, shown in the photo below. It's not quite straight but it should work. It is two different diameters. When I went to install it I discovered that the larger end does not fit though the hole in the overrider support tube. My acorn nuts don't fit onto the larger end, so that end should go into the guard. I looked at the stud on the left rear bumper guard and it appears to be the same thickness throughout its length. Checking the studs on my front guards they seem to be larger on the end that goes into the guard. I think the stud shown in the photo below is for the front. Are the studs different between the front and the rear?


Also, the acorn nut sent to me is slightly different than the ones on my car. (of course I do not know if the ones that were on my car when I bought it in 2005 were on my car when it was new) The photo below shows the one sent to me (left), one from my car (middle), and a modern acorn nut. Did Porsche use different styles of acorn nuts on T2 cars with overriders? I suspect they may well have.


This photo shows one of the nuts that came with my car (when I bought it, not necessarily when it was new) in place on my left rear guard.

[Norm Miller]

Barry,

By all rights that can't happen. I think the stud came loose from the overrider which caused the nut to fall off, then the stud gravitated back into the overrider and fell.
Have you searched around the exhaust bell?
It's possible the original stud was corroded enough to slip through the support, although unlikely.
This falls under the FM category.
Check the acorn nuts on a 58 they should match yours.

Norm

[Gary Swauger]

Barry:

You have rear overriders with the exhaust hole. They are completely different than the front overriders. Cars without exhaust hole in the rear overrider use the fronts on the rear.

The stepped studs are used on the front overriders. I don't believe the stud is stepped in the rear overrider with exhaust hole.

On the acorn nuts, the middle one looks right for those on my 59 ConvD which I believe to be correct for the that year.

[Barry Brisco]

Gary, thanks for confirming my suspicion that the studs are different between the front and the rear. I'll look for a rear stud at the 356 Club swap meet today in Anaheim.

Barry

Barry:

You have rear overriders with the exhaust hole. They are completely different than the front overriders. Cars without exhaust hole in the rear overrider use the fronts on the rear.

The stepped studs are used on the front overriders. I don't believe the stud is stepped in the rear overrider with exhaust hole.

On the acorn nuts, the middle one looks right for those on my 59 ConvD which I believe to be correct for the that year.

[Barry Brisco]

No luck today finding a rear overrider/bumper guard upper stud at the swap meet in Anaheim CA.

Does anyone have a stud (with nut) for the upper hole in the rear bumper guard on a 59 coupe with the exhaust through the rear guards? This stud will not be "stepped" it will be the same diameter on both ends. In other words, both ends will look like smaller end of the stud shown in this photo (below, this stud is for the front guards not the rear).

Thanks,
Barry

Gary, thanks for confirming my suspicion that the studs are different between the front and the rear. I'll look for a rear stud at the 356 Club swap meet today in Anaheim.

Barry

Barry:

You have rear overriders with the exhaust hole. They are completely different than the front overriders. Cars without exhaust hole in the rear overrider use the fronts on the rear.

The stepped studs are used on the front overriders. I don't believe the stud is stepped in the rear overrider with exhaust hole.

On the acorn nuts, the middle one looks right for those on my 59 ConvD which I believe to be correct for the that year.

[Bill Coghlan]

Try Bob Chase, if you haven't already done so - here's a link -

http://www.cc356c.com/id91.htm

[Albert Tiedemann]

The original acorn nut was a two piece design.

I can supply the correct two piece design nut for the application in Zn or Stainless Steel

A set of 4 Zn plated is $10
A Set of 4 in SS is $15

[Bob Paxton]

I am a bit confused about the type of stud used on the back bumperette of
the "A" car. I am referring to the upper stud of the USA bumper with
exhaust thru the bumper. I have 17 bumperettes laid out on the bench and
the bottom stud is without a doubt an 8mm straight stud. 12 are still in
place and 3 are missing and 2 are broken flush! Now the top is a bit
tougher for me cause 10 are missing 2 are badly rusted but there and the few
threads left are 6mm. 5 are broken. I have enough complete stepped studs
for one car. I have read recently on this list that the top stud on the
rear bumperette was an unstepped stud which means it is 8mm? Or is it
unstepped 6mm? Which is it? I have never read that Abe and Steve Proctor
(who makes the stainless studs) offer the acorn, two piece nut in both 6mm
(for the front) and 8mm for the back! It has always been my understanding
that the top stud...front or back...are stepped, 8mm into the bumperette and
6mm thru the overridder bar finished off with 6mm two piece acorn nuts front
and rear! Why would a stepped stud be ok for the front and suddenly not be
ok for the same application in the back!

Can smeone please set me straight so I know what to buy and put into my
bumperettes!

-
----- Original Message -----
From: "Albert Tiedemann" <afterwerke@comcast.net>
To: <356talk@356registry.com>
Sent: Monday, March 09, 2009 8:11 PM
Subject: [356Talk] Overrider bumper guard stud types

The original acorn nut was a two piece design.

I can supply the correct two piece design nut for the application in Zn or
Stainless Steel

A set of 4 Zn plated is $10
A Set of 4 in SS is $15

------------------------
Albert Tiedemann, C356C
"The Hermit", Reg #4998

Post generated using Mail2Forum via email.

[Gary Swauger]

I mis-stated that the top stud on a T2 356A rear upright with exhaust hole are not stepped. I was down in LA at the Literature Show and didn't have my ConvD with me and my memory failed me. I looked at a few cars on Sunday at the swap meet and confirmed with my car that indeed the upper stud is stepped. The acorn nut is 6mm. Sorry for the mis-statement.

[Steve Proctor]

I am out of the stud / nut business and have a few originals left that are not for sale. I recommend Bob Chase in Bakersfield for nice replacement studs and Ab for his replacement nuts. They are a nice combination for most cars (not super-anal restorations).

STP

[Chuck House]

I recently noticed that the stud (not sure of the correct terminology) and nut holding my right rear bumper guard and overrider bar together had mysteriously disappeared: the nut must have vibrated off and the stud fell out as well. I'm certain it was there a few weeks ago.

A 356Talk member kindly sent me another acorn nut and a friend offered me another stud, shown in the photo below. It's not quite straight but it should work. It is two different diameters. When I went to install it I discovered that the larger end does not fit though the hole in the overrider support tube. My acorn nuts don't fit onto the larger end, so that end should go into the guard. I looked at the stud on the left rear bumper guard and it appears to be the same thickness throughout its length. Checking the studs on my front guards they seem to be larger on the end that goes into the guard. I think the stud shown in the photo below is for the front. Are the studs different between the front and the rear?

Barry,

Below are a couple of photos of an original T2 rear guard with exhaust cutout. These are all chromed diecast aluminum with a part number inside. You can see the detail of the stud which does have a step. Maybe they made two versions but I've only seen this kind.

[Barry Brisco]

Chuck, thanks very much for the photos and info. There aren't very many original rear guards like that left to see! The ones on my car are definitely not original. No part numbers and they are much thicker. But it appears that my upper stepped studs may be the same type as the originals: 8mm on the end going into the guard and 6mm going into the acorn nut. So I'm still looking for one of those studs.

I am also puzzled about the acorn nuts. Ab Tiedemann posted in this topic that "The original acorn nut was a two piece design." I have only seen the one piece type. The one piece acorn nuts on my car are certainly not new but I have no idea if they are the original style. I've seen one piece nuts on other cars and the owners have stated they are original. Maybe there were two types?

Barry

Below are a couple of photos of an original T2 rear guard with exhaust cutout. These are all chromed diecast aluminum with a part number inside. You can see the detail of the stud which does have a step. Maybe they made two versions but I've only seen this kind.

[Steve Proctor]

I have several sets of original US bumper front and rear bumper guards in the pre-'59 version only. My observations from this sampling:

Front guards are smooth inside and are pretty malleable. There are no cast in part numbers. Again, this information is for the pre-'59 low overrider bar cars only. I am told the '59 units are die cast, are chromed and have cast-in part numbers. Also, rough insides of any 356A bumper guard indicate sand-cat repros. The studs are 8mm for the lower and stepped 8mm to 6mm for the upper. In the pre-T2 cars, the fronts and rears were the same. I believe these guards were "bright dipped," not polished or chromed.

Rear guards were the same as the fronts until T-2. At this point, the rears for '58 and '59 were die cast with exhaust holes and cast-in part numbers. They were chromed, smooth inside and have cast-in ribs in the lower part of the guard. They were brittle as compared to the fronts. I have seen several fractured rear guards, but no fractured fronts - dented, but not fractured. The studs are 8mm for the lowers and stepped 8mm to 6mm for the uppers.

The above is from memory. If I have misspoken ('56 - '58 guards only), would like to know.

Attached is a picture of original and Ab T's acorn nuts. Ab's are two piece and very close to the originals. I like them and am going to use them when I get around to getting my bumpers back on the car (with a Bob Chase overrider bar).

STP

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[Steve Proctor]

Barry,

The two-piece nut consists of a threaded nut portion and a closing dome that is a separate piece, apparently swedged to the threaded nut portion by a flange to made an apparently one piece nut. They appear to be one piece but are not.

Ab, being the consummate engineer can probably apply more technical terms to this item, but this is a layman's observation.

STP

[Chuck House]

I have several sets of original US bumper front and rear bumper guards in the pre-'59 version only. My observations from this sampling:

Front guards are smooth inside and are pretty malleable. There are no cast in part numbers. Again, this information is for the pre-'59 low overrider bar cars only. I am told the '59 units are die cast, are chromed and have cast-in part numbers. Also, rough insides of any 356A bumper guard indicate sand-cat repros. The studs are 8mm for the lower and stepped 8mm to 6mm for the upper. In the pre-T2 cars, the fronts and rears were the same. I believe these guards were "bright dipped," not polished or chromed.

Rear guards were the same as the fronts until T-2. At this point, the rears for '58 and '59 were die cast with exhaust holes and cast-in part numbers. They were chromed, smooth inside and have cast-in ribs in the lower part of the guard. They were brittle as compared to the fronts. I have seen several fractured rear guards, but no fractured fronts - dented, but not fractured. The studs are 8mm for the lowers and stepped 8mm to 6mm for the uppers.

The above is from memory. If I have misspoken ('56 - '58 guards only), would like to know.

Steve, good description. The only thing I would add is that '59 had both types as the change happened mid year and corresponded with the low to high overrider bar change. Earlier front guards were forged aluminum and bright dipped anodized (on T2s, this was the case even though the rear was chromed die cast Al). However, on T2 cars without overrider bars, both front and back were die cast chrome.