Fender measurement for SC? Help!

[Brian Cameron]

The hood of our 79 SC has never seemed to fit quite right at the front corners where they meet with the fenders. It turns out that the driver’s/left fender is almost 1 cm longer than the passenger/right side.

Hoping someone with an SC would be willing to take a couple of quick measurements to help me figure out how to proceed. The car will be going for paint this winter and if one of the fenders needs to be replaced, now would be the time.

I measured from the top of the fender where it meets the door, to where it meets the corner of the hood. See pics below for illustration.

I used a soft plastic / cloth measuring tape (like the ones that tailors use) and masking tape to protect the paint from the metal tip of the tape.

Not that it needs protecting since the next step in restoration is a respray, but if you’re willing to help with your own measurements you’ll want to protect your own paint (and don’t use a metal tape measure whatever you do).

Thanks in advance to anyone that can help with this!



At the door:


At the front corner (yes I know, it’s ugly):


Left/passenger side for comparison:

[ChrisHamilton]

I highly doubt the fender is longer unless it was some sort of Frankenstein type repair where two damaged fenders were cut and welded to make one good fender. Not very likely. The cause of misalignment is likely prior crash damage. Get underhood and do a cross measurement. Where you check for square. Might need two people to do it to ensure accuracy. Go from the hood hinge bolt (top one) to the center of the hood latch. Actually try and mark the center point on the front panel (where the latch bolts to) as that will be more accurate. Then go to the other side and repeat that measurement. Compare. It should be the same. If it's not that is the starting point to address the misalignment.

[ChrisHamilton]

The way you are measuring is not accurate. If the fender had a high spot in that area where you are measuring then it would cause it to read longer. Just not what you do.

Looking at the one pic I can almost promise you the car had prior crash damage and likely the DS hood hinge is bent or back to far. Notice how it is touching the fender and its short there that is indicative of that or structural crash damage. Likely it's the hinge.

Measure how I described. Visually inspect the hinges. Best thing to measure with is something rigid like a tram gauge. It is much more accurate.

What does the gap at the hood to cowl panel look like? Can you post a pic?

[ChrisHamilton]

Another way or rather a second measurement you should make is from the same hinge bolt to either the first or second fender bolt on the opposite side. Then repeat on the other hinge to DS fender. You are checking for square. If the measurements on both sides are not equal it would indicate the front section is out of square.

[Brian Cameron]

Thanks for the response Chris, i will check the hinge to fender bolt measurements and diagonals tomorrow (tho IIRC there is a bit of adjustability in the fender bolt locations to help with fitment so those measurements may not be entirely conclusive).

I will also include pix of the panel spacing at the cowl/hood/fender interface. However i should mention that i have spent many hours adjusting all these panels to no avail, the best i have been able to achieve is a compromise as the A-pillars are fixed and door adjustments vs B-pillars are pretty limited. So the available adjustments are primarily the hood (and hinges as you note) and fenders.

I was surprised to learn that there are different fender lengths for different years, as i learned from a vendor site (not our host):

“Porsche fitted 2 different length fenders on the cars from 74-77.
The long version is 1398 mm and the short version is 1390 mm.
From 1973-08 to 1977-07 the left front wing was 1398 mm and the right front wing 1390 mm
From end of 77 to 85 it was the long version for both sides
From end 85-89 it was again the shorter version for both sides”

Obviously those measurements are taken from different points than what i used, but i haven’t been able to determine what points they’re from.

There is also the possibility that one of the fenders (likely the driver side) is non-OEM, maybe from Dansk or Restoration Design etc so might not be exactly to spec.

I am pretty sure from other evidence that this SC had a front end event at some point in the past, for example the front suspension crossbar was the old steel tube style used until around 1974; I replaced it with the correct aluminum piece.

I also found the front end driver side was pushed up about 2.5cm when i replaced the front pan, fuel tank support, left fender quarter, and front latch panel due to rust discovered in those locations (likely due to failed alternator voltage regulator causing battery boilover… once sulphuric acid gets into those frame members the rust gets going pretty good, and the front control arm supports become compromised).

I used a tram gauge to measure the various points on the pan per the shop manual and they are good, and the new sheet metal is correctly aligned, using a purpose built pan jig for welding in place. In any case the hood/fender alignment problem is front/rear, not left/right, and is independent from the pan itself. That cowl/hood/fender front/rear alignment ultimately ties back to the A-pillar/door/B-pillar rather than the pan.

Since there’s no evidence the A-pillar is misaligned (both doors fit pretty well to those reference points, as well as the B-pillars), and the hood is square… that leaves the fenders as the only variable in the equation. The passenger side fender fits perfectly with cowl and hood.. driver side not at all.

Anyway let’s see what your suggested measurements tell us.

If they don’t shed light on the issue, would it be too much of an imposition to ask you to measure your own fender lengths as per my original post? It would be very helpful (or at least reassuring) to know if others have fender measurements that are equal left/right - or not.

Also please advise what year of 911 you have in case it’s one of the years with different left/right dimensions noted above.

[ChrisHamilton]

Originally Posted by Brian Cameron

In any case the hood/fender alignment problem is front/rear, not left/right, and is independent from the pan itself. That cowl/hood/fender front/rear alignment ultimately ties back to the A-pillar/door/B-pillar rather than the pan.

.

I don't know how much I can help you as you are not really grasping the concept of what I'm trying to tell you. Firstly let me say I know of what I speak. I have worked collision repair for many years.

You are focused on the wrong things. Judging from what you replaced and your lack of understanding, I would imagine it's possible the front panel got welded in place wrong. I say that because if you don't know to check for square then you either have to be extremely lucky when welding it in or you got it off. I would suspect the latter.

The left right measurement is checking for square. Square is at the core of correct panel alignment.

Stop focusing on the fender for a moment. Let me try to explain to you square. When you check from say the left hood hinge front bolt to the right front fender bolt and then the same measurement from the right hood hinge front bolt to the left fender bolt you are checking that the front section is square. If it is not you have a parallelogram instead of a rectangle (simplified but accurate) You can not have correct panel alignment with a parallelogram. One side is more forward one side is always more rearward. You want to have a rectangle so both sides are in the same place relative to each other. When you check for square you are checking that you have a rectangle not a parallelogram. That is a simplified but accurate description. A parallelogram would occur because of an accident or if replacement components were not aligned properly.

So do the cross measurements. Look in your factory manual if it makes you feel better and check the cross measurements given in the manual. My gut says they will be off.

Look at how close the hood is to the left fender in your pic, and the opposite side is wider, that is how I know it's an issue with square. The fender length is not causing that. Post a pic of the hood to cowl gap. I'm betting it will be closer on the left side and wider on the right side of the hood.

My gut says you welded stuff in while the front was still misaligned, I know what you said but I don't really have any confidence in that. Not trying to be insulting but I can tell you lack an understanding. (not your fault most have no experience with this stuff). Evidence of crash damage and it being up (don't know how you measured that with out it being on a machine and jigged) are big red flags to me. Welding in a front panel without checking the cross measurements are also red flags.

I'll try to help but lets keep it basic. Use a tram and take cross measurements and check for square like I described. Then take a pic of the hood to cowl gap or measure the gap at the left and right edges and report back with that. Once I know that I can better advise. And to be clear the only accurate way to measure is with a rigid tool like a Tram Gauge.

[ChrisHamilton]

One more thing. You mentioned the left side was up 25 mm. If your measurement was accurate that is a massive amount and was not caused by the suspension but was caused by prior crash damage. Trust me on that. How did you correct that? When you see a unibody rail up that much it's indicative of crash damage and it's needs to be be correctly pulled out and straightened. You don;t do that by replacement alone. You put the car on a frame machine and anchor and pull out the damage. Replacement alone doesn't correct that because it's not localized, it's throughout.

Everything you wrote in your second post points toward a vehicle that has been in a collision at some point, was never properly pulled/straightened, then you do repairs on it and replacement parts are welded to a unibody structure that is not straight. And the end result is you can't get things to align correctly. I'm not chastising you BTW. Just trying to get you to understand what is likely going on.

Do the measurements like I recommended above. We'll go from there. But likely it is what I'm saying and there is no easy "correct" fix to that. There are some fudges you can do to get the panels aligned and fitting but there is no easy fix for the underlying structural damage I suspect exists other than to put it on preferably a dedicated bench like a Celette with the correct jigs.

Sorry, not trying to be negative but I have been doing this stuff for a long time.

[Dpmulvan]

I’d just shorten the fender by flattening the underside lip and re bending and shaping the first couple inches so it lines up with hood.

[ChrisHamilton]

Originally Posted by Dpmulvan

I’d just shorten the fender by flattening the underside lip and re bending and shaping the first couple inches so it lines up with hood.

You can move the edge down that way but it's not going to shorten the length. It will also bring the edge of the fender in towards the center of the car. And it's backasswards as the fender isn't the issue.

[Brian Cameron]

Well this is going to have to go on hold for a few weeks, when i got home today my son had put the SC up on the storage lift so he could do some work on his volvo. Too much crap stored under the lift for me to move in order to lower the lift, and there is a tire rack just above the hood so i can’t open it enough to take the measurements. I will update when i get my garage back.