Rear body mounting?

[Jacob]

Am I right in that the rear of the body (all 4 locations) should be mounted first? The rear bolt sleeves, the longer sleeve is on the inside of the trunk area, dictate how far rearward the body should be pulled? Any of the.is make sense? In other words do the bolt sleeves determine the correct distance rearward for the body? (The longer one is 3.75”, so is this the critical distance that has to be satisfied?)

I should mention that I’m doing the threaded coupler mod on the rear, so asking a different way... what should be distance from the end of the threaded coupler to the fiberglass?

As I read body mounting recommendations, this is the first step... as always, thanks in advance!

[Jeff Kleiner]

I don't use the inside spacer tubes and let the trunk lid dictate the final rear distance as one of the last positioning adjustments. Here's my order---

Drop the body over the chassis and send it forward so that the body's door flange is just ahead of the chassis' striker tab as seen here:



If you haven't trimmed back the underside return of the cowl roll you may find that it hits the dash and won't let you get that far forward without doing so. Once the body is draped on I run lengths of all thread through the body and into the couplers at the rear. These are not tightened yet; they are just holding the tail up. I then move on to the front to install the QJ bolts and spacers and button them down to locate the nose (makes no difference whether you're using the early split type or the full length tubes). Next is the windshield and front splash panels. Now comes the fun part...the doors. Notice that I have not mentioned anything about locking down the body on the underside along the rocker panels. This is where lots of give & take comes into play because you are trying to strike a balance at 4 different places; the upper front of the door where it meets the cowl, the upper rear where it meets the rear cockpit opening, plus the lower front and lower rear. To further complicate things we're dealing with both horizontal as well as vertical interfaces along the upper part of the doors. Adjusting for one invariably affects at least one other. And people wonder why body men drink I've had the best luck adjusting for the door tops first. While dealing with the top area of the doors do not completely ignore the lower door edge's intersection with the main body but keep in mind that the lower body can be moved in/out independently with little to no effect to the upper cockpit openings. On both Mk3s and Mk4s I've found that the passenger door has been easier than the driver's side; once the adjustments were made to get the tops in order it just took a bit of outward movement to the lower body to have it meet the bottom edge of the door. On the other hand with the drivers side once the tops were fitting the bodies had to go in at the lower front corner of the doors and move out a great deal at the rear. I've found that these cars and bodies are quite consistent and one of those constants is that you'll need to push the rocker panel in as far as possible in front of the driver's door and pull it out at the rear. I can assure you that you aren't going to get all 4 corners to meet perfectly but your goal is to get them as close as possible so that they operate without interference and to minimize the bodywork necessary to match contours between the main body and moveable panels. Once you've accomplished that you lock down the body along the rocker panels and move on to the hood and trunk lid. The Mk4 trunk hinges allow movement in all axis so it's pretty straightforward to get it adjusted on the top and by using the coupler method for the bumper/QJ attachments along with nuts rather than spacers on the backside of the body you can move the valance in or out as necessary to match the bottom edge of the lid by adjusting the nuts on the inside in conjunction with spacer tubes outside. You may find that you need to trim back the rearmost lip of the trunk floor aluminum, and perhaps also the vertical edge of the trunk side aluminum to allow the valance to pull inward to meet the lid. For the hood I leave the hinges just loose enough to allow them to move somewhat freely then close and position it in the hole and get underneath and tighten the nuts.

That's what works for me---your mileage may vary

Jeff

[Jacob]

I can’t thank you enough for this advice! I did trim the cowl roll rear and front and I’m ok there and also trimmed 1/4” or so off the back pan. I’m ok at
The door latches as long as I don’t try to satisfy the rear 3.75”. I think I can make it work now!

[CraigS]

As an aside: Jeff said, "I've found that these cars and bodies are quite consistent and one of those constants is that you'll need to push the rocker panel in as far as possible in front of the driver's door and pull it out at the rear."
So now I see why there are SO MANY problems w/ the driver side headers and body opening. From my limited experience hanging w/ guys building MkIVs, I knew that the side of the body is very rigid (in top view) from the rear wheel opening to the exhaust cutout. But I didn't realize the above. Seems FFR needs to work on the driver door hinge jigs doesn't it?

[edwardb]

As an aside: Jeff said, "I've found that these cars and bodies are quite consistent and one of those constants is that you'll need to push the rocker panel in as far as possible in front of the driver's door and pull it out at the rear."
So now I see why there are SO MANY problems w/ the driver side headers and body opening. From my limited experience hanging w/ guys building MkIVs, I knew that the side of the body is very rigid (in top view) from the rear wheel opening to the exhaust cutout...

Not quite getting that one. Agreed the Mk4 body with the wraparound sill is stiffer than the prior Mk's without. But I haven't had any issue with holding the back part of the PS sill out 1/2 inch or more and then pushing the front part tight against the chassis to improve the door fit. I haven't noticed this adjustment changing the location of the pipe opening. The area behind the pipe opening is tight to the chassis. In front remains flexible and is fixed by the splash guard.

Certainly agree that PS door fit a major opportunity for improvement though.