Aligning body onto new chassis

[lowflyer]

After a long search in the forums I couldn't find an answer to this, so this is my dilemma.

We lowered the body of my 1965 built Elan Coupe onto a new rolling chassis and the alignment was pretty good, so I thought. The next step was marking the holes out for the new chassis.

When I inspected the front crossmember/rack plate for the hole position was right on the forward end of the plate, which didn't look at all right. The old rusty chassis had holes approx 20mm further back on the plate. See below:

Old chassis:

New chassis:

Simple, just move the chassis forwards - not quite! The rear suspension turrets are hard against the bodywork and even with the slightest tweaking I might get 5mm forwards movement, but not 20mm. The rack plate dimensions match in length between the two chassis, but I haven't checked the rear turret to plate length yet.

A bit of head scratching occured at this point. I could move the bobbins at the front crossmember but I thought I'd ask here first.

Has anyone else had experienced of this alignment issue?

[RichardHawkins]

Low Flyer,

I am not sure my comments will help, but I will proceed. My car is 1968 S4 FHC, I bought it as a basked case, I bought a new chassis, life got in the way and I am restoring the car in my retirement.

I dismantled the car, and fitted the new chassis, like you the front right rack mounting bobbin only just aligned with the extreme tip of the chassis, but I drilled the chassis anyhow. I had the body work done by SMS, and had the chassis blast-cleaned and finished locally. When I came to put the two items back together I could only get two bolts out of the total (16 I think) to fit. I don’t get on with G.R.P. which is one of the reasons I decided to employ SMS, who told me that as they stripped the paint there had been front end damage repair to the car which might explain my chassis to rack alignment concern.

Having read lots of reports about G.R.P. I conclude that in many cases the resin has not completely cured when new, and that putting the repainted item in a paint shop oven may complete the process plus distortion. For example my heater and ventilation hoses that came out would not refit by about 12mm vertical misalignment.

Most of my body to chassis bolts were approximately half a hole diameter misaligned. My solution was to fit threaded aluminium plugs into the bobbins secured with an epoxy recommended by Loctite and then re drill and tap. I also turned the thread off the bolts for about 6 mm nearest the head to help get the bolt through the chassis and into the bobbin while the body is supported slightly above the chassis.

Talking to SMS about this they told me that when they do a paint job and chassis change they use large clearance holes in the chassis and cover with repair washers. I am far to fussy for that, but then I don’t need to show a profit.

Hope this helps,

Richard Hawkins

[batfish]

Had a similar problem when I rebuilt my car although it was a new body and chassis. The front bobbins were too close to the front of the chassis so cut out and reglassed the bobbins further back to suit the chassis.
Andy

[Elan45]

Back in 1984 when I replaced the chassis under my Super safety DHC, the new galvanized chassis had much larger pad on the front turrets. The untapped pad was the whole length of the turret from front to back. I had to grind away part of this new pad to enable the body to go down onto the chassis far enough to meet its correct location.

I should also mention that I made up a set of temporary bolts that would thread into the bobbins but too short to go into the chassis mounting blocks. These then had a smaller diameter holes through them so that the body could be placed onto the new chassis. Adjusted for position and then the temp bolts used as a jig to drill smaller holes into the frame pads. These holes were maybe 3/16" in diameter. when the bolts were removed from the body, there was a nice accurately positioned pilot hole to then drill out with successively larger holes until the chassis/ body was fitted.

Roger