A few questions from a newbie...

Hi all,
I apologize if any of these questions have been covered, I have read through a good quantity of your previous posts (what, I'm supposed to work on a Monday!?!) and had some of my questions answered.

I have a CMC wide body that my brother and i assembled. The car has been on the road for about 6 years. It was built when i was living in New York, and now it is the perfect Florida car. (and yes, we drove it from NY to Fla, no trailer needed!)
I have about 5,000 miles on the latest engine build.(type 1 motor - 2.0l with dual webers)

My initial questions are these:

Body Flex
sure, i would like to think it is because of the huge amount of torque, but my car looks like it is going to snap in half. (check out the pic of the drivers door)
Other then installing a 4 point roll cage, i am not sure how to reinforce this.

Curious if this is something that any one else has noticed on any of the VW framed cars.

Second,
I have looked everywhere, but I can't seem to find the wiring instructions for my tach (VDO gauge, check pic if that helps)
right now I believe it is wired for a 6 cylinder, and I don't really want to admit what it took to figure that out. hint: thinking that when the tach is at 4K, i should have a lot more room to rev, so I figure it is running rich. to make a long story short, i kept leaning out the motor while I (unknowingly) had it pegged at 6 grand. you guys can figure out the rest of that scenario.
hooking up an external tach confirms that my gauge is off about 2/3. I am guessing that these gauges can be wired for 4 or 6 cylinder, just don't know how to change it.

Third,
what is the best way to calibrate the speedo's to compensate for the smaller wheels?
I like looking down and seeing that i am going 95 mph, but not when I am only doing 70.

Thanks for reading through this, and for having this forum. i wish i new about this 12 years ago, i would never have bought from CMC.

Lesson learned.

Rob

Here the link for wiring up a tach.

www.vdona.com/Tech%20Support/Automotive/Instructionsheets.htm

It either works or doesn't though - way its wired usually doesn't change the RPM readings. One I had (NOT VDO) had a switch on the back labeled 4/6/8 - you moved it to correct one. Suspect you will need to install a resistor to drop the reading. Any EE's out there that could help?

My CMC has a welded massive steel subframe built into the fiberglass body (ok big rivets). Check out the online CMC manual on this site. Looks like yours was just bolted to a VW pan without the reinforceing frame. Looks like it would be very dangerous driving it like that - one day its going to break in half!

Or if it was like that from day one the pan (most likely center tunnel) was cut and welded with a hump. If thats the case and you not want to go back to redoing the pan - you could shim the mounting points at each end until the door sits correctly.

Rob, When you hit bumps does your doors open up? My car did? I had the same problem. Push on the rear end to see how much flex you have. No too much or you'll crack the paint. While you are moving it look in the engine compartment at the side wall. See if they are flexing. Fiberfab/CMC used the rear side walls of the engine compartment to basically support the rear. My sides were also bolted. Try the large headed rivets and see if the work. Another alternative is welding additional support beneath the rear seat . I fabricated a small roll bar that is in the space between the engine compartment and back seat. It ties everything together. No flex at all. Tie rods will also be connect the the body frame and the engine mount fork.
Joe s

Rob,

If you remove a rear wheel or just look behind a rear tire you should see a few (4?) big rivets holding the fiberglass body to the sqare tube subframe. Most likely these rivets cam loose, the body was not mounted accurately or the subframe sagged. A long time ago a CMC builder told me you could put a board and a floorjack under rear of the body, drill out these rivets on both sides, slowly jack up the rear of the body until the rear of the door openings on both sides line up okay and then drill and re-rivet/screw the body to the subframe. Note: This gets more complicated if you have done anything else to hold the rear of the body to the subframe or pan, those will also have to be undone before jacking.

This works for cars that haven't been painted yet because there is a chance the rocker panel area may warp or crack then this will have to be repaired before painting. Not sure how to handle the fact that your car is already painted.

I looked at the picture and saw MY car!! CMC's do have a massive sub-frame under the body, and I don't believe any of them shipped without it. I DO believe, however, that a lot of bodies were poorly assembled to the frame and were not lined up and shimmed properly when they were assembled to the body, and this allowed the sag you see at the rear of the door. It's closer at the bottom than the top, indicating that the rear on at least one side (where the picture was taken) is too low on the frame.

Alan Merklin (I think) covered this corrective procedure a while ago, but my car was already painted and it's only one one side (the left, interestingly enough, same as yours) so I chose to live with it, but, basically, here's how it's fixed:

Put the rear of the car on jack stands (both sides) and remove the wheel from the side to be adjusted (You COULD do both sides at one time, but It'll be more complicated). Place a jack under the side to be raised, with a horizontal piece of wood (2 X 6) diagonally across, under the rear fender near the wheel and over towards the license plate - jack up against this piece of wood (you'll need a block between the jack and the cross-piece), but just bring the jack up enough to gently hold the cross-piece in place for now.

Look inside the wheel well and you'll see the vertical fiberglass piece used as an inner fender wall between the wheel and engine compartment. At the bottom are several LARGE pop-style rivets. Drill the center out of each and remove them completely. Look around for any other fasteners holding the body to the frame on that side. Once they are all removed, you may GENTLY begin to raise the jack and cross-piece, while having someone watch the gap at the top of the door to the body. As you slowly jack the cross-piece up, you should see that gap begin to even out between the top and bottom of the door (it shouldn't take much vertical motion to correct your gap). Once it's nicely even, stop jacking - you're there.

Look into the wheel well and see where the body has now lifted off of the sub-frame under the back seat. You should shim that area with something non-metallic. I suggest you go to Home Depot or Lowe's (in USA, DIY in Europe) and find a piece of plastic decking material or some similar plastic (fake wood) material and construct a shim of the proper dimensions to take up the space between the body and frame under the rear seat. Once that is made, glue it in place with something like "Liquid Nails" or a good, water-proof marine adhesive.

Now, back to that vertical inner fender wall - the one you removed the rivets from. The rivet holes in the fiberglass should now be far from lining up with the frame holes, so look at where they are against the frame.......if they are still within the frame material, just drill new holes in the frame, install new rivets of the same size and you're done. If the wall holes are above the frame, just pick a spot between existing holes and re-locate a hole such that it'll go through both the fiberglass and frame member, install the rivets and you're done. Replace any other fasteners that were removed other than the rivets, first shimming that fastener area with either washers or more plastic wood material.

Gently lower the cross-piece jack, replace your wheel, get it down off the jack stands and go have a beer. You're done.

Alan: Did I miss anything? I think you've been through this before, too!

gn

Thanks for the info,
Originally the gap was not apparent, after about a year it started showing up, but you can easily see the flex just by gently lifting up the back of the car.

Hopefully i'll get home from work early enough tomorrow to get under there and look for the rivets, i would rather not wait for the weekend, weekends are for driving!

r

Wow,
I am glad I looked when I did, I'm not sure which side is worse, the one where the body has "stretched" around the rivet, or the side where 5 of the 6 rivets are MISSING!

(OK i know which side is worse)

Thanks for all the info on this site, it is a godsend!

Holy S#&*!!! I won't complain about my CMC again!

Don't forget to NOT use those original holes - Once you get it positioned right, drill new holes in between the original ones. Why? The old holes may be either too big now, or egg-shaped (or both!) and will allow the body to move once riveted. Also, don't forget to shim the area under the rear seat where the body sits on the frame to take up the slack.

You might also rough up both the frame and that fiberglass sheet where they both come in contact, and slap on a generous coat of mixed Fiberglass Resin or some other suitable adhesive just before you pop the rivets in to make sure it's not going to move later on Use 80 grit on the frame and make it shiney, 80 - 100 grit on the fiberglass and just rough it up a little (take the shine off of it) and then apply the mixed resin/hardener and rivet them together.

Gordon,

Yes that's to proceedure to adjust the rear of a speedster body.
But I have never seen one as bad as Robs....kinda scary!

Rob,

Follow Gordon's post to realign the body, take your time and do the adjustments ever so slowly, the body and inner frame will "give" a bit if ....done sloooowly , go too fast and you'll surely have a nasty crack probably at the rocker panel to quarter panel area..

Alan M

Thanks,
Hopefully I will be able to start this weekend, I will let you know my progress.
Rob

You may also want to consider along with new rivets.....a little silicone adhesive between the frame and fiberglass. It will give it some holding power and will also reduce some of vibration and shock. Clean the surface first with acetone before you apply the adhesive . Install the new rivets after you apply the silicone. The installation of the rivets will displace most of the silicone. after the rivets are installed.... Wipe off the access silicone before it drys.

A suggestion you might want to try. I took two pieces of angle iron, believe they are 2" by 2". The idea is to lay them in the engine compartment on top of the square tube subframe and make them as long as you can from the firewall (or farther front if you can) to the rear of the square tube subframe almost touching the taillights/body. Now get a two heavy metal sheets as long as the angle iron (maybe 1/6" thick?) and about 4 or 5" high. The sheets will go in the fender wells, the bottom edge sits along the bottom of the fiberglass. Drill holes through the sheets and into the fiberglass and angle iron and bolt them all together. Then drill holes through the sheets and into the subframe and bolt them together. Lastly, drill holes down throught the angle iron into the square tubing and screw or bolt them together. What this will give you is a much stronger mount for the rear of the body and a little more strength for the rear of the subframe. Sounds like a lot of work but not too bad. Hopefully what I'm describing is clear, if not let me know.

Joe: I posted something similar above, and I considered silicon caulk (which would make a terrific water seal) but decided in favor or fiberglass resin to give it more strength. I'm more worried, here, about weak shear strength, since the two pieces (side wall and frame member) have the potential of sliding up and down against one , and that would be the caulks' weakest bond. If they were simply pulling apart, then silicon would probably be fine (that stuff holds surprisingly well) and, in fact, I'm using clear silicon to hold my front bumper mounts in place as they pass through the body, to keep them from rattling around (I also used it to hold the marble face onto my fireplace!!).

Rob probably could use all the strength he can get back there, since I surmise that the body's been moving around a bit in use and could use the extra strength bond that the resin would provide.

Bruce: I took a look back there on mine, and you must eiher have teeny-tiny hands and tools or a lot of patience........But still, I think yours was a great idea. Rob: If you're going to do the metal pieces that Bruce mentions, go to Home Depot or other tool supplier and get a right angle (90 degree) 3/8" drill adapter for your electric drill (I think "General Tools" makes them - about $20 USD) and use that to drill your holes onto the top of the frame - makes the whole job go infinitely easier as there isn't a lot of room in there.

gn

Gordon,

Yeah, actually I believe this was all done a long time ago before I installed the engine but I think is still possible with the engine in. Those tough-to-reach areas can be drilled from underneath - through the subframe and the angle iron - and then through-bolted. Makes for a very strong body mount.

I agree Gordon as long as you can prep the metal for proper adhesion of the polyester resin. 60 grit is perferred for a glass to metal application. The silicone application would just cut down the vibration/mechanical wear. If one were to install large headed rivets every 4" at the lower 1/3 of the frame rail and then install a staggered rivet at the top 1/3 .. would be sufficent fix. The main concern for all applications is to get the mating surface as tight as possible. Quik clamps work great for this application. The less conservation method that Bruce stated is also a great method.