E36 convertible vert flat bungee tension strap fix DIY

[Joylove]

Here is my flat bungee cord fix. It is not the first, others have gone here before, but here is mine.

This fix cures two problems
1) Tonneau cover hits bottom of roof.
2) Headlining does not stow correctly, tonneau crushes roof.

One or both of these issues is caused by the tension straps. They have elastic portions and it stretches like an old lady's skin over 15 years. The roof no longer operates as designed. The back window doesn't lift high enough, the headlinging doesn't fold as designed.

The BMW fix is to drill out four pop rivets, draw more tension strap through at bow 6, and re rivet. Unfortunately it is my opinion tha the eleastic had become longer that 6 inches. There is about 3 inches of tension strap to draw through before you get into problems with elastic stictched to the strap. You will see when you check for yourself what I mean.

Shortening the tension straps 2 inches isn't going to bring back the elasticity either.

You would need to remove the roof to replace the tension straps entirely.

So a workaround is to augment the knackered tension straps with flat bungees. Others have recomended surgical latex tubing. Sounds like a good product to try.

Check out this fantastic diagram by Davester. There are 6 bows in the car. Starting at the top of the windscreen is bow 1. The last one under the rear window is bow 6.



Testing the fix before starting

We are going to use 2 * 6ft/1.8m flat bungee from bow 5 back to bow 2 to augment the knackered elastic.

You can test if this will cure your problems. Get to this point, (1) tonneau hits roof.


Concertina bows 3 4 and 5 together. Magically bow 6 will go vertical and clear the tonneau.

Get to this point (2) Headlining does not stow correctly, tonneau crushes roof.



Raise the roof partially. Between bows 1 and 2, push the roof and headlining fabric out so it folds towards the sky not towards the leather.

Lower the roof. Headlining stows correctly.


On then to the fix.

Knots.
You don't want lumps showing in your roof. You want low profile knots. This is where surgical elastic tubing would be easier to use.
Your knots might slip after 6 weeks, don't trim the excess flat bungee until the 12th month of problem free folding. Surgcical elastic may slip less.
There are pages on the internet with 100 different sailing knots to try.

Route
I'm not going to tell you over this bow, under that one. It's too hard to follow, and you'll figure out a path when you get to the car.
Be aware the bungee might slide down the paint on the bows and into the roof mechanism. Try to loop-de-loop the elastic around the tension straps where they are riveted to the bows to stop the bungee sliding about.

Step 1
Tie a knot around bow 5.

Don't let this knot come undone, it's awkward to tie and to photograph

Step 2
Loop-de-loop around bow 4.

We don't use a knot here, tesnion is going to be shared between 3-4 and 4-5. You can see the bungee cannot slide down the paint into the roof mechanism.

Step 3
Knot around bow 3.

Tension the elastic to about 30% when the roof is in the position shown in the photos where it is easiest to work on, and knot it so it can't slip into the roof mechanism. stuff the spare elastic into the headliner. Consider repeating on the other side of the car. Test that bow 6 is now raising and tonneau no longer hits the roof. Test for lumps showing in the roof or headliner when roof is closed. You have now fixed problem (1) Lid hits roof.

Step 4
Knot around bow 2.

Elastic tension should again be 30% when the roof is in the position where it is easiest to work on the tension straps as shown in the photos. Don't let this knot come undone, same as bow 5. Elastic 2-3 it is quite easy to ripple the headliner when the roof is closed, so check with the roof closed for ripples. I had to put this knot in a specific place or it rippled the headliner. You have now fixed (2) Lid crushes roof.

Step 5
Stow the spares.

I loosely pull on the bendy metal bits to encourage them to bend up not down. I stow the spares between the headlining and roof.

Repeat on other side of the car.

The end result
A ripple free roof and headlining.




I also found and repaired two faults.

This strap had torn and was replaced with string. I also did the same the other side because that strap was on its last legs. Notice the metal bar (54318203869 $16). If that is upside down the roof won't fold correctly and will catch on the trim near the rear headrests.

This metal part had come away and was refitted to the elastic and the sharp end covered with thick electrical tape.



Additional improvements you will notice
The roof no longer drops into the storage area with an expensive sounding !thump!
On closing my fully auto roof, at the point where the last motor engages (the slow one - auto roof only), bow 6 is not yet touching the tonneau. It slowly lowers under its own weight, taking some stress of the tight roof fabric off the slow motor.

Hope this helps some people.

[Joylove]

Ooops mods could you please move this to the vert forum?

[MParallel]

Was just about to say why don't you post this in the vert section.

Good right up!

[Joylove]

Was just about to say why don't you post this in the vert section.

Good right up!

Thanks mate

[MParallel]

I mean write up of course.

[Joylove]

I mean write up of course.

I guessed that mate

Have you done your tension straps? Knowing you; you took the roof off

[Joylove]

Some more ideas from Fly
http://forums.bimmerforums.com/forum....php?t=1804186

[lumanikus]

Adding a question and possibly an idea to this thread. I am going to give using exercise / resistance bands in place of bungee chords. My only question was what strength should i get. I went with Red medium (whatever that means) guessing that if i dont have enough tension i can just tie them shorter. protherapysupplies.com http://www.protherapysupplies.com/Sh...=11089&whence=

[Joylove]

Please reply back with how you get on with that item for future visitors to the site.

[morzada]

For another data point - about a month ago I purchased some Vel-Stretch straps from Menards for my top. They worked great until today. Both straps had ripped (both sides) where the Velcro folds back on itself.

[flyfishvt]

Some more ideas from Fly http://forums.bimmerforums.com/forum....php?t=1804186

Since I did that DIY I've learned a few things. I'm now on my 3rd vert and this holds true for all of them. 1 semi auto and 2 fully auto tops.

The only thing you need to accomplish is to get bow 4 to pull back before or during the tension bow going vertical. You'll notice the original tension straps are not very heavy duty. I think a lot of us originally thought the tension straps were intended to pull on the tension bow and help the motor raise it up. Actually that's not true. The tension straps purpose is to pull bow 4 forward. It doesn't take much force/tension to accomplish this. Certainly the bungee straps are over kill.

Pulling bow4 forward also pulls bow 5 forward. Bow 5 must be pulled forward for the tension bow to go vertical so the tonneau cover doesn't hit it. The reason is the canvas creates a large fold between bow5 and the tension bow. If bow 5 doesn't move forward then that thick fold prevents the tension bow from going completely vertical. In order for bow 5 to move forward bow 4 must pull it. This is where the tension straps come in. Tension strap pulls bow4. Now 4 pulls bow5. With bow 5 forward then the large canvas fold moves forward and the tension bow can go vertical and just barely clear the tonneau cover as it comes up.

So the point I'm trying to make is that you don't need to attach your bungee cord to bow 2 or even to the tension bow as some people think you do. Attach it to bow 3 & 4 and everything should work fine. I did this on my 328 vert over 3 summers ago and it's still opening and closing just fine.

[infotron]

If it helps anyone I used 2 x Flat Bungee 24" from Home Depot - product code 1001 820 840 - took clips off and punched holds in the bungees and old elastic behind no 5 and zip tied then wrapped them 4 and then made a loop around no 3 and punched them and zip tied as well.

Thanks Joylove

Hard to get behind no 5 but it can be done - next time will be easy.

Here is my flat bungee cord fix. It is not the first, others have gone here before, but here is mine.

This fix cures two problems
1) Tonneau cover hits bottom of roof.
2) Headlining does not stow correctly, tonneau crushes roof.

One or both of these issues is caused by the tension straps. They have elastic portions and it stretches like an old lady's skin over 15 years. The roof no longer operates as designed. The back window doesn't lift high enough, the headlinging doesn't fold as designed.

The BMW fix is to drill out four pop rivets, draw more tension strap through at bow 6, and re rivet. Unfortunately it is my opinion tha the eleastic had become longer that 6 inches. There is about 3 inches of tension strap to draw through before you get into problems with elastic stictched to the strap. You will see when you check for yourself what I mean.

Shortening the tension straps 2 inches isn't going to bring back the elasticity either.

You would need to remove the roof to replace the tension straps entirely.

So a workaround is to augment the knackered tension straps with flat bungees. Others have recomended surgical latex tubing. Sounds like a good product to try.

Check out this fantastic diagram by Davester. There are 6 bows in the car. Starting at the top of the windscreen is bow 1. The last one under the rear window is bow 6.



Testing the fix before starting

We are going to use 2 * 6ft/1.8m flat bungee from bow 5 back to bow 2 to augment the knackered elastic.

You can test if this will cure your problems. Get to this point, (1) tonneau hits roof.


Concertina bows 3 4 and 5 together. Magically bow 6 will go vertical and clear the tonneau.

Get to this point (2) Headlining does not stow correctly, tonneau crushes roof.



Raise the roof partially. Between bows 1 and 2, push the roof and headlining fabric out so it folds towards the sky not towards the leather.

Lower the roof. Headlining stows correctly.


On then to the fix.

Knots.
You don't want lumps showing in your roof. You want low profile knots. This is where surgical elastic tubing would be easier to use.
Your knots might slip after 6 weeks, don't trim the excess flat bungee until the 12th month of problem free folding. Surgcical elastic may slip less.
There are pages on the internet with 100 different sailing knots to try.

Route
I'm not going to tell you over this bow, under that one. It's too hard to follow, and you'll figure out a path when you get to the car.
Be aware the bungee might slide down the paint on the bows and into the roof mechanism. Try to loop-de-loop the elastic around the tension straps where they are riveted to the bows to stop the bungee sliding about.

Step 1
Tie a knot around bow 5.

Don't let this knot come undone, it's awkward to tie and to photograph

Step 2
Loop-de-loop around bow 4.

We don't use a knot here, tesnion is going to be shared between 3-4 and 4-5. You can see the bungee cannot slide down the paint into the roof mechanism.

Step 3
Knot around bow 3.

Tension the elastic to about 30% when the roof is in the position shown in the photos where it is easiest to work on, and knot it so it can't slip into the roof mechanism. stuff the spare elastic into the headliner. Consider repeating on the other side of the car. Test that bow 6 is now raising and tonneau no longer hits the roof. Test for lumps showing in the roof or headliner when roof is closed. You have now fixed problem (1) Lid hits roof.

Step 4
Knot around bow 2.

Elastic tension should again be 30% when the roof is in the position where it is easiest to work on the tension straps as shown in the photos. Don't let this knot come undone, same as bow 5. Elastic 2-3 it is quite easy to ripple the headliner when the roof is closed, so check with the roof closed for ripples. I had to put this knot in a specific place or it rippled the headliner. You have now fixed (2) Lid crushes roof.

Step 5
Stow the spares.

I loosely pull on the bendy metal bits to encourage them to bend up not down. I stow the spares between the headlining and roof.

Repeat on other side of the car.

The end result
A ripple free roof and headlining.




I also found and repaired two faults.

This strap had torn and was replaced with string. I also did the same the other side because that strap was on its last legs. Notice the metal bar (54318203869 $16). If that is upside down the roof won't fold correctly and will catch on the trim near the rear headrests.

This metal part had come away and was refitted to the elastic and the sharp end covered with thick electrical tape.



Additional improvements you will notice
The roof no longer drops into the storage area with an expensive sounding !thump!
On closing my fully auto roof, at the point where the last motor engages (the slow one - auto roof only), bow 6 is not yet touching the tonneau. It slowly lowers under its own weight, taking some stress of the tight roof fabric off the slow motor.

Hope this helps some people.

[Armazia]

I'm trying to do this fix, I've seen this topic before and seems quite straight to the point... But since the images are corrupted, would anyone have those or could these be updated? Or if someone has another guide instead of this one, it would be really nice..

[rankin]

Great fix, worked a treat, thanks a million!!