Tension Strap Abuse! (and two tension strap fixes)

[trayson]

EDIT: While the "fix" below is still holding; it wasn't really solving my problem, so I tried another method using some black FLAT bungee cords. Read about it below on post #19:

Click here



Tension Strap Fix #1

On my 1996 with the semi-auto top, I took up some slack in the tension strap by attaching the elastic tension strap to the non-elastic nylon webbing that was immediately above it and behind the bow from where the tension strap is. It basically pulled the tension strap up towards the bow, and probably took out a CM or two. I think it'll help, and it took all of 5 minutes... The view of this picture is looking straight up as if you're laying on the ground looking at the top. I know it's hard to get perspective, but the point is that I used a zip tie to take out some slack...




Tension strap fix #2

I tried to repeat this "fix" on my 1998 M3 cabrio, but it appears that some of the top mechanics are subtley different. So, I couldn't do the above because the headliner attachement seemed to be in the way. Anyway, I wanted to effectively shorten the tension strap without having to unattach anything. So, I figured that I wanted to find some way to gather up a section of tension strap and "take out some slack". I decided to do some creative problem solving. I figured that with a flat surface like a tension strap, that I'd have to give the zip tie something to grab onto and wanted to make it so it didn't bunch up...

The concept I visualized in my mind was to essentially fold a section of the tension strap over onto itself (so it made a "Z" shape). Here's what I did:

1) I cut up an old gift card to about the width of the tension strap. Then I cut a pair of pieces that were about the length that I wanted to shorten the strap by. I knotched the plastic gift card pieces so that the zip tie would have a place to attach to and not slip. I cut off the corners so there was less of a chance of something that could snag something. I used plastic because I figured it'd hold its shape, but hopefully won't cut the tension strap!!



After that, I put the plactic pieces into the tension strap and made it into the "Z" I wanted, so it would take up some of the strap's length.




I think it should work okay. I figure for the price of two zip ties, it was worth a try.

Tension Strap Abuse

I found out that I'd been going all last summer with only ONE tension strap connecting the bow above to window to the bow immediately forward of that. The other tension strap (on the passenger side of the car) had come unattached from the bow immediately in front of the one above the rear window. Definitely a bummer, because I'm sure that the other strap got worked into a premature aging because of it. Now I have to figure out how to reattach the tension strap. I haven't figured out how the headliner attachment plastic comes off that bow... it seems like it might be rivited on??? Anyway, I have some thinking and troubleshooting to do. But at least I've identified a guaranteed problem that I'll be able to fix soon enough to make my top operate better. (yes, I'd been having the decklid scraping on the top fabric because the rear window section wasn't pulling vertical enough.)

[rebel.ranter]

I hope this works out for you as I am going to tackle the same issue this weekend. I bought some elastic marine rope a few months ago for the job but never got around to it.
I cannot work out how I am going to use the elastic rope without it being visible (knots) from outside.
I am trying to think what kind of elastic web might be available instead, maybe something a dress maker would use is the answer?

[Alpine6And7]

I Shorted 2 bungie cords(1 for each side right on the edges) and shorted the tension straps with a couple zipties works great now! Got over $1k off the car Because of this issue and fixed it with things laying in my garage

[MParallel]

Wonderfull thinking Trayson. I know it works as I used a ziptie in de past. Instantly made the top work without mandraulic interferance. Only shame was the zip-tie broke after the 1st time. And it did sqash the strap when pulling the tie. I also tried a paperclip. Work perfectly too. But slides on the strap, so also a one-operation cycle only solution.

This is so simple, yet clever, you just don't think about it. Way smart this. Lets hope the zip-tie holds up.

I wish they did micro strap+ratchets!

Wonderfull thinking Trayson. I know it works as I used a ziptie in de past. Instantly made the top work without mandraulic interferance. Only shame was the zip-tie broke after the 1st time. And it did sqash the strap when pulling the tie. I also tried a paperclip. Work perfectly too. But slides on the strap, so also a one-operation cycle only solution.

This is so simple, yet clever, you just don't think about it. Way smart this. Lets hope the zip-tie holds up.

I wish they did micro strap+ratchets!

[mreloc]

I did the bicycle inner tube fix this past weekend. Cut a 26" tube in half, removed the valve section, had enough to do both sides. What I like about the inner tube is that when you zip tie it to the bow above the window, it is tight enough and grippy enough not to slide down the side (as the velstretch fix did). Seems to be working great! What's also good about it is that it is flat, so not visible from above.

[Yanmar46]

Great Idea,
May I ask how many pieces did you use? (what did you connect?)
the original strap has several elastic parts along the top. Do you still have the liner on? (I have removed mine). I guess in case of a snap there is no problem if you have the liner. Did you attach them both ends with zip tie? Thank for sharing!!!!

[rebel.ranter]

Hi, I thought I would update on my fix. My roof is now working fine after about 15 minutes of looking & fitting the set up below.

I used two small bungee chords with the metal hooks hack sawed off & used cable ties (or tie wraps) in their place.

Here is the "kit" I used:



2 Bungee chords (€5 for 4), 4 cable ties (cheap)

I just fed the cable ties through the "loop" at the end of the bungee chord like this (you'll have to imagine the metal hooks, seen here in the middle of the chord cut off. I just held them carefully in a bench vice making sure I didn't damage the bungee):


I attached one of these to each side of the roof at the points indicated in the diagram below:


I used 25cm (max stretch 37cm) small bungees. Here is the exact brand. I'm in Ireland but these are made from Malaysian rubber in Milwaukee, Wisconsin. They are distributed in Europe from Neuilly Sur Seine & sold via the UK in B&Q stores. So they had a long journey to me!!I guess you can get them everywhere!


It works a treat so far, it doesn't show through the outer roof. It seems to be made for it, in black and all!!
I also fixed one of my bat wings with a paper clip. I think I might just buy the repair kit though, it is worth the €30 or so. It works absolutely fine but just for completeness.

[Yanmar46]

Super!!!
Good job, I have done something similar with flat cord. However, I have used crazy glue. It has improved a lot but still needs some help as soft top does not come to 90 degrees when is going down.

I have a couple of questions if you can help me

Do you have the underliner on ?
Do you face any issues when soft top is folding in the housing?
Does it fold easy or need help (to push it in) before the lid closes.

I have some of the above. I am not sure if they are linked to additional elastic straps (similar to yours) I have installed.

I think I have those issue because I have removed the underliner (it was in a very bad state, I need a new one anyway). I want to solve the issue with the elastic strap before I buy and fit a new underliner.

thank you for you help!!!


yanmar46

[rebel.ranter]

Not sure if the question is directed my way, but anyway...

My inner head liner is in great condition & in place the way it should be. Also I do not have to touch the hood in any way whether going up or down. It folds they way it should do.

[byrona8]

My Velstretch broke too!!! I'm tackling this after work!!!

[rebel.ranter]

My Velstretch broke too!!! I'm tackling this after work!!!

Be sure to update with your version of the repair.

[libravcs]

I did the zip tie method over a year ago..and its still holding fine.

[Yanmar46]

thank you Rebel, I will work on mine and post pics with outcome (based on your ideas)s

[Hugo]

I need to to this. Tried the cut up plastic card/zip/z folding over itself and it didn,t hold up, the plastic card snapped.

[Hugo]

Woo-hoo!

The fix in post #7 worked!!!!!!!!!!

[Hugo]

Aw f*ck it, one of the zip ties snapped, I'm back to square one, the top still doesn't go up by itself.

[trayson]

Aw f*ck it, one of the zip ties snapped, I'm back to square one, the top still doesn't go up by itself.

Don't be too discouraged... I mean, all you have to do now is find something stronger than a zip tie. How hard could that be? Seriously, start looking at things that you can attach to the bungee that won't break like plastic zip ties. How about going to a store like REI that sells rock climbing supplies and get some nylon webbing, or some spectra rope that has some seriously high strength to thickness ratios...



On another note, where did you source your bungees? I mean, were they something that you could simply find at Home Depot? That's the only thing that's preventing me from tackling this. I'm sure that after I get back from Vacation (after Memorial Day) I'll be looking into a tension strap fix that's a bit more "permenent".

I mean, really, as long as I find the correct item with the right elasticity and durability (bungee, bicycle tire, whatever) the attachment of said item to the bows shouldn't be that difficult.

[Hugo]

I bought them at Canadian Tire, but any hardware store should have them. As long as the length is as posted above, you should be fine.

[trayson]

ROUND TWO

Okay, since my inital posting didn't really fix my problems, I decided to go at it with a more traditional "bungee cord" method.

I trip to Home Depot Found me a pair of these:



I liked the fact that they were a "flat" bungee and that they were black. They were $3.96 for a pair at Home Depot.

So, after some trial and error, I actually ended up looping the plastic hook over bow #5 that's just above the plastic rear window. Then I ran it over the next bow (#4) and attached it to bow #3 after that(I basically ran the bungee between the exact bows as Rebel Ranter above).

To secure it to bow #3, I basically wrapped the bungree around the bow, and then tied a knot in the end and wrapped a couple zip ties to secure the bungee to itself. It basically looked like this, except that I used two zip ties after the knot and of course clipped the ends of the zipties:


And then I cut off the remaining bungee that I didn't need after the knot.

I was actually able to accomplish replacing both tension straps with only one of my Bungees used and still had material in the center left over.

Now, the only thing I'm a little leary about is the longevity of the top with a plastic hook underneath it... As you can see from this picture, I get a small bulge on the top where the plastic hook's under it. It's possible that this could create a wear point, but maybe not.


But my top really doesn't spend THAT much time in the up position. If I roll drop top and park it in the garage, I leave the top down. Once we hit late fall and I can't have the top down anymore, the Hardtop goes on and the soft top is stowed for the entire winter...

I took a few pictures of the top up with the platic hook over Bow #5 and depending on how hard you look, and how the shadows line up, it's sometimes noticeable, sometimes not as much. Here are some pics:










Between replacing my top storage compartment decklid shocks, and now the new flat bungees, it's like having a new top again.

[lightflyer1]

So when you installed this how much if any tension do you put in the strap? Slightly loose, snug or under some tension?

What problem does this fix actually fix? I guess I should say is what is the function of the tension strap?

[trayson]

So when you installed this how much if any tension do you put in the strap? Slightly loose, snug or under some tension?

What problem does this fix actually fix? I guess I should say is what is the function of the tension strap?

At the point where bow #6 lifts the rear window upward, the tension strap will pull bow #5 (top of window) towards Bow #3. This will pull bow #6 (bottom of window) more vertical and towards the front of the car, so that the front edge of the top storage compartment decklid does not drag on the fabric of the top when the decklid's opening.

Therefore, if you're installing the bungees, you need to install them "stretched" if the top is mostly in the closed postion. The bungees are relaxed when the top is folded and stowed (drop top).

I would imagine that's why the tension straps wear out, because they're stretched the entire time the roof is up...

But for the cost/effort of this fix; I wouldn't care if I had to do this every year. The bugnees cost me 3.90 for TWO, so I've still got a spare left over. and now that I've done it, I'd say that I could repeat in ~15 minutes.

[lightflyer1]

Thanks! Mine already had some bungees installed when I got it. It works though. I will be doing a top, straps, headliner replacement soon though. Do you know what technique is used to set the tension on the original straps?

[trayson]

Thanks! Mine already had some bungees installed when I got it. It works though. I will be doing a top, straps, headliner replacement soon though. Do you know what technique is used to set the tension on the original straps?

I'd guess that they're only so long, and they attach to bows 3 & 5 respectively, so I'd say that you probably just attach the ends and that's how they're supposed to be.

[vlakci]

Do you know what technique is used to set the tension on the original straps?

there is nothing to set. the original straps are made to 100% lenght that when fixed they are tensioned at 100% as they should be. BMW made and upgrade kit as the first tension straps (until 1997) losed quickly the strech. But even this new kit isn't perfect and in worm places after ~5years they go bad. I still think that the best solution is to buy marine bunge rope as it's more durable. And then put it on both sides. If some ones hates the bulk on the softtop, can use the smaller rope and put 4x one (2 on each side).

The problem with the bike tube is that is not intendet for straching and shortly after some werry hot days the rubber will start to crack and finaly brake.

I fixed my top with the bunge rope (1/4 inch rope) and it works perfectly.
no more braking noise when the now is storaged under the lid (before it made a slaming noise when lowering), no more crack on window (if the 5 bow doesn't retrack to bow3 the window is almost at 180° betwen now6 and 5), no more holes on side if soft top (they are a problem connected with the tension ropes), no more problem of motor gears brakeage.

[mreloc]

The problem with the bike tube is that is not intendet for straching and shortly after some werry hot days the rubber will start to crack and finaly brake.

My inner tube fix has held up great for six months and counting... what do you think makes bungee cords stretchy? Rubber, most likely.... Inner tubes are really the same as a flat bungee without fabric woven around the outside.