Since having the car painted I have noticed that the hood isn't receiving sufficient force from the torsion bar and tends to drop. What is the process for increasing the preload ?. Nothing is broken, I'm just assuming the guys at the shop didn't reinstall it exactly as it was when removed.
Hood Torsion Bar Adjustment
- Thread starter E3_UK
- Start date
jmackro
Well-Known Member
The thing isn't adjustable. If the shop took the torsion bar assembly apart (and I can't imagine why they would, unless they wanted to paint each component separately), they could have messed up installing the two blocks that anchor the fixed end of each torsion spring. But more likely, the springs have just lost their tension and a replacement is needed.
Do the torsion bars have almost enough force to hold the hood, or not nearly enough? In other words, is it dramatically weaker than it was pre-paint?
Question: are replacement torsion bar assemblies still available?
Do the torsion bars have almost enough force to hold the hood, or not nearly enough? In other words, is it dramatically weaker than it was pre-paint?
Question: are replacement torsion bar assemblies still available?
Here are some helpful hints curtesy German forum !
Basically you should do this with two people, otherwise you will scratch the whole hood.
Loosely mount the bearing block, torsion bars, and tube with struts, but do not yet install the end stop. Insert the complete hood strut assembly and tighten the screws. Then, by slightly twisting the struts, secure the end stop. This will create a slight preload when the hood is open. Finally, attach the struts to the fender.
You must mount the hood strut to the hood without any tension, as shown in the first two pictures. Then, you must extend the strut away from the hood, approximately at a right angle, and position and tighten the stop bracket. (From GR)
Basically you should do this with two people, otherwise you will scratch the whole hood.
Loosely mount the bearing block, torsion bars, and tube with struts, but do not yet install the end stop. Insert the complete hood strut assembly and tighten the screws. Then, by slightly twisting the struts, secure the end stop. This will create a slight preload when the hood is open. Finally, attach the struts to the fender.
You must mount the hood strut to the hood without any tension, as shown in the first two pictures. Then, you must extend the strut away from the hood, approximately at a right angle, and position and tighten the stop bracket. (From GR)
Take a look here: BTW, the torsion bar ends (the pot metal part that distorts) were still available from BMW at the time I made this post below.
https://e9coupe.com/forum/threads/e3-hood-torsion-bar-again.45373/
NB: Keshav, the E3 bar is a totally different animal than the E9 bar.......why, who knows.
https://e9coupe.com/forum/threads/e3-hood-torsion-bar-again.45373/
NB: Keshav, the E3 bar is a totally different animal than the E9 bar.......why, who knows.
The torsion bar was simply disconnected from the hood. It feels like it almost has the same strength as before, maybe it has just loosened a bit from being removed. I thought perhaps that the torsion springs could somehow unwind, requiring re-setting.
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jmackro
Well-Known Member
Well yes. But the pot metal parts that bavbob refers to in post # 4 are secured with the same bolts that mount the whole assembly to the hood. And those parts are what anchor the fixed ends of the springs. So conceivably, one could have shifted outward when the spring assembly was loose, allowing that spring to lose its pre-load. If that were to happen, one arm would require less torque to rotate it than the other. But I don't think there is a way for the spring to loosen just a bit; it would either move 180° or not at all. And given the amount of preload on the springs, the clunk would be pretty audible if one came adrift.
If I had removed it myself I would have been aware of it losing preload I suppose but the shop removed and refitted it and they aren't necessarily fully conversant with the mechanism. Should I therefore unbolt one side and rotate the block to increase the preload ?.
jmackro
Well-Known Member
You can try. But that presumes that the fixed end of the spring did slip out of its slot. If that happened, one arm would require less torque to rotate it than the other - is that the case?
You should also be aware that those torsion bars take a LOT of torque to rotate. Treat these hood torsion bar assemblies like a rat trap designed to kill a human-sized creature. If it snaps on some part of your body, it's going to cause injury.
It doesn't seem like one side has lost its preload. The hood does stay up, but it slammed down when the engine was idling roughly after a cold start and it has never done that before the body shop worked on it so I am assuming that there has either been a loss of preload due to it having been removed somehow. Thanks for the heads up on the dangers though, I think I might just leave it and use another prop for safety to avoid being decapitated by the hood.
If the center part of the mounting brackets are worn, twisted or damaged then it may cause this problem I think. When I replaced the hood on my car during the restoration I got a used hood with the brackets still attached but not the bar. There where obvious signs of wear on them, so naturally I replaced them with new ones.
E3AV is on point. If the orientation of the anchor part in the image above is fine and the orientation of the arms are fine (see my post, I describe where they should be), then the center keyhole in the image above is stretched and distorted and will cause your problem. That was the issue with mine. New brackets solved the problem. Send us some images of what you have.
The E3 bar is much more user friendly and can be loaded when partially installed unlike the E9 which is a mouse trap and loaded before installation. IIRC, the arms on the E3 can be placed backwards and still allow the hood to close, not the case with the E9.
The E3 bar is much more user friendly and can be loaded when partially installed unlike the E9 which is a mouse trap and loaded before installation. IIRC, the arms on the E3 can be placed backwards and still allow the hood to close, not the case with the E9.
I'm willing to unbolt the end brackets from the hood, I was just unsure if they would violently unwind when released. Is this not so ?. I can then check if the anchor blocks are deformed.
You should firstly support the hood when open. While holding the arms carefully undo the bolts that attach them to the engine bay mounts. Hold the upper part of the arms while folding the lower part upwards and secure them with tape or something to the upper part. Then move the whole assembly slowly against the front of the hood. Most of the tension is released, but some will still remain. Now it’s possible to undo the brackets.
Hope this helps
Hope this helps
Thanks, that's what I was looking for, I'll disconnect it and review the condition of the brackets.
jmackro
Well-Known Member
Well, I guess I don't know. My warning in post #8 was based on my experience with e9's. But in post #11, bavbob says that "the E3 bar is much more user friendly", so it appears that there is less risk when working around one of those.
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Yes just support the hood and then undo each arm from the fender while holding the arm itself. The torque is not much and this allows a controlled release of the tension. Do both sides then remove the bar from the hood and just pull the brackets off and inspect their condition.