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Drophead front bumper

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stevie_a
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Drophead front bumper

Postby stevie_a » 08 Jul 2018 21:03

my DHC front bumper has got the droop !

I am thinking of removing the end weights, I know there are different things you can do on fixing,
But what is the best thing to do , don't want to go down route of FHC bumper.
thinking of solid fixing but how is the best way to do this?
If it's not broke don't fix it.

Beans
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Re: Drophead front bumper

Postby Beans » 08 Jul 2018 21:20

Have a look at the site of the German http://www.tr7ig.de/
Go to Das Fahrzeug > Werkstatt > Stoßstangenhalterung
Image
1976 TR7 FHC (currently being restored ...)
1980 TR7 DHC (my first car, a.k.a. Kermette)
1981 TR7 FHC (Sprint engined a.k.a. 't Kreng)

http://www.tr7beans.blogspot.com/

stevie_a
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Re: Drophead front bumper

Postby stevie_a » 08 Jul 2018 21:37

Looks like an alternative to the rubber mount, unfortunately I cant google translate that site for some reason.

would you put this on and remove weights and that's it?
If it's not broke don't fix it.

saabfast
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Re: Drophead front bumper

Postby saabfast » 08 Jul 2018 22:45

There is this setup on ebay for a solid mount.
https://www.ebay.co.uk/itm/TR7-TR8-Fron ... 1438.l2649
I keep thinking of taking the weights out but think it has dropped now for so long that it will need more.
Alan
Saab 9-5 2.3t Vector Auto Estate Stage 1
Saab 9-3 2.0 SE Turbo Convertible
'81 TR7 DHC
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FI Spyder
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Re: Drophead front bumper

Postby FI Spyder » 09 Jul 2018 16:22

I took the weights out when I had the bumper off, not because the ends where drooping (they were fine) but to see if I could notice any difference. I couldn't but maybe could if I could do a side by side comparison. Left them off as it's too much trouble to put them back on. A combination of taking them off and bolting the mounts so they are solid may be the answer for those with drooping bumpers. Doing it that way will have minimal impact although it will take away a talking point as to why the bumpers are drooping and the high tech computer designed engineering that went into maximizing the customer driving experience in the TR7. 8)
- - -TR7 Spider - - - 1978 Spitfire- - - - 1976 Spitfire - - 1988 Tercel 4X4 - Kali on Integra - 2013 Volt - Yellow TCT

Beans
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Re: Drophead front bumper

Postby Beans » 09 Jul 2018 20:57

stevie_a wrote: ... would you put this on and remove weights and that's it?

Don't know, still have (adapted) original mounts with the weights in place, and they are not to bad.

Image

I have accepted a bit of droop on the front bumpers :roll: so not high on my To-Do-List.
And I think the dreaded droop is often caused by bent bumper bars, caused by "parking incidents".
This is almost certainly the case with the bumper bar on my car, as one side is worse compared to the other side.

I do have the outlines for alloy mounts almost ready on my computer for several years!
But it'll probably be a few more years before that drawing file is transferred into a machining file ...
Image
1976 TR7 FHC (currently being restored ...)
1980 TR7 DHC (my first car, a.k.a. Kermette)
1981 TR7 FHC (Sprint engined a.k.a. 't Kreng)

http://www.tr7beans.blogspot.com/

littlepippin
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Re: Drophead front bumper

Postby littlepippin » 10 Jul 2018 07:11

Are they not meant to droop a bit on the soft top ? I understood the weights act as a balancing type of device although I could not say what they are meant to be counterbalancing.

I think I read on the forum that the tin top cars don't have the droop and the weights ? Certainly the front bumpers on them always look more in line with the body styling.
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Hasbeen
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Re: Drophead front bumper

Postby Hasbeen » 10 Jul 2018 08:56

I've been told that they are to help counter scuttle shake.

My 7 has never had scuttle shake, so when the bumper was off the 8 for painting, we removed the weights. I can detect no difference in the car.

My son had no idea of what we were talking about. Then we bought an Oz built Ford Capri [Mercury Capri in the US], convertible for a daughter.

After driving it my son declared he now understood what scuttle shake is.

Hasbeen

saabfast
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Re: Drophead front bumper

Postby saabfast » 10 Jul 2018 12:56

I had understood it was a 'harmonic damper'. Cant pretend to understand the working of it but the centre is mounted on a pivot pin and it has softer rubber mounts towards the ends and weights right in the ends. Somehow the movement of the weights about the pivot counteracts vibration/shaking of the car. I think the rubber mounts get too soft over time and cannot support the weights in the ends without drooping. Maybe at that stage it stops working anyway - if it ever did?
Alan
Saab 9-5 2.3t Vector Auto Estate Stage 1
Saab 9-3 2.0 SE Turbo Convertible
'81 TR7 DHC
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Beans
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Re: Drophead front bumper

Postby Beans » 10 Jul 2018 20:13

Beans wrote: ... the dreaded droop is often caused by bent bumper bars, caused by "parking incidents" ...

As these pictures show, one bent centre pivot & plate, and a bent rubber mount (RH one) ...
Attachments
2009-05-16 Frontbumper centre pivot.jpg
2009-05-16 Frontbumper centre pivot.jpg (82.41 KiB) Viewed 7796 times
2009-05-23_14 Frontbumper mounts and balance weights.jpg
2009-05-23_14 Frontbumper mounts and balance weights.jpg (85.67 KiB) Viewed 7796 times
Image
1976 TR7 FHC (currently being restored ...)
1980 TR7 DHC (my first car, a.k.a. Kermette)
1981 TR7 FHC (Sprint engined a.k.a. 't Kreng)

http://www.tr7beans.blogspot.com/

supercass
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Re: Drophead front bumper

Postby supercass » 12 Jul 2018 17:49

There is a bit of adjustment in the fitting of these but what often happens is that the rubber at the top of the mounts becomes separated leading to it pulling away and drooping. It is prevented from falling off all together by safety fasteners which for obvious reasons need to be present and fitted properly. In my case removing the mounts, cleaning and abrading the areas where the rubber had detached, applying epoxy resin, clamping till set and refitting taking care to ensure the safety clamps are correctly located solved the droop. If you are going to remove the weights and rubber mounts it makes sense to use a secure and robust solid fitting or a fhc bumper and to take the opportunity to fit the bumper closer to the body as per fhc. It looks neater. supercass

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