bumper weight reduction?

[gav2021]

I was wondering if any members had removed any of the weight from the bumpers? Is the weight needed for stability? Thanks in advance
Gav

[dursleyman]

Lots of opinions and theories about those weights but I just took them off with no regrets since.

Russ

1981 TR7 Sprint DHC
Dursley
UK

http://tr7russ.blogspot.co.uk/

[gav2021]

Thanks russ I read somewhere they were needed for stability and they are ridiculously heavy think I'll lighten them as well was it easy enough done?

[FI Spyder]

They're harmonic balancers and aren't for stability but to minimise scuttle shake. Can't say I noticed much of a difference. Maybe if I drove one then another car for comparison on the right type of road. Won't make much of a difference in acceleration/fuel mileage either. If you have your bumper off for whatever reason, take them off, if not don't bother. Your time would be more productive cleaning each electrical contact to eliminate most electrical problems. I had my bumper off to clean up area behind, waxoil sprayed in through front holes to get between inner and outer fenders and front bumper bar, coated frontal area with paint extender so I left them off..

- - -TR7 Spider - - - 1978 Spitfire- - - - 1976 Spitfire - - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra - Yellow TCT

[dursleyman]

Spyder is right they are technically harmonic dampers intended to reduce DHC scuttle shake on poor roads. They work with that centre pivot and the rubber bumper mounts. Thing is, after 30 years most of those pivots and rubber mounts have deteriorated so they don't work properly anyway. A lot of folk have modified/repaired/removed the rubber mounts so the original idea is lost again.
I just swapped to a coupe bumper which is just bolted on solidly and threw those weights away. Cannot tell the difference in driving.

Russ

1981 TR7 Sprint DHC
Dursley
UK

http://tr7russ.blogspot.co.uk/

[Hasbeen]

I removed mine, & could detect no difference at all, other than the back of the bumper sat better.

If I were really interested getting the best in handling & or performance from a 7/8, I'd be chucking the whole ridiculously heavy bumpers in the scrap bin too. After all they were only put there to meet the 5 MPH crash test the yanks were going to introduce, but didn't. The Fiat X19, & a couple of that vintage Hondas have ridiculous bumpers for the same reason.

Removing all that weight from the ends of the poor thing would definitely improve the handling, & the performance to some extent. It might however reduce it's usefulness for knocking down trees.

Hasbeen

[gav2021]

In that case I'll remove it, the metal might come in handy for hammering on or something!

[UKPhilTR7]

This may sound a bit of a silly question, but if you take them off how do you attach the black plastic?

[saabfast]

I think the weight screws to the 'frame' bar behind the plastic cover. You have to remove the whole bumper to unscrew the weights. Its something I intend to do when I get time (and weather) to reduce the end droop. Will be interesting to see the state of the rubber mounts and consider how to replace with something more solid.

Alan
Saab 9-5 2.3t Vector Auto Estate
'81 TR7 DHC

[FI Spyder]

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by UKPhilTR7</i>

This may sound a bit of a silly question, but if you take them off how do you attach the black plastic?
<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

The rubber/plastic is attached by bolts with clips. These break off very easily as they are small unless they are like new (my Spider) and not rusted in (like Yellow TCT). The British attaching bolts are different than the N/A ones. Much care is needed removing them.




- - -TR7 Spider - - - 1978 Spitfire- - - - 1976 Spitfire - - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra - Yellow TCT

[Hasbeen]

As Spyder says, those little bolts holding the cover brackets are a pain.

I had to drill out about 5 of them that I had sheared.

If you have not handled one of these bumpers, be ready for the weight. Even after being warned, you are not going to believe how heavy the things really are.

Hasbeen

[dursleyman]

I was at the NEC Classic Car Show today and was able to speak to Gordon Birtwistle the factory test driver about the dreaded weights. He explained to us that they were added to reduce scuttle shake, but much of that was caused by poor quality tyres. He said that they often had to have tyres fitted to the rims and then get them machined so that they were actually round. Apparently this was also a big problem on the Dolomites. His opinion now is that given modern tyres the weights are probably not necessary and can simply be removed.
So there you go - Gordon says get them off!

Russ

1981 TR7 Sprint DHC
Dursley
UK

http://tr7russ.blogspot.co.uk/

[troubador]

I skeletonised my 'girders' with an angle grinder.
I just left enough for a little protection and the fixing points
for the plastic covers

[john 215]

Hi,

Mine went in the bin years ago, didn't notice a thing.With a strut brace and roll over bar the car feels as stiff as my FHC.

Anyone ever driven an early Rover 200 Convertible would know what real scuttle shake is, makes your vision go funny [B)], first one I PDI ed I thought the subframe must be loose or worse [:0]


Cheers John


LIVE LIFE A QUARTER OF A MILE AT A TIME!

1976 Speke FHC BEAUTY FITTED WITH OVERDRIVE GEARBOX

1979 3.5 FHC CURRENTLY GARDEN ART !

1982 2.0 DHC NOW A 4.6, BUILT NOT BROUGHT !!!!

[Hasbeen]

No we didn't get the Rover 200 here John, but I know what you are talking about.

My son had no idea of scuttle shake until I bought my Oz Ford Capri, 2+2 convertible. As soon as he drove that he decided the 8 had virtually none.

In fact I don't remember my Morgan +4 having much, but perhaps all my early cars had it only worse.

It is hard to believe that a 62 Morgan, with it's flexible chassis, & rigid suspension would not have had it. Perhaps I was too young to notice.

Hasbeen