Bumper Removal and LHD to RHD Conversion

[David James]

Always one to modify my vehicles I would like to remove the excessively heavy bumpers on a 7/8.

Anybody have any pros and cons to this move. I presume Grinnals did away with them but was a strut put in place across the original bumper mounts for sructural integrity?

 

Secondly I have a good rust free LHD convertible shell I would like to build up and am wondering whether I should go to all the trouble of converting the bulkhead to RHD or should I be looking for any advantages of a LHD car?

 

Thanks David

[Alec Pringle]

Remove the bumpers on a ragtop and you'll soon enough discover why the front was beefed up over the tintop . . . . .

 

That apart, all Wedges had substantial bumpers for good reasons, and if you remove them you need to replace the structural strength for one and the impact absorption factor for another . . . . . OK, you don't have to, but in the event of a front or rear end collision a pretty steep learning curve will make itself known in a split second.

 

Cheers,

 

Alec

[BizMan]

I have investigated several options:

 

 

1. Fit FHC bumpers to a DHC as they are lighter (no weights for scuttle shake) and honeycomb the bumper.

 

2. Follow the route chosen by Racetorations (http://www.racetorat....uk/page12.html) and incorporate the 'towel rails' behind the bumper skins (they will offer minor crash protection but will do little to reduce front end flex).

 

3. Fit bumper bars from an E21 BMW as these are aluminium (they require a lot of fabrication to make them fit).

 

4. Have a set of aluminium bumpers cast from a mould of the steel ones (expensive).

 

5. Remove them altogether. (if your car is a DHC forget it as removal of the front bumper will not improve turn in nor reduce oversteer as the front end will flex terribly which will ruin the drive. If its a FHC flex is not so bad but you will have to supplement the rigidity in other areas by bracing the shell but all you are doing here is adding weight back into the car, admittedly, within the wheelbase).

 

NB> Whatever route you choose, you will have to reduce the ride height of the car as removing 30kg from the front and rear will raise it.

 

 

If you have read my thread on modifying the 7 you will see I am no stranger to making changes to the car but I have elected not to carry out any mods at all to my bumpers and this is for two very good reasons. Firstly, I do not know anyone with the right experience who can understand or simulate the effect the modifications will have in a crash and secondly, my insurance company refused to give me cover if I made ANY modifications to these safety critical items.

 

IMHO, if you are using your car on the public highway, leave your car as BL intended.

Edited July 17, 2012 by BizMan

[David James]

Hi Chaps - Thanks for your replies. A great shame that all that weight, that does little to enhance the looks of the 7, cannot be replaced with an aftermarket off the shelf kit that maintains structural integrity.

Cheers David

[Alec Pringle]

Hi David,

 

that would be one hell of an expensive "aftermarket off the shelf kit" . . . . .

 

The TR7 isn't a car with a separate chassis, it's a monocoque for heaven's sake, and the bumper armatures are an integral part of that monocoque design. One thing you can say for the Wedge, it was a seriously strong car in its day, as anyone who has had a big accident in one can testify. Well ahead of most of the competition. Replacing the bumpers would be a challenging exercise in engineering.

 

BL were not able to come up with a lighter weight option at even half reasonable cost, and competition cars required what was for the time a massive construction by way of full roll cage to substitute. Having once tried a standardish early 7 with bumpers removed, around Goodwood, the difference was astounding - probably 7-8 seconds per lap, that's how much the handling suffered. Scarey as heck to drive as well !

 

Cheers,

 

Alec

[fenta]

thanks for all of these .guys .