Lead weights in the front bumpers

[hbrand]

My original 1968 911 still had the 2 lead weights in the front bumper.
Question:
After restoration, should I install them back or not. They weigh 80 pounds

Thanks, harold

[twistoffat]

they were trim/balance weights. They should weigh 11kg/24lb a piece.
911 models had them around the end of the 60´s. I´d keep them

[Bill Verburg]

They were originally installed to reduce the twitchyness of the early chassis, they increase the polar moment of the car making it slower in pitch and yaw.

It's up to you whether you want to keep them or leave them out

[Two Rivers]

If memory serves me Porsche put the lead there to help straight line stability. The battery's where in both front fenders for the same reason I believe.

[M5guy]

I have a set for sale, if anyone is looking for some to complete a '68 restoration.

[Flieger]

They should be cast iron. They were put there to help straight line stability before they figured out the issue was aerodynamic lift. They increase the polar moment of inertia but probably not enough for you to feel slower turn-in. They will not really help straight line stability as much as a front and rear spoiler would. Later cars used two big heavy batteries at the corners instead of the cast iron weights. So, is a weird way, they now were lead weights.

[304065]

Yes put them back.

[chris_seven]

IMHO they were put there to keep Road & Track quite after the original poor review that really panned the handling and declared the car as dangerous. Lets face it sticking lumps of cast iron into the front bumper is hardly elegant or excellent.

I am sure that the poor handling affecting some of the early cars was more to do with the original 'fixed strut' location on the front end and poor build tolerances.

I believe that after the first batch of cars all production vehicles were individually adjusted and the cars test driven until these problems were smoothed out.

I think the introduction of the adjustable camber plates helped the situation but how could anyone admit that the first cars built at launch were poor.

Well set up SWB cars shouldn't be twitchy or handle badly and I don't believe they need batteries in the wing corners either, if you look at the performance of some of the SWB race cars they are very quick indeed and the 911R didn't seem to mind having a very light front end (17mm torsion bar ?)

I think the decision is easy, if you want the original spec fit them but otherwise why lug around excess weight.

I would use them as door stops in the meantime.

[tcar]

Originally Posted by chris_seven

I am sure that the poor handling affecting some of the early cars was more to do with the original 'fixed strut' location on the front end and poor build tolerances.

Actually it was mostly due to the rear engine overhang on the Short Wheelbase cars.

Increasing the rear wheelbase in 69, really to a large extent, fixed the problem.

[John W.]

Like Tcar said, I remember reading the lead weights were a temporary solution for front end instability at higher speeds. Moving the wheelbase back corrected it.

[Flieger]

I would have to disagree. I would say that front and rear spoilers and the associated downforce are much more effective at stabilizing the car than the couple inches increase in wheelbase. Tire stagger also helps.

[haycait911]

tires are light years ahead of where they were when porsche used those weights. leave them off but stash them somewhere.

[hbrand]

Originally Posted by haycait911

tires are light years ahead of where they were when porsche used those weights. leave them off but stash them somewhere.

That's exactly what I was thinking, tires are much better now
The weights are Lead.
I will not install them

[tcar]

Originally Posted by Flieger

I would have to disagree. I would say that front and rear spoilers and the associated downforce are much more effective at stabilizing the car than the couple inches increase in wheelbase. Tire stagger also helps.

I disagree with your 'disagree'.

Twenty-some pounds is not going to contribute anything to controlling a floaty front end at speed. They had nothing to do with 'downforce'.

There were no tails and no spoilers to speak of when they used the weights. That was even pre-Ducktail.

It was nothing more than a way to increase to polar moment at the front of the car... to help with the engine hanging way out there. The weights were placed as far forward as possible.

The weights had a slight positive effect on trying to control the oversteer at speed on the skinny 165R15 tires of the day. Shoot, my '69 Bug had 155R15's... The weights were also removed long before 'tire stagger', that started in '78.

I did some reading about the early history of the 911. It's very clear what they were for.

They removed the weights when the wheelbase was lengthened rearward almost 2 inches, not when spoilers appeared, or tires got better.


(Thanks, JohnW, I'm from ABQ).

[Flieger]

So you are saying the weights worked? I thought Porsche found the real solution and so ditched them. I always was under the impression that they were just a crude stop-gap measure to tame the car until they could engineer stability into it.

[Bill Verburg]

Frère gives a great explanation, vol 6, chpt 5

the Boge Fluid bloc bush's originally used led to handling issues, add to that corner balance issues and short wheel base amplified by aero issues which all amplified the erratic handling of the early cars.

Porsche has waged a 40+ year war on the evils inherent in the rear engine placement.

step 1 was a temporary solution of installing the lead weights, later they went to the dual battery setup. The lead weights weigh 11kg each and raise the polar moment in both yaw and pitch and front end weight

step 2 was to replace fluid bloc bush's w/ now standard Silent blocs

step 3 was separating steering and suspension w/ revised ball joints(this was a temp measure until suitable ball joint materials could be used) accompanied by revised castor and toe settings, addition of camber adjustment

step 4 wider tires all around

step 5 longer wheel base

step 6 wider tires in back

step 7 f spoiler

step 8 rear spoiler

[ttweed]

Originally Posted by hbrand

The weights are Lead.

I took these weights out of my original '67S and they were definitely NOT lead. They appeared to be cast iron to me. Maybe production methods changed for '68, but I would be surprised if they switched to lead for these castings. By the time I got my current '68, the weights were no longer in the bumper, so I can't confirm that.

This can easily be tested. Lead is very malleable and soft--so much so that it is usually alloyed with antimony or tin to toughen it up so it can be machined. Even in alloyed form, it can still be shaped with woodworking tools. Take a sharp knife or chisel and try to shave the edge of your castings. I'll bet you can't easily raise a sliver and see the bright, shiny silver look of freshly cut, untarnished lead. You can also check with a magnet--it will stick to iron but not to lead.

BTW--the handling characteristics of my '67S were transformed by simply switching from the 4.5" Fuchs w/ 185 tires to 6" Fuchs with 205s. No more wandering and "floatiness" to the front end at speed in a crosswind. A competition alignment and 7" rims w/ R-compound tires turned it into quite an autocross/track weapon, with no suspension/aero changes other than new bushings.

TT

[MBruns]

I have a pair from my 1966 911, they are cast Iron
Mike Bruns

[haycait911]

only ever cast iron. I think the 'lead weight' thing was more of a term of endearment. my SWB is under 1900 lbs and ( surprise!) no bumper weights. toyo R888's. with stock bumpers in glass the stability is decent, a little jumpy over 130. with an S spoiler and a duck it was better but I didn't like the look. a street car so I don't NEED to do those speeds anyway.

[h.wale]

H

I have a set for sale, if anyone is looking for some to complete a '68 restoration.

Hi please send photo,and price,also what would bd the shipping cost to the UK
h.wale@yahoo.co.uk