Weight reduction: Running out of ideas.

Spent a few hours tearing the dash apart to get to the brake booster bolts to eventually put in a lighter weight C4 booster, but had to take a mental health break from that uncomfortable, frustrating endeavor. Spent a little time working on the D36 batwing that I'm kicking around putting in the car to replace the heavier D44 C3 batwing.

IM002515_zps5zgbyitn.jpg

The D36 batwing is 7# lighter than the C3 batwing, and the spring mount is about another pound lighter than the C3 part (I should also be able to use slightly shorter spring hanger bolts also). The 3/4" aluminum adapter is presently at 3#, but there's still a bit of material that needs to be shaved off yet. I still need to narrow the batwing one inch on each side (to clear the narrowed suspension) and weld new frame tabs, but so far it looks like I can probably get another five pounds off the car.
 
Additional 5.6 pounds off the left front.

Finally got the brake booster off. Major PITA, as I hadn't done it before. Now that I figured out what tools to use, and what additional pieces needed to be removed first, it went semi-smoothly. Don't really ever want to have to do it again, though.

Once I had the booster out I was curious how heavy the nearby vacuum tank was (as I was always kicking around putting a smaller plastic reservoir in there instead). I pulled the tank out and weighed it (5.6#). I think for now I'm just going to leave it out, as I rarely need to cycle the headlights or wiper assembly when the engine isn't running.

Did a trial fit of the '84 booster. It seems to sit in there nicely. I also did a trial with a later C4 plastic booster, but as I suspected (due to a larger diameter than a C3 or '84 booster), it wouldn't fit between the valve covers and the upper fender area.

If the '84 booster fits in as I'm hoping, this semi-frustrating exercise should take about 10# off the left/left-front of the car.

With this change, and the D36 batwing installation, I should be darn close to 2800# during track days, and about 2775# during autocross days.
 
OH CRAP, MIKE, did anyone tell you the heavy iron casting up there was replaced with a sheetmetal fabbed up piece at maybe 25% of the weight???

you commented you never pulled the booster off, which needs done to replace that cast piece....dunno the exact years for the swap, and never did it myself, just that I noted that on a friend's car some years ago, and seen comments on the .net......

:flash:
 
mrvette said:
OH CRAP, MIKE, did anyone tell you the heavy iron casting up there was replaced with a sheetmetal fabbed up piece at maybe 25% of the weight???

you commented you never pulled the booster off, which needs done to replace that cast piece....dunno the exact years for the swap, and never did it myself, just that I noted that on a friend's car some years ago, and seen comments on the .net......

:flash:
Click to expand...

I swapped out the cast iron piece about two years ago.
 
Got the C5 master cylinder installed on the '84 booster. The rear of the m/c where it goes into the booster is smaller on a C5 part than a C4 m/c. I ended up making a .062" bushing (1/2" wide by 1.5" ID) out of some sheet aluminum that I bent into a circle and welded. It slips into the booster and centers the m/c in it. Another silly item slowing things down is that the m/c bolt spacing is .065" narrower than the booster bolt spacing. I did a slow bit of filing to oval out the m/c holes by about .030" per side to get the m/c to slide over the booster studs.

IM002533_zpswn098zke.jpg

Did a trial application of the brakes (no vacuum yet). The pedal was firm, and the calipers did seem to release afterward. The pushrod end in the C4 booster is slightly different shape than the C5 pushrod, so I didn't know where things were going to engage in the m/c. So far things look reasonably close, and I'll adjust it later if necessary.
I'm looking around for some sort of cheap vacuum pump to "supply vacuum" to the booster for some testing, as I've got the steering column out of the car at the moment and can't start the engine. Any suggestions are appreciated.
If the system works okay I can install the dust covers that go on the top and bottom of the adapter. I have removable covers so I can get to the bolts that fasten the booster to the adapter, and the adapter to the firewall.
So far it looks like I got the four pound weight reduction I was looking for.
 
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AutoZone etc have an electric brake pump for about 60 bucks - could replace the booster, too (not what you want to hear after all that work)!
Ain't Hot Roddin' fun?

Cheers Jim
 
Another seven ounces off the left side.

Got the steering column back in. Was ready to install the stamped steel bracket that locates the lower part of the column at the firewall when I decided to weigh it while it was handy. The steel bracket is 11 ounces, so I ended up cutting out an aluminum piece at four ounces. The down side is the two bolts in the original piece are captured (welded), while this replacement piece will require holding onto both ends when I tighten the bracket.
A coat of semi-gloss black paint and the bracket will be unnoticeable.

Edit: Picture of the replacement piece prior to being painted. Old piece (10.9 oz), new piece (4.9 oz with bolts), for a 6 oz reduction off the left side. Left off the tab that holds the steering lock cable as I haven't had the cable on for the past 30 years when I first put the DN5 trans in.

IM002534_zpsgqryaksu.jpg
 
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Here's a what if:

If you replaced the oem steering column with this one which is 6 lbs, how much is the weight difference?

Sweet Mfg
Sweet Manufacturing 405-10310 L/W ADJ STEERING COLUMN

I know that turn signals, etc would need to be rigged up.
 
We're like a bunch of little old ladies helping a friend spend money - eh?
Last year I measured/weighed my '78 column - now sold - it was 16-19 pounds - can't recall exactly - and I'm on the road right now, so not on my home pc- but that would be a BIG savings!

Cheers - Jim
 
rtj said:
Here's a what if:

If you replaced the oem steering column with this one which is 6 lbs, how much is the weight difference?

Sweet Mfg
Sweet Manufacturing 405-10310 L/W ADJ STEERING COLUMN

I know that turn signals, etc would need to be rigged up.
Click to expand...

IIRC, my t&t steering column and wheel weighs about 25 pounds. Obviously a lot more than a race car column, but I'm trying to keep a stock look to the car and particularly the interior, and as you mentioned, turn signals and the ignition switch and horn assembly would probably need rigging up.
 
Why are you not using a hydraboost? any problems with them? I am planning on a hydraboost.

have you gotten rid of the wipers, headlights & vac wiper door?
 
Pulled the parking brake armrest/console off the other day to check out the actuator linkage, and was a bit surprised on how relatively heavy that plastic console is. Looked underneath and saw a stamped and welded steel support that was typical Chevy design for the time: big, cheap, and heavy. Just spent a little time bending up and welding some 1/16" aluminum to replace it. The original piece was 9 ounces, and the aluminum piece came out at 3 ounces. Not large numbers, but I'll take it where I can find it.
 
Made a little more progress on the D36 batwing conversion. Still need to tweak the adapter shape a touch to get rid of unneeded material (at 37 oz currently), and weld up the unused (original) bolt holes in the batwing cover area. This project would certainly go quicker if I had a milling machine instead of just a jigsaw and some carbide grinding bits.
I also still have to narrow the batwing outer mounts one inch inward on each side to match the present narrowed C3 batwing width. I'll probably modify the frame tabs that the batwing bolts to cuz I'm guessing that it's not likely that the C3 batwing can easily be swapped out while the differential is still in place.



Should be a 5-6 pound net reduction compared to the present C3 batwing, which was a 15# reduction over the stock steel and cast iron differential mounting system.
 
The HF mill drill is pretty good for the money, plus they let me use a coupon to 20%. Grizzly sells the same model so I bought digital read outs from them. I got collets off amazon.

I saw on another forum that Speed Direct is marketing an oem early style diff cover in aluminum now. I know you have the late model, but thought it was good some companies are stepping up.
 
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rtj said:
The HF mill drill is pretty good for the money, plus they let me use a coupon to 20%. Grizzly sells the same model so I bought digital read outs from them. I got collets off amazon.

I saw on another forum that Speed Direct is marketing an oem early style diff cover in aluminum now. I know you have the late model, but thought it was good some companies are stepping up.
Click to expand...

I don't believe I'm familiar with that item. I'll have to try to find it at the next HF shopping stop and see what the heck that thing is.
 
1-1/2 HP Milling/Drilling Machine

I did a lot of reading and this got good reviews for being a good machine for the price. You can order through the store for pickup, or at least they did at one time. There is a video on YouTube showing how one guy added lcd read-outs.
 
rtj said:
1-1/2 HP Milling/Drilling Machine

I did a lot of reading and this got good reviews for being a good machine for the price. You can order through the store for pickup, or at least they did at one time. There is a video on YouTube showing how one guy added lcd read-outs.
Click to expand...

Gotcha. I'm familiar with milling machines. From the reference mill drill I had some vision in my head of something that would somehow perhaps fit in/on my drill press or something.
I've always wanted a milling machine for the shop, but lately it just won't fit into my budget.
 
image_3.jpg


This supports the heater on the trans tunnel, or at least it did on my 73 vert body. Very heavy!

I started scraping out the sound deadening material and it is up to 0.25" in places. That stuff is everywhere. I'll bag it and weigh it when done, but there must be 8 lbs of it.
 
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