Dusterbd13 New Reader
1/16/09 6:26 p.m.

im starting to get pretty heavy into autocross. my vehicle is an 87 gmc s15 (same as an s10). also a work truck, and also a GRM 2009 challenge competitor.

im looking at my truck on the scales. according to AL lowders (local scrap metal yard), its 3100 with driver and full tank of gas. full street trim (all my crap and tools)

i wanna get it down to 2800, race weight with driver . that means i have to lose 300 lbs, and still be a street truck.

where im looking:
1. lexan back glass
2. lexan side glass
3. remove inner fenders
4. remove jute padding from under carpet
5. cut under hood bracing out
6. aluminum heads
7. plastic and aluminum radiator
8. punch holes in the door frames. 2 inch should do it. 9. lighter air cleaner assembly.
10. remove insulation/deadening from doors and door panels.
11. shorter, 2.5 inch exhaust. and headers.

i have heard that the 5 speed trucks were 80lbs lighter. any truth to that?

so, what do y'all think? i dont wanna ditch the AC, gut the interior, etc. and with as far as the autocrosses are from me, id love to keep my cruise control. any more ideas? all the suggestions i found was for mostly race only trucks, not street trucks like mine. and definately not a budget truck.


P71 GRM+ Memberand HalfDork
1/16/09 6:54 p.m.

Woah, woah! You're going for the super-dedicated stuff first! Wrong way around!

First, wheels. Factory wheels are heavy, especially steel ones. Find a good set of aftermarket aluminum ones or the lightest factory alloy (actually weigh them). This is double-as-good because they're unsprung, rotational weight, and you might as well go for sticky tires at the same time. Being a truck I'd actually spring for r-compounds and bring them with you to the autocrosses in the bed.

Next look at un-needed fluff. Obviously you can take your tool box and spare tire out at the track. Look at stuff that you never use. Does your truck have the little jumpseats in the back? Do you really use the A/C? Can you convert the power windows to manual? Swap out that mechanical fan for an electric? Convert to manual steering?

Next go for the exhaust. Factory exhaust systems are heavy and restrictive. Headers save lots of good pounds right on the nose over iron manifolds and they give you more power.

Now I'd look at the interior. Factory seats are heavy and un-supportive. Grab a set of cheap, lightweight buckets. Think RX-7, Miata, small sportscar seats here. Or even better aftermarket (no-name Summit seats come to mind). Do you really need the factory carpet and matting? Replace with lighter dynamat and thinner aftermarket (eBay) carpet. Do you really need 3 amps and 4 14" subs? See where I'm going?

Finally look at replacing or lightening easy stuff. Take the tailgate off at the autocross. Get a fiberglass hood and bumpers.

All of the above combined should get you down pretty good without sacrificing drivability or practicalness like lexan windows and cutting out important structural pieces.

mw New Reader
1/16/09 7:03 p.m.

Take a cherry picker with you to autox's. when you get there, use the cherry picker to lift the box off the truck. I'm sure you would rather lose weight over the front wheels, but it would save a lot of weight.

Volksroddin HalfDork
1/16/09 7:35 p.m.

Do not cut the bracing for the hood! It is made that way so when you get in a wreck you will not be hurt as bad.

Dusterbd13 New Reader
1/16/09 8:27 p.m.

heres a link to my project thread over on PT.com
should help you to see what im working with here, http://www.pro-touring.com/forum/showthread.php?t=43374

the factory spare is already gone, as well as the lift mechanism, jack, handle, etc. im running 16X8 IROC wheels (dunno what they weigh, but they were lighter than the factory 14 inch steelies) and have a set of 15X8 Z28 wheels if needed. manual windows already, reg cab shortbed so no jumpseats, already an electric fan. the manual steering in these trucks ws just horrible and ive found no other manual boxes that will bolt in that are much better.

as far as the AC, i dont hardly ever use it, but since my infant will occasionally ride in the truck when i go to lowes, etc, i figured i'd keep it. still up in the air right now, as it doesnt work anyway. but then again, i have all the parts to fix it....

the amp amd subs are already gone. all i have left is the radio and the dash speakers. i pulled the rears when they started going bad.

thanks for talking me out of cutting up the hood. didnt think about the saftery element there...

as far as removing the bed, in a word: no. traction is already an issue, and that would just make it a lot worse. i think if i could get more grip in the back, id drop a LOT of time. right now, i roast the tire out of most turns.

the aftermarket stuff will have to wait until i find a great deal on it. right now, im just looking at stuff i can do for stupid cheap. like i said, look at the build thread. it'll show you where im at, both with the challenge budget and the truck itself.

Will Reader
1/17/09 7:28 a.m.

If you're building the car for the 2009 Challenge, do whatever it takes. But if you plan on autocrossing the truck regularly after that I highly suggest you pick a class and build the truck for that class. One wrong mod (rear gears) and instantly you're in SM.

aussiesmg HalfDork
1/17/09 9:07 a.m.

never underestimate the value of losing weight from yourself and getting into shape....(assuming you are built like me anyway)

sachilles Reader
1/17/09 9:39 a.m.

Remove the passenger seat on "race day". Lighter wheels as was suggested. Is this a 4wd truck or 2wd only?

this might also be one of those projects where adding power is easier/cheaper than reducing weight.

iceracer Reader
1/17/09 9:45 a.m.

Gasoline weighs about 6.5 lbs per gallon. The hood is designed to fold in a crash. The bracing is mostly to keep it from folding when you open it. How about the front bumper. Maybe you could find a lighter one.
Smaller radiator ? Would depend on requirements.

noisycricket Reader
1/17/09 10:58 a.m.

Find a front-steer R&P car and get rid of the steering box.

This will definitely introduce bumpsteer issues, but if you have a stiff suspension it probably won't hurt. Geometry doesn't matter if the suspension doesn't move much to begin with.

While you're at it, hack off the front of the frame and go with struts. The frame is really heavy in the front because all of the suspension loads are trying to load the framerails in twisting. This is kind of an advanced mod, but it's something I'd consider if seriously thinking about racing a truck. The nice thing about strut suspensions is that they really spread the suspension loads out.

Dusterbd13 New Reader
1/17/09 12:30 p.m.

2wd truck.

struct front suspension, etc is getting a little extreme for a dual prupose truck. after all, i still put lumber and concrete in the bed.

hadnt thought about removing pass seat. is that legal for autocross? i run in sts currently.

and adding power may be easier, but im still brewing it all over. tomorrow it becomes a 5 speed, and then im going to start seeing what stuff weighs now. im hoping the 5 speed shaves a few pounds. i know the clutch pedal set up was 8 lbs lighter than the auto pedal setup.


DirtyBird222 HalfDork
1/17/09 4:59 p.m.

burn more calories than you eat and you should be fine

Raze Reader
1/17/09 5:17 p.m.

All good ideas on here, I'd go through and figure out the cost/weight loss, rerank everything on this list, then GET TO IT!

Dusterbd13 New Reader
1/17/09 6:45 p.m.

its already been dropped 1/3 with belltech stuff. 1 inch front coils bring the LCA's parallel with th ground, wich is right where im told they should be, and the spirngs are 650LB/in springs.

and good call on the cost/weight ratio stuff. i need to steal my wifes bathroom scale permanently and strat making a list.

safety for my daughter and i are of primary concern. after all, if i get busted up, whos gonna look after her and kill the first guy to break her heart? and if she got hurt.....

well, i dunno what id do.


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