60 to stop distance ?

[67 chevelle]

Anyone have a clue as to what this would be on a stock 4 drum truck , as opposed to a front disc , or aftermarket brake setup , I put discs in the front of my 68 and its fare , think I have too small a booster , but drove my nieces husbands 69 with 4 drums last week and its horrible compared to a newer vehicle , might switch to hydroboost , but was woundering want the stock number might be

[brad_man_72]

A properly adjusted and setup all drum truck might stop 5' after a properly adjusted disc setup.. the first time anyways.

Power vs non power different size boosters won't effect stopping distance just pressure required to push the pedal.

[Stocker]

Originally Posted by 67 chevelle

I put discs in the front of my 68 and its fare , think I have too small a booster

Other than possibly needing a larger booster -- did you install a proportioning valve with the front discs?

[67 chevelle]

I changed to a cpp disc/drum master , booster [7 inch dual] , and their combo valve . Im going to try getting an original rebuilt 11 inch booster

[yuccales]

Originally Posted by 67 chevelle

but drove my nieces husbands 69 with 4 drums last week and its horrible compared to a newer vehicle

How true! I just drive these trucks like the old man that I am, and all is good! As for stopping distance, can't help you there.

[mrein3]

Originally Posted by brad_man_72

A properly adjusted and setup all drum truck might stop 5' after a properly adjusted disc setup.. the first time anyways.

Power vs non power different size boosters won't effect stopping distance just pressure required to push the pedal.

That is the number I'd be looking in to. If you just got your drums hot, and you need to make a 60mph stop, how much further is that stopping distance over what a disc setup can do over and over.

[19673ontree]

When I got my 67 the 60 to 0 stopping distance was 4 miles on level ground LOL napa sells great drum brake shoes I put a set on and my truck has good brakes now ,,,

[leftybass209]

I agree a booster reduces the pressure required on the pedal, I do however disagree with the booster not providing more stopping power, and this is why. If your leg NEVER got fatigued, size of the booster wouldn't matter. However, our legs do fatigue, and as a consequence we perceive the strength used as exerting more "pressure" on the pedal to maintain previous stopping power. The more energy you use up, the less strength you would have to apply pressure to the brakes, resulting in a longer stopping distance, over a larger driving distance. A larger booster would reduce the amount of overall pressure you apply throughout your drive, in turn reducing your energy output. I know that's a lot of ridiculously in depth jargon, but long story short, bigger booster = less leg strength over a longer drive distance to operate. Keep in mind i'm talking like, stoplight to stoplight downtown traffic. I know this because I have a non power disc/drum setup and i'm short! I definitely get fatigued driving this thing through town when the stoplights aren't on my side. Hopefully you get your issue sorted out, and best of luck to you!

[Stocker]

Originally Posted by leftybass209

I have a non power disc/drum setup

Good idea to have a booster when running disc brakes, especially since you're getting fatigued without it...

[leftybass209]

Originally Posted by Stocker

Good idea to have a booster when running disc brakes, especially since you're getting fatigued without it...

I completely agree with you! It's on my to do list in the coming month or so.

[cool68]

need to have the proper length rod that activates booster from brake pedal arm. have a '68 with all drums and power booster that is easier to stop than my '76 with front disc/drum rear brakes and no power booster.

[oldcane]

The bottom of this article has some numbers.

http://www.earlyclassic.com/Tech.asp...;s+Makeover+II

[brad_man_72]

Originally Posted by mrein3

That is the number I'd be looking in to. If you just got your drums hot, and you need to make a 60mph stop, how much further is that stopping distance over what a disc setup can do over and over.

Have you ever experienced brake fade? It can be quite impressive/scary. Id say that it would take at least 5x as long to stop a truck experiencing brake fade.

This is why people with toyotas brakes "failed" with the stuck accelerator. They were trying to slow down gradually, building massive ammounts of heat to the point of brake fade instead of doing a panic stop.

I've had brake fade a few times with my 4x4 sonoma, living on a long curvy road and driving like it was a racetrack. Ive never had brake fade with an all drum truck because I don't drive them like they are racecars or ride the brakes when towing.

About 5 panic stops back to back from 40 is enough to get smoke rolling off the brakes in a new silverado 2500.

[67 chevelle]

thanks oldcane


15) We then upgraded to a shiny new set of 17x8 Cragar Street Pros wrapped in Hankook Ventus St Tires. 255/50R17’s were chosen for the fronts and 275/55R17’s filled out the rear fender wells.


16) This wheel and tire package took the 60-0 braking distance down from 266ft. to 237ft. and the slalom speed from 32.4mph up to 36.2mph.

Adding a hydro boost booster will defiantly alter the effort and stop distance , and line pressure , if you guys upgrade to one , your lines will be blowing , Id suggest changing all rubber line at the time of install , hoping a new stock spec vacuum booster gets me the desired results

[brad_man_72]

Originally Posted by 67 chevelle

thanks oldcane


15) We then upgraded to a shiny new set of 17x8 Cragar Street Pros wrapped in Hankook Ventus St Tires. 255/50R17’s were chosen for the fronts and 275/55R17’s filled out the rear fender wells.


16) This wheel and tire package took the 60-0 braking distance down from 266ft. to 237ft. and the slalom speed from 32.4mph up to 36.2mph.

Adding a hydro boost booster will defiantly alter the effort and stop distance , and line pressure , if you guys upgrade to one , your lines will be blowing , Id suggest changing all rubber line at the time of install , hoping a new stock spec vacuum booster gets me the desired results

So new disc-drum brakes with new tires stop better than old not adjusted/maintained drum-drum brakes, I guess that makes the stuff we got for free sound good to potential customers....

[mrein3]

Originally Posted by brad_man_72

Have you ever experienced brake fade? It can be quite impressive/scary. Id say that it would take at least 5x as long to stop a truck experiencing brake fade.

This is why people with toyotas brakes "failed" with the stuck accelerator. They were trying to slow down gradually, building massive ammounts of heat to the point of brake fade instead of doing a panic stop.

I've had brake fade a few times with my 4x4 sonoma, living on a long curvy road and driving like it was a racetrack. Ive never had brake fade with an all drum truck because I don't drive them like they are racecars or ride the brakes when towing.

About 5 panic stops back to back from 40 is enough to get smoke rolling off the brakes in a new silverado 2500.

Yes I have experienced brake fade. That was my point. Well maintained, perfectly adjusted drums will stop OK once. Once.
What if after that panic stop you get back up to speed then an over worked, tired mom in a minivan pulls out in front of you at an intersection with her kids strapped in the back. With disc brakes you got a chance on that 2nd stop. With drums...

[67 chevelle]

You guys should read the article posted by oldcane it answers the question I was looking for , and shows what lowering and suspension upgrades do for handling

Originally Posted by oldcane

The bottom of this article has some numbers.

http://www.earlyclassic.com/Tech.asp...;s+Makeover+II

[burnin oil]

A good way to help your stock drums out is to increase the size of the wheel cylinders. Bigger cylinders will add more braking power with less effort. One of the tricks on the Dodge diesels from the 90s was to add a set of chevy interchange 7337 wheel cylinders. They increased the rear stopping by 44%! Dodge figured this out and increased the cylinder size also around 96. Those where around 22% better than the 94-95 models. Point being is that there is probably a cheap upgrade that will bolt right in.

[brad_man_72]

Originally Posted by 67 chevelle

You guys should read the article posted by oldcane it answers the question I was looking for , and shows what lowering and suspension upgrades do for handling

That story hardly compares apples to apples.
"Let's compare 40 year old junk with unknown maintanence, damage, alignment specs on old tires with all new stuff and not include any alignment specs". For all we know a rebuild of the factory parts, agressive alignment and big sticky tires could perform better than swapped on parts.
They also don't include the effort it takes to get either braking system to fade. Its a fluff article to sell parts.

[oldcane]

Of course they are trying to sell stuff and this is from a magazine at that. But if it wasn't an impovement nobody would do it. Plenty here have done it but probably didn't have access to a speedway or old airport to measure. Here is the line that was done after going discs. The one quoted above is only adding big tires. Not sure how that affected stopping at all.

With the new Early Classic Enterprises front disc brake conversion installed, the braking distance dropped an additional 65ft., netting an impressive 172ft.


Personally if I drove a 4 drum setup daily I'd be fine. But for those of us that drive a 2xxx something every day and take a drum vehicle out on the weekends it's easy to forget that you need to think ahead. Especially with all the looks, whistles and conversations at stoplights I get. The again, some like my truck too.