The Stovebolt Site Forums The Shop Area The HiPo Shop front disc conversion on a 3/4 ton

im looking at getting this front disc brake kit for my 52 3/4 pickup
http://www.classicparts.com/prodinfo.asp?number=71-974C5
the thing is, im not sure if it will work on a 3/4 ton, it says nothing about it and was wondering if anyone else has bought this kit.

if it is only for a 1/2 ton, id do have a complete spare front end from a 52 1/2 truck, and would like to know, if the above kit wont work with a 3/4 ton truck, would i be able to use either the complete 1/2 ton front axle or even better just the spindles on my truck. thanks in advance.

drummin52
It will fit. There's no difference between the 1/2 ton and 3/4 ton up front.

what will fit, the disc brake kit? i imagine both as you have stated that they are the same

Right, both will fit.

does anyone make a kit that will retain the 8 lug pattern but switch you over to disc brakes for the AD?

Whoa, I don't think that disk kit above will work on a 3/4-ton without also changing the axle and spindles.

The bearing sizes used on 3/4-ton trucks are different than those on the 1/2-ton, and I'm pretty sure that difference starts with the spindle diameter.

There is a guy here on The Stovebolt who details an 8-lug disk brake converstion and another guy over on OldGMCTrucks who has done it. A third guy, Mark, or ccpanel, who hangs on the yahoo groups truck sites is marketing a kit to do this.

But check those spindle diameters before buying the 1/2-ton kit, I don't think its going to work.

From my experience dating back to the 60s and my old 3/4 ton, the parts I used (front wheel bearings etc.) were for a 1/2 ton.
Chris I would check further before spending $600+ on this. It's been 40 years and memories fade and Steve may be right. I just remember buying 1/2 ton parts for the front brakes for my 3/4 ton. For my current 3/4 ton I avoided all that by replacing the front suspension with an IFS.

I guess i will pull a wheel off both and check the size of the spindle.

if the spindle size is different, will i be able to just change the spindle and not the whole axle?

thanks

Yeah, like Steve said check and see if the wheel bearing on the 1/2 ton will fit the 3/4.

Here's what I would do:
You have a 1/2 ton you can rob parts from. I would go ahead and order the kit, if it doesn't fit the 3/4 you can swap the 1/2 ton parts that will fit it. I know the frame up front is identical to your 1/2 ton so the front end will swap over. Ain't it fun?
jim

ITS A BALL

thats a good idea, i will probably have time to play around with it later as i dont plan on buying this till next year, sometime in the spring. thanks again!

The following information is specifically '53 instead of '52, but I don't believe '52 is any different.

Resto Pack Front Axle Page

What you'll see here is that spindle and king pin diameters are different between 1/2- and 3/4-ton trucks.

The axles are somewhat different too, though the suggestion you can swap the 1/2-ton to your 3/4-ton truck is correct. If your goal is a hot rod, not a 3/4-ton truck, this may be a good approach. If you want to preserve the 3/4-ton load rating you need to look at the approaches to disks on the bigger axle.

thanks for the information

do they make disc brake kits for 3/4 ton trucks?


also how much better would braking be if i just added a power brake booster and still had drums on all 4.


the trucks going to be an occasional driver but i will probably use it once and a while for hauling small minor stuff in the bed.

Chris:
Check out Classic Performance Products website: http://www.classicperform.com/
You may find what you need there. I would call their tech line and let them know what you have 3?4 ton and what you want. Let the tech walk you through the process. I don't see anything there for 8 lug wheels but it just may not be listed. If they can't help check with other vendors for what you need. If still no luck you might want to swap front end with the 1/2 ton. If you're not hauling real heavy loads I believe the 1/2 will work for you.
Hope this helps.

Ditto what Old Sub said...the spindle and bearing size on the 3/4 are definitely Bigger..as are the kingpins, thus the spindles won't interchange either. You can swap in the 1/2 ton axle and use the kit but you'll still have 8 lugs in the rear.

actually at the moment, i guess i forgot to mention, i have a rear end out of a chevy nova and it has 5 lugs that is already on the truck.

i think i will still look around for a 8 lug disc brake kit as the 3/4 ton axle had all new parts when i got the truck just recently.

Well, you have several options here, go with 8 lug disc if you can find them or upgrade with the 1/2 ton front end and swap out the rear with the Nova. Next question is, what about tranny and engine?

well the nova rear is already on the truck, done by previous owner

as far as engine/tranny, previous owner also transplanted a freshly rebuilt 235 and 3 speed saginaw into the truck so i plan to run them until they go and i also get money up for possibly a 350.


another question that deals with the power brake booster.

would i be able to plumb the large vac line into this port on the side of the intake
http://i175.photobucket.com/albums/w124/rockfan1815/chevy%20truck/PIC00010.jpg?t=1194045583

That was originally for the windshield wipers. Some of the 4000 and 6000 models ran a tee off the manifold there, one to the wipers and one to brake booster. However that was for the big boys, I don't know how that would work on your 235. What are you using for wipers now? You will need enough vacuum for wipers (unless you upgrade to electric) and your distributor. A question has been posted here on how much vacuum is needed when running a booster system. Look through the archives (search) for this topic. Remember anything can be done with enough $, time, and thought.

wipers are going to be electric. only thing running on vac at the moment is the distributor.

thanks for the help!

I believe you will have enough vacuum to share with the booster, however believe is not good enough when it comes to stopping. Always check with the tech where you buy the booster and ask here on the Bolt where, I believe others have done this. An aux vacuum pump is also a possibility.

If you are keeping your hubs, the bearings don't get involved. Bearings change if you switch a 6 lug 1/2 ton to 5 lug. If your 3/4 ton is 6 lug, then the issue is the pilot dia of the drum. Or if the rotor centerhole will clear over your hub.

If you are still worried about bearings, you could always check the bearing sizes. A TF 1/2 ton uses a B01 and B52, prettty sure the AD 1/2 tons are the same.

I kind of did what 3600 said...I bought a 1/2 ton axle and spindles off ebay. Haven't compared them to my 3/4 ton 55 yet but no matter how they compare I've got some flexibility which is good since I change my mind every day.

The 1/2 ton / 3/4 ton chassis interchangeability thing is a grey area. Even when I ask vendors who sell 1/2 ton components "will it fit a 3/4 ton truck", they often answer "I don't know"

Have fun,

Keith

3/4 ton trucks have 8 lug wheels.

The assembly manual shows the general differences and the restoration packs include a lot of detail specs that show the differences. Looking at those two resources you'll easily find what you need to know to determine the 1/2-disk conversion kits won't work on the 3/4-ton trucks.

I don't think its a grey area since these kind of issues can all be identified with a little research. When a vendor doesn't know and won't find out or point you to a source of informaion you have to wonder if the vendor cares.

Sometimes you have to do the research yourself. Yesterday at a swap meet I was having trouble identifying a part. I finally bought four of them and carried them to a booth where I knew an expert would school me. It worked, I now understand the identification of that part. I paid $10 for an education and got to keep four examples of the wrong part...

Look at;
http://www.stovebolt.com/gallery/tolbert_trey_1948.html

The one fact I can testify to is that the 3100 frame is 11" wider than the 3/4 ton at the rear axle.

The frame rails on the 3/4T are parallel from about Mid-cab back. n The Rear frame width is 36" The frame rails on the 1/2T dont parallel until after the rear axle. The rear frame width on the 1/2T is 46 1/32" (per the shop manual)

Front spring mount location dimensions are same, however the 3/4T has different springs

The frame dimensions in the front are similar, however slightly different with the frame channel being bigger on the 3/4T

Long/short. stock 1/2T axle and springs will bolt to the 3/4T and visa/versa.

Scott

For those thinking that this may help with the 1 ton stuff remember that 1 ton has 2" wide front springs, and the 3/4 and 1/2 ton has 1.75" wide.
The axles don't exactly swap from 1/2 and 3/4 ton into a 1 ton. With some hole stretching for the wider u-bolts it may work, but I would never want to put a lighter than stock axle under a truck...

Grigg

I just reread this entire thread.

Drummin52 is modifying a '52 3/4-ton. It already has a Chevy Nova rear under it, and therefore is no longer a 3/4-ton truck and in fact has the 5 x 4-3/4 pattern on the year.

If it were mine I'd swap a 1/2-ton axle under the front and install a 5-lug disk kit on the front. Then upgrade to a power assisted dual master.

Follow that with polished oak on the floor of the bed so I'd never even be tempted to put a load in it.