The Stovebolt Site Forums The Parking Lot Tons 'o Fun Single wheel 8 lug axle swap to get Disc Brakes

OK, here's what I've turned up so far:

The 8 lug I-beam axle with the dual wheel hub/rotor one piece combo as shown here (but the 8 lug version) looks like the best place to start. (I've used 1988 for looking up parts)
I realize that it'll be to wide, here's my solution to that , about half way down the page, and lots of picture links too.

As suggested in another forum Chevy 3/4 or 1 ton 2wd independent front pickup hubs/rotors seem the logical choice, or at least a starting place.

I've learned that 3/4 ton rotors may only work if it is the HD axle option, 8,600 lb I think, (which I assume is same as 1 ton). So to keep it simple we're looking at 1 ton rotors/hubs.
Year range is all of the 80's and even early 90's I suspect, I've used 1988 to look up parts.
Napa number 4885974 is the single wheel combined hub/rotor one piece contraption, cost about $90.

Comparisons between two front hubs and bearings from both vehicles/axles.

• Outer wheel bearings (the small ones) NAPA part numbers for both axles are: 15103S for the bearing 1.030 inch inside diameter and BR15243 for the race. Appears to be no problem there.
• Rotor diameter for both is 12.5"
• They use different calipers, I expect the stock P30 calipers and brackets should work with the new rotor.
• They use different seals, don't have any more info or solution on that yet. (not worried) The single wheel hub/rotor uses seal # 21771 (on what inner diameter?)
• The single wheel hub uses inner bearing (big bearings) set # BR35 which I think translates to individual parts SKF #LM501310 and #LM501349 Still need to confirm these numbers. The dual wheel hub uses a larger inner bearing set.

Problem is:
I-beam axle inner bearing inside diameter is 1.688"
Single wheel hub bearing inside diameter is 1.625"

One solution is to turn 1/16" off the spindle so the bearing fits.

Another possible solution is to find a bearing cone/rollers that have the 1.688" inside diameter and work with the original bearing cup which I think is SKF #LM501349?? .

Just for info the OD on the bearing set that fits the P30 hub is 3", which is somewhat larger than the one that fits the single wheel hub (I forget the size) and it didn't look like a bearing cup/set exist to fit the smaller than 3" hub and match the original P-30 inner bearing cup/rollers.
If someone whats to double check and prove this wrong that'd be great!

What I don't know is if the separation between inner and outer bearings between the two different hubs is the same or close enough, I hope so but need to check for sure.

Other than that can anyone see any other problems or concerns or solutions?

Grigg

I'm not a machinist but it seems to me you could also increase the size of the hole in the hub by 1/16th. I'd rather put a hub in my lathe than a spindle.

Your approach seems reasonable to be. I've not tried back checking your part numbers and conclusions.

To use the original inner bearings for the P30 the OD needs to go up to 3", I think about .109" jump. Might not be enough meat in the hub?

Other concern is the hub is also the rotor, the rotor is not separately replaceable. I don't like the design but this hub/rotor seems close to working dimension wise.

If the hub gets bored out to fit larger bearing it'll have to be done for every replacement rotor/hub. But for my use that may never happen, some how I can't seem to wear out brakes...

As far as chucking a 12.5" rotor or the spindle to modify, either is fine with me.

Grigg

I'm getting conflicting info on the bearings now...
Look here in the Timken bearing application guide for automobiles.
http://www.timken.com/EN-US/product..._Seal_Application_Catalog_1989_older.pdf
Pages 124 and 131

I thought I was looking for bearing # BR35 (from my visit at NAPA today)
The Timken catalog looks like it's Set45 for the inner bearing set for the 1 ton single wheel independent hub/rotor
(edit, same thing, different brand)

Set45 has these dimensions
Bore Diameter 1.625 inches
Outside Diameter 2.891 inches
Which sound right for the single wheel hub and spindle.
Anyone know the individual part numbers?

In the Timken catalog it looks like the I-beam axle uses
26884 for the cone, Bore Diameter 1.688 inches
26823 for the cup, Outside Diameter 3 inches
which sounds right for the old dual wheel hub.

Grigg

Set components are listed inside the back cover on PDF page 581.

Where are you finding the dimensions? I don't see dimensions in this book, is it in another?

Did some googeling for dimensions, Amazon has the simplest and easiest to find dimensions if they offer that bearing for sale..
EDIT here's a good link for finding bearing dimensions by part number, use the PDF search/find function (Ctrl + F)
http://www.baumhydraulics.com/files/catalog/sec-r.pdf

I'll see if I can get a real copy of that catalog to thumb through.

To clarify the confusion a:
Timken SET45 = Federal Mogul A-35 = CR (Chicago Rawhide?) BR35 (the one NAPA told me).
As found in the back page Steve found on the above linked PDF.

And to answer the question, the components of that SET45 (inner wheel bearing that fits hub but not spindle) are indeed LM501349 and LM501310 for the cone and cup respectively.

On first attempt I could not find a different cone with 1.688" bore and to match the LM501310 cup.
I'll look some more.

Thanks,
Grigg

To head off in a completely different direction...
looking for other trucks that use the 1.688" inside wheel bearing ID; cone part number 26884 which fits the GM I-beam axle spindle

I find International liked them for a number of 2wd (not all) trucks from 69-81

One of several examples from the Timken PDF, actual page #s 318 and 319

1975-1969 FA-12: 1.686" OD knuckle
Cone/Cup (inner) ...... 26884-26823[2]
Cone/Cup (outer) ...... 15100-15245[2]

Or a 2wd 74 Travell all with a 392, I think may use a hub that's close?
Are these IH 2wd with disc brakes I-beam or independent front? I'm thinking independent but not sure, seems I would have noticed by now if they were I-beams...

One problem is they use 1" ID on the outer bearings, which is 0.030" smaller than the GM spindle is. (And some of the IH hubs use just less than 1")

Another problem is rotors may not be available? perhaps GM 4wd front rotors fit somehow? wouldn't that me a mix and match?

I'll look into modifying the IH hub to fit bearings that fit the GM axle, and find rotors that work with the GM calipers and brackets.
Might be a long shot, but worth investigating some more I think. If it works it should make for replaceable rotors.

Grigg

Back when they were new trucks I knew people who bought them. I'm pretty sure I would remember if they were not IFS.

Some more checking on the IH hubs reveals that they are disc brake hubs and that disc/rotors are no longer available (at NAPA or RockAuto). I'm hopeful that some other make of rotor will interchange for these purposes, won't know till I find a hub to inspect. The 8 lug pattern should be common, which may be the only way there is a chance of finding a rotor to substitute.

The hub in question is from a mid 70's 3/4 or 1 ton IH 2wd with spindle diameters of 1.688" and 1".
Then with original GM I-beam inner wheel bearings (same as the IH) and off the shelf outer bearing set Timken part number 15103 and 15245 (cone/cup) it might adapt to the GM spindle.

But so far this is only going by bearing sizes, I don't know if the separation between the bearings in the hub is close, or what to do about a seal.
And probably biggest concern is what to do about a rotor.

Anyone have one or two of these IH hubs to measure or donate?
Careful though, some of them have the right inner bearing (the big one) but to small of an outer bearing, (can't use the hub with outer bearing that measures 0.937" ID and 2.240" OD.)

Grigg

Since you're using single wheels on this application (if I'm reading it right), why not use the hat style slide on rotors from a '00-'10 2500/3500 HD on the original spindles?

I've been meaning to look into that as well, could be the simplest option.
However others have looked into this and never report back with a completed solution either simple or difficult, so far no results that I know of for single wheel 8 lug disc on original axle or hubs. This is why I didn't investigate this rout first, I trusted that others have, but I'm beginning to think I should at least give it a few hours of searching and figuring to decide for myself.
It'll take a fabricated caliper bracket for sure.

I'd also like to investigate original spindles and axle with different hubs.
Until I get a chance to pull my original 1 ton axle apart does anyone have any bearing numbers or diameters for the original stuff?

Grigg

These are bearing numbers for 3/4-ton AND 1-ton trucks. The only difference between the two is that the later 1-ton uses a different seal than the later 3/4-ton. (1-ton seal numbers are in parens.)

'53 to '59
seal -- 5756 (40973S)
inner -- b46
outer -- b45

'46 to '52
seal -- 40973S (40973S)
inner -- b26
outer -- b25

A solution that works for a 1-ton is likely to also work for a 3/4-ton since they use the same axle and spindle.

Might try checking the rear rotor's on the late model 4 wheel disk's trucks, they would be the hat style. Use them on your existing hub and spindle, just have to come up with a caliber mount. On our race car rear ends we would clamp the caliper to the rotor with air pressure to locate the caliper bracket to the rear housing. Might work to locate the bracket to your existing spindle, just remember to space the caliber off the rotor to eliminate rubbing.

The rear rotors would be too deep in the hat section due to the parking brake drum located there. Also, using the front disks from the late trucks will get a much thicker rotor than using the rear. I would suggest using the rears from the late model trucks, with the complete brake assembly, for use on the rear axle, though.

I think my '89 K3500 single-wheel has hat type rotors on the front.

They are, sort of. While the rotor is separate from the hub, it actually mounts to the backside of the hub rather than the frontside like the GMT800/900 trucks do. They are held in place by having the wheel studs pressed through them into the hub itself. That particular rotor is also different from the later ones by havng a square hole through the center, rather than a round one. The square hole is so that it will clear the mounting flange for the hub assembly.

Bill none of that convinces me the GMT400 rotor is the wrong approach.

The square hole in interesting but not a big deal. I don't see why the rotor could not be attached to the single-wheel hub the same way it was attached on the GMT400.

I never meant to say it wouldn't work, only that it is a different design from the later style.
It will take a little research to get appropriate studs, especially if you want to keep std threads, and perhaps redrilling of some holes to match whatever studs are used, but I think it could be used in the same way the original was attached.
Now that I think about it, I seem to recall that the 6 lug conversion for the 1/2 tons actually mount the rotor that way, using 3 screws through the original rivet hole adn wheel studs to hold the rotor on from the backside. The original application for the rotor for that conversion ('71-'87 1/2 ton 4x4) mounted the rotor in the same way.

Rashly assuming the GMT400 rotor will bolt to the original 3/4- or 1-ton hub similar to the way it attaches to the stock hub the questions are does it clear everything, and can a practical caliper bracket be created.

I guess I have no objection to increasing the size of the studs to support the rotor, but I'm not hung up on running original wheels. This approach does assume using the stock ball bearings is acceptable or that a roller replacement can be identified and installed.

I checked availability of the rotor and caliper at RockAuto and both appear readily available. I was using an 89 K3500 since that is what I have the remains of parked outside.

Let's look into this some more.

Trying to find the spindle diameters for the two different year ranges of 3/4 and 1 ton axles.
So far I'm guessing (by looking at section 6.3 in the 29-54 parts manual.)

That the older axle has spindle diameters of 1.40" and 0.84" (inner and outer respectively)
That the newer axle has spindle diameters of 1.5" and 7.8"

I've got a 52 axle I can drag out of the woods to dissemble and measure.
Who has the later one to measure?
Or can anyone confirm this from bearing numbers and dimensions?

With this info I can investigate swapping different hubs/rotors.
One problem will be the original bearings (older axle for sure) have an extended inner ring for the felt seal to fit on. Most modern axles use a machined portion of the spindle for the seal. If using the older spindles and new hubs a seal solution will be needed.

Grigg

I've got an early one stashed somewhere in my shop and a late one in place under one of my trucks.

But easier yet is to check the Restoration Pack specs for each.

1950

Inner: 1.4051 to 1.4056
Outer: .8427 to 8432

'51 and '52 are the same.

1953

Inner: 1.4986 to 1.4991
Outer: .9052 to .9057

So the break seems to be between '52 and '53 with a small increase in spindle diameter.

The kingpin diameter on both the early and late axles is the same. Some of the other specs seem to vary, but I wonder if swapping from the early to the late spindles might be a way to solve the seal problem.

If swapping spindles isn't a solution, it's sure easier to swap a '53 or '54 axle under a '47 to '52 truck than it is to cut and weld an axle from a much later truck.

Found the bearings in the Timken catalog.
Hard to make a table, but here's a try:
Front (original) wheel bearings for 3/4 and 1 ton Chevy.

Bearing # ---- Bore --- O.D. ----- Overall Width --- Outer cup width --- Inner cone Width-
'53 to '59
B-46 ------- 1.4995 --- 3.1500 ---- 1.2360 ----------------- .8510 --------------- .9170
B-45 -------- .9058 ---- 2.2503 ---- .8000 ------------------ .6900 --------------- .6590
'46 to '52
B-26 ------- 1.4060 --- 3.1500 ---- 1.2260 ----------------- .8510 --------------- .9170
B-25 -------- .8435 ---- 2.2503 ---- .8000 -------------------.6900 --------------- .6590


The outer rings being the same width tells me the sealing method is probably the same, and the later spindles may not solve the seal problem. But no problem, I can't find an inner bearing to adapt the 2wd Chevy disc/hub to the old spindle. So I could make a bushing/adapter to also include the seal diameter.
Obviously this is still speculation 'til I get a rotor/hub to measure and try.

Grigg

What hub do you need? I have a '49 or '50 1-ton axle with hubs I could take a hub off if that would help. I might now move fast, but I do have it.

Thanks for the offer but for right now I'm set.
I've got my 52 axle in the shop already and have one hub pulled off.
I'll measure and figure and search the auto parts and bearing catalogs and see what I come up with.

Best I can tell the early and late axles only differ in the spindle diameters (and corresponding bearings), looks like the hubs are the same from 47-54, part number 3683232.

So I'll keep the later model larger spindles in mind if it helps with finding new bearings.

Grigg

Well,
Just measured my 52 axle and it appears to be a 53 and later as far as the spindle and bearings go.
Either it's a late 52 truck or someone swapped axles already?

If a rotor is going to slip on the original hub it'll need a 4.600" bore.

Grigg

The pictures on Rock Auto of the GMT 400 type 1-ton four wheel drive rotors suggest the opening will be 4.6+. It's not a round hole or bore as such, but the opening comes close to the holes for the lugs.

Got a lot figured today.

Checked on availability of front wheel bearings.
-- NAPA does not offer the early axle wheel bearings
-- NAPA can get the later axle wheel bearings, ~$90 each, or about $360 for a complete set for the whole front axle, seems really expensive to me. They did not list a tapered roller replacement.

Picked up a front rotor front rotor for a mid 90's Chevy 1 ton 4x4 dually, as well as the caliper and a set of pads. The rotor is 12.5" diameter and 1.5" thick, caliper has a huge bore.

Removed all the old brake parts from the 52 (or is it 53?) axle. Also removed studs and the grease deflector that the studs held to the hub.

Test fit the new rotor to the back side of the hub.
For a permanent solution the stud holes in the hub will need to be enlarged to match the rotor, and a pretty heavy bushing needs to be made to locate the bore of the rotor to the snout on the backside of the hub. Seems a very reasonable solution.

Test fit hub and rotor to axle and it fits just fine with plenty of room where needed.

Hung a caliper on the rotor and can see that it's possible to make a caliper bracket, even have a plan in my head for one.

And finally test fit hub, rotor, and caliper in the wheel . Caliper fits in the 19.5" wheel with about 1/2" clearance, plenty I think.

So, one method involves mid 90's 1 ton parts, bushings for the center of the rotor/hub, enlarged wheel stud holes and new studs (9/16" in place of the old 1/2"). And a fabricated caliper bracket.

Downsides are it uses old bearings that are expensive and the old felt type grease seal.

Grigg

Looked into the complete rotor and hub assembly for 2wd Chevy trucks, problem is they have the wheel mounting surface close to the outer wheel bearing, and to use with an I-beam axle it needs to be closer to the inner wheel bearing.

this is so the center of tire contact patch on the ground is close to the center that the tire turns about when turning. Or in other words the contact patch needs to be about centered on the point on the ground that the center line of the king pin points to.
This could be adjusted with different wheel offsets, but I don't want to do that, not many if any different offsets are available in the 19.5" single wheels I want to run.

So the above posted solution with original axle is looking like choice number one right now.

Second choice might be the International 2wd hubs on the P-30 I-beam axle, but that's not a complete idea yet, still need to check a bunch of dimensions when I find an IH hub. This would also require narrowing an axle which is not so easy.

Grigg

Those sealed hub/bearing units these newer trucks use are pretty expensive too.

I considered using one of those units to mount a modern rotor on an old axle and was surprised at nearly $300 a side from Rock Auto. I think I priced 1-ton four wheel drive units, but didn't make a note and don't recall with certainty.

My thought was to bolt on the hub using the same steering and backing plate bolt holes that would be used for the caliper bracket.

That could work, but you will have to have some sort of stub shaft to go through the bearing to keep it from separating and to put the preload (approx. 180 ft/lbs) on the bearing. That's if you use the 4x4 style. The '01 and newer 2wds use a different style bearing, still a unit bearing, but doesn't require the axle nut to preload the bearing.

My thought was that I'd use the existing stub shaft portion of the spindle with some kind of machined piece to fit over the spindle and against the bearing.

The nearly $300 per side for bearings put an end to that line of thinking before digging out any drawings to determine if the idea was at all possible.

My Corvette has a bearing unit on the front corners so I know what I was thinking has been done by a manufacture, just not if it is adaptable to our old trucks. Those bearings were about $150 last time I had to buy.

I also know that some people claim to have removed the four-wheel-drive stuff from the front of an S-10 to get the advantages of the torsion bar suspension and slightly wider track, but without the added weight and other disadvantages of four-wheel-drive.

So I put all this together in my head and imagine there may be a way to make this work on our trucks, just have done nothing about researching details to confirm it and aside from the 8-lug disk brake discussion haven't thought it important.

The stub shaft part of the spindle wouldn't work with the 4x4 unti bearing, as the way they go together, the stub shaft would have to be able to rotate with the hub.

Okay, dump that idea in the scrap heap.

Are there two wheel drive 8-lug GM trucks that use one of those unit bearings? Is that possibly worth looking at?

I don't care for a unit bearing. Don't have any experience with them but haven't heard anything good about them.
Some companies even take the time and effort to offer replacements that use traditional replaceable wheel bearings.
http://www.dynatrac.com/products_freespin_dodge.html
"...Heavy Duty Hub Conversion Kits replace the factory unit bearings with fixed spindles for superior strength, improved fuel economy, and smooth performance. The complete kit includes inexpensive, serviceable Timken bearings,..."
They offer a kit for fords too.

I think that's enough about "unit bearings".


Looks like I've got the disc brake thing figured (but not implemented or tested).
I'll look into replacement wheel bearings some more for the original spindles and hubs.
Were the same hubs used up to 1959 for 1 tons?
What year was the last year for a 1 ton I-beam axle; are there any other hubs and or spindles to consider that may have modern bearings or a conversion available?

Grigg

I'm not absolutely certain, but I think the only change in hubs was when Bendix brakes replaced Huck. All the evidence I've been able to gather says the hubs on a TF are the same as a Bendix AD.

I've seen a '61 C-30 with the torsion bar IFS. I presume '60 had it also, making '59 the last year for the 1-ton I-beam.

I came back to this thread because I read about a hub that was once available for these spindles. I've been reading race car chassis and fabrication books because they seem to be a good source of information on automotive fabrication in general. In Steve Smith's 1977 book Race Car Fabrication and Preparation they suggest using commercially available race car hubs designed for use on GMC spindles.

That got me to thinking and I found a source of aftermarket steel hubs for the 4x4 market priced at $400 a pair.

While its probably not commercially feasible it is not impossible that we could design our own hubs for a limited run. I don't think I'm going to start making hubs on my little lathe but I can imagine my brother doing so on his larger setup.

I'm not an engineer but I would start the design process by choosing a rotor and borrowing the external dimensions from the hub associated with it, and then using the internal dimensions from the stock 3/4- or 1-ton hub, possibly modified to better support roller bearings.

Another thought is that because the 4100 and 4400 standard axle uses the same spindle as the 3/4- and 1-ton trucks, making hubs might open the door to creating a 5/10-lug pattern hub for a disk conversion on 1-1/2 ton trucks too.

I'm not a machinist I only play with machine tools at times. I may have unrealistic expectations regarding what it takes to carve a hub out of a piece of round bar 10 inches in diameter and six or eight inches long...

I'm sure you'll conclude I'm nuts, but that's okay I've been blaming a lot of things on the drugs I'm taking these days and this could be just one more.

I've considered making hubs from scratch, For me to do it on my manual machines would take a little while, and I'd probably only do it once, doubt anyone would want to pay what it'd cost me to make them, although might not ba all that bad if I did several at once. Material wouldn't be cheap either way.
To have a batch of them run in a production/CNC shop might be an option, but would require other interested folks and probably some money up front. I don't want to get into that.

I'd still like to find a reasonably simple combination of already made parts to do this conversion, only needing to make simple (cheap) parts.

About the 5/10 lug hubs for a 1.5 or 2 ton. To make a dual wheel front hub would take a pretty big chunk of material, or a casting. At which point the complete narrowed axle swap is probably cheaper. And very few if anyone has done such a swap other than me, so either it's really hard or the demand is not there.

I think I've found a good solution for the 1 ton single wheel already. (above)
But what I really don't like is the cost of the replacement ball type bearing and no possibility that I could find to upgrade. And the old type seal, which is not bad, but not great either.
I'll continue to look for other options,a nd if nothing works out I'll default to the 90's rotors with the original hubs and bearings.

Grigg

I discussed this thought with my brother who makes his living using CAD to design tooling used in a CNC shop to mass-produce parts commercially. Auto manufacturers seem to be their biggest customers these days.

He has a small manual machine shop at home and said it would take him 40 hours or more to make a hub using his own stuff. But if he could use CNC equipment after the design was complete it might only take an hour to turn out a part.

At this point it's an idea I'll hold in reserve until I feel like your approach is proven to work or not. The project I'd use it on is definitely not one I'll do in 2010 or likely even 2011 anyway.

I've got a pretty good sized Lodge & Shipley lathe, and with sturdy tools and some coolant it'll really remove some metal, just guessing if I was already setup to make them (so the second one) would take a day, probably a long day. I feel pretty sure I could make two hubs in less than a week, which seems worth wile to me, but it only solves my problem, and would not be economical for anyone else.

With luck a simpler solution will present itself.

Unless you designed the hubs using a CAD system to check that everything fit and moved correctly I'd fear having a failed prototype or two that would consume both time and materials.

On the other hand I keep thinking I might try it using my little Craftsman lathe which might take two weeks or more...

This afternoon I learned that the husband of one of my wife's friends just bought a CNC Mill to play with at home and he is looking for projects. He is a middle-aged engineer looking to get his hands dirty.

Next time I see him I'll discuss with him making up some new hubs. I'm beginning to get ideas together on what I think they would need to look like.