So how do you change a sows ear into a silk purse? AKA rear wheel hub assembly! You take it back to a logical design that incorporates safety, performance & durability! 

The first thing will be to take the 2 10mm threaded holes that are currently blind drilled All the way through the knuckle as .368 (u drill) to be tapped to 7/16 x 14 threaded holes. The other two holes that are already through holes will be finished to size & tapped to the 10mm x 1.5 thread. After that 4, studs will be made. 2 long ones 2 short ones. I will detail these later, but here is an additional disconnect of the assembly design. They use 10 mm bolts to attach the wheel bearing hub to the knuckle! Yet when you see the bearing hub assembly the holes that those 10 mm bolts go through measure.460 in diameter! Not .3937 or even .400 or .405! They have .460! That’s.066 of clearance! That’s insane!

So it will be awhile before I get a chance to do any of this work, like a winter project, but I will updated  as I step through this.

Edited December 27, 2025Dec 27 by Last Indian

Here is one other thought of how dumb this design is! In an old standard design that used a spindle with Timken tapered roller bearings when you applied the brakes there is zero load applied to the spindle or it’s bearings or castle nut! But in this design there is!! Since these 4 bolts hold the bearings hub in the manner they do, this sets them in single shear! Not even double shear, but single shear. So every time you apply the brakes you are applying a shear force to those  bolts! Again, that just stupid & unsafe.

Edited August 24, 20241 yr by Last Indian

Ok, well I finally had a small amount of time to revisit this concept for an upgrade to the rear suspension knuckle/wheel hub bearing modification! Things have changed a bit. 

So speaking of the rear suspension, I would offer this cautionary story if you plan to build a ground pounder as they are called! I can not speak about all FWD’s as I have not built the suspensions of all manufacturers, but of all GM & the like there is a serious issue with McPherson strut/knuckle suspension vehicles, especially when it comes to building an aggressive handling suspension. This is due to the illogical application of the wheel bearing design!

In a traditional rear wheel drive the bearings are installed on a traditional spindle with two tapered roller bearings. This design can not fail, I.E. the wheel falls off! Other than to have a bearing go bad, there is little else to occur beyond stranded! As it would be virtually impossible, due to bearing failure, for the wheel to come off!

That is not the case with a FWD! The rear hub bearings are held in place by bolts that thread into the knuckle. Which pushes the wheel hub into the knuckle. The wheel obviously bolts to the hub. If the hub bolts that are threaded into the knuckle fail for any reason, the hub has nothing to keep it in the knuckle, or the wheel on the car!

This was such the case for me! Fortunately I caught my problem before it became a dilemma or catastrophe. When I built this suspension many years ago I built everything new from the ground up, including hub bearings. They were done more than correctly! The fit to the knuckle was a little tighter than factory & the torque was 5 pounds more. And yes it has taken nearly 20 years to raise its head, but that’s only about 15,000 miles. 

So it went like this. For the last half of last summer & most of this past summer every time I would make a hard, I.E. aggressive right turn I would get this rattling noise from the left rear that kind of sounded like decelerating exhaust while in the cornering sequence. Straight forward driving it seemed quiet. Over & over again I would check & recheck, exhaust, brakes, tire rub, suspension clearance, suspension component torque, etc., but nothing! It drove me nuts, because I knew something was wrong. I took out the back seat pulled the access plate to the fuel pump. Now it appeared more metallic then. Took it on the freeway & now I would hear a intermittent hard metallic crack. That was it, I knew I needed to put it up in the air & go through the whole back suspension piece by piece, oh great!

Well I didn’t have to go far. Removed left wheel, caliper, rotor & bingo! There it was! Looking through the access holes of the bearing hub tire mounting flange was a hub mounting bolt. Loose & bent. I replaced it & checked the torque on the other 3 bolts. All were loose! I check the other side. One needed re-torque slightly, the rest were good.

My take on this is this. The hub bearing mounting setup is poor at best, but the front is better than the back. The front use 3 larger bolts mounted from the back. This is better because in hard cornering, the loaded wheel, this places the bolts in compression & the bearing receives more of a angular vertical load. So while this is far less than optimal, it’s by far better than the back. Additionally the bolts of the front thread into the steel bearing hub. This is substantially different that threading into an aluminum knuckle.

On the other hand the back is abysmal! In a hard corner the rear load wheel has a similar load as the front, but the bolts are a third of the diameter & they’re being stretched & the following wheel is also being stretched because they hold the bearing hub from the front. 

Yes, that post was to make anyone who wished to do any of the modifications I’ve done aware of the possibility. I wouldn’t think you would see this type of issue in a non modified vehicle. I have no doubt that the aggressive nature of the Indian’s suspension is the reason for the occurrence. When you’ve increased the track width by a foot, stiffened the suspension components so they transfer power effectively to the ground were it belongs & you actually use it in the manner you built it for; it’s not surprising! 

What is surprising is that any head engineer would let such a flawed design make it to production! Let alone prevail for decades & hundreds of thousands of vehicles. The simplest of design change would have kept the possibly of the catastrophic failure like the wheel coming off, should have been the mind set no matter how unlikely. 

 

One of the other issues with the factory rear design are the bolt heads & fit. The compression part of the bolt head, the diameter, is to small & the fit of the bolt shank is far to small. The diameter of the through hole in the brake backing plate is .395 to .400, but the through hole in the hub bearing is .460! With the bolt size being 10mm (.390.), the more important fit is the bolt size to the hub bearing! So the whole setup is garbage! The clearance fit of the bolt to the hub bearing should be no more than .015 total, .0075 on a side, with .010 total or .005 on a side being ideal.

So here is the start of this improvement modification. My advice would be get a spare set of knuckles. So obviously I would recommend sandblasting or glass bead the knuckles if they’re not new.

Now drill the two 10mm threaded holes that are on the opposite side from the caliper mounting flange of the knuckle deeper, about 2.250” deep total. These two holes are blind. The setup to do this should be done on a mill as you will see in the attached pictures. 

Now you will flip the knuckle over to spot face the backside of the two short 10mm through holes. This is done to make a flat surface for the new bolt arrangement that will be used. This arrangement will change the two through holes from 10mm x 1.5mm to 7/16 14 thread. This is done by drilling those two holes out to the tap drill size of a 7/16 x 14 bolt. Then tap the hole with a 7/16 tap. You will notice that drilling out the 10mm taped holes does not remove all the threads. That’s ok! Metric threads are a very different animal when compared to US threads! American threads are far & away superior to metric, fact based from the principles of what threads are! I don’t just say that because I’m American. Metic threads are weaker, strip more often & in general defy the good principles of threading, which is considered an art form! And has been from almost the beginning. I can speak to this later if someone wants to know more, but for now you’ll never know that there was ever a 10mm thread there when finished!

Next you will need to open up the two holes on the brake backing plate that corresponds to the 7/16 bolts. Drill them out to 7/16. 

Amazing work as always buddy.  Few would tackle such a job let alone know that the system was so flawed.

So before I move on with the detailing of this modification I want to show just how poor of an engineered setup this is! As I said before the head engineer that ok’d this design is a disgrace to the craft! 

Look at the following pictures. First is the bearing hub bolt. The shoulder of the bolt head is .682 thousands by .100 thick. Yet the hole in the bearing hub is .470 thousands. Put in perspective that is only .106 thousands on a side bigger than the hole! On top of that the bolt shaft is .388 thousands in diameter. That is typical of a bolt thread as they are always a few thousands small diametrically, of which case means there is .294 total difference in diameter & .147 on a side! That is not how you engineer bolts & their respective fits. Considering the fact that these 4 bolts on each hub carry the entire transferred lateral load of the rear suspension; it isn’t surprising that under aggressive handling they fail.

Edited January 6, 20251 yr by Last Indian

One more picture to give a perspective of JustA how little these factory 10mm bolts are holding the hub on by.

notice the thin dark circle on the outer edge of the bolt head! That’s all the contact these bolt heads have as clamping force! Pitiful really pitiful!

Now on with the modification that needs done for the other side of the knuckle. While the other 10mm threaded holes are now at around 2.250” deep you’ll need longer bolts. I would seriously suggest using 304 stainless steel! Why? Steel & aluminum don’t get along with each other & since these are blind holes the likely hood of there being electrolysis between them is inevitable with corrosion that will freeze them up, being that they are in a blind hole. This makes that corrosion difficult to effect because of that. So the difficulty of getting them out later may be significant. So basically you I’ll make two long studs & set screw them. Where they interface with the set screws the threads will need to be removed by undercutting. For reference I used 8x32 thread set screws. I also cut a screwdriver slot into the top of each stud to use for installation.
 

Edited January 7, 20251 yr by Last Indian

Amazing work as always buddy.  Few would tackle such a job let alone know that the system was so flawed. The master  Guess I didn't clear the editor.

Edited January 8, 20251 yr by JUSTA6

7 hours ago, JUSTA6 said:

Amazing work as always buddy.  Few would tackle such a job let alone know that the system was so flawed. The master  Guess I didn't clear the editor.

Buddy if I had been through what you have, I’d be lucky to remember how to punch those little squares with letters on them! You duh man!

I am fascinated to watch Last Indian build a world-class handling FWD G-machine. Clearly GM never designed the GP to be anywhere close to being track worthy, otherwise they would have designed the suspension a lot differently.

9 hours ago, Frosty said:

I am fascinated to watch Last Indian build a world-class handling FWD G-machine. Clearly GM never designed the GP to be anywhere close to being track worthy, otherwise they would have designed the suspension a lot differently.

You are right Frosty. That said though as I did say, from a safety perspective it is a big misstep! A traditional double wishbone that uses a spindle is about as much of a fail safe as you can design. It would be nearly impossible for the wheel to come off the car due to a complete bearing failure & the odds of the castle nut or cotter pin completely failing is even less likely. This arrangement though, one bolt failure will exacerbate the demise of the other 3 bolts, as I saw. When that happens, it’s bye bye wheel!

GM created the famous 1LE suspension for the F-body csrs. I think we should call Last Indian’s FWD mods the 1LI (for Last Indian). 

Edited January 10, 20251 yr by Frosty

At this point the hub bearing is secured soundly. The two 7/16 bolts now only have .016 thousands clearance on a side when in the bearing hub! That’s a decent fit & will eliminate the bearings hub from any rotational movement. We also are now going to have a much larger clamping force on each hole of the bearing hub, but we are not done yet. Now comes the part that makes the complete failure of the bearing hub, I.E. wheel coming completely off the car, highly unlikely. Not to mention a much stronger more solid & robust setup that will now, like many other components that have been modified on the Indian, to reduce or eliminate flex, & subtle vibrations that keeps the suspension from transferring all the energy you can to where it belongs, the ground!

All 4 bolts are locked in place in the knuckle. The two 7/16 bolts have lock washers & are torqued to 60 ft lb. in the knuckle, more than what the factory specs call for. The two 10mm studs are locked in place by the 8-32 set screws. And now we are going to machine castle nuts for each bolt & drill each bolt for a cotter pin. This arrangement is as close as can be to a spindle arrangement from a safety & secure perspective. This is now a solid racing setup for hard aggressive cornering!

still need to do the same to the 10mm bolts.

Edited January 10, 20251 yr by Last Indian

CAN PREVENT WHEEL LOSS,