Axles on Lowered Minis

[rickyr53]

Do R53's use the same axles as R50's?

[hardingsan]

i sent a message to the driveshaft shop about gen 2 options.

they said they were gonna prototype some off a sample, but the person sending the sample never came through.

sounds like they'd at least be open to the idea...

[Rally]

Originally Posted by hardingsan

sounds like they'd at least be open to the idea...

If they'll take a broken one, I can send it shortly

[not-so-rednwhitecooper]

Mine were fine for the 25k miles I drove on coils.

[Rally]

Originally Posted by not-so-rednwhitecooper

Mine were fine for the 25k miles I drove on coils.

Ya, my r50 made it 30k+ on coilovers spun down.

[hardingsan]

and just to finish out this thought, lowered on springs your fine.

lowered on coils you're ok, but the farther you go down the coils, the more your stressing the parts. the more you stress the parts, the quicker they'll fail. some as quick as 20k.

but is the angle of the axles stressing the cv boots and that's what's failing? so as long as the cv boot looks / feels ok it's alright? or is there something else that is / could be breaking?

[Rally]

The angle at which the CV boot sits is effected by your ride height and your camber (or lack thereof). The lower you go, the more drastic the angle.

The angle does two things. One, it could potentially tear the CV boot, allowing dirt in which will lead to the CV joint failing. Two, extreme angles can cause binding, particularly while in a low car, that's turning and the suspension is compressed due to the speed or a bump. That's the unfortunate part of FWD, your CV joint goes through A LOT more angle abuse than a RWD ever would since your drive wheels turn/steer too.

Whose axle blew in 20k? I don't think anyone's oem axle has gone THAT quickly. I could be wrong though.

I still think it's worth looking into the concept of ADDING negative camber to fix the binding issue up front. On paper it seems like it would work because you're matching the angle of the lowered axle with the angle of a cambered steering knuckle.

[hardingsan]

Originally Posted by Rally

Whose axle blew in 20k? I don't think anyone's oem axle has gone THAT quickly. I could be wrong though.

my bad, the lowest was rick saying 25k but when i re-read it it looks more like at least 25. ducks said he replaced them at 50,000km which is ~30k miles, so realistically it looks like it's in the 30-60k range.

Originally Posted by Rally

The angle does two things... Two, extreme angles can cause binding, particularly while in a low car, that's turning and the suspension is compressed due to the speed or a bump.

this 2nd issue sounds more like a one and done kinda thing. i can see the strain on a cv boot being an 'over time' sort of thing, but if you're low and driving around without caution and bind up the cv joint is that instant failure? or does this also have to be repeated multiple times to ruin the axle?

Originally Posted by Rally

I still think it's worth looking into the concept of ADDING negative camber to fix the binding issue up front. On paper it seems like it would work because you're matching the angle of the lowered axle with the angle of a cambered steering knuckle.

so as you lower the car the engine side get's lower while the wheel side stays the same. you add camber that theoretically puts the wheel side lower and effectively returns it close to the stock relationship. but at the same time, adding the camber pushes the knuckle out farther, so don't you risk over-extending the axle?

[Rally]

Originally Posted by hardingsan

this 2nd issue sounds more like a one and done kinda thing. i can see the strain on a cv boot being an 'over time' sort of thing, but if you're low and driving around without caution and bind up the cv joint is that instant failure? or does this also have to be repeated multiple times to ruin the axle?

Sorry, maybe "binding" is the wrong word. This would be a wear-over-time sort of thing where the "binding" causes grinding which will eventually wear down the joint after a great deal of mileage.

Originally Posted by hardingsan

so as you lower the car the engine side get's lower while the wheel side stays the same. you add camber that theoretically puts the wheel side lower and effectively returns it close to the stock relationship. but at the same time, adding the camber pushes the knuckle out farther, so don't you risk over-extending the axle?

Nah, it's more just the angle.

Let's say that after lowering the car, the axle itself is now at 10 degrees from the horizon line (I made that number up completely.) If you're running no camber that means the wheel axle is still at 0 degrees from the horizon line, leaving the angle of the outer CV joint at 10 degrees where it meets the axle itself (or -10). It's this angle that causes problems.

Now imagine you camber your wheels 3 degrees (from the horizon line), the axle is still at 10 degrees after lowering. This means the angle at the outer CV joint is just 7 (or -7) degrees which may be within the normal tolerances of the CV, or at least help cut down on wear.

That's my initial THEORY. I haven't really put much thought into it or explored how the camber angle effects the CV joint angle when the steering wheel is turned or anything.

[hardingsan]

cool. thanks for the lesson.

you're theory sounds like it's on the right track. i'm still a little curious as to whether the camber would put any lateral strain on the axle and if that would make the issue better or worse. just thinking if you camber the wheels out you'd be increasing the length the axle has to span. if that thinking is correct which is worse? a more extreme angle for the cv joint or the span being longer than the axle?

then again, if you lower the car without changing the camber you're decreasing the span and could be putting a compressive force on the axle. man, discussions like this make me wish i had a 4 post handy...

[Rally]

To make things even odder, most people notice the vibration (from axle grinding/binding) at specific RPMs in specific gears (i.e. it's generally most noticeable 1-2.5k in second gear).

[not-so-rednwhitecooper]

I don't think the camber has as much of an effect on the life of the CV as you are thinking.

The CV is only going to get damaged if it binds up. They are designed to run at an incline. A CV will get damaged faster if it is perfectly level.

[Rally]

Right, but they aren't designed to run at the incline that we're using. The idea is to get the relative incline back to normal...or close.

[not-so-rednwhitecooper]

Originally Posted by hardingsan

just thinking if you camber the wheels out you'd be increasing the length the axle has to span. if that thinking is correct which is worse? a more extreme angle for the cv joint or the span being longer than the axle?

It doesn't change the length it has to span. The inside joint it a plunge joint. It takes up the slop in suspension travel.

[not-so-rednwhitecooper]

Originally Posted by Rally

Right, but they aren't designed to run at the incline that we're using. The idea is to get the relative incline back to normal...or close.

In theory, the can be used at any angle until it binds up. The reason you get vibration is that the roller bearings wore in a path, and when you change the path, the bearing are constantly going in and out of that original groove made by the bearings for the first x amount of miles.

If you are getting vibration on a brand new axle, the axle is close to binding up.

By attempting to change the angle of the outside CV by adding negative camber, you are only fixing half the problem. It probably wont alleviate any vibration since the inside CV is the one that goes thru a more aggressive range of movement than the outside CV.