Spindle flex under cornering....beware!

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Maurizio
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Post by Maurizio » Sat Jan 13, 2007 12:40 pm

:roll: Hmm thinking about the matter, it is pretty complex to get a feel for forces on the spindle.

If we take the outside wheel there are 2 forces working:
- the rim is pullling due to the corner speed and adhesion.
- and the spindle is bend to the other side, due to the weight transfer on the outside wheel and perhaps some extra braking.
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Post by Micke » Sat Jan 13, 2007 2:04 pm

The vertical load is not very relevant and it counteracts the real force coming from cornering. The ET as well as camber do not matter. They do in street driving where you drive for miles in more or less straight line.

The important "force" is coming from cornering and acts on the axle with ~ lateral acceleration * front axle mass * tire radius or about 2-2.5 kNm in this case.
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Post by Jim K » Sat Jan 13, 2007 2:23 pm

I agree the main thing is wheel radius and max instantaneous g's (or steady state g for a constant radius/speed turn)and the front axle portion of the pig's weight. Camber shouldn't make a difference and neither should offset (within the realistic values we deal with). And then, with stickier tires you can have more speed = higher g.... :(
While we wait for the coroner's report, I'm looking for thicker spindles...not easy to come by! :cry:
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Post by Zamani » Sat Jan 13, 2007 10:24 pm

With a bigger spindle, won't you need a whole slew of new things? The bearings will have to be smaller or the hub needs to be bored out. Now since you discovered that even the spindle can flex, how will milling the hub affect the strength of the hub?

BTW Jim, did the 75 1.8T racers have bigger spindles?
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Post by Barry » Sat Jan 13, 2007 11:16 pm

Alfa Six sedan had GIANT spindles..

I do know that the early GTV Strada coupe had baby spindles -the GTV6 went bigger...
I still reckon theres some thing else here..I have never come across this before.
Untill I do,Im really not worrying myself about it here...Jim,I have hit a curb side on and rolled cars and the spindles have not bent..the upright was pretty fk`d..but the hub and spindle were good..

Your hubs where the bearings locate aren't worn perhaps?? :?:
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Post by Jim K » Sun Jan 14, 2007 1:28 am

Everything is new Barry (well, 4 months old!)
Zamani, bigger spindles come with bigger bearings and hubs...for once AR knew what they were doing but quickly decided to save some metal on subsequent cars :x Yes, racing 1.8T's had special spindles (alloy+steel) seen somewhere in the site a while ago and the Evo had the big ones Barry mentioned.
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Post by Mats » Sun Jan 14, 2007 2:09 am

The evo had bigger ones? Maybe I should take a drive down to the garage and measure on the ~10 different 116 cars standing there including 75 t and 75 Evo. 8)
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Post by Barry » Sun Jan 14, 2007 2:23 am

Ok,I graciously bow out from the topic...
Last edited by Barry on Wed Aug 17, 2011 10:06 am, edited 1 time in total.
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Post by Maurizio » Sun Jan 14, 2007 3:21 am

The vertical load is not very relevant and it counteracts the real force coming from cornering.
I agree for the fast math take the G's, corner weight and outside wheel diamter.

So for a fast calculation I need some dimensions.

Distance between rotation point upper and lower balll joint.
Distance rotation point lower bj to axle centre.
Minimal cross section spinde.

Axle: distance between bearings and cross section axle.

Micke did use a g meter on the ring in my car and also did the same with Ron's demo car. I remember Ron doing a consistant 1.5 G's in the corners and a 1.6 through carrossel (I was doing 1.3 and 1.5 ). He is running very sticky P zero's. A TS is less front heavy so will do a faster turn but ok as reference for the fast sum.
@Micke Is that 2-2.5 kNm you predicted?


Better spindles, how a bout SZ spindles, will only work when using 16" wheels. The car was claimed to do a 1.1G in standard trim.
Improves your roll centre as a bonus :lol:
Have looked for them a long time and they are $$$$$ if you find them.
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Re: Spindle flex under cornering....beware!

Post by scott.venables » Fri Apr 22, 2011 5:33 am

Thread revival!

Did you figure something out Jim? At our last club sprint meeting a friend of mine with a 75TS turbo racer was having trouble with the inside of the wheel rim rubbing on the bottom ball joint stud. I've made up these for him to try out at the next meeting. They're threaded with a 1mm pitch to set the wheel bearing play. Any comments from the engineers?

If it works I might do a run of them.

Scott
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Re: Spindle flex under cornering....beware!

Post by xrad » Fri Apr 22, 2011 8:17 am

were the 75/gtv6 spindle units all cast at the same facility?
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Re: Spindle flex under cornering....beware!

Post by Maurizio » Fri Apr 22, 2011 9:11 am

They're threaded with a 1mm pitch to set the wheel bearing play.
I guess this bush is placed between the two inner bearing rings...
But how do you set the wheel bearing play. Dismantle the hub several times?
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Re: Spindle flex under cornering....beware!

Post by scott.venables » Fri Apr 22, 2011 7:40 pm

Maurizio wrote:
They're threaded with a 1mm pitch to set the wheel bearing play.
I guess this bush is placed between the two inner bearing rings...
But how do you set the wheel bearing play. Dismantle the hub several times?
Basically. You could install it too long, then measure the play with a dial gauge and shorten the spacer accordingly. That would be quicker.

xrad wrote:were the 75/gtv6 spindle units all cast at the same facility?
The upright is forged then machined and the spindles are machined and then pressed/welded in. But I'm not sure where they all came from.

Scott
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Re: Spindle flex under cornering....beware!

Post by MD » Fri Apr 22, 2011 8:49 pm

Scott,
In this set up, how is the steering arm fitted to the whole assembly? Would it be possible to position it in a different arc location to cater for bump steer adjustment at the same time ?
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Re: Spindle flex under cornering....beware!

Post by scott.venables » Sat Apr 23, 2011 6:48 pm

Hi MD. This fits standard 75 upright/spindle, this is a spacer that gets clamped between the inner races when the nut on the end of the spindle is tightened.

The first car they will be fitted to has lengthened uprights with bent steering arms for bump correction.

Scott
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