Hub Bore for Tripod Bearing

[eleung2]

Hi guys,

I'm making a hub for our car. We're using tripod bearings that would sit inside the hub, and I was wondering if there needs to be a taper in the bore of the hub where the tripod bearing fits in, or if it should be straight? Also, is there a way to determine how that bore should be dimensioned?

Thanks

[eleung2]

Hi guys,

I'm making a hub for our car. We're using tripod bearings that would sit inside the hub, and I was wondering if there needs to be a taper in the bore of the hub where the tripod bearing fits in, or if it should be straight? Also, is there a way to determine how that bore should be dimensioned?

Thanks

[kcapitano]

As far as I know the bore should be straight. The manufacturers I have spoken with recommend a loose fit so I would consult your machinery's handbook and choose one of the running and sliding fits.
Hopefully that answers your question and if I have neglected anything, someone, please let me know as my team is designing the same style hub.

Thanks

[dmacke]

If by "tripod would sit inside the hub" you mean that the tulip will be inside the hub (sorry might use different terminology). The profile inside the tulip is not tapered. The tripod needs to be able to plunge as the suspension cycles. Also from my experience unless you are using a tripod from a manufacturer that will give you it's dimensions (Taylor Race is only one I know of) you are on your own. Or you could get a existing tulip from a vehicle that uses the same tripods and try and measure that. I have tried dimensioning it with a pair of calipers and a compass and it didn't work well). If you have a sponsor that has a CMM maybe they will dimension it for you?

[Simon Dingle]

Hi eleung2,

Do you mean that the tripod housing is recessed into the hub (like in the image below) or are you trying to use the hub as the tripod housing? Maybe a simple sketch of what you are trying to do would help?

http://www.brunelracing.co.uk/...?folder=31&photo=693 (http://www.brunelracing.co.uk/gallery/folder.php?folder=31&photo=693)

[shark.ashwa]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Simon Dingle:
Hi eleung2,

Do you mean that the tripod housing is recessed into the hub (like in the image below) or are you trying to use the hub as the tripod housing? Maybe a simple sketch of what you are trying to do would help?

http://www.brunelracing.co.uk/...?folder=31&photo=693 (http://www.brunelracing.co.uk/gallery/folder.php?folder=31&photo=693) </div></BLOCKQUOTE>
Hi Simon,

Just wanted to continue this thread. I could not make out clearly from the pics as to what you meant by "reccessed" into the hub. http://fsae.com/groupee_common/emoticons/icon_rolleyes.gif Is the tripod housing press fit into the hub bore?? http://fsae.com/groupee_common/emoticons/icon_confused.gif A closer look would help me with my doubts. http://fsae.com/groupee_common/emoticons/icon_biggrin.gif Also those dont look like tripod bearings, look like Rzeppa CV joints to me. Correct me if I'm wrong. http://fsae.com/groupee_common/emoticons/icon_biggrin.gif
We were thinking of manufacturing the hub with the tripod housing integrated, so your answers will help us a lot. Also, are the hubs made from Aluminium?? If so, do you harden the bearing surface?
Thanks in advance. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Simon Dingle]

Hi,

My mistake, you're righ, they're Rzeppa not tripod (had tripod on the other end, but nothing unusual). Sorry combination of mis-remembering and then assuming the picture showed what I remembered, rather than simply looking(!)

I'll try and get an image/sketch of the cross-section, but it's not spectacular and as you pointed out not a tripod. Until then, the image shows a hub that has had the majority of it's internals bored out so that the CV joint slots into the inside of the hub. The drive is transmitted via 6 (I think) 8mm dog pins.

[shark.ashwa]

Hey Simon,

Any info on the hubs?? http://fsae.com/groupee_common/emoticons/icon_confused.gif
Also, was it difficult iin any way to machine the profile in the hub??

Regards,
Sharath

[Simon Dingle]

http://imageshack.us/photo/my-images/248/captureks.png/

http://imageshack.us/photo/my-...s/248/captureks.png/ (http://imageshack.us/photo/my-images/248/captureks.png/)

The hub, does end up being fairly complicated, but then they generally are on most FS cars anyway. We outsourced these to a sponsor, rather than machining them ourselves. The worst part was probably machining the joint down to make it a good size to fit into the hub. I think the joint was originally from a Ford Fiesta but I might be wrong on that.

I don't see why you couldn't do something similar with a tripod joint, but in hindsight, I'm not sure that the benefit to cost ratio is high enough. The main reason that we went for it was to improve the joint angles, but this can be better acheived by improving the positioning of the differential (as shown by our 2011 car).

[shark.ashwa]

Simon,

Just checked out the link you posted, I thought the joint housing was a straight bore?? Anyway,thanks for the pic. I was more interested in the material of your hub, is it Aluminium?? Any heat treatment done??
We were thinking of machining the tripod housing profile into the bore of our hub (as of now made from steel), but I was tempted to make it out of aluminium, press fit tripod sleeves (check link below),was wondering if the bearing surface would also require a steel sleeve??
Any input appreciated!
https://www.pegasusautoracing....tails.asp?RecID=5816 (https://www.pegasusautoracing.com/productdetails.asp?RecID=5816)
Thanks again.

Sharath

[Simon Dingle]

The hubs were aluminium, I can't remember the exact grade and heat treatment, but it would have been similar to 6061-T6, maybe towrds 7075-T6. They weren't hard annodized (from what I remember).

I'm pretty sure teams have done what you're proposing in the past, but I don't know to what success - it certainly seems feasible.

Which bearing surface do you mean? The surface for the wheel bearings? Is so, then no they don't need to have a steel sleeve, the aluminium is fine as long as the press-fit is appropriate.

[kcapitano]

Teams have tried similiar setups in the past. There is a good thread from one instance here:
http://fsae.com/eve/forums/a/t...=229108404#229108404 (http://fsae.com/eve/forums/a/tpc/f/125607348/m/229108404?r=229108404#229108404)
or
Live spindle with aluminum hub (http://fsae.com/eve/forums/a/tpc/f/125607348/m/8286001475?r=8286001475#8286001475)
I think there are some other threads too, but those are all I could find at the moment.
We use aluminum front hubs made from 7075 T6, and the upright bearings ride directly on the hub. We also machine a CV profile into our rear hubs, but those are made from 4340. From the research I did on aluminum hubs you will need a steel sleeve for the tripod.

[Thrainer]

I would recommend reading this thread: http://fsae.com/eve/forums/a/t...554941?r=97420584941 (http://fsae.com/eve/forums/a/tpc/f/125607348/m/48120554941?r=97420584941)

[shark.ashwa]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Thrainer:
I would recommend reading this thread: http://fsae.com/eve/forums/a/t...554941?r=97420584941 (http://fsae.com/eve/forums/a/tpc/f/125607348/m/48120554941?r=97420584941) </div></BLOCKQUOTE>

Thomas,

Yes, I have read that thread, very informative I must say. http://fsae.com/groupee_common/emoticons/icon_smile.gif But from what I could gather, in the first year, some of the needles in your roller broke due improper contact surface which is why you reduced the PCD of the non-cylindrical bores the next year. Please correct me if I'm wrong here! http://fsae.com/groupee_common/emoticons/icon_biggrin.gif
Also, very informative that the two circles of the non-cylindrical bore do not have to have a common center point. http://fsae.com/groupee_common/emoticons/icon_smile.gif
But then as you said, you did not do any calculations and wanted testing to speak for itself, therefore I am much confused as to how much the non-cylindricity should be. http://fsae.com/groupee_common/emoticons/icon_confused.gif
Any pics that you could share with me! http://fsae.com/groupee_common/emoticons/icon_smile.gif
Any help much appreciated.

Regards,
Sharath

[whiltebeitel]

Thrainer, did you just experiment with the bore geometry or do you have some calculations that you'd be willing to share that led you to your solution?

[scotty young Taylor Race]

Sharath.

The inserts you see from Pegasus are from us.These fit our larger aluminum housings
( 02002061)
These are inserts for the larger 30spline x 25mm OD axles found on most of the 2L formula cars.We just started making the small FSAE version 02002084 but I do not have any drawing available to share yet. But I will be more than happy to share the 02002081 steel version., The inner profile will be the same. Just shoot me an e-mail

[shark.ashwa]

Hi Scotty,

Thanks for the info. Should be mailing you soon!

Cheers,
Sharath

[Thrainer]

Sharath,

I didn't simulate or calculate the needed geometry, it was a result of observation and guesstimation. Here's a picture of 2010, but not very close-up:

http://www.amzracing.ch/files/cache/d5614ea2fe563ad76b79a73b1c271668.jpg

The tripod housing is also holding two bearings and the sprocket. Function integration: The lightest part is the one that isn't there.

The needles broke as a result of the large PCD and the plastic deformation of the contact surface (at least that is my guess).

Regards
Thomas

[shark.ashwa]

Thomas,

Thanks for sharing the pics! Much obliged....

Regards,

Sharath