got 15mm knuckles & want them to be 16mm?

[ClodMaxx]

i bought a used EXT Pro suspension set, with the old 15mm openings. i then bought 8mm cvds, without doing my homework first. i did like many others and looked for the right size bearings, which are 8x15x5 (and are non-existent). i happened to call a local machine shop (they made dies) to see if they were up to the task of boring my 15mm holes to 16mm. they turned out better than i hoped!

front view (both have the new 16mm holes - one just shows an avid 8x16x5 bearing and the other shows the nicely-machined hole)



and from the inside:



he had to use a lathe and machine 2 solid metal rods: 1 was 15mm to hold one end, and the other rod was 16mm to hold the new 16mm hole side and open the remaining hole. the rods fit right were the bearings seat, and a big milling machine opened the other end. these things are machined to perfection - the bearing slides in easily with little to no play. his normal corporate rates are $80/hr, and i was in there this morning for 1.5 hours. only about 20 minutes were used to mill the holes out - it took over an hour for him to figure out how to hold the knuckles and have the holes be exact when he was finished.

i told him to keep the 2 pins and i would see if anyone else wanted this done to their 15mm knuckles. he said he could do more for $40 (about a half hours worth of work to do a full set) but that i should see how many people would be interested first. if anyone is interested, respond to this or PM me. you'd of course have to pay shipping here and back, but i wouldn't guess it would be more than $5 to ship them back to you, as long as you're in the U.S. :027:

[Serum]

That's not bad at all!

A lathe makes perfect holes, seems like he knows his stuff. :)

[ClodMaxx]

he's this little old german guy - super nice and showed me around all of his CNC machines, presses and other things i've already forgotten the names of. he told me that i'm welcome to stop by for any other 'challenges' like this...but i'll still order my aluminum motor mounts from mike. :005:

the lathe wasn't what opened the holes, although that would've been ideal except we couldn't figure out how to hold the irregular shaped knuckle and keep it true. he used the lathe to mill 2 pegs - one that was 15mm and the other was 16mm. the pegs were then put in this big milling machine that looked like a giant drill press on steroids. he had a 16mm drill bit thing that came down to open the holes. the milled pegs he created held the knuckle from the bottom, fitting into the lower bearing slot.... i just re-read this, and there's no easy way for my creative brain to 'splain it. :eek: i hope i'm making sense.

[Serum]

I've got a clear visual.

Now you can use 8mm cvd's.

[ClodMaxx]

yep, and i'm so glad i can now use the 8mm cvds. i thought i was stuck with the 6mm cvds (which aren't so bad, but i wanted tougher)

if anyone else has 15mm bearing knuckles and would like them to be 16mm, let me know.

[ClodMaxx]

well i'm sorry to say i heard from robin (at UE) tonight and the news wasn't great. his quote:

You should be machining these with .001" of clearance.

We never did it with a bit, we bored it with a boring tool (infinitely adjustable.)
You could also circular interpolate it with a smaller bit.

The boring is best because you can do both sides from one setup. That keeps everything on axis.

i guess i'll scrap my idea of doing it for others now... i don't believe my local guy has this technology. i don't want anyone spending the $45 and not having something right. :007:

[Serum]

Sounds like Robin made his holes with a reamer, if the guy did a good job by centering the two holes (aligning them parallel) it should be no problem (if the holes are a good tight/loose fit for the bearing). perhaps he told you he used a drill, but he used something different.

a drill has 2 cutting flanges, and an adjustable reamer has got many more. a drill has got the tendency to make triangle holes instead of perfect round ones.

I just checked a new racer-X I've got here; the front knuckles are 16.00 mm, and the rear knuckles are 15.98 mm

Typical size for a 16mm OD bearing is 15.97.

[Gustav]

Originally Posted by ClodMaxx

well i'm sorry to say i heard from robin (at UE) tonight and the news wasn't great. his quote:



i guess i'll scrap my idea of doing it for others now... i don't believe my local guy has this technology. i don't want anyone spending the $45 and not having something right. :007:

If there's no slop then it is fine,it should be 16mm,the bearings are meant to go in a 16mm hole after all.This guy did a great job for you,sounds like he knows his stuff.he probably used a 16mm end mill?

[ClodMaxx]

he did do a great job, and was very patient and kind. i know he said what he used was a big milling machine, but the bits were double sided (not sure what they're callled - could be end mill). he didn't have one that was exactly 16mm, but he did have one that was just barely over. his calipers read something like .635 (16mm is .629") so it was very close. the 16mm bearings don't press fit as hard as the 15mm ones did, but they don't fall out either.

i can't imagine the bearings have that much load where .035"+ tolerance will make that much of a difference. robin's stuff is extremely precise and perfect, which is what makes UE the quality that it is. all i can do is run them and see over time how they hold up. it was suggested to use loctite stud and bearing mount, but i want to be able to take the bearings out and replace them when they wear out, lol.

[Serum]

robin's stuff is extremely precise and perfect

Normally yeah, but with the servo saver there is a small error. The bearings are pressed together if you tighten it, causing them to fail.

I've got 3 ue savers, and all three have the very same problem.

A bearing hole that is .13 mm too large is not good? have you got a caliper? if the bearing is a snug fit as you describe, the bit was most likely smaller.

clod, I wouldn't worry about it. If it fits, it fits. A true machinist with talent can do amazing things. Not to pat myself on the back or anything, but I've done things on a lathe that some said I couldn't do. The guy that you went to sounds like he's been doing it for a while. A good experienced machinist that's been around longer than small cnc machines knows how to get over hurdles and has probably forgotten more than the younger guys today will ever know.

Besides, he probably did use a reamer and accounted for variations in the size of the bearings. Those holes that I saw in the pics were NOT made by a simple drill bit.

I've also found that manufacturers really do like to overstate things, or make mountains out of mole hills.

[Serum]

amen.

and by looking at these holes make me realize they are not .12mm too large either.

[ClodMaxx]

thanks serum and aangel. i don't have calipers, but have my eye on a nice digital fowler set on ebay.

he's an older guy - probably late 60's or early 70's - and does know his stuff. and everything he did was measure 4 times, cut once. he told me that some of the big shops wouldn't have taken the time - which i believe - and that if i had any other problems like that to stop by. a great guy. :003:

serum - your UE servo savers have me worried as that's my next purchase. were all 3 of them gen. IV?

aangel - if i had to guess, i'd say you nailed it - robin is most likely very, very picky!

If you are looking for a decent caliper, you could check out the cheapie made in china jobs that harbor freight has. The digital model goes for under $20, when on sale. I have a few of them laying around and they are more than accurate enough to do general measuring and machine work. If you really want to get accurate, I'd say go with a micrometer.

[ClodMaxx]

yeah, i've seen the cheapie ($7) digital calipers floating all over ebay but questioned how good they are. i'll check harbor freight to see if they're the same thing - if not, i'll get one from harbor freight. thanks!