Alfa Romeo 4C Forums banner

Problems fitting uniballs due to variations in rear arm sleeve dimensions

  • With fit problem MY14

    Votes: 0 0.0%
  • Without fit problem MY14

    Votes: 5 19.2%
  • With fit problem MY15

    Votes: 3 11.5%
  • Without fit problem MY15

    Votes: 9 34.6%
  • With fit problem MY16

    Votes: 4 15.4%
  • Without fit problem MY16

    Votes: 1 3.8%
  • With fit problem MY17

    Votes: 0 0.0%
  • Without fit problem MY17

    Votes: 2 7.7%
  • With fit problem MY18

    Votes: 0 0.0%
  • Without fit problem MY18

    Votes: 2 7.7%
381 - 400 of 455 Posts
As you are aware, there is some variation in the hole size of the A-Arms. Rudi has stated the preferred interference between the A-Arm and uniball which I can't remember right now, but press fit interference is typically between 0.0005 to 0.002 inch. I do have two suggestions... First, MEASURE everything (accurately) before doing anything. This will help prevent any issues in the future (or damaging during insertion). Second, I suggest using Loctite 638 when you press in the uniballs. This will help lock them in place if the A-Arms are slightly larger than the desired interference. Mine slipped a tad and had to be removed and reinserted (with the loctite). They have been perfect (even with heavy track use) ever since (nearly 2 years now).
 
Discussion starter · #382 ·
Hi guys just received Uniballs within 3 days all the way to Perth Western Australia. Well done Rudi. Unbelievably fast.

Question.... I have a 2016 Launch Edition, if the uniballs do not fit how much reaming is required on the arms and what tool/ process is recommended?

Regards

Steve
To fit in standard size uniballs the ideal size should be (40,95mm - 41,15mm BIG hole and 34.95mm - 35,15mm SMALL hole).
 
So is the issue usually that the holes are too big? If they are too small do need to get my arms machined by a machine shop or do I use some other manual method?
On memory with mine, two were too small, one was too large and one was just right. In the making of the arm assembly, the bush sleeves were pulled out of round by the welding process, I think. It obviously didn’t matter to Alfa since the original bushes were rubber and could conform to the deformed mounts.
 
@Masterofpuppets - It could be either too large or two small, which is why measurement before doing anything is so critical. If too small, have them ream it out to the dimensions that Gale said. Don't just "drill" it, the ream is much more precise and significantly higher tolerance than a drill bit. This will ensure proper dimensions. If it is too small, you will damage the uniball if you just try and press it in. If it is too large, then the loctite is a good solution if the difference isn't too large. If the difference is too large, you will need to come up with a different solution.
 
On memory with mine, two were too small, one was too large and one was just right. In the making of the arm assembly, the bush sleeves were pulled out of round by the welding process, I think. It obviously didn’t matter to Alfa since the original bushes were rubber and could conform to the deformed mounts.
Can I ask what you did to get them to fit? Did you use a die grinder, or sand them with wet and dry? What was the process? Obviously the slightly too big ones would be sorted with the loctite. Thanks mate. Noticed you are in Australia I'm in WA ?
 
@Masterofpuppets - It could be either too large or two small, which is why measurement before doing anything is so critical. If too small, have them ream it out to the dimensions that Gale said. Don't just "drill" it, the ream is much more precise and significantly higher tolerance than a drill bit. This will ensure proper dimensions. If it is too small, you will damage the uniball if you just try and press it in. If it is too large, then the loctite is a good solution if the difference isn't too large. If the difference is too large, you will need to come up with a different solution.
Just spotted your reply ?. So I'm going to have to actually machine them then on a mill? Bummer. Car could be off the road for a few weeks then. Or did you use a drill press with reamer Bit?
 
Can I ask what you did to get them to fit? Did you use a die grinder, or sand them with wet and dry? What was the process? Obviously the slightly too big ones would be sorted with the loctite. Thanks mate. Noticed you are in Australia I'm in WA ?
I entrusted my car to a local race shop. All I know is they had to carefully grind out the excess metal. For the slightly oversized Bush they loctited and tack welded (one spot) it in place. No problems yet experienced. These guys prepare cars for Porsche Cup and do lots of one-off work. They’ve just restored a genuine aluminium bodied 1300GTA and a Montreal so are also dedicated to the Alfa cause. I’d be looking for someone in WA with Alfa race prep credentials or similar to entrust your car to.
 
Discussion starter · #389 ·
All the problems so far came from incompetent shops. Pressing the bushes in without following the instructions.

Alignment is also a common problem with 4C as my experience tells me is that quite a few alignment shops can't set the 4C and then they say it can't be done. I can assure you that with GMS uniballs and camber and caster plates you can get whatever desired specs according to our recommendations are. So if the shop is telling you they can't get more than 1.5 degree or camber or caster is missaligned then get a other shop to do it.

We did 4 uniball conversions for customers so far and all fitted with standard bushes. Not sure if lucky or skilled. ?
 
I entrusted my car to a local race shop. All I know is they had to carefully grind out the excess metal. For the slightly oversized Bush they loctited and tack welded (one spot) it in place. No problems yet experienced. These guys prepare cars for Porsche Cup and do lots of one-off work. They’ve just restored a genuine aluminium bodied 1300GTA and a Montreal so are also dedicated to the Alfa cause. I’d be looking for someone in WA with Alfa race prep credentials or similar to entrust your car to.
Yeah I have a shop that I used to use for fabrication and machining on my Japanese cars so I will go to them. Thanks for the help and advice.
 
Hi Rudi, received perfectly on time your uniballs and had them mounted by my workshop without much trouble.

In the next days I’ll get the car back and am so much looking forward to test them.

thanks a lot again in the meantime for your speed and efficiency!

Btw my mechanic told me that wheel hub at the end of the rear right arm is getting loose and creates a “clank clank” under acceleration/deceleration. Has anyone experienced this? Would this be dangerous during spirited or track driving? Is it true that I’d have to change the entire rear arm to solve the problem?
 
@emacos - I know of one bearing failure by @Call me Al. His failed on the track and lead to some adventure.... I believe that it is a "simple" bearing that needs to be pressed in & out.
 
Discussion starter · #398 ·
@emacos - I know of one bearing failure by @Call me Al. His failed on the track and lead to some adventure.... I believe that it is a "simple" bearing that needs to be pressed in & out.
In case you are referring to, the front arm uniball failed. We have zero failures with our GMS uniball rear arms so far.
 
Discussion starter · #399 ·
Hi Rudi, received perfectly on time your uniballs and had them mounted by my workshop without much trouble.

In the next days I’ll get the car back and am so much looking forward to test them.

thanks a lot again in the meantime for your speed and efficiency!

Btw my mechanic told me that wheel hub at the end of the rear right arm is getting loose and creates a “clank clank” under acceleration/deceleration. Has anyone experienced this? Would this be dangerous during spirited or track driving? Is it true that I’d have to change the entire rear arm to solve the problem?

Same happened to me a few times. A clunking noise on the track was caused by loosend rear shock to hub carrier. Check there first.
 
381 - 400 of 455 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top