My Car So Far...

[Dr.Jeff]

Stiffness of the spring need to be adapted to your shocks.

I would prefer to say, the shock should be matched to the stiffness of your springs (not the other way around), and the springs need to be matched to your car/set-up. But it is all a package that should go hand-in-hand as a matched set. And yes, individual preferences will certainly differ.

 

[Ben Louis]

Ive spent years running 125 shifter chassis and they have no suspension at all (not entirely true) so needless to say I tend to like a stiffer setup. I like driving racecars in general and always planned for this car to be in the street racer style well see if 425 is too much.

Also as an aside... never say your car handles like a kart... it doesnt...not unless you can sustain 2.5+ Gs and have a center of gravity 1/2” off the ground

 

[Dr.Jeff]

Ive spent years running 125 shifter chassis

On the streets and freeways?

 

[Ben Louis]

No the track
If your interested find the short you tube video of me driving the X earlier in the thread and follow it to my youtube channel. I havent posted there in while but there are a couple older videos of me spinning up some practice laps at Sonoma. Would you believe I took a break from racing to fix up this yellow pile? It was suposed to be a cheaper option that took less of my time...

 

[Ben Louis]

Here this is easier

https://m.youtube.com/channel/UCaTSRaXbcXwALHGDYJeodGQ

 

[Ben Louis]

Took the shocks apart, stripped, painted and re installed with new mounts and various other new parts.

This is how it was installed when I pulled it apart. I know it is wrong but it kinda works so itll have to do for now until I completely upgrade the whole shock assembly. Hoping up front there will be a thrust plate...

 

[Ben Louis]

Also got into the stupid dirty job of disassembling the CV joints and cleaning them for a regrease and new boots.

Me like shinny things!!

 

[DanielForest]

Ben,

I don't seen anything wrong. The "usual" order is fine for a stock set-up. On your struts, everything seems to be in the right place.

How is your collar stay in place on the threaded tube? Is there a screw in or is there something else underneath to jam when torqued against the collar?

 

[Ben Louis]

@Daniel
You hit the nail on the head. Ok now you got my consience going... should prob track down a second set of lock collars. Im wondering how to measure the thread size tho...

 

[Ben Louis]

Because so many things are wrong Im always asking myself with this car
“Is it right?”
Case in point:

Left is the old mount I removed. Right is replacement from Eurosport so Im inclined to trust it as being correct. Is it possible the old one is adapted from a 128 or something? Or is this actually the OEM X shock mount?

 

[Dr.Jeff]

Those lower threaded-perches are tall enough that you could drill a hole and tap it for a set-screw. It will not play nice with the threads on the sleeve, but a whole lot easier/less expensive than trying to find the correct locking rings. The thread sizes on coil-over sleeves vary a lot from brand to brand, and no telling what those are. Plus that is how some coil-overs do it anyway.

 

[lookforjoe]

Also got into the stupid dirty job of disassembling the CV joints and cleaning them for a regrease and new boots.

Me like shinny things!!

View attachment 10434

Did you mark the inner & outer CV races so they go back in the same orientation? Typically a wear pattern exists that may result in more rapid wear if not assembled as removed. This has been true for every one of this style joint I have serviced. Volvo used this identical style joint for the fore/aft driveshaft on their AWD models. Many are actually marked from the factory

In that application, they appear symmetrical, but in fact are not. They will go back together a number of ways, however, they will bind if not correctly oriented. Just check that the axles have full rotational swing through its intended arc.

 

[Ben Louis]

Very good point mine were marked from the factory but only on the inner piece. Because everything was greasy and wanting a more permanent solution since I intended to wire brush I used a punch to mark the outer race in a place that doesnt contact the hub flange (non sealing).

For the bearing cage I just used a pick to scribe a line. And once the inner pieces were out I punched them too that way all the witness marks would be present after solvents and a wire brushing

 

[Ben Louis]

One thing to note is that all four of my factory markings corresponded to ‘landmarks’ on various pieces leading to a standard which will give you at least one plane of orientation that you know will be right regardless of paint marks. (At least on my car)

Looking at the inner piece there is a distinct collar on one side

Looking at the opposite side you can see the difference

On all my CVs the factory marks had the center piece with ‘collar’ pointing away from the ‘boot’ end. The outer race has this machine mark and the ‘collar’ should be facing the same way.

***Note: my car may be completely different or your CV joints may have been assembled differently. These are only to be used as reference points!!

 

[Ben Louis]

It should be no surprise that the one CV with a ripped boot was no good so for now everything is bagged up waiting for a new CV to ship

This is why boots are important

 

[Steve Hoelscher]

Has anyone here installed poly bushes? Im wondering how much of an interference fit they are compared to the stock steel sleeves? Im hoping a little heat/cold will do the trick. Im pretty adept at installing bottom end bearings (motorcyle) this way but no amount of skill will help if they truly need a press fit.

This is my first look at your thread. Lots of cool stuff here. Nice work. I do have one comment regarding the above: You really don't want to use poly bushing in the control arms. If those are as stiff as most poly bushings they will bind badly as the control arm moves through its normal range of motion. This is because the axis of the two pivots are not on the same plane. Thus the bushing have to twist and they don't do that very well. The best solution is the OE type rubber bushings. They actually work very well.

Also, on the previous page you posted a picture of the coil-over springs. Do all 4 struts have the same 7" 425 lbs/in spring?

 

[Ben Louis]

So now you tell me!!!

Thanks Steve I appreciate it. Knowing people are actually interested puts a bit of wind in my sails.

First of you should know that I challenge everything in a coldly critical way so Im not at all saying you are wrong or attacking. Almost never is there 1 right way to get something done and the fact that Im challenging something at all usually means I think there is validity in it, if I thought it was Bs I would ignore it. I hope we can still be friends

This is why discussions and alternative viewpoints are necessary.

About the bushes... I have recieved only positive reviews on the poly setup from people who have used them. My understanding is that although poly bushes often transmit the feeling of bind more, they actually bind less. The reasoning is two fold
- softer bushes increase the angle of deflection giving more leverage to the binding force. This doesnt account for the damping action of softer bushes though.
- analogous to how a sway bar acts, poly bushes tebd to push back more on any force applied thus distributing the load to the opposite side more than a standard bush evening out the load and reducing bind.

This is all theoretical of course. More input on this issue is greatly appreciated!

I had not considered that the mount points werent on the same plane. This no doubt as you said contributes a signifigant twist.

This forum is great because you guys always seem to anticipate whats next which makes a great segway to a very related issue about twist and bind

 

[Ben Louis]

So ever since I first looked at the control arms I said this is wrong. What Im talking about is the huge unclosed gap here ( dont mind the damage, I think this arm was curbed at some point)

To me this area, and opposite side, create a scenario which is just begging for twist and distortion under load.

So my plan is to partially close (box) the middle points of the control arms where I imagine there being the most flex with a bit of steel plate. Did fiat intend for this to flex? Seems to me like a bean counters compromise more than anything

 

[Ben Louis]

Steve actually the front springs are 600.225.450...Facepalm.... its not my fault I swear

PO strikes again

 

[Steve Hoelscher]

First of you should know that I challenge everything in a coldly critical way so Im not at all saying you are wrong or attacking. Almost never is there 1 right way to get something done and the fact that Im challenging something at all usually means I think there is validity in it, if I thought it was Bs I would ignore it. I hope we can still be friends

This is why discussions and alternative viewpoints are necessary.

About the bushes... I have recieved only positive reviews on the poly setup from people who have used them. My understanding is that although poly bushes often transmit the feeling of bind more, they actually bind less. The reasoning is two fold
- softer bushes increase the angle of deflection giving more leverage to the binding force. This doesnt account for the damping action of softer bushes though.
- analogous to how a sway bar acts, poly bushes tebd to push back more on any force applied thus distributing the load to the opposite side more than a standard bush evening out the load and reducing bind.

I have had a pretty successful career in motorsport based on the simple idea of 'questioning conventional wisdom'. I think we'll be fine.

My assumption for the "positive reviews" on the poly bushings is this: Most users are replacing completely failed bushings with them. They have no experience using "new" OE bushings. Also, their cars are setup as primarily street cars that see occasional spirited driving or an occasional track day or autocross.

Try this test: Since you have the bushings installed already, fit one of the control arms to the car and torque the bolts. Do not attached the upright or strut. Now test the range of motion and see how smoothly it moves throughout its range. If these are typical of poly bushings then they will move reasonably well near the center of the range but the further away from the center you get the harder it is to move. This is because as long as the bushing centerlines are on the same plane they are fine. But the centerlines of the pivots are not on the same axis so the bushing must deflect to allow the control arm to move beyond the common plane. This causes the binding issue.

Softer bushings to not increase binding. They increase deflection. The deflection allows for unintended wheel movement, which isn't desirable either. I will address that issue in a moment. It is that un-intended movement that the poly bushings are supposed to prevent. They do but that comes with the binding issue.

Not sure I am fully understanding your second argument. You can't compare a swaybar bushing to these control arm bushings because swaybar bushings are designed to twist on a common axis. The specific problem I am describing is the result of the two pivots _not_ being on the same axis. For the control arm to move it must force the bushing to distort. And the purpose of using poly is to minimize distortion.

When I built my Championship DSP autocross car I had enough knowledge to know to evaluate the bushings. I was intending to replace them but upon studying them closely realized that would be counter productive. There are two primary reasons: 1) because the poly bushings would bind. 2) because the OE rubber bushings don't deflect as much as one might think. They are softer than the poly but only allow for a small amount of wheel movement before the rubber is compressed to its limit. To test this I replaced a bushing in a control arm with a new OE bushing. I then put a bolt through the bushing that I welded another bolt head to at 90 degrees. I then used a torque wrench to lever the bushing and measure the amount of torque it took to move the bushing. I no longer have my notes but I was surprised that the bushing moved easily for the first few degrees of movement and then quickly limited movement beyond that. This permits the bushing to twist as is necessary to accommodate the range of motion but doesn't deflect much from lateral cornering loads.

The effect of binding on the car's performance is two fold: 1) it causes a harsher ride as the control arm has to move beyond the centerline position to track over bumps. 2) It reduces mechanical grip as the suspension compresses and the bushing bind.

So, while all of my competitors used poly bushings in their control arms (conventional wisdom) I used replacement OE rubber. They worked surprisingly well.