119 replies to this topic

[RWP80000]

I like Jim's idea on floating a hard epoxy to fill the void of the irregular top hat surface as we would not give up any shock travel to accommodate a thicker washer.  The fronts do not have this issue due to the black Delrin hard spacer being used.  My concern is what this distortion will due to the long term durability of the orange jounce bumper cushion.  Will the irregular distortion start to initiate cracking? I believe there was discussion of this material not being able to absorb extreme compression with out incurring damage.  Will the stress concentration from being compressed over the distorted washer affect the life and integrity of this part?  

 

Another thought is to use a much larger outer diameter on this washer so it spans the void out to where the top hat is at the same height.  That would prevent such a large distortion of the current washer.

 

Rich Powers

[Jim Drago]

OK, just looked at Ralph’s original FB posts (thanks again Ralph!). I’m repeating myself, but I really don’t understand why they didn’t shorten the rear shock body by at least 1/2 inch, or even more so they could stack two stops of different rates as they do up front. I don’t know how firm the rear stop is but it looks quite short so even if fairly soft it will just compress quickly then effectively go to infinity anyway. As much as the washer is deformed it must have done exactly that. Hopefully that was just one really big hit but curious to see what others find on each corner of their cars.

 

I only saw Carters, It was not as bad as mine, but 50-75% as bad

[ChrisA]

I like Jim's idea on floating a hard epoxy to fill the void of the irregular top hat surface as we would not give up any shock travel to accommodate a thicker washer....

 

Rich Powers

 

However, filling the void around the pillow-ball mount with an epoxy or whatever, would make getting a socket on there in the future rather difficult.

[Danica Davison]

So you are saying you think they made a bad decision    

 

No, I am not saying they made a "bad" decision. I am saying they made a different decision than the alternative, which would have stopped the clock, and saved more time for racing.  I think either one would have been an acceptable decision in this instance.

[Jim Drago]

No, I am not saying they made a "bad" decision. I am saying they made a different decision than the alternative, which would have stopped the clock, and saved more time for racing.  I think either one would have been an acceptable decision in this instance.

Its ok.. You can say it

 

[Brandon]

Would this be considered a "complete assembly" and thus excluded from the "hardware and fasteners are free"?

 

Swap a wider & thicker fender washer to span the void between the top hat and the through-nut, problem solved, no?

[Bench Racer]

Steve S. or anyone else please open the following address and scroll down to post #190 for a graph of the Penske and FatCat bump stop rates. 

 

https://mazdaracers....sa-scca/page-10

[Steve Scheifler]

Steve S. or anyone else please open the following address and scroll down to post #190 for a graph of the Penske and FatCat bump stop rates.

https://mazdaracers....sa-scca/page-10

What’s your point Bench?
At 8mm the rears are effectively identical to the old, the new ones much stiffer when compressed more, though that’s misleading if the new top mount reduces the amount of room at the top, in which case the new ones are effectively somewhat stiffer than his numbers imply.

It is a more complicated comparison than those simple numbers, so exactly what are you trying to demonstrate?

[Bench Racer]

What’s your point Bench?
At 8mm the rears are effectively identical to the old, the new ones much stiffer when compressed more, though that’s misleading if the new top mount reduces the amount of room at the top, in which case the new ones are effectively somewhat stiffer than his numbers imply.

It is a more complicated comparison than those simple numbers, so exactly what are you trying to demonstrate?

Steve, the rears in the graph don't travel to 8mm. They travel to 4mm (.156 inch) and the load is 1,400 pounds. For all practical purposes at 4mm travel the rear is solid. And more stuffs going to break than bending the thin shim/washer. Wonder what the rear bump stop looked like after being test squashed by 4mm (.156 inch). Wonder what Jim Dragos rear bump stop looks like after deforming the shim/washer. Jim, did the rear bump stop have memory and return to original shape? If it didn't return to original shape please post a picture.

 

I reread all the posts in the Mazda Spec Miata Shock Upgrade thread posted 8/14/18. Many comments about using the what I'll call normal ride height of aprox. 4 5/8 inch and no one from the special test team mentioned anything about oversteer/understeer or deforming any parts. That troubles me because Jim Drago setup his car for Sebring much higher than normal and his shim/spacer was deformed. With that sort of banging to deform the shim/spacer more parts will fail. With a car setup at normal ride height of 4 5/8 inch parts are going to fail quicker than Jim's part failed from his higher ride height at Sebring. Jim, thank you for posting your shim/spacer picture and setup heights. Many racers travel on the Gators and the shocks/mountings should withstand such treatment as most of us are not professional drivers with the capability to stay off the Gators therefor for the shock manufacture to say stay off the gators is unrealistic. Using the normal ride height of 4 5/8 inches with the shock rod mounted higher, there would be more shock travel before the shock body top mashed anything.

[Jim Drago]

Steve, the rears in the graph don't travel to 8mm. They travel to 4mm (.156 inch) and the load is 1,400 pounds. For all practical purposes at 4mm travel the rear is solid. And more stuffs going to break than bending the thin shim/washer. Wonder what the rear bump stop looked like after being test squashed by 4mm (.156 inch). Wonder what Jim Dragos rear bump stop looks like after deforming the shim/washer. Jim, did the rear bump stop have memory and return to original shape? If it didn't return to original shape please post a picture.

 

I reread all the posts in the Mazda Spec Miata Shock Upgrade thread posted 8/14/18. Many comments about using the what I'll call normal ride height of aprox. 4 5/8 inch and no one from the special test team mentioned anything about oversteer/understeer or deforming any parts. That troubles me because Jim Drago setup his car for Sebring much higher than normal and his shim/spacer was deformed. With that sort of banging to deform the shim/spacer more parts will fail. With a car setup at normal ride height of 4 5/8 inch parts are going to fail quicker than Jim's part failed from his higher ride height at Sebring. Jim, thank you for posting your shim/spacer picture and setup heights. Many racers travel on the Gators and the shocks/mountings should withstand such treatment as most of us are not professional drivers with the capability to stay off the Gators therefor for the shock manufacture to say stay off the gators is unrealistic. Using the normal ride height of 4 5/8 inches with the shock rod mounted higher, there would be more shock travel before the shock body top mashed anything.

I am going to record to recognize this day in Mazdaracers history... You hit many good points and I am in agreement with all 100%

 

I did not look at the bump stop as I had a flight to catch.. The guys are off today and we are slammed so not sure when, but I will pull all four shocks off and take a look and report back.

 

In hindsight... I wish I would have looked at the shocks after Homestead, Turn 1 there is very fast, I would guess 115 or so and I put the car on the wall at apex which is directly over rumbles that are not intended to be driven over. Did that do it? I don't know.  I dropped a wheel or two for certain over the weekend at Sebring as well, did that do it? No idea. I don't think that normal driving at Sebring caused it only because I didn't feel any big shunts off the stop?   Maybe driving 15 years on the bilsteins the bounce wasn't as drastic as predicted? Sebring is definitely the exception, not the rule.. So I think this should be worst case scenario..  It is by far the bumpiest we go to.

 

We will work around it, it will end up being fine I'm sure, there are some smart people on the case. But, I too am surprised that we didn't start with a shorter shock body in the rear.  

[Steve Scheifler]

Bench, as usual we’re failing to communicate.

What I see from Ralph on the rear Penske (actual value list, not chart) is exactly three data points: 12mm = 0 lbs, 10mm = 740 lbs, 8mm = 1460 lbs. The fat cat is much taller and softer but by the time it is compressed to a height of 8mm he shows a pressure of 1490. I said “at 8mm they are effectively identical to the old”. That would be 1460 vs 1490. Look again at his actual data. You are speaking of the amount of compression of the bump stop while I am talking about the remaining thickness of the stop itself. BIG difference. Your appoach doesn’t account for the difference in free length. Ralph listed the data to reflect the bump stop hardness at various points in SHOCK travel, which is what’s relevant. Of course rate of progression is also relevant and that too is easily seen in the data. Looking at the graph misses the most important half of the story.

So as I said, The old and new cross when the shock body is 8mm from the hard top hat/nut assembly. Before that the old setup was actually stiffer but more gradual because it was so much taller. Below 8mm probably doesn’t matter but if you could get there without splitting them the new ones are probably stiffer.

Other than looking at the data from opposite ends we aren’t actually all that far apart. If someone has a set not yet installed I would very much like to know the difference in the top “seat” position new vs old. As I alluded to above, when using Ralphs data as a proxy for shock position that’s the value still missing. For example if the new nut & washer under the hat extend down 4mm more than the old setup, then all else being equal you have lost 4mm travel (or go 4mm deeper into whichever bump stops). Right? So those of us who like to analyze and theorize things to death need that.

As for Jim’s case I expect it was from particularly big hits. I’m worried about still needing to chase camber in back since they didn’t shorten the tube, but unless the new top mounts are giving up a lot of travel I don’t see how Jim could hit them that hard under normal cornering even at Sebring given the shock valving.

[Ron Alan]

Steve...just put mine together yesterday. The nut for the spherical bearing in the top hat sits maybe 3mm below the top hat surface. So tight in fact my only 1 1/4" socket(thicker impact style) would not grab it! In the fat cat you have the yellow foam and the aluminum washer. If I had to guess we picked up maybe 4-6mm of travel there?

 

I saw Jim's picture the night before so when I got to this point, and then understood, I was searching for a slightly thicker fender type washer to install! And as Rich mentioned...only concern is having the new bump stop break over time if its not supported in its entirety on the nut side. In the end I installed as it came...hopefully it wont be an issue!  

[Steve Scheifler]

Thanks Ron. So the nut flange/head is about 1/8” thick and pulls up to the bottom of the hat, or a 3mm gap? Sounds like the latter but want to confirm. Given what I recall as a concave shape under the hat I don’t think the tapered yellow foam, installed correctly, actually spaces the red washer down at all, so that isn’t a factor.

A little direct measurement would settle it, but it sounds like we are very close to break-even on that dimension. I believe the old red washer is slightly thicker than 1/8” and is probably larger in diameter (making it sit lower in the tapered hat when viewed as installed), but of course no 3mm gap as you describe.

Seems silly to look at few mm until you see the bump stop rates in the event that you actually need those last 3-4 mm. In that case it’s the difference between a sponge and a brick!

[Ron Alan]

The head of the nut pulls tight against the top hat metal...and is only 3-4mm thick...no gap. Basically the surface below the underside of the top hat at which the new bump stop makes contact is higher than were the old bump stop met the red washer...by how much i dont know...but its measurable for sure. 

[Steve Scheifler]

Ah, very good, thanks!

[Preston Pardus]

Had a blast hanging out with everyone the past few weekends! As mentioned, it was a shame we didn't get much track time on Sunday since the Saturday race was shortened as well   

[Jim Drago]

Those videos are a clinic on how to drive Sebring... Unfortunately for most.. It is far easier to see what to do and know what to do than it is to actually do it! Very nice Preston. You don't get the credit you deserve behind the wheel! You are as good as any I have raced in 15 years of Sm! 

[Richard Astacio]

Awesome drive! You and the car are on rails! 

[Bench Racer]

Preston, Bilstein rails or Penske rails?

 

EDIT:

 

Ok, so I backtracked and found the shock information. In this corner is Billlsteeein and in the other corner is Pennnskeee, AND THE WINNER IS Billllsteeein. 

[Danica Davison]

I called it! P$ the GOAT !!!!