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EBJ vs. Offset Bushings and Slotted Control Arms Question.

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#1
bmarshall1

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I have 2 questions:

 

Which is better and why: the EBJ or Offset Bushings,  They both give the same results but the difference is how one gets there.  Are there any advantages one over the other?  It would seem the EBJ might widen the track a touch since they are pushing the bottom out vs. Offset Bushings pulling the top in.

 

Secondly, on slotted rear control arms, with the alignment cams at the 12:00 position I have 3.6 degrees camber.  My question is should I be using the inboard portion of the slot for camber (giving me too much camber) and pulling the lower control arms in (while setting toe), or use the alignment cams for camber/toe and 'save' the slot if I need more camber (or if I get hit, bend something and need more range than the the cams can give me).  To put it simply - use up the slot first for initial camber adjustment or use the cams first?



#2
Ron Alan

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You answered your own question in the 1st paragraph...LOL. That said...for the real amateur the ELBJ is a much easier install and probably less expensive! 

 

Only slot your upper rear control arms if you need to for the camber you like(to each is own)! Otherwise leave them alone!


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#3
bmarshall1

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You answered your own question in the 1st paragraph...LOL. That said...for the real amateur the ELBJ is a much easier install and probably less expensive! 

 

Only slot your upper rear control arms if you need to for the camber you like(to each is own)! Otherwise leave them alone!

 

Welp... too late for that :noidea:   I thought it was the new hotness to be able to change camber while not messing toe in.  Either way I have the choice of using the 'slot' or not.  And if I get hit I have extra room to adjust before I need to start replacing parts at the track, at least that's my theory.



#4
Jim Drago

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Welp... too late for that :noidea:   I thought it was the new hotness to be able to change camber while not messing toe in.  Either way I have the choice of using the 'slot' or not.  And if I get hit I have extra room to adjust before I need to start replacing parts at the track, at least that's my theory.

nope, it was a rule that was never needed IMO

Perhaps some on the rules committee like to run 4 degrees on the rear ;) 


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#5
Jamz14

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IMO, you did not answer your own question in the first paragraph. Pulling in the top of the wheel is not the same as pushing out the bottom even if you land on the same camber number. Just like in balancing a cars grip. You can either take away grip from the end that is sticking, or you can add grip to the end that is sliding. The result is the same with a car that has balanced grip but in one case you have a car with less overall grip but balanced, and in another case a car that is balanced but with more overall grip.

 

So IMO, it is important how you go about achieving something. How you achieve something can have an impact outside of the specific thing you are trying to achieve. Knock on effects. IMO things like setup geometry are dynamic and there are sacrifices based on how we do things.

 

But just so you know, no one agrees with me on this point either. So if it is important for you to be accepted by others in how you do things, go with the bushings. They will also tell you that the ball joints fail at a higher rate (even though I have had the same set on a car for 4 years). I will also concede that the knock on effect i am worried about in using the bushings over the EBJs is probably very small. However I listened to the same people advising you now very early in my SM life and what they told me was that champions worry about very small things. And that by adding up very small things they aggregate them into a championship winning car.

 

Now if I was a betting man and I listened to people here and they all said it doesn't matter which way you do it; and there was one raven lunatic that said it did matter; then I would go with the lunatic because he just might be right. And per others you can't be wrong going with the lunatic because it doesn't matter, right??


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#6
Jamz14

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I also agree with JIm. You should be able to achieve sufficient rear camber without slotting unless there is something bent.


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#7
ChrisA

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One thing to be aware of is, that with the ELBJs pushing the wheel out, you reduce the number of threads the tie-rod has within the tie-rod end links. Depending your final front numbers, it could push you toward a safety margin issue. Unless you like a LOT of toe-in that is...


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#8
bmarshall1

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One thing to be aware of is, that with the ELBJs pushing the wheel out, you reduce the number of threads the tie-rod has within the tie-rod end links. Depending your final front numbers, it could push you toward a safety margin issue. Unless you like a LOT of toe-in that is...

Thanks All,

 

The arms are slotted so I see no reason not to use them.  And I suppose like the EBJ vs. Bushings,  I can at this point (on the rears) pull the tops in or push the bottoms out via the cams.  If I get hit in a race Ill have extra adjustment room.  Since my wheels aren't the max offset, and at this point I have the EBJ's, I'll use the rear cams to get the needed camber while getting the widest track possible.  

 

Is that a reasonable way to look at things?

 

I'll also be aware of making sure I have plenty of threads on the tie-rod ends.  On a similar note, I was reading a white paper on bolt threads and such, the first threads on a bolt takes 34% of the load, then 23%, 16% , 11%, then 9%.  So... if you have the first four threads of a bolt, nut, or something you have the vast majority of the strength. Five threads and you're around 90%



#9
bmarshall1

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IMO, you did not answer your own question in the first paragraph. Pulling in the top of the wheel is not the same as pushing out the bottom even if you land on the same camber number. Just like in balancing a cars grip. You can either take away grip from the end that is sticking, or you can add grip to the end that is sliding. The result is the same with a car that has balanced grip but in one case you have a car with less overall grip but balanced, and in another case a car that is balanced but with more overall grip.

 

So IMO, it is important how you go about achieving something. How you achieve something can have an impact outside of the specific thing you are trying to achieve. Knock on effects. IMO things like setup geometry are dynamic and there are sacrifices based on how we do things.

 

But just so you know, no one agrees with me on this point either. So if it is important for you to be accepted by others in how you do things, go with the bushings. They will also tell you that the ball joints fail at a higher rate (even though I have had the same set on a car for 4 years). I will also concede that the knock on effect i am worried about in using the bushings over the EBJs is probably very small. However I listened to the same people advising you now very early in my SM life and what they told me was that champions worry about very small things. And that by adding up very small things they aggregate them into a championship winning car.

 

Now if I was a betting man and I listened to people here and they all said it doesn't matter which way you do it; and there was one raven lunatic that said it did matter; then I would go with the lunatic because he just might be right. And per others you can't be wrong going with the lunatic because it doesn't matter, right??

You seem to offer an alternate opinion, so what's your final answer?



#10
Jim Drago

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Thanks All,

 

The arms are slotted so I see no reason not to use them.  And I suppose like the EBJ vs. Bushings,  I can at this point (on the rears) pull the tops in or push the bottoms out via the cams.  If I get hit in a race Ill have extra adjustment room.  Since my wheels aren't the max offset, and at this point I have the EBJ's, I'll use the rear cams to get the needed camber while getting the widest track possible.  

 

Is that a reasonable way to look at things?

 

I'll also be aware of making sure I have plenty of threads on the tie-rod ends.  On a similar note, I was reading a white paper on bolt threads and such, the first threads on a bolt takes 34% of the load, then 23%, 16% , 11%, then 9%.  So... if you have the first four threads of a bolt, nut, or something you have the vast majority of the strength. Five threads and you're around 90%

If you slotted rear arms, it is my opinion you should use the entire slot and adjust camber with cam bolts. They are not designed to be slotted, while I have not tested, i believe under load they could move in board under load or when you hit a curb. 

 

On fronts, do whatever you want, both will work fine. 

Running the cars as we do, we have failed extended ball joints, perhaps we have more curbs, run the cars harder or just bad luck, IDK.  FWIW, the cars that won three of the last four Sprints, Runoffs and Super Tour championships all ran offset bushings, I know as we built them here  :)   My theory has always been copy what works until you are at that level, then work on improvements. 


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NASA Champs Winner - NASA Champs Winner Hoosier Super Tour points Champion - Hoosier Super Tour points Champion ARRC Champion - Won the ARRC Race in a Spec Miata Series Champ - Won a points based series in a Spec Miata BFG Supertour Winner - Majors Winner - Circuit of the Americas Winner - We have a Winnah! - Won their 1st race... Congratulations! June Sprints winner  - June Sprints winner June Sprints winner  - June Sprints winner June Sprints winner  - June Sprints winner June Sprints winner  - June Sprints winner SCCA National Champion - Won SCCA Runoffs at Road America SCCA National Champion - Won SCCA Runoffs at Road America

#11
bmarshall1

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If you slotted rear arms, it is my opinion you should use the entire slot and adjust camber with cam bolts. They are not designed to be slotted, while I have not tested, i believe under load they could move in board under load or when you hit a curb. 

 

On fronts, do whatever you want, both will work fine. 

Running the cars as we do, we have failed extended ball joints, perhaps we have more curbs, run the cars harder or just bad luck, IDK.  FWIW, the cars that won three of the last four Sprints, Runoffs and Super Tour championships all ran offset bushings, I know as we built them here  :)   My theory has always been copy what works until you are at that level, then work on improvements. 

Thanks Jim - this is the type of analytical information I am looking for and what you stated makes perfect sense.  I don't get out as often and am not as fast/aggressive as you/your drivers are so the EBJ's will last me a vary long time.  My front wheel bearings lasted about 6 years if that is any frame of reference.



#12
Jim Drago

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Thanks Jim - this is the type of analytical information I am looking for and what you stated makes perfect sense.  I don't get out as often and am not as fast/aggressive as you/your drivers are so the EBJ's will last me a vary long time.  My front wheel bearings lasted about 6 years if that is any frame of reference.

EBJ are easier, go that route.. You can always swap if they fail.  Best of luck

Jim


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