Rear Suspension...i Have Some Questions

LOTAHP

LOTAHP

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Apr 7, 2008
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Florida
First, let me start by telling you I have a VBP Dual Mount rear composit spring with Carrera adjustable shocks (on the stiffest setting, 50/50 supposingly), no rear sway bar.

I would like coil-over shocks that need NO fabricating (I do not weld).

Questions:
(1) Can I eliminate the dual mount spring with a set of coil-over shocks?

(2) Will the rear suspension be just as stiff as it is now? (it's pretty firm now)

(3) Will I lose any side to side support/stiffness? seeing the composit spring and the sway bar (if I had one) connect to the trailing arms.

(4) What are some high quality coil-over shocks (that would be a bolt-on application) you guys can recomend?

Thanks

The car is a street car, I do drag race it frequently but never autocross or roadrace the car
 
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LOTAHP
Greetings -- I have been doing a bit of research on the coil-overs and monoleaf comparison. I was going to do a 6-Link with coil overs (see my Roadmap fro Rear suspension Postings), BUT, now am moving to a dual mount monoleaf!
Why? Well, one thing you can't do (without buying new shocks it seems) is adjust ride height. The coil-overs look like you could - but as you compress the springs -- to try and adjust ride height -- you make significant changes in spring rate( with many if not most springs). SO, I'm now firmly in the get a (keep) a monoleaf camp-- having ordered one TODAY!

Varishocks were mentioned to me by Mark at Sadveske as a very good shock - and I will be getting dual adjust (non-coil overs) to do street/drag/autoX. for both teh front and rears.
They have a COUPLE OF GOOD ARTICLES HERE:
http://www.varishock.com/vas_articles.html, JUST READ PAST THE COIL SPRING ADJUST PARTS - if you are going to keep the monoleaf.

Here are a few words from the guys at VanSteel[as I recall] (on another board):

You will see a real benefit with the dual mount and rear adj shocks if you like tinkering with the suspension and are interested in doing different events. You get the adjustable spring rates and the ability to adjust rebound and compression of the shock for different applications. Have a street setting and a track setting. Once you get it dialed in, you'll know what to change when you go to the different events. ​

I thought it interesting that they were making that statement as they don't sell a monoleaf setup -- or maybe I just misplaced the correct reference? Maybe it was VB&P - as they do sell the monoleaf! I forget.

Hope that helps - or at least there is plenty of reading!

Cheers - Jim
 
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phantomjock said:
LOTAHP
Greetings -- I have been doing a bit of research on the coil-overs and monoleaf comparison. I was going to do a 6-Link with coil overs (see my Roadmap fro Rear suspension Postings), BUT, now am moving to a dual mount monoleaf!
Why? Well, one thing you can't do (without buying new shocks it seems) is adjust ride height. The coil-overs look like you could - but as you compress the springs -- to try and adjust ride height -- you make significant changes in spring rate( with many if not most springs). SO, I'm now firmly in the get a (keep) a monoleaf camp-- having ordered one TODAY!

Varishocks were mentioned to me by Mark at Sadveske as a very good shock - and I will be getting dual adjust (non-coil overs) to do street/drag/autoX. for both teh front and rears.
They have a COUPLE OF GOOD ARTICLES HERE:
http://www.varishock.com/vas_articles.html, JUST READ PAST THE COIL SPRING ADJUST PARTS - if you are going to keep the monoleaf.

Here are a few words from the guys at VanSteel[as I recall] (on another board):

You will see a real benefit with the dual mount and rear adj shocks if you like tinkering with the suspension and are interested in doing different events. You get the adjustable spring rates and the ability to adjust rebound and compression of the shock for different applications. Have a street setting and a track setting. Once you get it dialed in, you'll know what to change when you go to the different events. ​

I thought it interesting that they were making that statement as they don't sell a monoleaf setup -- or maybe I just misplaced the correct reference? Maybe it was VB&P - as they do sell the monoleaf! I forget.

Hope that helps - or at least there is plenty of reading!

Cheers - Jim
Click to expand...

Gotta disagree with the spring rate change claim.
 
Yes, you can not change spring rate unless you cut the spring changing the # of active coils. What you do by preloading the spring with the adjuster more or less is change the static spring load. Raise the static load and it takes even more weight to compress it from there on. The only exception is a set of variable rate springs where the coils are wound tight and loose from end to end. The tighter wound part has a lower rate (very simple, more coils to divide total compression over, so each one takes a smaller increment and as such spring rate x deflection per coil is a lower total). Preload one of those and the lower rate section compresses first until the spring load in that part starts to rise to where the rate of the other part is met and those are compressed too on increasing load. This does change the effective spring rate when preloading and does change the feel of the spring.

Van Steel does sell the monoleaf setup.
 
Yeah - Like what Twin Turbo said - Thats what I meant... :eek:

hadn't seen theVanSteel monnoleaf in the catalog - but that makes sense regarding the comments then.

ANYway - you can change both Ride Height - and Spring Rate on a monoleaf.
Its gotta be simpler than swaping out springs, and shocks!

Cheers - Jim
 
phantomjock said:
Yeah - Like what Twin Turbo said - Thats what I meant... :eek:

hadn't seen theVanSteel monnoleaf in the catalog - but that makes sense regarding the comments then.

ANYway - you can change both Ride Height - and Spring Rate on a monoleaf.
Its gotta be simpler than swaping out springs, and shocks!

Cheers - Jim
Click to expand...

Why would you have to keep changing shocks? Once you have the shocks your done. You may have to change springs for different apps but a spring change is about 10 minutes per shock that you don't have to use a coil spring compressor with and that includes removing the shock from the car.

Varishocks are just as good as a QA1 shocks and that doesn't say a whole lot as far as a performance shock goes. Both are great for basic entry level guys. If you want to step up to the plate and play ball, you need Penski's or Koni's with Hyperco springs. Chinese spring are to inconsistant in rate.

LOTAHP
With the VS kit, you have to weld a reinforcement bracket over the stock upper shock mount. There are some DIY'ers making kits but I don't think they address the upper bracket issue.

1) Yes you can elimate the dual mount rear spring
2)You can make it as stiff or as soft as you want
3)Yes you will gain body roll with a coilover if you don't have a rear bar. Each side is more independent.
4)Read above about shocks
 
SOLO,
My comment was regarding the ride height- and yes once figured out, and the shocks are bought and installed - you're done.
But as I am still in the - wheel/tire/rear end combo design/build/fiddling stage - I änticipate some "ïssues" with ride height.
And, I can't mess around with too many shock combos before my CFO looses interest - and I loose financial support!:D

If you choose to use the shock for ride height adjustment - as I understand it -- you create a whole set of problems.

RE QA1s: Other boards have had less than favorable comments on those - and have even compared them to the TCIs - a real low cost entry at least price wise. I had a long conversation with Mark regarding the QA1s and it seems you can create another problem with their coil overs -- that they are "tapered," they tend to give less than consistent performance when compared to non tapered springs. That issue has been hinted at/documented in several other threads/boards - seems some aftermarket suspension houses have been trying to get QA1 to make some mods to the spring heights, design, etc and maybe coming.

BUT, that won't be a problem for me that I am on the monoleaf side now.

BTW - you have a good source/recommendation - UP from- the Varishocks Dual Adjust - ONLY -- No Springs attached?

You can do a lot of research, but a great thing about this forum - a lot of experiencied folks willing to share! Thanks!! :friends:

Cheers - Jim
 
Not sure I can completely go along with TT's explanation. Neglecting cross weighting effects to simplify the explanation. The load on the spring is constant. The load is the weight supported by the spring at that corner of the car. Adjusting the spring perch on the shock body just raises or lowers the position of the top shock mount which is how you adjust the ride height. The spring compressed length, compressed height and rate stay the same until you run out of shock travel. At that point you can crark load into the spring. The spring force will be in equilibrium with it's load.
 
phantomjock said:
SOLO,
My comment was regarding the ride height- and yes once figured out, and the shocks are bought and installed - you're done.
But as I am still in the - wheel/tire/rear end combo design/build/fiddling stage - I änticipate some "ïssues" with ride height.
And, I can't mess around with too many shock combos before my CFO looses interest - and I loose financial support!:D

If you choose to use the shock for ride height adjustment - as I understand it -- you create a whole set of problems.

RE QA1s: Other boards have had less than favorable comments on those - and have even compared them to the TCIs - a real low cost entry at least price wise. I had a long conversation with Mark regarding the QA1s and it seems you can create another problem with their coil overs -- that they are "tapered," they tend to give less than consistent performance when compared to non tapered springs. That issue has been hinted at/documented in several other threads/boards - seems some aftermarket suspension houses have been trying to get QA1 to make some mods to the spring heights, design, etc and maybe coming.

BUT, that won't be a problem for me that I am on the monoleaf side now.

BTW - you have a good source/recommendation - UP from- the Varishocks Dual Adjust - ONLY -- No Springs attached?

You can do a lot of research, but a great thing about this forum - a lot of experiencied folks willing to share! Thanks!! :friends:

Cheers - Jim
Click to expand...

Jim,
I don't think we are on the same page here.

Shocks do not determine ride height. Springs do. For the IRS, spring bolts determine ride height along with spring rate and arch. So swapping shocks is not the answer, swapping springs are.

Tapered springs and QA1's: Tapered springs only apply to the FRONT, not REAR like we are talking about. Less consistant spring rates apply to the spring manufacture and the type of wire used. If your going to use a coil go with Hyperco. They are consistant to within 5 lbs of the giving spring rate you purchase. Plus they have a fairly new coil to the market called OBD(optimum body diameter) which is a lighter than average coil.

If your considering a REAR coilover system, talk to speed direct or van steel about their rear coilover systems and ask about their coils and spring rates and how/what you can do to get the ride height your looking for and the ride your looking for. I wouldn't rule out coilovers b/c you think you can't get ride height.

I could recommend other shock options but only Koni and Bilstein have the correct lengths that I know of. More reseach would have to be done if you wanted Penski's or like. Are they really worth it though if your not racing? In my opinion, there is nothing wrong with QA1's on a street car. Do you know why they other shocks are better? Have you seen the guts in other shocks in comparison to the QA1's? I can tell you the guts in a QA1 shock are not as bad as what most people say. Does/will varishock show you show you a shock dyno sheet? If you invert that shock as some do, you may see a different dyno result. Depends on how/who built it. If you ever visit CF, check out the racing section. There is going to be a thread on shock internals shortly and they will show you a comparison of the QA1's, Penski's, Bilsteins and Phadt shocks. I bet you'll be surprised. My buddy if doing a comparison for a vendor that does C5/6 coilovers and will be posting up some pics.

People get so into whats the best in a perfect world but whats best isn't always for everyone. Jonny joints vs rubber vs poly comes to mind. Sure johhny joints are optimal but are they for everyone? Not really, especially if you don't know the theory behind it all. Same goes for shocks. If you don't know the answers above and your just a street car, there is no need to spend 3 to 4 times the amount of money. You'll never see the benefits of the piece on a street car.
 
Solo said:
phantomjock said:
Yeah - Like what Twin Turbo said - Thats what I meant... :eek:

hadn't seen theVanSteel monnoleaf in the catalog - but that makes sense regarding the comments then.

ANYway - you can change both Ride Height - and Spring Rate on a monoleaf.
Its gotta be simpler than swaping out springs, and shocks!

Cheers - Jim
Click to expand...

Why would you have to keep changing shocks? Once you have the shocks your done. You may have to change springs for different apps but a spring change is about 10 minutes per shock that you don't have to use a coil spring compressor with and that includes removing the shock from the car.

Varishocks are just as good as a QA1 shocks and that doesn't say a whole lot as far as a performance shock goes. Both are great for basic entry level guys. If you want to step up to the plate and play ball, you need Penski's or Koni's with Hyperco springs. Chinese spring are to inconsistant in rate.

LOTAHP
With the VS kit, you have to weld a reinforcement bracket over the stock upper shock mount. There are some DIY'ers making kits but I don't think they address the upper bracket issue.

1) Yes you can elimate the dual mount rear spring
2)You can make it as stiff or as soft as you want
3)Yes you will gain body roll with a coilover if you don't have a rear bar. Each side is more independent.
4)Read above about shocks
Click to expand...


Thanks for all the help, knowlegde and advice. After all this discussion I will stay with what I have. The main thing that helped make my decision is #3 above. This is why I asked the question and you guys (SOLO) confirmed it.

Thanks again
 
Solo said:
I could recommend other shock options but only Koni and Bilstein have the correct lengths that I know of. More reseach would have to be done if you wanted Penski's or like. Are they really worth it though if your not racing?
Click to expand...
You are spot on there! - I'm looking for Autocross and Drag Racing apps and making a series of compromises for sure. Seems like even ïnfrequent racing - might be worth the investment -- again something each of must consider.

In my opinion, there is nothing wrong with QA1's on a street car. Do you know why they other shocks are better? Have you seen the guts in other shocks in comparison to the QA1's? I can tell you the guts in a QA1 shock are not as bad as what most people say. Does/will varishock show you show you a shock dyno sheet?
Click to expand...

DAMN GOOD QUESTION -- I can work with that! Email on the way this week to them! We'll see if they are really interested in my $$!

If I read between the lines -- you wouldn't like QA1s - for racing then?

If you invert that shock as some do, you may see a different dyno result.
Click to expand...
Right again -and a worthwhile question to ask all suppliers! The benefit there is reducing minutely the unsprung weight as I understand it. -- Or, maybe a means of swapping bound/rebound rates if set values or single adjust? Interesting application that.

If you ever visit CF, check out the racing section. There is going to be a thread on shock internals shortly and they will show you a comparison of the QA1's, Penski's, Bilsteins and Phadt shocks. I bet you'll be surprised. My buddy if doing a comparison for a vendor that does C5/6 coilovers and will be posting up some pics.
Click to expand...
Will your buddy/you repeat that posting/study here too?

People get so into whats the best in a perfect world but whats best isn't always for everyone. Jonny joints vs rubber vs poly comes to mind. Sure johhny joints are optimal but are they for everyone? Not really, especially if you don't know the theory behind it all. Same goes for shocks. If you don't know the answers above and your just a street car, there is no need to spend 3 to 4 times the amount of money. You'll never see the benefits of the piece on a street car.
Click to expand...
Again - good advice -- thanks again! My rear TAs will get Johhny Joints this next week or so. Regarding the rubber/poly, I just wish VB&P sold delrin bushings so I wouldn't have to fab my own. My (front) SPC uppers move without any of the typical - poly "snuggness." A shame to have Poly in the (front) lowers -- so I'll do that work myself.

Glad that LOTHAP -- got some useful information -- even if it wasn't from me. Thats the value of these discussions!

Cheers - Jim
 
Solo said:
Jonny joints vs rubber vs poly comes to mind. Sure johhny joints are optimal but are they for everyone? Not really, especially if you don't know the theory behind it all.
Click to expand...

Poly bushings are a bad choice for the trailing arm and the camber rods because of the arc they swing deflecting the bushing. Stock rubber is much more compliable and a better solition there. However the JJ is vastly supertior, has full freedom of motion so no added stress on the already pretty thin bolt and flimsy stock trailing arm. It's urethane lined so it's not wear prone like a spherical joint and it doesn't transmit vibrations since the poly cups do absorb, not as much as rubber but still.

Why would johnny joints not be superior in any application? The only reason the factory uses rubber is because it'c cheap and easy.

Guess what you will find for bushings on high end exotics? Not rubber, you will find nylon liner solid bushings and johnny joint resembling solutions.

Here's some Ferrari stuff, check out the spherical end on the pushrod. The bushings are all plastic, not rubber.

f50-17.jpg
 
Twin_Turbo said:
Solo said:
Jonny joints vs rubber vs poly comes to mind. Sure johhny joints are optimal but are they for everyone? Not really, especially if you don't know the theory behind it all.
Click to expand...

Poly bushings are a bad choice for the trailing arm and the camber rods because of the arc they swing deflecting the bushing. Stock rubber is much more compliable and a better solition there. However the JJ is vastly supertior, has full freedom of motion so no added stress on the already pretty thin bolt and flimsy stock trailing arm. It's urethane lined so it's not wear prone like a spherical joint and it doesn't transmit vibrations since the poly cups do absorb, not as much as rubber but still.

Why would johnny joints not be superior in any application? The only reason the factory uses rubber is because it'c cheap and easy.

Guess what you will find for bushings on high end exotics? Not rubber, you will find nylon liner solid bushings and johnny joint resembling solutions.

Here's some Ferrari stuff, check out the spherical end on the pushrod. The bushings are all plastic, not rubber.

f50-17.jpg
Click to expand...

I have to politely disagree with you on SOME aspects here. JJ's are superior but you can't honestly tell my they are not more rigid than rubber or poly. It may not transmit as much to the chassis as a solid heim but it still will transmit some vibration. It's not like the poly cushions are that thick in a JJ.

GM w/Rubber vs Ferrari/high end exotics with spherical ends:
1)Your talking 2 different class of cars and 1 being what 98% of the population can not afford yet alone maintain.
2) Rubber bushings are cheap but I don't feel that is why all other major car manufactures use them. Most people want comfort in a car and if you notice most modern day cars use big rubber bushings to accomidate that. You would be hard pressed to see a caddy with spherical ends and sell the way they sell.
3) GMPP was shot down from using anything else besides rubber due to the car being to stiff.
4) Most Ferrari/high end exotics are not diven daily like other cars. You will not get the longevity out of any spherical end that you will out of a rubber piece.

Fun Fact: Prototype cars that drive the 12 hours of Sebring every year completely rebuild the suspension and drive train after the race b/c of the pounding the ends take. Another fun fact, load bearing suspension heims have an average life span of 8 thousand street miles of daily driving.
 
phantomjock said:
Solo said:
I could recommend other shock options but only Koni and Bilstein have the correct lengths that I know of. More reseach would have to be done if you wanted Penski's or like. Are they really worth it though if your not racing?
Click to expand...
You are spot on there! - I'm looking for Autocross and Drag Racing apps and making a series of compromises for sure. Seems like even ïnfrequent racing - might be worth the investment -- again something each of must consider.
Again I will bring up the point of QA1's being a good value shock for the money. With autocross/cone racing and drag racing your temp values will not increase that dramatically that you will see a difference. The shocks more than likely won't even have enough time on the to foam up. If you can tell a difference, you need to stop cone racing and hit the long tracks.

In my opinion, there is nothing wrong with QA1's on a street car. Do you know why they other shocks are better? Have you seen the guts in other shocks in comparison to the QA1's? I can tell you the guts in a QA1 shock are not as bad as what most people say. Does/will varishock show you show you a shock dyno sheet?
Click to expand...

DAMN GOOD QUESTION -- I can work with that! Email on the way this week to them! We'll see if they are really interested in my $$!

If I read between the lines -- you wouldn't like QA1s - for racing then?
Depends on the racing that your doing. For short tracks line cone racing and drag strips, I don't think you can beat the bang for the buck of the QA1's

If you invert that shock as some do, you may see a different dyno result.
Click to expand...
Right again -and a worthwhile question to ask all suppliers! The benefit there is reducing minutely the unsprung weight as I understand it. -- Or, maybe a means of swapping bound/rebound rates if set values or single adjust? Interesting application that.
Correct

If you ever visit CF, check out the racing section. There is going to be a thread on shock internals shortly and they will show you a comparison of the QA1's, Penski's, Bilsteins and Phadt shocks. I bet you'll be surprised. My buddy if doing a comparison for a vendor that does C5/6 coilovers and will be posting up some pics.
Click to expand...
Will your buddy/you repeat that posting/study here too?
When the post goes up, I'll copy and paste it here.

People get so into whats the best in a perfect world but whats best isn't always for everyone. Jonny joints vs rubber vs poly comes to mind. Sure johhny joints are optimal but are they for everyone? Not really, especially if you don't know the theory behind it all. Same goes for shocks. If you don't know the answers above and your just a street car, there is no need to spend 3 to 4 times the amount of money. You'll never see the benefits of the piece on a street car.
Click to expand...
Again - good advice -- thanks again! My rear TAs will get Johhny Joints this next week or so. Regarding the rubber/poly, I just wish VB&P sold delrin bushings so I wouldn't have to fab my own. My (front) SPC uppers move without any of the typical - poly "snuggness." A shame to have Poly in the (front) lowers -- so I'll do that work myself.

Glad that LOTHAP -- got some useful information -- even if it wasn't from me. Thats the value of these discussions!

Cheers - Jim
Click to expand...

:friends: I agree these forums are useful. It's good that everyone learns something.
 
Solo said:
I have to politely disagree with you on SOME aspects here. JJ's are superior but you can't honestly tell my they are not more rigid than rubber or poly. It may not transmit as much to the chassis as a solid heim but it still will transmit some vibration. It's not like the poly cushions are that thick in a JJ.

GM w/Rubber vs Ferrari/high end exotics with spherical ends:
1)Your talking 2 different class of cars and 1 being what 98% of the population can not afford yet alone maintain.
2) Rubber bushings are cheap but I don't feel that is why all other major car manufactures use them. Most people want comfort in a car and if you notice most modern day cars use big rubber bushings to accomidate that. You would be hard pressed to see a caddy with spherical ends and sell the way they sell.
3) GMPP was shot down from using anything else besides rubber due to the car being to stiff.
4) Most Ferrari/high end exotics are not diven daily like other cars. You will not get the longevity out of any spherical end that you will out of a rubber piece.

Fun Fact: Prototype cars that drive the 12 hours of Sebring every year completely rebuild the suspension and drive train after the race b/c of the pounding the ends take. Another fun fact, load bearing suspension heims have an average life span of 8 thousand street miles of daily driving.
Click to expand...

The problem is, you people want 2 things at the same time, it can't be done. If you want a precise working suspension that holds it's geometry you simply can't use rubber. Case closed.

Sure you sacrifice comfort when upgrading to JJs, but you will also if you upgrade to reg. poly which will quickly deteriorate because you're wanting them to do something they can not. If you want a smooth ride, buy a Cadillac. And I don;t think most of these cars are daily drivers either. Surely hopped up engines aren't going to cruise silky smooth without excessive noise. If you want that, buy a complete stock car.
 
Twin_Turbo said:
Solo said:
I have to politely disagree with you on SOME aspects here. JJ's are superior but you can't honestly tell my they are not more rigid than rubber or poly. It may not transmit as much to the chassis as a solid heim but it still will transmit some vibration. It's not like the poly cushions are that thick in a JJ.

GM w/Rubber vs Ferrari/high end exotics with spherical ends:
1)Your talking 2 different class of cars and 1 being what 98% of the population can not afford yet alone maintain.
2) Rubber bushings are cheap but I don't feel that is why all other major car manufactures use them. Most people want comfort in a car and if you notice most modern day cars use big rubber bushings to accomidate that. You would be hard pressed to see a caddy with spherical ends and sell the way they sell.
3) GMPP was shot down from using anything else besides rubber due to the car being to stiff.
4) Most Ferrari/high end exotics are not diven daily like other cars. You will not get the longevity out of any spherical end that you will out of a rubber piece.

Fun Fact: Prototype cars that drive the 12 hours of Sebring every year completely rebuild the suspension and drive train after the race b/c of the pounding the ends take. Another fun fact, load bearing suspension heims have an average life span of 8 thousand street miles of daily driving.
Click to expand...

The problem is, you people want 2 things at the same time, it can't be done. If you want a precise working suspension that holds it's geometry you simply can't use rubber. Case closed.

Sure you sacrifice comfort when upgrading to JJs, but you will also if you upgrade to reg. poly which will quickly deteriorate because you're wanting them to do something they can not. If you want a smooth ride, buy a Cadillac. And I don;t think most of these cars are daily drivers either. Surely hopped up engines aren't going to cruise silky smooth without excessive noise. If you want that, buy a complete stock car.
Click to expand...

TT,
I agree both can not be achieved both at once. I'm not trying to steer anyone away from anything. If you want the precision you go one way if you don't you go another. All I said in my 1st comment about the JJs is that they are not for everyone and I listed MY reasons why. If you don't agree you don't have to. I know why GM uses what they use in cars they make today and why. A few of the friends of mine that were with GMPD told me.

How much toe change does the bushing deflection cause in a comparison of rubber , poly and JJ? Has it been measured?

How does the JJ affect forward bite?
 
The bushing deflection does not create a toe change, since the bushing is shimmed and the bolt stationary the pivot point remains the same since the camber strut and halfshaft don't change length either. The problem is that the bushing deflects and puts stress on the bolt and the trailing arm. It's not uncommon to see bent trailing arms, the stock things are flimsy at best. The JJ allows free unrestricted movement throughout any misalignment angle that the trailing arm can possibly make. Identical to a spherical end but more forgiving easier to keep lubricated and of course the reduction in vibration compared to a spherical end.

Forward bite is all in the anti squat characteristics and since the trailing arm angle isn't changed there's no change there either. Anti squat isn't effective at all in a frame hung diff (IRS), no more than maybe 25% w/ torque reaction IC @ 100% CG height
The only way to change that would be to move the trailing arm bolt hole up.
 
Solo said:
I have to politely disagree with you on SOME aspects here. JJ's are superior but you can't honestly tell my they are not more rigid than rubber or poly. It may not transmit as much to the chassis as a solid heim but it still will transmit some vibration. It's not like the poly cushions are that thick in a JJ.

GM w/Rubber vs Ferrari/high end exotics with spherical ends:
1)Your talking 2 different class of cars and 1 being what 98% of the population can not afford yet alone maintain.
2) Rubber bushings are cheap but I don't feel that is why all other major car manufactures use them. Most people want comfort in a car and if you notice most modern day cars use big rubber bushings to accomidate that. You would be hard pressed to see a caddy with spherical ends and sell the way they sell.
3) GMPP was shot down from using anything else besides rubber due to the car being to stiff.
4) Most Ferrari/high end exotics are not diven daily like other cars. You will not get the longevity out of any spherical end that you will out of a rubber piece.

Fun Fact: Prototype cars that drive the 12 hours of Sebring every year completely rebuild the suspension and drive train after the race b/c of the pounding the ends take. Another fun fact, load bearing suspension heims have an average life span of 8 thousand street miles of daily driving.
Click to expand...

Couple of things, vibration noise through a joint is not necessarily caused by the same material conditions that cause deflection in the joint. A johnny joint could easily be superior to a poly bushing in deflection an also provide better isolation (from noise) than a poly bushing. I think the issue here is compliance. The poly sleeves I have seen used in trailing arms are axial bushings, not designed for the twisting of a traling arm pivot.

All Sebring prototype cars have drive train and suspension service after every race, not just to replace rod ends. Well, these days there might be a couple of teams with no money that race with worn out crap!
 
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