Adjustable Rear Suspension

[Desert Sasqwatch]

Putting this thread out there to ask the question - mainly to those who have been autocrossing and track racing their Goblin - to get some facts on setting up the rear suspension correctly. Caster, camber, toe in, Ackerman, ride height, bump steer, body roll and everything else that everyone deems to be important to achieving the ultimate in handling, for both smooth and bumpy tracks.

We all know the front suspension is fully adjustable and can be readily set up to meet most track conditions. The rear suspension, not so much. Getting a consensus of what factors are most important to make a McPherson strut suspension work and what the adjustment 'wish list' is that would make it better?

Side note: theoretically a Goblin should be able to sustain 1.2Gs in a turn with a street tire, higher with race DOTs.

 

[TheNuker]

It would be nice if DF could make the rear control arms out of chromoly tube that is fully adjustable like ZZP makes for the LSJ cars.

Nuker-

 

[JBINTX]

Putting this thread out there to ask the question - mainly to those who have been autocrossing and track racing their Goblin - to get some facts on setting up the rear suspension correctly. Caster, camber, toe in, Ackerman, ride height, bump steer, body roll and everything else that everyone deems to be important to achieving the ultimate in handling, for both smooth and bumpy tracks.

We all know the front suspension is fully adjustable and can be readily set up to meet most track conditions. The rear suspension, not so much. Getting a consensus of what factors are most important to make a McPherson strut suspension work and what the adjustment 'wish list' is that would make it better?

Side note: theoretically a Goblin should be able to sustain 1.2Gs in a turn with a street tire, higher with race DOTs.

I need to get a G meter going to record things. I have not been able to break loose around a corner yet. But, I am not operating all the way to the end of the performance envelope. I am on Proxes R1R 17X9. 1G is no big deal. The thing just goes where you point it. On rails......

 

[JBINTX]

It would be nice if DF could make the rear control arms out of chromoly tube that is fully adjustable like ZZP makes for the LSJ cars.

Nuker-

retrofittable of course!!!!

 

[TheNuker]

retrofittable of course!!!!

Honestly if ZZP made them for the LNF I would buy them. I need new control arms anyway.

Nuker-

 

[Desert Sasqwatch]

The ZZP arms would work on the LNF FE5 suspension with a ball joint change to the larger stub diameter, the overall dimensions are the same. The problem, if you can call it that, is the ZZPs have a single adjustment at the rear mount. What if the arms could adjustable in all three axis for caster, camber, length and steering knuckle height? How much better could the suspension set up be with this increased adjustability?

 

[JBINTX]

Come on Tim! Get Lonny on the phone and get er done!

 

[AleX1/9]

I really wanted those ZZP LCA's to go on sale black friday but, no....

Not saying that $500 is unreasonable, because it isn't. But are they $500 better than the GM aluminum version I paid like $125 for??? Not to me. Also, they are one of the few pieces on the car that someone couldn't make in their garage and have a certain OEM-ness the ZZP's do not. At least, that's what I keep telling myself

Getting back to the OP

Getting a consensus of what factors are most important to make a McPherson strut suspension work and what the adjustment 'wish list' is that would make it better?

Camber bolts x4 gave me all the adjustment I needed definitely a must have

New / consistant durometer bushings on the LCA's (or go spherical / delrin / ZZP)

Some way to adjust the spring and damping rates is a must for most of us, but a well picked stock strut is nice on a street goblin

There are mixed opinions on the sway bar but I like it.

 

[Desert Sasqwatch]

Come on Tim! Get Lonny on the phone and get er done!

I've got my design hat on and have been sketching out some ideas after taking many measurements. Making an adjustable control arm for the rear, if it will allow for adjustment of the caster must also allow for camber and height adjustability at the same time - making a change of one affects the other settings. I've got some parts and materials on order and should have this figured out sometime in the near future. I don't want to call Lonny and burden him with this idea as he has too many other things to be focused on - **** COVID. More to come on this.

I really wanted those ZZP LCA's to go on sale black friday but, no....

Not saying that $500 is unreasonable, because it isn't. But are they $500 better than the GM aluminum version I paid like $125 for??? Not to me. Also, they are one of the few pieces on the car that someone couldn't make in their garage and have a certain OEM-ness the ZZP's do not. At least, that's what I keep telling myself

Getting back to the OP

Camber bolts x4 gave me all the adjustment I needed definitely a must have

New / consistant durometer bushings on the LCA's (or go spherical / delrin / ZZP)

Some way to adjust the spring and damping rates is a must for most of us, but a well picked stock strut is nice on a street goblin

There are mixed opinions on the sway bar but I like it.

I remember seeing something in a post that had some discussion about changes to the caster, another with knuckle height adjustment, and another about control arm length, but can't seem to locate them or who posted these. This is some of the info I am soliciting for this post.

I agree the compressability of the control arm bushings is bad for track duty and changing the factory rubber stuff out is a must. These are also a pain to do if the right tools are not available. In my idea all bushings and the ball joint are charged out for heims, similar to the front suspension.

The gross camber adjustment must be made at the strut to steering knuckle mount, but a fine adjustment is a feature I am looking at with my idea that is made with one bolt that could be made at the track.

The springs and swaybar are not a part of this idea, but I agree that the addition of a swaybar can help control the lean of the car and allow softer springs to be used.

Keep posting and hopefully some of the 'missing' information will be rediscovered or reposted. Thanks! 'll

 

[Lonny]

I've been working on this over the last few weeks when I have time. I am starting on the prototype this week and could have it on my car in the next month.

 

[Desert Sasqwatch]

I've been working on this over the last few weeks when I have time. I am starting on the prototype this week and could have it on my car in the next month.
View attachment 13537

Lonny, you are full of surprises...and have us all wondering if you ever sleep! Interesting you swapped sides with the uprights to put the steering link attachment at the front and tied it go the control arm. Hmm, no bump steer or toe change during suspension travel, brilliant! If you get the chance to prototype this will be interesting to see if it changes the overall handling. I would suggest baselining whichever car you will be installing these to get a slalom and/or a skid pad measurement and then do the same after getting the new arms set up. Can't wait. I will be working on my own version and will share as this progresses.

 

[Ross]

It looks like Lonny created all new uprights for their CNC machines. The lower 2 heim joints are on the same plane as the blue swing arm, and parallel to the 2 frame mounts. The end result, no bump steer.

 

[Lonny]

The original control arm inboard hinge line is not parallel to the centerline of the car. They are at an angle. This is probably really good for a front wheel drive car. But I think it is not beneficial for our Goblins.

 

[DCMoney]

 

[ccannx]

Interested

 

[ctuinstra]

Subscribed.

 

[Desert Sasqwatch]

I've been working on this over the last few weeks when I have time. I am starting on the prototype this week and could have it on my car in the next month.
View attachment 13537

Lonny, any update on your rear arm prototype? Curious to see how this may be progressing.

 

[Lonny]

I started working the tube cutting programs this morning. I only work on it a little reach morning.

 

[Desert Sasqwatch]

Was just curious about your progress. I'm sure there are some interested builders who would love to see this as option someday.
My idea has been on paper to this point, but I did get most the parts and materials to build some arms. Need to wait for the weather to get reasonable again, it's really hard to accomplished things when the morning temps start at 90+ and go north of 110 for weeks at a time.
I will keep this thread alive and check back later, thanks!

 

[TheNuker]

Yeah I don't have any rear arms yet so i would be really interested in the DF adjustable ones.

Nuker-