Front a-arm & suspension weight discussion

CMS-GT4

Active member
So I was oping someone could shed some light about how these a-arms functioned. I am interested in making the suspension lighter, but I am looking for easy replacements of certain components first before trying to create new ones.

The 185 a-arm is very different from these other cars, but I am not sure why.

Here is the The st185 a-arm. It has two pivot points. Can anyone elaborate why? I have been wondering if travel and strength are the reasons the a-arm is designed the way it is with two chassis mounting pivot points.
picture2ql2.png


St205. This setup uses a single bar like the sw20 although there are many other components at play here.
picture1qc4.png


st231 Celica. It looks like this a-arm would almost be compatible with ours but the secondary mounting point looks strange. Seeing this is what made me wonder about suspension travel in rally. I wonder how much lighter this is vs our a-arm and what it might take to convert it.
picture3ri9.png


sw20 Mr2. A single bar system. I am not sure if its cause of less weight that they can get away with this simpler arm. I have been wondering if this could be swapped over on the 185 w/o ill effects on the suspension and safety.
picture4sz1.png


Thoughts, insight?
 

RedCelicaTRD

Moderator
All suspensions will have two mounting point to the body for the control arm (or a-arm depending on your nomenclature). If they only had one point the hub would be able to move to easily under force. The MR2 pic is not complete, they have a torsion bar that connects to the main arm, and then goes back to the body. The st205 uses the two bars also, they then bolt to that adapter plate and then to the hub. All those arms function about the same, they simply go at it in different ways. You best bet would be to copy the stock design, but make it out of rods (like the rear suspension) instead of one large stamped piece.
 

CMS-GT4

Active member
I see. I am starting to think there can be no simple swap option. It is likely something that will have to be fabricated.
 

Denver_whiteST185

New member
i think the only decent thing to do with the front A-arms is to remake them out of lighter alloys, but your going to loose strength unless you spend alot on a very high strength alloy. since the front a-arm deals with both front, rear, and side-to-side loads, i would think that would be a bad idea.

i think a better way to remove unsprung weight would be to make the three rear suspension arms on each side out of high grade aluminum (at least the longer rear trailing arms). they would be relitivly simple to machine or cast in comparison to a front a-arm.
 

CMS-GT4

Active member
From what I weighted the st205 rear lower arm is ~1lb lighter than the st185 version. The others may weight less too but I am unsure as of yet. The issue is they are longer than the 185 part so you will need to swap them all and possible the rear 205 axles as well. From what i compared and read on the 205 data, I have concluded that it will also increase the rear track by 20mm on each side.
 

gtfourdreams

New member
hmm.. are you trying to loose weight just from the suspension? or in the car entirely?

because just from personal experience, the heaviest thing on the car is probably the engine/transmission combo. especially that transmission. there are a lot of engine/transmission brace brackets that are quite heavy. also the manifolds themselves are pretty heavy. that transmission housing is very heavy also. i think if you were going to replace parts with lighter materials, i would work on those first before pulling the suspension apart.

but if you're looking specifically at the suspension, yea the damn thing is overbuilt. good luck. :p
 

Denver_whiteST185

New member
well, unsprung weight (mostly suspension, wheels, and brakes fall in this category) make a much bigger difference when weight is removed than when sprung weight is reduced (everything sitting on the suspension)

The engine/transmission is extremely heavy, but your not going to be able to reduce much there without it being costly. exhaust, intake piping, stripping out unnecessary stuff like the charcoal canister and EGR system (ABS and A/C if you don't care) will only go so far, and most things beyond that will be pricey unless you have access to a machining shop.

some brackets could be easily machined from some cheap aluminum stock, but once you get into anything needing to be cast or forged, it gets expensive fast for one-off parts.
 

phattyduck

New member
CMS-GT4":3mmzzj16 said:
From what I weighted the st205 rear lower arm is ~1lb lighter than the st185 version. The others may weight less too but I am unsure as of yet. The issue is they are longer than the 185 part so you will need to swap them all and possible the rear 205 axles as well. From what i compared and read on the 205 data, I have concluded that it will also increase the rear track by 20mm on each side.
If you swap rear ST205 lateral links (suspension arms), you will need the ST205 axles. The rear track is increased, but I don't remember by how much. It would work quite well on a widebody ST185 - no need for spacers to get the right fender gap and no extra pressure on the wheel bearings. I had to roll the fenders on my Camry Alltrac just to fit the stock wheel/tire combo without rubbing.

As for the A-arms... the Celica has a very standard style a-arm in the front. If anything, I would ADD extra metal to it to increase its strenghth. The aluminum front arms for the WRX/STi increase performance slightly for the decreased wieght, but most of the performance improvement comes from increased stiffness. Stiffer bushings would also help in this regard. Remember that only about half of the a-arm wieght is unsprung.

-Charlie
 

Roundy

New member
i too have ummed and ahhed about something like this.

I think Chrome-moly would be a good material to use.

Very light and exceptionally strong.

When i took my arms off to change the bushes i was surprised by how heavy they were.

Another advantage is you could try to make them adjustable for caster as well :wink:
 

RedCelicaTRD

Moderator
Here is an example for a Focus.

Photo-0045.jpg


If someone made something like this, then you could make an adator for the ball joint like the kind that is used on tie rod ends. Just a simple tapered insert and a bolt.
 

CMS-GT4

Active member
I would be interested in these if we could get them made for a fair price. I like the idea of caster adjustment especially since caster plates are already so expensive.

Anyone got the hookup to get these made?
 

$200GT-4

New member
If you could get tubular arms like that made, get them made a little longer to increase the front track width. These widebodies have a lot of fender to fill and given the understeering tendencies I think an increased front track width would be a godsend. Of course you'd need some upper camber plates, but you'd start off with some camber from the get go and be closer to where you really want to be in terms of alignment. The 205 fronts use what's called a super strut suspension, it's better than the straight McPhereson crap on the 185 in that the camber angle doesn't change so dramatically with suspension travel, of which there is a lot in this boat. The other (not MR2) arms are the same design as of my AE111 Trueno and I hate them. They're a pain to install, they look retarded, and worst of all nobody makes poly bushings for that one in the back. I really don't know why that design ever came to be, it looks like it'll let your toe bounce around under hard driving as well.
 

CMS-GT4

Active member
I don't want a wider front track. I fill my front fenders with lots of tire. I would have to run less tire and smaller wheels if I had a wider front track.

17x9 255/40
 

$200GT-4

New member
You could pull the fenders out more. . . just a thought. I'm assuming with that wide of a wheel that the offset is somewhat conservative thus scrub is not an issue?
 

CMS-GT4

Active member
38et. No issues so far.
I can't imagine that just by making a longer a-arm that you can widen the track too much. Would you not really just be adding camber since the strut top is still in the fixed oem position and the axle isn't getting any longer.

I think if you swap over the the camry spindle like gtfour77 did you can increase the front track since the hub seems to come out a little more. He modified his front fenders since he runs 315s all around.
 

gtfour77

New member
Great thread Josh! I was hoping to fabricate something like this over winter but I am not sure if that will happen or not. The front arms are actually not that heavy, it's the rear solid steel piece that makes the difference. As mentioned above, we need two points, just like any other car. There aare forces that move the arms backwards and inwards (braking and turning) The rear arm mount is most important as it takes the most abuse. The front mount is easier controled as it mostly encounters in and out motions, not front to back. So a stiffer bushing up front is ok IMHO, it's the rear bushing that will need to be 100% stiffer/stronger to limit camber and toe deviations under braking and cornering.
People have used solid aluminum blocks and spherical bearings to accomplish this... that's what I was hoping to recreate for our purpose. Of course if you're not worried about SCCA/NASA rules that the job becomes a bit easier as you can fabricate you own brackets and custom fit any bearing/bushing you want... A duplicate A-Arm can be easily made that will be just as strong or stronger than our stock units.

Something similar to this would be super strong and much lighter than our arms... using proper materials that is. Spherical bearings are a must for any racing application IMO.

http://ocnav.com/cars/Parts/a-arms.JPG
 

CMS-GT4

Active member
I am glad you joined in. I am instrested in making the entire front suspension lighter as much as affordable.

I have been debating if I really want to install my st205 calipers due to increased weight. I decided against using my sti calipers due to weight, and am planning on a 2-piece smaller rotor set that will keep me from needing brackets.

I have even considered the superlite wilwoods as an option as well but I have to look at a price standpoint and the car does need improved brake tourqe.

What else can we trim on the front suspesnion to save ome weight?

I know wheel amd tire weight is a big factor as well.
 

gtfour77

New member
I just want to point out that all of my input is from an SCCA competition standpoint, specifically Street Mod Class.

Some background on my car:
My car is currently at the weight minimum for this class which is around 2860 lbs in full race trim. (it's actually a little less, in the 2820 -2830# range for now)...will need to add some ballasts for 2009 season since the weight minimum changed from this year. (it was around 2760lbs or so this year)
Sooo, the point of this being, it is still very beneficial to lose weight in the unsprung department and add it to the mid-bottom of the car. I think this is a very decent weight that ANY celica can achieve quite cheaply. Currently I am running stock Z06 front rotors which are about 22# if I am not mistaken. Two piece rotors (with aluminum hats) are about 10# lighter. Don't forget these are 13 inch monsters. How much do stockers weigh? If you want braking torque without brake fading, bigger rotors are must. ilwood calipers are quite cheap on ebay, they are easily rebuildable
and weigh very little....
Quick Wilwood part numbers that would work for our application:

Front Rotors: 160-7172 (right) 160-7173 (left)
Hats: 170-8132 (bolt pattern: 12x8.75")
Hat offset: 0.41"

All of this will fit the alltrac spindle without much trouble (simple single plane bracket like the one I posted in my autocross build)

If we can find/make a control arm that will limit its motion under stress we'll be in really good shape...

A-Arm front to back motion will improve braking feel, in and out motion will help improve camber and toe loss/change.... spherical bearings are the only option here IMHO. Duralin would be an option I might try but longevity will be questioned. (might be ok since I just took the alltrac off the road, buying a truck and a trailer soon)...

Also, I think for any racing application a camry/lexus spindle conversion will be very beneficial (will prevent brake pad knock-back and give us the bigger 5x114.3 bolt pattern)...
 

CMS-GT4

Active member
I changed the thread topic so we might include more details in the respect of where this thread is heading. more or less fabrication and lightening of suspension components.

Here is some info from a thread I started on gt4dc about switching to the st205 rear hubs, and arms, which are lighter. At least the lower arm is 1lb lighter. It extends the rear track 20mm each side which reduces the need for a spacer.

From other thread:

I have an entire rear st205 suspension (less the struts) in my possession and I was considering swapping it into my st185. I took weights of the rear lower arms and found that they are ~1lb lighter.

I have read that the arms could be swapped but I measured them and the holes are ~25mm further on the 205 arms than the 185.

So I thought I might swap the entire assembly axles and all.

The only issue I am concerned about is the position of the strut top is in the same location yet I am moving the bottom further out. I am unsure of the strut top distance on the st205 and how it relates to the 185.

Being that the strut top is to remain in the same location and the bottom is moved out nearly an inch will this cause camber issues?

Has anyone does this swap, and can any alignment issues be sorted with rear camber bolts or is the st205 made to compensate for this?

From what I have read the st205 rear track is ~40mm wider than the 185.

Diceman":2asocjkx said:
I know of someone who has fitted an entire ST205 rear subframe, hubs & arms on to his ST185.

It does increase the rear track, he also found that one of the ST205 arms did not fit.

IIRC the increase in track is from the hub not the arms. The Driveshafts are I believe the same length. From what I understand the hub inner flange has the same track as teh ST185 but the outer flange/drive flange is 20-25mm further out per side.

If this is correct then it is likely that the strut mounting is in the same place and will not effect the camber/alignment.

Apparently teh reason for one of the ST205 struts being onger is more to do with teh chassis mounting point being in a different location on teh ST205 underside.

This is only what I have read and I do not have any first hand experience but it is also something I have been thinking of doing. The use of teh ST205 rear hubs will also mean teh rear calipers & discs bolt up without teh need for a very small shim/spacer to overcome the difference in drive flange centre bore of 54.1mm on teh ST185 & 55mm on teh ST205.

If you have the hubs - measure them up and please post the info to confirm if I am babling or correct :)

Here are some image notes on the two rear suspensions.

185
diag_ZqmFc.png


205
diag_1rwx9Xe.png


It also looks like the rear cross frame might be lighter as well for the 205. I wonder if this will mount up as well. It looks smaller than both the 185 and 165 models.

185
diag_ABjavP.png


205
diag_2tOOgi.png
 

CMS-GT4

Active member
gtfour77":1v4fk7xz said:
Also, I think for any racing application a camry/lexus spindle conversion will be very beneficial (will prevent brake pad knock-back and give us the bigger 5x114.3 bolt pattern)...
I have been wondering if I could modify my Tein mounts w/o having to remove contents of the strut housing. I have really been thinking about doing this conversion. It would make supra rotors a direct bolt on then just a caliper bracket is needed for whatever calipers are used.

Another note about lighter brakes, the rocketeer kit is much lighter than stock. I think they were ~10lbs lighter than stock. Not sure if that was per side or combined.

As far as weight goes, my 17x9 wheels weigh about the same as my 17x7 wheels (19lbs). The tire weight is a big issues though, and likely unavoidable on street tires of that size (255/40/17).

While the grip was much better with the larger stickier tires I did feel a response difference with the lighter 205/40 tires.
If I remember correctly the stock wheel/tire combo weighted in the low 40-45lbs.

One solution is to buy lighter wheels, but that is an expensive solution. Down the road I will get something lighter but I will have to make other investments first. I will likely go with a 17x8.5 wheel instead next time to save a little weight, maybe something in the ssr flavor and 16lb range.

I will also be running a smaller 245 tire next time around.

Anyhow, back on the topic of fabrication. What all can we look into benefiting our suspension, especially the front. I have been wondering if there is MR2 and supra components that might be able to be adapted to our cause.
 
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