Front a-arm & suspension weight discussion

Suspension and other discussion

Postby gtfour77 » Tue Nov 25, 2008 2:52 pm

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
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Martin V.
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Postby CMS-GT4 » Tue Nov 25, 2008 3:39 pm

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.
Coldiron
92 st185 (205 swap) | 03 350Z Track (sold) | 13 Pilot | 17 Mazda3
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Postby gtfour77 » Tue Nov 25, 2008 5:19 pm

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)...
Martin V.
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Postby CMS-GT4 » Tue Nov 25, 2008 11:51 pm

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 wrote: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
Image

205
Image

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
Image

205
Image
Coldiron
92 st185 (205 swap) | 03 350Z Track (sold) | 13 Pilot | 17 Mazda3
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Postby CMS-GT4 » Wed Nov 26, 2008 12:04 am

gtfour77 wrote: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.
Coldiron
92 st185 (205 swap) | 03 350Z Track (sold) | 13 Pilot | 17 Mazda3
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Postby phattyduck » Wed Nov 26, 2008 12:11 am

CMS-GT4 wrote: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 wrote: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 :-)


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.
The increase in rear track on the ST205 compared to the ST185/ST165/SV25 comes exclusively from the longer arms. You will need to match your axles to do this swap.

You will gain about 3* of camber until you get some alignment bolts in there. The shop had to put 2 bolts on one side and one on the other to get back to 1* total camber (stock for my Camry Alltrac). I'm not sure what is different on the ST205 struts/chassis to account for this (different top mounting point or different lower mounting points).

I kept my stock hubs for the moment, but the ST205 hubs are essentially the same as far as I can tell. ST205 rear brakes bolt on to earlier hubs, aside from the well known 55mm vs. 54.1mm hub difference.

Also note that the part numbers for the rear subframes are the same across the years (ST205/ST185/ST165/SV25). The mount bushings and other minor parts may have different part numbers (the ST205 and SV25 subframe mount bushings are different but interchangable, for example).

Hope that clears up a few things.

-Charlie
'89 Camry LE Alltrac 3S-GTE - SV25/ST205 hybrid
'99 4Runner SR5 4WD 5VZ-FE
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Postby CMS-GT4 » Wed Nov 26, 2008 12:16 am

So can the camber bolts adjust 5 degress of camber? I am already sitting at 2 degrees in the rear from lowering. If I add 5 to that, I might run into more issues. I wonder about strut top placement on the celica vs the camry. Does a 185 strut bar fir the camry alltrac? I know its not needed since its a sedan but that would give us an idea of strut top distance.
Coldiron
92 st185 (205 swap) | 03 350Z Track (sold) | 13 Pilot | 17 Mazda3
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Postby phattyduck » Wed Nov 26, 2008 12:26 am

CMS-GT4 wrote:So can the camber bolts adjust 5 degress of camber? I am already sitting at 2 degrees in the rear from lowering. If I add 5 to that, I might run into more issues. I wonder about strut top placement on the celica vs the camry. Does a 185 strut bar fir the camry alltrac? I know its not needed since its a sedan but that would give us an idea of strut top distance.
The camber bolts generally give you a 2* adjustment range - adding a second will give you another 2* or adjustable range or so. The ST205 arms should only add 3* if camber, not 5*. Depending on what you already have in there, you should be able to get back to 2* (which is about right for performance) without trouble.

Rear suspension geometry is exactly the same Camry vs. Celica (alltracs) as far as I have been able to tell. Same subframe, same arms, same hubs, same axles, compatible (but not same) swaybars, etc. Even the exhaust mounts are in the same place. Think of it as a Celica with a 2" stretch in the middle (yay rear legroom!). I'm getting some Tein SS coilovers tonight, so we shall see if it works out like I hope.

-Charlie
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Postby CMS-GT4 » Wed Nov 26, 2008 12:43 am

I mis-wrote it. I have two, will be adding 3 for a total of 5 degrees of camber. So with two sets of alignment bolts I can get down to 2-1 degrees of camber in the rear?
Coldiron
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Postby Roundy » Wed Nov 26, 2008 2:47 am

gtfour77 wrote: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)


Sorry slighty OT here.

What bracket are you talking about? I couldn't spot anything in your thread?

Also how do you go with the hat having 4.5" PCD? Just redrill for 5x114.3 in your case?

Cheers
Nathan
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Postby vip09 » Wed Nov 26, 2008 5:27 am

Josh, just wanted to point out that the 7th gen isn't an ST231.. :P
Best GT-S STOCK times: 1/4: 14.788 @ 94.98mph 1/8: 9.640 @ 75.87mph
Best Alltrac times: 1/4: 12.2 @ 115mph 1/8th: 7.9 @ 91mph
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Postby CMS-GT4 » Wed Nov 26, 2008 5:53 am

I just had another idea. Use the st205 rear lower arms, have them cut and a threaded section added with a locking collar nut then you could have adjustable camber via the arm instead of having to do the camber bolts. Save weight and gain function.
Coldiron
92 st185 (205 swap) | 03 350Z Track (sold) | 13 Pilot | 17 Mazda3
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Postby alex237 » Wed Nov 26, 2008 7:55 am

just a thought- i know a person in the uk thats put a 205 subframe on his 185,he swapped the lot.bear in mind halfshaft lengths if you just swap the arms,ill try to find out more info for you :)
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Postby gtfour77 » Wed Nov 26, 2008 2:19 pm

Roundy wrote:
gtfour77 wrote:Quick Wilwood part numbers that
Sorry slighty OT here.
What bracket are you talking about? I couldn't spot anything in your thread?
Also how do you go with the hat having 4.5" PCD? Just redrill for 5x114.3 in your case?
Cheers
Nathan


Nathan,
I have converted to a camry/lexus front spindles/hubs so my front bolt pattern is now 5x114.3 (5x4.5). It's a Mustang Cobra rotor hat that is bolt-on. You can also re-drill it for 5x100...
Brackets are described here:
http://alltrac.net/phpBB2/viewtopic.php ... c&start=45

It's page 4 just in case it takes you to the 1st page of the thread... :wink:
Martin V.
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Postby Terracar » Wed Nov 26, 2008 3:46 pm

I am a little hazy on the spherical bearing use in the A arms idea...

If I am understanding correctly (please forgive me - very little sleep in last few days due to thanksgiving prep) you would replace the bushing in the A arm with spherical bearings - you mention aluminum blocks also (I think) - might question is would the spherical bearing be the same size as the bushing and pressed into teh A arm or would it be two smaller spherical bearings pressed into the A arm?

The use of the bearings make sense to me to take out the slop from the bushings - but would be concerned over the stresses on the bearing caused by in/out & side to side forces (probably thinking about this reverse of what you are at this time lol)

Also to CMS what about lightening the axles? Not sure if any options for this exist for our cars - have seen them for the honduh crowd though.

Also somewhat OT - but also what about remaking engine cross members from lighter materials - not alot of savings but potentially some there.



-Terracar
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