84-7 Rear toe adjustment (Page 1/3)
1985 Fiero GT OCT 01, 09:05 AM
I have an 85 GT, lowered on coilovers rear and cut Camaro springs on the front, all poly everywhere.

I gave it a partial alignment over my lunch break (I know how to use the machine, but that's not my actual job), I've read that for poly you want 0 toe, so I did that on the rear (only had time to do the rear).



Here is the updated alignment specs from gm via TSB.



I did not touch the front, the readings changed because the thrust angle (rear toe) was changed, I wrote in the updated specs on the side of my paper, you can see both rear wheels were toed to the right, although there was enough of a total different to effectively give each rear wheel -0.115* of toe. Changing from that to 0* gave me a much worse ride, very twitchy on the highway, felt like it was getting blown around, etc. I can't even imagine going to the original specs of +0.15*, which interestingly enough, is what the machine specified, clearly Hunter hasn't updated the specs to reflect the TSBs. So when I next realign, I'll do -0.1*for each rear wheel, and try 0 on the front, I know poly is stiffer, but the rear still has decent play just by kicking the tire when it's jacked up, and I'm sure the engine just driving is putting more forward (toe in) pressure on those bushings than my foot, so it would make sense to have toe out so that while driving it is neutral. Let me know what you all think of that, and what you're all using for your alignment specs.
Frenchrafe OCT 01, 10:35 AM
Hi there,
In my experience, you need to have either straight ahead (slightly twitchy, but OK for trackday) or at least 1mm toe in (much less twitchy and good for drag racing).
If you have the slightest toe out, the Fiero will want to kill you at high speeds!🤪

I did a video on this:

------------------
"Turbo Slug" - '87 Fiero GT. 3800 turbo. - The fastest Fiero in France! @turboslugfiero
https://youtu.be/hUzOAeyWLfM

1985 Fiero GT OCT 01, 11:13 AM

quote
Originally posted by Frenchrafe:

Hi there,
In my experience, you need to have either straight ahead (slightly twitchy, but OK for trackday) or at least 1mm toe in (much less twitchy and good for drag racing).
If you have the slightest toe out, the Fiero will want to kill you at high speeds!🤪

I did a video on this:






That's the thing, I had essentially 0.115 degrees toe out on each rear wheel, along with everything else wrong in the "before" on the sheet, and went 235km/h and it was dead straight, completely controlled and almost relaxing, I change it to 0 toe and it's much much less controlled and much more twitchy. I assume toe out (-degrees) is the front of the rear wheels pointing out, toe in (+degrees) is the front of the wheels pointing inwards right? My dad's Fiero had original bushings, and was aligned to original specs (+.15 toe in) a couple years ago and has been somewhat scary at 110km/h on the highways.
Frenchrafe OCT 01, 12:36 PM
Try getting the camber the same on both sides first. Then adjust the toe.
It seems that you had more camber on the left before, which was compensating the general toe towards the left.
In the "after" setting, your camber is less apparant so the outside of the tyre is gripping more and wanting to pull the car (even with less toe).
And do remember to load the drivers side with your eqivalent weight (cements sacs, water bottles, etc...). This will compress the supension a little on your side; you must make the ajustments as if the car was loaded.
Being a lowered car the suspension mouvement is towards the edge of it's normal mouvements and starts to go into the zone where the geometry can change toe much more in dynamic use.

------------------
"Turbo Slug" - '87 Fiero GT. 3800 turbo. - The fastest Fiero in France! @turboslugfiero
https://youtu.be/hUzOAeyWLfM

[This message has been edited by Frenchrafe (edited 10-01-2025).]

olejoedad OCT 01, 01:14 PM
What drivetrain do you have in your car?
1985 Fiero GT OCT 01, 02:06 PM

quote
Originally posted by olejoedad:

What drivetrain do you have in your car?



Turbo'd 3400 block with the Fiero top end, and F23 transmission.
1985 Fiero GT OCT 01, 02:26 PM

quote
Originally posted by Frenchrafe:

Try getting the camber the same on both sides first. Then adjust the toe.
It seems that you had more camber on the left before, which was compensating the general toe towards the left.
In the "after" setting, your camber is less apparant so the outside of the tyre is gripping more and wanting to pull the car (even with less toe).
And do remember to load the drivers side with your eqivalent weight (cements sacs, water bottles, etc...). This will compress the supension a little on your side; you must make the ajustments as if the car was loaded.
Being a lowered car the suspension mouvement is towards the edge of it's normal mouvements and starts to go into the zone where the geometry can change toe much more in dynamic use.



Yes, from what it looked like as I was adjusting the camber, both rear wheels were originally the same toe (whatever that was), then the camber slipped a bit and changed the left toe to what it was in the before results (steering wheel was straight last time I got it aligned, it had drifted off center since then, after fixing the rear it is centered again), lowering it slightly increased the measured camber and rear toe for both rear wheels in the before results, but either way, the total toe in the rear was -0.22 degrees, and it was perfectly stable, now it's 0.02* (close to perfect according to Pontiacs TSBs) and unstable. The rear specifically is not lowered far, maybe 1/2 inch, I also only weigh 140lbs, so next time I'm in I'll put some weight in but it shouldn't matter to much.
pmbrunelle OCT 01, 07:54 PM
Toe-out on the rear is kind of bizarre I am not sure what to think.

On the White Bug, I started with zero toe at all four corners. Under braking, I had to hold the steering wheel tight as the car pulled in the steering.

Then, I went to +0.1 deg toe-in per front wheel. This improved stability under braking. Then I went a bit further to +0.15 deg toe-in per front wheel. Then, I was quite satisfied.
1985 Fiero GT OCT 01, 08:04 PM

quote
Originally posted by pmbrunelle:

Toe-out on the rear is kind of bizarre I am not sure what to think.

On the White Bug, I started with zero toe at all four corners. Under braking, I had to hold the steering wheel tight as the car pulled in the steering.

Then, I went to +0.1 deg toe-in per front wheel. This improved stability under braking. Then I went a bit further to +0.15 deg toe-in per front wheel. Then, I was quite satisfied.



Well next time I bring my Fiero in, I'll just do the front (either 0 toe or a little toe in), leave the rear at 0, double check the camber in the rear, and see how it drives then, I know my front is still way off, so I'll see what ends up happening then. My only limits on the alignment machine is the 1 hour lunch time, and the bother of having to go through the process several times, so I can experiment a bit with different settings, but whether it makes sense or not, it was super super stable at all speeds with the before results on that sheet.
cartercarbaficionado OCT 01, 10:20 PM

quote
Originally posted by 1985 Fiero GT:


Well next time I bring my Fiero in, I'll just do the front (either 0 toe or a little toe in), leave the rear at 0, double check the camber in the rear, and see how it drives then, I know my front is still way off, so I'll see what ends up happening then. My only limits on the alignment machine is the 1 hour lunch time, and the bother of having to go through the process several times, so I can experiment a bit with different settings, but whether it makes sense or not, it was super super stable at all speeds with the before results on that sheet.


chiming in with a driveway alignment on the 88 formula.
we put toe in the rear and had to readjust the camber drastically and once done the front the car would corner in a nice standard street turn (like a neighborhood street) at around 55 mph almost touching the inner curb.
the front does alot and if you have messed with the toe on a pre 88 car do remember it tends to throw it wildly out under load because of the inequal length of the tie rod and control arms
also if it was fine before i would try to put it back the way it was for now until you can verify the hubs arent bent, the wheels are perfectly straight and that the machine has been recertified in the last few years. personally after having 12 different alignment shops screwing up my s10, f250 and fieros ive done the race alignment with jackstands and string and had great luck.
also go on the miata forums and look around there for the effects of rear toe since those people know how to tune a car quite well, the gist is toe out increases rotation into a corner and toe in helps it stay a little more stable.
i could probably grab the measurements off my 87 from the subframe to the hub to give you a general idea of what length you need to shoot for and adjust from there.