1988 GT Suspension (Page 1/2)
Chief08 JAN 06, 02:57 PM
Can the suspension from an 88 GT be swapped over to an 86-87 GT?
wftb JAN 06, 03:44 PM
Yes but there are mods requred to the 84-87 strut towers and to the front mounting points I think. The rear cradle is the easiest to do and wil give the best bang for the buck. Do a search, lots of threads will show up.

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86 GT built 2.2 ecotec turbo
rear SLA suspension
QA1 coilovers on tube arms

cvxjet JAN 06, 07:35 PM
Rear subframe is not hard to do- You just need to get rear coil-over set ups with the offset top brackets.....Don't know if anyone is making the brackets now but they are not hard to make. The only other problem is a bit of flexing of the coolant hoses- the one coming off the left side to the rocker pipe is the difficult one.

The front is a bit more difficult; The frame has to be notched and some of the holes for screws are somewhat off- I was going to do this mod but then I found that the 88 front hub/bearing assembly has become problematic; Rodney has built some really good ones but started having problems with them- may have solved those problems, but it was not worth it for me....

There was a guy on here that auto crossed his Fiero- he stated that the best handling set up for the Fiero was 88 rear with early front.....And I have to agree. I walked away from a Mini Cooper S that was tailgating the heck out of me on Del Puerto Canyon road, and I beat an S2000 in a parking lot Gymkhana (He was an ex-Miata racer- knew how to drive his car)

Having been a Ford Mustang guy in my teen years, I have had the idea floating around in my head to modify the geometry of the early front suspension; Carroll Shelby did this to the 1965 GT 350s.....Drill the mounting holes for the upper A-arm one inch lower for a much improved camber curve. The Fiero has the upper arm mounted on TOP of the subframe, so, looking at the situation, I came up with the idea of moving the mounting tube one inch lower- through the spring mounting area, then welding in a ramp and using the spiral of the spring to clear the mounting tube. Haven't had a chance to do this- have a spare crossmember, but also have Lupus......
Notorio JAN 07, 10:30 AM

quote
Originally posted by Chief08:

Can the suspension from an 88 GT be swapped over to an 86-87 GT?



Something to consider is that some 88 parts like the brakes are getting very hard to find ...
Chief08 JAN 07, 05:57 PM
It sounds like it is too much work for the benefit. Could a similar result be achieved by updating the suspension with coilovers etc?
wftb JAN 07, 07:12 PM
If I was to do it all over again from what I have learned from doing my car and reading a lot of what everyone else has done, this is what I would do:

1-Coilover struts on the back with 350lb 12" springs.
2-Lowering springs on the front.
3-Koni shocks on the front.
4-Aluminum cradle mount bushings.
5-Get an alignment done and fix what the mechanic says needs to be fixed.
6-Get some 17" wheels and put some really sticky tires on. The rears should be a lot wider than the front. I have 205 on the front and 245 on the rear. I would like wider but in the 16" wheels that I have choices are limited. That is why I say go with 17" wheels. Or:

7- Skip the first 4 steps and just do 5 and 6 and see how the car works with the sticky tires.

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86 GT built 2.2 ecotec turbo
rear SLA suspension
QA1 coilovers on tube arms

cvxjet JAN 07, 07:34 PM
The rear suspension is a huge improvement , in my opinion...And is not that hard. The front suspension is a very small improvement while needing more work.

I noticed this years ago; The 3rd gen Mustangs had 4 trailing arms that were angled- each one helped locate the axle fore & aft, side to side and controlled wind-up...Because each link did more than one job, NONE of them did a good job. The F-body cars had a different type of suspension; A trailing arm on each side controlling fore & aft movement, a Panhard rod which controlled side-to-side movement, and a torque arm to control wind-up...Because each arm did basically only one job, each could be perfected for that job.

Same with the 1984-87 Fiero rear suspension- the A-arm locates the tire fore & aft and Side-to-side (wind-up is controlled by the strut)....so it doesn't do a very good job...But the suspension designer Also committed a big mistake; With a strut-type suspension, you calculate the PROPER tie rod length by a triangle based on the arm length at the bottom and the strut; With the tie rod being ABOVE the Arm, it should Obviously be SHORTER than the Arm length (12.5 inches)....Instead, the designer thought, "I will make this tie rod really long so it doesn't change length during suspension travel....Yeah, that 'll work!" So he made that tie rod length 15 inches....the problem is the ARM DOES change length during suspension travel...which means the wheel/tire assemblies are constantly changing angles as the suspension moves up and down.

The 88 rear suspension has two parallel links that locate the wheel laterally and control wheel angle- since they are parallel there is basically no toe change at all- and the bushings are THIN because they take very little stress during impacts. The trailing arm has thick bushings to allow some shock absorbency during impacts....also it is at a steep angle to control brake dive and accel squat.

As for the brakes, there are a number of options for other brake systems- but yes, the 88 brakes are hard to replace/repair/find.....I have picked up 2 spare sets from the JY just in case (Also for Golden gate Fiero club members)

Sorry if this is a lot to read and understand....Suspensions are one of my things.....(I spend WAY too much time thinkin' 'bout them...)
Chief08 JAN 07, 08:32 PM
This sounds like a decent set up, although I'd do a bigger staggered wheel set up.


quote
Originally posted by wftb:

If I was to do it all over again from what I have learned from doing my car and reading a lot of what everyone else has done, this is what I would do:

1-Coilover struts on the back with 350lb 12" springs.
2-Lowering springs on the front.
3-Koni shocks on the front.
4-Aluminum cradle mount bushings.
5-Get an alignment done and fix what the mechanic says needs to be fixed.
6-Get some 17" wheels and put some really sticky tires on. The rears should be a lot wider than the front. I have 205 on the front and 245 on the rear. I would like wider but in the 16" wheels that I have choices are limited. That is why I say go with 17" wheels. Or:

7- Skip the first 4 steps and just do 5 and 6 and see how the car works with the sticky tires.



Chief08 JAN 07, 08:48 PM
Not too long, quite interesting actually.



quote
Originally posted by cvxjet:

The rear suspension is a huge improvement , in my opinion...And is not that hard. The front suspension is a very small improvement while needing more work.

I noticed this years ago; The 3rd gen Mustangs had 4 trailing arms that were angled- each one helped locate the axle fore & aft, side to side and controlled wind-up...Because each link did more than one job, NONE of them did a good job. The F-body cars had a different type of suspension; A trailing arm on each side controlling fore & aft movement, a Panhard rod which controlled side-to-side movement, and a torque arm to control wind-up...Because each arm did basically only one job, each could be perfected for that job.

Same with the 1984-87 Fiero rear suspension- the A-arm locates the tire fore & aft and Side-to-side (wind-up is controlled by the strut)....so it doesn't do a very good job...But the suspension designer Also committed a big mistake; With a strut-type suspension, you calculate the PROPER tie rod length by a triangle based on the arm length at the bottom and the strut; With the tie rod being ABOVE the Arm, it should Obviously be SHORTER than the Arm length (12.5 inches)....Instead, the designer thought, "I will make this tie rod really long so it doesn't change length during suspension travel....Yeah, that 'll work!" So he made that tie rod length 15 inches....the problem is the ARM DOES change length during suspension travel...which means the wheel/tire assemblies are constantly changing angles as the suspension moves up and down.

The 88 rear suspension has two parallel links that locate the wheel laterally and control wheel angle- since they are parallel there is basically no toe change at all- and the bushings are THIN because they take very little stress during impacts. The trailing arm has thick bushings to allow some shock absorbency during impacts....also it is at a steep angle to control brake dive and accel squat.

As for the brakes, there are a number of options for other brake systems- but yes, the 88 brakes are hard to replace/repair/find.....I have picked up 2 spare sets from the JY just in case (Also for Golden gate Fiero club members)

Sorry if this is a lot to read and understand....Suspensions are one of my things.....(I spend WAY too much time thinkin' 'bout them...)
wftb JAN 07, 10:37 PM
The 88's do have a bit of rear toe change but it is minimal. The long trailing arm runs at an angle from front to back, not in a straight line. Blooseberry's thread in the construction zone has detailed drawings and graphs of exactly how it works. It is a big improvement over the 84 to 87 suspension but it isn't what you see on a modern supercar.

The reason I made the list I posted is because I think it should not be all that hard to get more cornering force out of the older suspension. My car is the way it is because I like to tinker with it-is it really better than a car that has been properly maintained and has just had a set of killer tires put on? I don't know, and I am not buying another Fiero just to find out.

I have the Feb 86 Car and Driver test of the 86 GT Fiero. On a skid pad, it pulled .8 G's with the factory spec tires. In the same issue, there is a test of a 86 Corvette convertible. It pulled .85 G's. 400 lbs heavier than the Fiero but with P255 VR50 series tire. The Fiero was practicly running snow tires compared to the Vette. And back in the 80's, .8 G's was considered pretty good.

So this is my advice to anyone out there who wants to improve their cornering- spend your money on better tires and wheels first.

------------------
86 GT built 2.2 ecotec turbo
rear SLA suspension
QA1 coilovers on tube arms

[This message has been edited by wftb (edited 01-07-2020).]