84-87 rear spindle - why not swap out for a newer GM FWD spindle w/ large brakes? (Page 1/6)
qwikgta MAY 22, 11:39 AM
I'm a long time owner of several 88 Fieros. I've done a few engine/trans swaps but always on 88's. Starting with an 88 I know that no other GM rear spindle is close to what GM did in 88. With an 88 you are stuck with the suspension geometry unless you get very creative and spend a lot of $$$$. ( I know a few have done it).

I just picked up an 87 GT, with no engine, and have been hitting up my local Pick n Pull for ideas and any parts I may need for future projects. When looking at the rear spindle for the early cars, I notice that the spindle is very similar to what GM has been doing for years. Upper part has the two holes for the McPherson strut and the lower has the single ball joint. Many newer GM cars have this same setup and come stock with larger, vented, double piston brake calipers.

I know enough to know that they are not true "bolt on" spindles. And it may be that the top two holes are not capable of working with a Fiero specific strut, (holes to close, to far apart, drilled at wrong angle ect) and that we'd have to use hubs with the correct spline... BUT... has anyone tried to use newer GM spindles on the older Gen I Fiero rear suspension?

If the long pole in the tent is the holes for the McPherson struts it seems to me that we could create brackets like FieroGuru did for his when he relocated the struts inboard.

So, what are/were the challenges? Why cant we find a workaround that would allow us to use newer GM suspension parts on Gen I cars?



Thanks in advance for any thoughts.

Rob
cvxjet MAY 22, 12:24 PM
I have thought of this before but the obvious problem is that the Citation/Fiero strut bolts are at a different angle than all other struts....That limits both spindle and strut choices.....But now I am thinking that an Aluminum spindle using a different strut with more availability would be a great idea....Lighter mass, better brakes more strut choices.

Relocating the top of the strut would be possible with a coil-over conversion....On my Fiero, I converted it to 88 rear subframe/suspension, and of course had to convert to coil-overs and relocate the strut top. But there are only so many 88s out there, and most go to the crusher with the rear subframe and brakes.
Spadesluck MAY 22, 12:48 PM
Why dont you do it then let us know how so we can copy you?
fieroguru MAY 22, 01:25 PM
I am working on solutions for the 88 front and back, but haven't looked at anything 84-87 (and probably won't). Generally speaking, for an upright to be compatible, all the following needs to be within an acceptable range.

Bolt pattern spacing (and size of the holes) at the strut
Angle of bolt pattern from spindle to strut
Tie rod placement (elevation)
Tie rod placement (location - on top of steer arm or below)
Tie rod distance from wheel bearing (length of steering arm)
Steering arm angle from wheel bearing center-line

All of these come into play when you are trying to fit a new spindle under the car, keep the camber in the adjustable range, keep bump steer to a minimum, and not mess up ackerman angle (all these aluminum spindles are rear steer and we are making them front steer (if used in the Fiero front).

The other myth is that you will end up with something lighter... depending on caliper and rotor selection that likely won't be the case.

My motivation with the 88s is strictly to get larger wheel bearings (front and rear) for increased strength and stronger CVs to support my Turbo AWD LS4/F40 project.

Here is an overlay of the W-body spindle with the 88 rear spindle...



jscott1 MAY 22, 05:12 PM

quote
Originally posted by fieroguru:

I am working on solutions for the 88 front and back, ....
My motivation with the 88s is strictly to get larger wheel bearings (front and rear) for increased strength and stronger CVs to support my Turbo AWD LS4/F40 project.





Please Please, Please include a bolt pattern change to 5 x 4 3/4" front and rear and you can have my bank routing numbers for as much as you need.
Raydar MAY 22, 06:47 PM
Seems like I have heard of people transplanting Pontiac 6000 struts and knuckles as an assembly into the rear of a Fiero, in order to allow the use of the larger bearings/hubs/axles. I don't remember exactly what the story was, however.
qwikgta MAY 22, 07:02 PM

quote
Originally posted by Spadesluck:

Why dont you do it then let us know how so we can copy you?



Well after I posted the question, I went to Pick n Pull and grabbed a set of spindle units off the 2016 Buick Regal that I pulled the LTG motor from. I figure that even if they don't work for what I'm asking about, i'll still have a use for them down the road.

and the cool thing is that these have a 5x120 bolt pattern.

[This message has been edited by qwikgta (edited 05-22-2020).]

ericjon262 MAY 22, 07:49 PM

quote
Originally posted by fieroguru:

I am working on solutions for the 88 front and back, but haven't looked at anything 84-87 (and probably won't). Generally speaking, for an upright to be compatible, all the following needs to be within an acceptable range.

Bolt pattern spacing (and size of the holes) at the strut
Angle of bolt pattern from spindle to strut
Tie rod placement (elevation)
Tie rod placement (location - on top of steer arm or below)
Tie rod distance from wheel bearing (length of steering arm)
Steering arm angle from wheel bearing center-line

All of these come into play when you are trying to fit a new spindle under the car, keep the camber in the adjustable range, keep bump steer to a minimum, and not mess up ackerman angle (all these aluminum spindles are rear steer and we are making them front steer (if used in the Fiero front).

The other myth is that you will end up with something lighter... depending on caliper and rotor selection that likely won't be the case.

My motivation with the 88s is strictly to get larger wheel bearings (front and rear) for increased strength and stronger CVs to support my Turbo AWD LS4/F40 project.




as far as light goes, I agree that it probably won't end up lighter, but you can offset a ton of the added weight added by the higher performance parts.

That being said, I'm very interested in seeing what you come up with.

------------------
"I am not what you so glibly call to be a civilized man. I have broken with society for reasons which I alone am able to appreciate. I am therefore not subject to it's stupid laws, and I ask you to never allude to them in my presence again."

cognita semper

http://www.fiero.nl/forum/Forum2/HTML/119122.html

qwikgta MAY 23, 07:40 AM
also, while I was walking around i found a 2013 Chevy Sonic and grabbed some pics of the spindles to see if they would also be a good candidate.



Rob
sourmash MAY 23, 08:58 AM

quote
Originally posted by fieroguru:

(all these aluminum spindles are rear steer and we are making them front steer (if used in the Fiero front).




If you had a suitable substitute spindle, it's just a matter of swapping sides to make them front steer, right? That's what we did with some 1970s GM car. Maybe it was Nova to GTO.