Well, I've wasted about an hour with the jbo search engine. I'm posting this on 2nd gen forum because there's more "old timers" here.
1) Does anyone have any information or thoughts as to why GM moved the brake calipers from the front to rear of the steering knuckles in 92?
2) The larger knuckles look exactly the same as the smaller, 91 and older knuckles, with the addition of some metal to allow the calipers to be mounted farther from the axle. I spent a bunch of time last night looking at the locations of holes, casting marks, etc and they look the same. Has anyone actually tried installing the later knuckles on the earlier cars and not using the rear mounted caliper configuration? This would require putting RH knuckle on LH side of car and vice- versa, but it would not require bending and routing new steel lines and replacing rubber hoses. I'd expect some caster to be built into the knuckle, but my primitive measuring tools here at the house seem to say the knuckle has no caster built in.
-->Slow
We'll have to see what the alignment guy says. I've installed the parts on the "wrong" side to keep the brake caliper location the same. That way the '89 hoses bolted right up. It drives well enough, feels fine at low and highway speed, and does stop slightly faster. Now to put the parts I removed on the parts car so I can roll it outta here.
-->Slow
Everyone i've ever known to do the swap has swapped the knuckles to the opposite side to prevent having to swap lines also. It does not make a difference in anything except caliper position. Some people will arque having the caliper in the rear will give more stopping power, but really, how could it make a difference?
Quote:
Everyone i've ever known to do the swap has swapped the knuckles to the opposite side
Well, that's reassuring. I just got back from a drive to town and I'd convinced myself that there really isn't any problem with doing this.
Quote:
Some people will arque having the caliper in the rear will give more stopping power, but really, how could it make a difference?
I agree, no difference. It's like having the hand brakes on a bike on the front or rear of the fork... it stops either way.
Now to see if I can come up with a "no weld rear disc conversion." I doubt it, but it's worth a look.
-->Slow
slowolej wrote:
Now to see if I can come up with a "no weld rear disc conversion." I doubt it, but it's worth a look.
-->Slow
Well so far the closest to that anyone has come up with is a Saab rear disk setup which uses the same rear axel setup as the J body. But as far as i know, no one has actually gotten the parts and tried the swap, only looked at bolt patterns. I think the main problem is the saab uses a different wheel bolt pattern, so that turned most people away from it, and its hard to find the saab parts.
I have seen a post where a guy with a beretta bent the steel lines so he could mount the knuckles so the brakes were on the right sides. Search on V6Z24.
However, I don't believe that you would stop better with the caliper mounted in the rear. When you stop the car's momentum is going forward. It would seem that you would stop better when grabbing the rotor from the front. Probably, the reason that they were switched back to the front for the 3rd gens, which are a heavier car.
Slow, I have 3rd gen knuckles on my 1st gen and have a slight problem getting the caster angle correct. I'd be curiuos to know how the car specs out on an alignment.
-Tom
Quote:
Well so far the closest to that anyone has come up with is a Saab rear disk setup which uses the same rear axel setup as the J body. But as far as i know, no one has actually gotten the parts and tried the swap, only looked at bolt patterns.
Yep... I've spent some time looking at that possibility also. I even found a junkyard relatively close that claimed to have those parts, but I never got down there to look at 'em. There's also a Saturn or two that may provide donor calipers and backing plates, but the rotors won't work due to wheels having a 4 lug bolt pattern.
I'll probably end up making a backing plate to hold a one of the sets of calipers that I've collected. The rotors are similar to what James Cahill is using and are available for fairly cheap. I'll try to make a template and dimensions available if / when I do something.
Quote:
Slow, I have 3rd gen knuckles on my 1st gen and have a slight problem getting the caster angle correct. I'd be curiuos to know how the car specs out on an alignment.
Ok, I'll post the info when I get it aligned. Are you having problems with too much caster, or too little? I suppose you (or your alignment man) has already tried slotting the strut bearing mount holes? I may not run stock alignment specs anyway. I'll spend some time with this over the next few days.
I noticed in my brake catalog that the LH caliper for the 92-95 car is the RH caliper for the 96+ car. Is this a typo, or did GM move the calipers to the forward position in 96?
-->Slow
Well 92+ brake systems are identical as far as the calipers go.
As the caster problem goes, all of my J's have had wrong caster. The only one that came close to being perfect was my 94 after i put in the new control arm bushings. I think caster problems usually come from worn control arm bushings, a bent control arm, or a bent subframe, as the caster is not adjustable. Caster doesn't seem to cause any trouble on any of my cars anyway, the toe and camber are what affects tire wear and handling.
As far as i know, 92+ knuckles are identical except the 95+ has the steering arm on it.
*brain hurts from amount of technical info* it all makes sense, though, and this is probly really stupid to say, and i imagine 5 minutes of thinking would prove to me that i'm right, but isn't there some way you could fit a front setup to be stationary in the rear? (just using bolting no welding ect ect)
"I live my life a quarter mile at a time..." "for those ten seconds or less I'm free"
Quote:
i imagine 5 minutes of thinking would prove to me that i'm right, but isn't there some way you could fit a front setup to be stationary in the rear? (just using bolting no welding ect ect)
Yes, a front system could be used in the rear. GM did this with the Fiero. But I doubt it would be bolt in. You'd need to alter the upper shock mounts to accept struts, find a place to connect the lower control arms, and fabricate a mounting point for the inner tie rod ends. You'd end up with IRS as well as rear disc brakes.
If you're thinking about just connecting the front knucles to the rear axle, that's more work than grafting in the IRS imo.
-->Slow
Pezed - Do you have any specs on the as-left alignment angles for your car?
I have a full new suspension in the car and I am the second owner and am very sure it was never hit. So I doubt it is do to any bent parts. I am thinking that over time the radiator support can move. This would cause the front mounting point of the frame rails to move. Which would affect the caster angle.
I have thought about slotting the strut towers a little more, but I want to get some more input before doing something that is not reversible. I had to widen the left side to get the camber in spec. I need to drive the car a bit to see how it feels. I want to see if the steering response feels slow. I think that's what too little positive caster would cause.
Finally, I notice that different J-cars from the same year had different caster specs. Does anyone know why? Was it based on tire size (width & height)? I think the buicks actually list a range of slightly negetive to positive.
You cant put the front calipers on the back cause theres no spot for a E brake cable, and were I'm from you need a parking brake to get the car on the road, but I have a friend with a fiero and he put fiero front calipers on the rear and the bolted right on and there bigger tahn the factory rear ones, but I dont know what he did with teh parking brake cable, I'll ask him when I get a chance.
Hey new guy here.
The only reason I can think of moving the caliper may be because of cooling. Just a guess.
Tom wrote:Pezed - Do you have any specs on the as-left alignment angles for your car?
I happen to have the alignment sheets right here. I'll show the factory spec range in parenthesis.
94 Cav with Eibach springs:
---front Left ---
Camber: 0.3 ( -0.9 / 0.6 )
Caster: 1.5 (0.3 / 2.3)
Toe: 0.03 (-0.1 / 0.1 )
-----front right ----
Camber: 0.5
Caster: 1.8
Toe: 0.00
----Front Totals----
Cross Camber: -0.2 (-1.0 / 1.0)
Cross Caster: -.03 (-0.7 / 0.7)
Total Toe: 0.03 (-0.20 / 0.20)
------Rear left----
Camber: -.7 (-0.8 / 0.3)
Toe: 0.05 (-0.03 / 0.28)
-----Right Rear----
Camber: 0
Toe: .17
-----Rear Totals-----
Cross Camber: -0.6
Total Toe: 0.22 (-0.06 / 0.56)
Thrust Angle: -0.06 (-0.35 / .35)
I Also forgot to add: I doubt you'd be able to slot the strut tower in order to change the caster a noticable amount, the strut mount fits up in there pretty tight, there isnt much room for movement at all. If your caster is out of spec the first thing i would check is the ball joint and measure the control arms. (string a tape measure from the ball joint to the rear axel on both sides and make sure its the same or at least very close) Also pull the control arms out of the subframe and check the bushings. If the bushings are worn it will throw your caster off. (now is also a good time to put in some nice polyurathane replacements)
The control arms in these cars bend pretty easily. I wouldn't really suspect the radiator support / subframe to be bent unless the car had been in a pretty serious accident.
pezed - thanks for posting the info. If I had a 94, I'd be in spec
The control arms are new GM units with the ball-joints attached and new bushings. I wonder if the design changed to fit multiple years. That would seem to explain things.
Tom wrote:pezed - thanks for posting the info. If I had a 94, I'd be in spec
The control arms are new GM units with the ball-joints attached and new bushings. I wonder if the design changed to fit multiple years. That would seem to explain things.
Nah, The control arms where the same on all pre 95 J, L, and N bodies. And as far as the year goes, it shouldn't make a difference in the specs. The different suspension levels are probably where the spec changes are. I talked to my alignment guy and he said all of them align to the same spec (RS/Z24/VL) etc. I was concerned because i have the eibachs along with Z24 sway bars and braces on a RS and wanted to make sure it was aligned correctly.
My car is pulling to the left, but only when its in gear but not when its in neutral, so my alignment is fine.. I'm currently trying to figure out whats going on with that.. (thinking my motor mounts or something wrong with my trans
)
Tom writes:
Quote:
pezed - thanks for posting the info. If I had a 94, I'd be in spec
The specs I have here for an 87 Z24 aren't really any different.
94 Cav with Eibach springs: 87 Cavalier RS
---front Left --- ---front Left ---
Camber: -0.9 / 0.6 Camber: +0.2 / +1.4 ( +0.8 desired )
Caster: 0.3 / 2.3 Caster: +0.7 / +2.7 (1.7 desired)
-----front right ---- -----front right ----
Camber: -0.9 / 0.6 Camber: +0.2 / +1.4 ( +0.8 desired )
Caster: 0.3 / 2.3 Caster: +0.7 / +2.7 (1.7 desired)
----Front Totals---- ----Front Totals----
Cross Camber: -1.0 / 1.0 Cross Camber: 1.0 max
Cross Caster: -0.7 / 0.7 Cross Caster: 1.0 max
Total Toe: -0.20 / 0.20 Total Toe: Zero for all cars except Z24, Pontiac w/ 60 series tires
-.12 deg for Z24, Pontiac w/ 60 series tires
These are from a GM TSB ( #87-59) which advises that these alignment specs were revised for improved tire wear over previous year cars.
GM will make updates from time to time to things like alignment specs. And the way the specs show up in large lists or databases of alignment data, they don't always indicate whether or not they should be used on previous model year cars. These specs are the same from 87 to 94 ! I just looked at every year listed.
And both tire type and suspension type can make a difference in alignment settings, as well as driving styles. If you're not having a problem with the handling, the Caster angle is non wearing. You can choose to ignore it if you desire.
Pezed, Probably a dumb question, but have you rotated the front tires to the back of the car? Different diameter tires can cause this problem. Also check drive axle alignment while looking at motor mounts. And make sure the car ride height hasn't changed on one side.
-->Slow
Holy freakin #$#@
Well, Tom, it seems that we were both born on the same day. I dunno about you but there wasn't much fanfare in the hospital room for me. The moon walk received all the attention!
It's kinda strange, but you're the second person I know of born on this day, and all three of us have J cars. Somebody cue that twilight zone music please.
Oh, well. Back to your regularly scheduled discussion.
-->Slow
Slow - I'll have to remember to send you a happy b-day. It's probably stranger that all three are into j's. I take a lot of heat from my friends over that. I used to be a big mopar guy.
-Tom
pezed wrote:
Nah, The control arms where the same on all pre 95 J, L, and N bodies. And as far as the year goes, it shouldn't make a difference in the specs. The different suspension levels are probably where the spec changes are.
Not true, the 94+ Berettas got updated control arms and subframes with a vertical style bushing in the rear of the control arm.
I think the Nbody got updated with the same control arms on those years as well.
<img src="http://boner.berettaspeed.com/cavysig.jpg">
slowolej wrote:I'll probably end up making a backing plate to hold a one of the sets of calipers that I've collected. The rotors are similar to what James Cahill is using and are available for fairly cheap. I'll try to make a template and dimensions available if / when I do something.
-->Slow
The only custom part I'm having made is a spindle "adapter". Its only a stub axle that matches the Neon spindle, and it has a plate on the back side to bolt through the factory J bearing hole in the axle. I really didn't want to go and cut/chop/weld the axle. I'm trying to make a deal with the guy making it to produce a few sets, maybe 5 or so, and then sell them. It will probably run around $50-60 for the pair, then all you would need to buy is the Neon backing plate, caliper bracket, and caliper. Working out the ebrake is another issue. I'm going to use the factory Neon cable ($45 each right from the dealer) and just make a little bracket to adapt the two cables into the single cable J handle.
Juicedz4 actually measured up some of the Saab stuff and it will work, but the two of us decided to drop the idea because of the bolt pattern difference and the Saab stuff is about 1/2" wider, thats why we never did any bolting up.
During my quest for the front upgrade, I thought about doing the aftermarket thing and building a bracket to adapt the Bonneville caliper to the J spindle. Its pretty close dimensionally, so I think a flat plate with 4 holes would cut it.
As far as the alignment questions are concerned, I've always had the caster problems too. My car has always pulled to the left. I assume it because it was in an accident years ago, but I've never measured up the front end for squareness. I've had it aligned so many times in the past few years (various suspension changes), and I've only ever had it to the point where I really liked it once.
reason calipers go on the rear of the wheel/rotor is because when you apply a force to a spinning object it doesn't take effect until 90 degrees later. In theory putting the calipers on the rear side makes the wheels stick to the road while braking. However I agree that it won't make a significant difference having them on the front side, just a little food for thought.
<img src="http://www.geocities.com/fudd_22602/elmer-shoot.gif"> Old school Js rock
Quote:
reason calipers go on the rear of the wheel/rotor is because when you apply a force to a spinning object it doesn't take effect until 90 degrees later.
This is new to me. I'd love to hear an explanation of this one.
-->Slow
slowolej wrote:Quote:
reason calipers go on the rear of the wheel/rotor is because when you apply a force to a spinning object it doesn't take effect until 90 degrees later.
This is new to me. I'd love to hear an explanation of this one.
-->Slow
I've never heard that one either.....
