Budget Suspension Rebuild

[brotherGood]

Alright, now that I've got brakes back under the car and the dash back together..its time to start focusing on the next phase of the build:Rear axle/suspension.

I've got another 8.25 sitting on a bench, this one with SG and a set of 3.54's in the cabinet. Im going to have someone rebuild the axle for me, with the gear change being done in the process. To the best of my knowledge, nothing on the rear suspension has been touched since it was new aside from a set of rear shocks (5 years ago). The 5 leaf springs are looking rough, and due to a busted clamp seem to have a negative bend on occasion (hard to explain without a picture). This car does have the sway bar, and the odd shackles as well. I am all for ditching the ISO clamp setup back there, only I've not seen a cheap way to do this. I know Firm Feel sells the delete kit, but Im not in the position to drop Firm Feel kind of money. Are there any alternative ways to accomplish what Im trying to do, or am I just being cheap.

 

[Duke5A]

It's easy if you don't want to keep the rear sway bar. If so, you need the plates I have to go between the axle and spring - they have the tab on them for the sway bar links. I bought them through Firm Feel, but I don't see them listed anymore.

You also need B body shock plates that mount under the spring, u-bolts and shocks. The shocks you have now will not work.

This swap ain't really cheap unless you can fabricate the provisions to mount the sway bar yourself.

Start with trying to find 66-70 B body shock plates. If you know anyone in the Mopar circle they should be fairly cheap. Make sure they are for 3" axle tubes and not 2.5".

 

[brotherGood]

Is there really any benefit to dumping the Iso setup on a car that will see 90% street use? I've also been kicking around the idea of cleaning up the shackles/mounts/etc and just throwing new bushings in everywhere (poly if necessary/budget approved)

Im also up in the air as far as new springs, or just getting them rearched/repaired. i dont notice any sort of sag or anything unless the car is up in the air-more or less due to the location of the pipes up front, and the busted clamp in the rear toward the shackles. If that makes sense.

 

[Aspen500]

This is my 2 cents, and I'm sure others will have a very different opinion, on the Iso setup. I kept it on my car and just replaced the pads with urethane ones. Have absolutely no problem with wheel hop or anything else that I'm aware of. That's with a 500" stroker BB and automatic, with an 8 3/4" rear. The urethane pads have little to no give in them so it's almost like not having the springs isolated.

That said, I'm not sure if the handling suffer any from them or not. My springs have round bushings int he front, not the original oval style (new 4 leaf springs). Mine is strictly a street car, 100%.

The clamps you refer to don't do anything for ride height. They're main function is to keep the leaves aligned. Without the clamps, the leaves could potentially move. With an Iso setup, that isn't possible due to the spring boxes though. They do have some effect on the springs during acceleration and braking also, to a small extent.

 

[volare 77]

For the street I would stay with the original set up. Racing would be a whole different ball game.

 

[Duke5A]

I would have to agree with everyone else that has weighed in: for a street car you'll be fine keeping it as is. My motivation was wanting access to better shocks and I was setting my car up for corner carving. If I was building a cruiser I would use poly ISO bushing in back and poly K frame isolators.

As far as springs go I had my original set re-arched and never had any problems with them. When I was going through the back end though a few year later I just decided on a new everything.

 

[brotherGood]

I'd be interested to feel how it handles with new suspension and a tighter box. I can thrash on my new car vs the Diplomat and if there wasnt a mile of play in the wheel, it feels like it could keep up.

 

[brotherGood]

Alright, I think I'm gonna go ahead and replace the bushings/axle pads and just clean up the shackles/Iso clamps and reclamp the springs.

Anyone know where I can get all new bushings? I'm not seeing the pads anywhere, the only leaf spring bushings I'm seeing are for the front of the spring, and I cannot find the bushings for the rear sway bar.

Thanks in advance

 

[brotherGood]

Food for thought..could I swap these in, and keep the factory sway bar mount? I know I'd obviously have to change shocks.. but still.

Speedway Leaf Spring Lower Shock Mounting Plate

 

[Duke5A]

Springs and Things is where you can get all the poly stuff for your car. As far as swapping in B body style shock mounts while leaving the stock shock plate in place that has the factory sway bar mount, don't think so. It's designed to sit with a rubber pad underneath it. I haven't seen one of these in years though, so I'm working off of memory.

 

[4speedjim]

No not those. You want the 3" shock plate brackets. Speedway has them for $20. You can keep your iso clamp set up if you wish. The shock stud is bigger than stock. You'll need to push the steel spacer out of the shock bushings before you install them.

 

[brotherGood]

So, what would be the difference if I switched to a b body top plate with the sway bar mount? All I'm seeing is the lower mount, but finding that was kind of an accident as it was.

Then I'll have to figure out comparable budget shocks to the HD shocks I've got now.

 

[brotherGood]

Picked up lower plates at Mopat Nats yesterday, found clamps for the leaf springs (had a couple broken ones) so once I finalize the dash I'm gonna take the axle in for a rebuild/gear change and then swap axles-hopefully before it gets cold out. I'll probably go for the Monroe b body shocks, as I've heard the KYBs are overrated for lack of better terms.

I'm going to try to use my upper plate with the sway bar mount, the picture I have seen from a FSM shows it can be done..although while there is supposed to be a bushing underneath it, I'm not sure what difference thatd make versus a different top plate.

 

[Duke5A]

The factory plates won't work. They're designed to have that bushing in between. There is a lip on the bottom side that sits inside the rubber bushing. You might be able to mill it flat, but I don't know. What I do know for sure is they will need to be modified if you want to make them work.

 

[brotherGood]

Gotcha. I'm not finding any upper plates, that's more or less why I'm trying to utilize what I've got.

 

[Duke5A]

There are no upper plates. The plate between the axle pad and spring is an F/J/M thing. A/B/C/E bodies never had it and their rear sway bars attached to the axle housing instead using plates. You're not going to find any combination of factory parts that will allow you to convert to B body shock plates on the bottom while retaining the sway bar mounts on top.

Your only three options are: fabricate your own plates from scratch, modify your car's factory plates (don't know if this would work), or purchase the plates from Firm Feel.

 

[brotherGood]

That makes total sense as to why I couldn't find any.

I did some further digging on farley's, which confirmed the need to modify the top plate to keep the sway bar.

I'd be interested to see what I'd be looking at for the top plate/sway bar mount via FF. really just that and U bolts are the most I'd need.

 

[BudW]

The upper plate (sway bar) you currently have (police/AHB) will need to be modified but will work fine afterwards.
That said, I would make (weld up) new plates and keep your originals intact for resale.

The lower ISO plate (C shaped) is the weak link and highly recommended to get rid of. Sense yours are for 5-leaf springs – they are also somewhat desirable and can (also) be sold for a few coin.
I have seen cars with upper plates (w/factory sway bar) and using older shock plates on bottom (no biscuits).

Getting rid of the flat ISO rubber biscuit will, by itself, make the car feel 100% better, for both street or race (even for grandma’s car). You would think it is almost a new car, the way it feels better over bumps.

Item to keep in mind is rear shock plates have a smaller spring center bolt diameter than what FMJ springs have. The spring shop will remove/replace the center bolts when re-arching the springs. You have the choice to either go back with original type bolts and drill out the new shock plates to a larger diameter OR get spring shop to use the older center bolts and use a spacer to get rear differential perch centered with spring.
If you are not using the upper rubber flat biscuit – you will need to make spacer(s) anyway. New spacers are not hard to make with a holesaw and re-drilling the center bolt hole bigger (you have a lot of different options here).


The shackle bushings were used on a ton of Chrysler vehicles (up to 2000, I think).
Rubber – Moog K7308 for a box of 4 (two boxes needed).

Front bushing can be pressed out or have leaf spring shop do it (when re-arching your springs) Rubber – Moog SB364 (2x needed). These bushings are same ones being used on today’s Minivan – I believe).
Tip, to make the new bushing stiffer, get a bolt or metal dowel pin the diameter of the holes in it and insert, before pressing bushings in.

If car will be driven on street for most driving, I recommend staying with rubber for front and rear leaf springs.

Urethane (or polyurethane) bushings are available (except for front spring – I’m not sure). Being your shackles are already the AHB trapezoid shaped ones to begin with – I don’t think you will gain much benefit, as much as those still using the square/rectangle shaped shackles (non-AHB) will benefit.

If you had had extra cash to spend, getting a new upper leaf spring made with round bushings would be nice (instead of the factory oval shaped ones) – but that kinda defeats the budget part. I plan on retaining the oval shaped bushings (but with a bolt installed in the holes first) when I do the same thing for my current cars.

Note: the AHB rear springs had firmer rubber for front bushings – but after 30-40 years of service, I doubt anyone can tell the difference now. I hadn’t seen any firmer bushings made for these cars (or available for purchase) sense the early ‘90’s – except for urethane.

I would replace every sway bar bushing with urethane – if possible. This does not transmit any road harshness to you and will (also) make car feel so much better in turns (in-active on straightaways).
BudW

 

[BudW]

From my many differential replacements – this is, by far, the easiest way to replace the rear differential as well as leaf spring repair - if you do not have access to a lift:
When you get ready to perform the repairs, jack up rear of car and place on jack stands – high enough so rear tires clear the body. You might have to get some taller stands to do this.

Mark yoke and remove propeller shaft. If reusing same yoke, make sure to get propeller shaft back in same position at reinstall.

Disconnect brake lines and brake cables. Expect brake fluid to leak out - so have a catch can ready.

Apply penetrating oil to the shock studs (lower), shock bolts (upper), U-bolt threads, and the 8 studs at front of leaf springs. You might want to do this a few times (like starting now).

Unbolt rear sway bar. It might be easier to remove the bar to frame bolts and leave sway bar attached to differential, for now.

Loosen the U-bolt nuts a turn or so. This might require a 1/2" (or larger) ratchet or breaker bar.

Unbolt the rear shocks. I recommend leaving the lower shock studs alone for now and just remove both upper bolts. Shocks might push down at this point for a smaller package.

Loosen all and remove all but 1 stud (per side) on front leaf spring bracket.

Loosen the rear shackle to frame bolts.

(If removed) place rear tires back onto differential with a couple of lug nuts. They can be left “snug”.

Place floor jack under differential center and lift differential up a tad.

Remove the rear shackle bolts.

Lower floor jack down and remove from under car.

Remove the remaining front spring nuts.

Roll the entire rear differential out from underneath the car. This gives you a lot more room to work on things and less head bumps while working under the car.


Before going back together, replace the rear brake hose (about $10) – and it is already ½ way off. Also check and service the rear lug studs (if needed) and check and service rear brakes (if needed).

Note: your AHB will have 11” drum brakes. Make sure your replacement differential also has 11” brakes before install. It is not too hard to put 11” drums on – but it requires both axle shafts to be removed, first.


Reverse procedure for reinstall.

When going back together this way, leave the U-bolts snug. Before car is placed back on ground, tighten the U-bolts a bit more (last thing before placing weight back on rear tires).

Bleed rear brakes before putting rear tires back on (a lot easier now than later).

After car is back on ground, tighten the U-bolt nuts – but this is not real easy but doable.

If you removed the biscuits, and your spacers are uniform (not lopsided) or if you used urethane biscuits, then your rear alignment will not have changed.
Your front wheel alignment will have changed if you re-ached your leaf springs.
BudW

 

[Cbodyuser]

Very useful information for you is in a posting in this same category: how to lose the iso leaf springs started by Ed Dorey on May 30, 2018 and had a posting last by low budget on July 4, 2018. (Pictures included.)