Leaf spring reset: Can you fix a sagging spring? | Auto Expert John Cadogan 

That was the best spring info I have ever seen...thank you for taking the time to make the video

Last century (in my youth) loved listening watching Julius Sumner Miller explain stuff. Tamuchly John this is that now.

I think that this whole subject re-setting of springs has changed in my lifetime. Back in the 60's 70' and well into the 80's it was a common and frequently done thing to have springs re-set or reset and an extra leaf, but that is because we did not have the ready availability of aftermarket leaf springs AND we did have a lot of local spring works. While one of my local spring works is still in business, their business model; has probably changed too. The days where local mechanics and enthusiasts walked into spring works every day for custom springs or spring repairs have gone. Of course one of the reasons springs did sag, was poor quality control in original manufacture, probably errors in the tempering process. Local spring works with highly skilled staff and a reputation that mattered probably did a better job than the mass market producers.

Having flashbacks to me as a 16 year old way back in 1981, doing one of my first jobs; employed at a local steel works that reset leaf and coil springs. Many hours were spent as a TA to the guy working it all in front of that big forge feeling like a medieval blacksmith and drinking gallons of water a day to replace the lost fluids from the heat. Thanks for bringing back the memories, John. 👍

I miss the old P76 from when I was a teen driving. Best camping vehicle ever.

This channel is just a constant stream of wisdom.

Love these deep dives. Always learn something. Thanks John.

John, this is a great video for me. I have a 1992 Isuzu Rodeo 4x4 that has 233,000 miles on it, with a sagging right rear leaf spring. I'll inspect all the ubolts and replace them if suspect.

Well sir I would have to leave a comment after watching this clip just to say that you by far have done the best and most informative description of this topic. Its obvious your very intelligent and I will be tuning in to your videos in the future. Thank you for putting in the obvious man hours in your lifetime to learn so much so that I do not have to. Lol but seriously great job sir

I had a set of OEM Toyota leaf springs 'reset' on a project Landcruiser of mine from the early 70s, I wanted to keep the originals in line with the rebuild. I wasn't aware you could repair leaf springs but apparently they're quite serviceable. Old mate that did the job had been doing it for donkeys years in his family run fabrication business, but rarely ever does it anymore. Was a common repair back in the horse cart and early motoring days but not anymore.

First time coming across one of your videos, and I won’t lie. You are right up my alley! Great style! Great presentation!

Agree, just buy a new set from the local parts place I run some fairly intensive heat treating stuff for making kitchen knives, some of which are quite long but at the size of something like a leaf spring you're not going to get much off the shelf which is capable of heat treating that sheer bulk of metal. Then you're going to need many gallons of very expensive heat treating oil (no, not vegie or old motor oil) to the point I'd be budgeting in about 200 bucks just for that, the tank to stick it in and the oven costs are getting into the 10k alone just for a precision furnace to accommodate them, then one for tempering it in as well. A lot of leaf springs are usually in the SAE 5160 type of steel of thereabouts, its a great steel But it does benefit from precision heat treatments and to some extent if you've gotten a leaf spring completely played out, its also probably full of microfractures and other metallurgy mess that wouldn't give it much of a life anyway. So they just send the old ones off to be re-melted as its still a good carbon steel and will find its way back into new ones eventually.

1:37 - How refreshing to hear you referring to that graduated strip of metal as a rule rather than the frequently heard misnomer 'ruler'. Thank you, John.

Where has this channel been!!? Great stuff, thank you sir!

Yes. As a truck mechanic, we used to get springs reset regularly at a local springmaker.

Good summary mentioning Hilux and sagged springs. This was a thing that happened to my 1984 model. Toyota resolved the rear sagged springs just before the guarantee ran out but a further 20,000km they were sagged again together with the front springs. I did an after market upgrade with a small lift but they also sagged about 60,000km later. I paid to have them reset and traded the Hilux in before the next spring reset. The Hilux was often climbing a mountain trail to a hang gliding launch site with a few extra people and a few gliders on the roof but didn't consider it was overloaded. The next Hilux is 30yo now enduring a considerable work life and still on original springs.

Steel quality does vary; my 80's Mazda van has had many loads over 1 tonne, as well as towing a trailer so heavy, that body spot welds deformed, yet the leaf springs haven't sagged at all; why? high quality Japanese steel; the steel from other Asian countries now would be sub-standard in comparison.

had the factory springs reset on my 40 series was perfect with a 2 in lift, better than aftermarket, however you missed a big issue that the current car companies are making extremely inferior springs i have a mate with a 2 year old bt 50 that carries less than 200kgs in the back (sparky) drives it like a granny and the leaf have collapsed, another mate runs a chassis shop and said every modern utes springs will deform after 3 years of standard use. no one is talking about this issue because aftermarket springs are cheaper than taking the manufacture to court

There was a place at coopers plains in QLD that used to do that. Did my 1979 F250. Power cost shut em down.

All hail the P76 the only Australian vehicle capable of taking a 44 gallon drum of fuel in the boot...I seen it done and the old coils held up quite well.Whats more it was semi surplus drum of Avgas that made the ol girl run quite spritely.

Thanks for sharing, you answered my question. New springs

Insert an additional leaf in the original pack, gives you back your ride height and makes the pack a little stronger. Often have to adjust the leaf lengths to correctly distribute the load but that only takes a grinder and cutoff wheel. Done it, works well.

As recently as the 1980s or 1990s I visited a shop that recurved leaf springs. I don't think he heated them up. He used two methods. He had a fixture that would support the individual leaves of the spring spring at two points, perhaps 8 inches apart and would strike it with a heavy hammer. He would move the spring side to side going from one end to the other creating some additional curve. He also had a machine that would apply hydraulic pressure in place of striking it with the hammer. He would work his way through all of the springs in the pack and until he was satisfied and then reassemble them. This was not cheap, but less expensive than buying new springs.

lov your work. Got Mazda via your stand-over side kick stick. Two grand better than the bastxxds quoted me. Waited 6 months and shazam, a new car appears. The best bit of your You Tube thingo is course is the girlie interludes (makes the WOKE so angry) and secondly by a long shot, bringing real engineering to car considerations.

I have never had a leaf spring sag but had one break at the centre hole, had more problems with them binding up due to salt water and giving a very harsh ride, for decades now I have been washing them out and spraying them with lanolin keeps the rust away and makes for a better ride

My 1967 VE Val had a bit of a beefy, solid suspension. It was used to tow a 22' foot trailer sailer before I got it (my father owned it before me). It had stabilisers and heavy-duty air shocks, as well as beefier springs. The front had the standard torsion bars and a set of heavy-duty gas shocks. The old VEs tended to handle like a boat at times. However, this one was solid with next to no body roll at all. It had one strange quirk that I never figured out. If I went too hard around a left-hand corner the car would shut down. I'd have to pop into neutral and restart it as it was rolling once I was pointing straight again. Right-handers were fine and if I took it steady around a lefty it would be fine. Yeah, never figured that one out.

Yeah nice, that was actually some pretty good and accurate information there…. I’m starting to think you may have read “ materials in the service of man” , gosh it’s a good read…,,, but my old UK MGb has undue elasticity in the leather straps that stop the rear axel from “being in a German night club” whatcha gonna do bout that👍

Wow you know a lot. Thanks.

another great video John. 30 years ago i had a set of rear leaf springs reset with an extra leaf added for a 1974 Mazda 808 Sedan, the guy looked at me funny and asked why the hell i wanted it done, i took him out to see my 65Kg dog and the huge tool box that lived in the boot. he had never reset springs to factory height & added a leaf in a long career doing springs. i now live in country vic and need front leaf springs reset for a 1948 Wolseley Ten, but i can't recall the company name (in Ballarat Vic) and suspect the guy might have retired.

You turn them into a knife set.

You made it look so easy!!! Keep sharing please… love your channel :) I’m subscribed! 😋

I get a spring in my step, every time I see a new JC video is out.

Had the leafs in my old corolla reset 2 inches flatter ( because im a wanker) and it cost me $400 at Liverpool Springs in Western Sydney. The old bloke there does an awesome job IMHO.

In the states, in Omaha, NE. We had a company that would repair, replace or re-arch any leaf spring 5 days a week. They provided a 1 year warranty for non-commercial vehicles and 90 days for company trucks. These were 4 guys who knew metal, replaced a single leaf and used two books to arch the leaf springs. You could walk in there and tell them you had 68 Dodge Charger; they stopped you and ask mono leaf? Yep, we will a second leaf only and install then for $72.50 plus tax in 1986 dollars, bib, Squid, Quid, PiD, whatever it’s called!

50 year old HG Premier rear springs, leaf springs, yes they do deform. That’s why my restoration is having the springs reset, by a spring works who would be professional in that methodology. You provide them with the OEM eyebrow height and off we go…

finally someone i thing can answer my question-i have a 1947 lincoln continental front end needs a couple inches of lift maybe 3 -so can i raise body and put shims on top of the leaf spring probably have to put in longer u bolts-if this will work that has to be easier than changing the leaf i know raising it will probably put linage rod in a bind but i think i can correct that -love you video thanks

My old Mitsi L300 4wd rear leafs had 'sagged' due to many jumps etc - suspension shop reset them and Added a tapered but dead-straight 'over-rider'' leaf; just enough to help. One day I was racing the tide down Teewah beach, and it was humped - about every 200 to 400metres for 80 kays I launched it, at 100km/h. My Camping plates were Corelle - didn't break. The Torsion-bars in the front you ask?: replacement genuine Mitsi. Ahem, all bump-stops removed, and aftermarket shocks all round that exceeded the springs reach even with the stops removed. At 20 years the gearbox gave up . . . I miss the Venga-Bus.

P76 had McPhersen strut front and coil rear suspension, which is what made them a far better car to drive than Holden or Falcon

Good advice, aftermarket springs are often better than OEM.

Yeah you can fix it with a new one. I reckon you could probably do the same with coils.

About 1990 I bought an XC falcon Wagon. It had sagged rear leaf springs. Can't remember what co it was but they were in Newcastle, don;t think it was Lovells. For stuff all $$ from memory $300 they reset them. Sold the car about 6 yrs later still looked the same.

P76 didn't have leaf springs, they had coil springs and unequal length trailing arms like a HQ Holden

I see you’re a Milwaukee fan John that’s good to see that makes two of us……

I had my Falcon wagon springs reset lower to drop the rear end. It was about 1/5 the cost of a set of new springs.

P76 exotic? lol, rear springs were coil. Great info as always John.

I generally agree with most things you get to say, and without starting a shouting match backwards to each other, I think there is a case for the restoring of old or worn out springs (if they can be..that is) rather than going out to buy new ones...just because its convenient to do so. Our motor industry and machine shops around the country need our support by us using their services before they go under as a result of us ignoring them. Cost wise, I know that replacement springs for my BG falcon ute come in at around $1700.00 (unfitted) while having my existing ones "re-worked" and lasting another 10 years is about $1000.00 (Fitted).

hi U need to tell local spring maker about the "hot" method . He follows the cold press method apparently . I suspect after hearing your correct methods its all about price /cost . Generally what I have found is the springs that have been reset do not last even thou they are used normally no excessive loads . My ute tradesman 250kg tools in the back and 130kg on the tow ball yet most go flat b4 100,000km . So from what your saying the factory springs cannot even handle this, under rated for the job.

I seem to recall the venerable HQ Kingswood being renown for sagging in the rear end, almost dragging the rear quarter and bumper on the road - and they were on coil springs, rather than leaf. At the time, it was blamed on crappy dampers that wore out quickly, letting the spring bounce way too much and eventually causing it to soften, but I have no way of knowing if this was actually true or just a wives' tale. Presumably material science has moved along a way since then, so maybe it's not quite the problem it once was - at least for coils.

I remember back 40 year's ago when our trucks when required Springs they would be sent to Rotorua to the specified spring workshops, I wonder if these special offers are still available, as most things are but thrown out now.

Oh John, I was sooo distracted by the perpetual motion of that 'bastard' of a file from about 8.30m to the end. Just how did you manage that? New spot in the workshop and there we have the real headline "Cadogan Cracks Perpetual Motion Pendulum"

Hi John. I work in a dealership and I see so many tradie’s utes or vans that are completely over loaded and don’t have heavy duty springs.

30 something years ago I was witness to an attempt to build the ultimate ambulance. The result was a ford f-150 i believe with a fuel injected 351, auto and a fibreglass body on the back that held everything a paramedic could possibly desire. All was good until someone thought it would be a good idea to put one over a weigh bridge. We were overweight to buggery and the fix was to send every truck one at a time, to specialist spring/ suspension workshops to have the leaf springs removed, reset and reinforced, (I think with extra leaves from memory but I might be wrong. ) I took months and cost god knows how much. Ahhhh good times.

I am now having flashbacks of material science classes from my first year of engineering.

Are trailer leaf springs supposed to be more flatter than how bow shaped actual truck leaf springs look? Are they same or different? Thanks.

I had the springs on my old Falcon reset and tempered (lower) with an extra leaf added. Nearly 30 years and nearly 350000km later they're still at the height they were. Yes, I still have the poor rust infested machine.

Leland P76 have coil springs in the rear. Just saying. thanks for another informative video.

Oh no! Sagging, DOWN THERE!

Anyway regarding springs, when we had an old Landrover 50 years ago (and no money), it was out with the springs, pull them apart, find big concrete slab and bash crap out of top side with freeking big hammer (big ball peen hammer did it too) and "voilá" reset spring with a lift! For a while anyway....

The old Austin A55 from 1960 had very dodgy rear leaf springs and took on a very nasty sag without any overloading ... they just didn't have enough 'helper' leaves ...

@Autoexpert what bit would you used to drill through a 1930's Pre-war Spring Steel bumper?

Of course you can. There are signs on many automotive repair shops that say “leaf spring resets”.

As always, amusing and informative. As a fan of the Ford Fairlane, LTD of 76 to 79, I owned quite a few as did some friends, they had a huge boot but the springs were made for comfort not loads so I just used to buy ute springs, which were load capable and sacrificed a little comfort to maintain ride height. If you are thinking of loading your vehicle talk to a suspension shop about options before you bend them. The P76 POS was a good design in many ways but ugly asf, Leyland Australia didn't have any quality control which made them worse, when I was in the shop we used to call them the P38 because they were only half a car. (spelling F U)

Come on JC, the mighty P76 has a sophisticated 4 link coil suspension like an HQ. Except it handled and stopped better

Would you consider a tour of your fatcave (one or two words ? ) to show us all those outstanding items in the background of your videos .

what i don't under stand is we had a Chevy maple leaf around 1943 and we would over load it all the time with hay big time and sometimes it would sit for weeks and we unloaded it and up shed come back to standed height, Bought a 200series cruiser put a three draw tool box in the back all highway work took out toolbox after 9 months and the cruiser didn't come up i was told shit steel shit springs bought after market springs not a problem i think the steel is not what it used to be

If leaf packs don't have p-tons or shim spacers then have one added at the ends of each leaf cause the leaves to bend improperly and change their shape if a large bump is hit on the road?

why? they break when they get old. I just replaced mine in the driveway and it did'nt cost that much. Why put all that work into something that might break next week?

Having watched this explanation on leaf springs, it got me thinking about torsion bar front suspension that was available on many 4wds in past decades, and still available on some (e.g. Mahindra). The standard method to “lift” the front is to wind them up a few turns on the adjusting bolts. Using the explanation given for leaf springs and pushing them beyond design, wouldn’t the same apply to any torsion bar lift? As I see it, by winding up a torsion bar you are allowing it to twist a lot more than design on upward compression of the front end. Or is there a lot more flexibility available in this design of spring? I have an IFS 100 series Landcruiser and am keen to improve its remote area touring reliability more than its ability to climb rocks.

Love the bastard file swing for the last half of the clip…perpetual motion.

Add an helper blade How simple can it be

Reset to original ride height is double but reset to original bend/carry property is impossible. My boss decided to reset springs on trailer in shop that just does that for living. And they did awesome job at first glance. Ride height was great, he pastidip all of them so no more lubricants and wd40 to the stop noise... All great. First load and boy what a uneven load those 6 tires have... Disaster 3 - 6 tons. We have 8 tons per axle max here in Europe and one wheel was at 6... For that shit you get straight to jail... When shop removed all springs they were same shape, like pin point exact same shape but bending properties were completely different. Maybe for one axle vehicles this is viable option but for 3 and you are all the time on full law limited load ...

P76 had coils on all four corners....ahead of their time.

i bought a new truck in 1994 knowing i was going to keep it as a classic survivor it has never seen a load never seen rain never seen snow. it is now nov 2022 going on 29 years old with 25,000 miles on it and in like new condition and has a half inch sag on the drivers side and the only thing i can think of that could have caused the sag is a tank of gas. so im thinking it "sagged over time"

How do coil springs behave under a constant compression? Most people think that they weaken when left compressed, but presumably they will also be in the elastic operating window. At what point do materials creep?

Why not get ASPW's expert opinion? He's very knowledgeable about suspension setups, plus he has the experience to prove it. ☺👍

Are those files at background from Bahco? If they are you have made excellent choice.

I just had springs replaced on 1983 Jeep Scrambler, when I had it refurbished. A lot less work.

I drove with 600KG’s of cement and sand bags for 8 minutes home carefully and they’re now sagging (lower than the rear) The cars a 2016 Hilux with 139,000k’s

I prefer to have sag as I can access tools easy. I don't understand why Ford Rangers etc have such a high lift which does nothing to the vehicle as it's for vanity. High lifts don't give extra ground clearance which only bigger diameter tires or portals give.

Most aftermarket springs are heavier duty than standard . If u think its hard to get stock replacements which is a joke try coil springs . Most coil options areonly available setup for raise 30-40mm and with bullbar fitted . They are so hard when fitted to a standard vehicle only driving thru a DEEP road drain is the only way to actually compress them . The aftermarket is targeted at one thing your wallet !!

If iron looses its magnetism at around 770°, how does this relate to the earths magnetic field and it’s molten core?

Hi John. Any chance you could provide your insights on HHO cleaning for a diesel/petrol. So many opinions out there and yours seem to be based on facts, science and engineering. So would love to know if its worth doing a HHO clean. Cheers Deon

It's interesting as most utes are rated to 1tonne or whatever, and you put the service body on and some tools,, still under weight, yet they are on the bump stops.

The file moving in the background are you doing that on purpose JC?! Thanks for the video

Bahaha @ Leyland P76…. Still laughing 😂

What if it's bad steel recycled from a ship graveyard? Comes pre-corroded in select models.

But if you do the whole heat treatment and bending process with the whole pack, you'll lose the preload designed in and they'll feel less stiff than original, and squat more under load. I think Yuri Geller could have missed a massive career opportunity here!

Leaf spring sets 350kg and up are cheep as, why stuff around with your old under sized ones as it would happen again next time you launch over a speed hump.

1: springs definitely sag 2: springs can definitely be reset Source: I work one of the biggest spring factory in the country and make leaf springs.

More importantly, can I drop the missus around to fix the sagging?

Sorry mate you don't heat to red colour it is fairly warm and you hit with a specific hammer to rest

Why reset Leah springs. If you have OEM springs, just get another set of gumtree or Facebook. There are a lot of people who struggle to give them away after they have lifted their utes. If you are running lifted leafs, just get another set. They are not very expensive.

Yer you can fix it, get with times and run a coil set up.

How much would two new spring packs cost?

If you do decide to have your leaf springs changed, please at least knock off some of the mud you accumulated on the way to Dingo Piss Creek. Thanks in advance from me, a grateful aftermarket spring fitter!

glass transition temperature?

Dude leafs do sag over time regardless of load and over time your ruler would be permanently bent.

John, thanks again. I am an engineer too, electrical, so not overly knowledgeable of materials science. I seem to remember fatigue failures with steel operating within the elastic range and a high cycle (>10^4) count. Is this applicable to vehicle leaf springs?

I seem to remember from when I did my engineering quals years ago that steel creeps. i.e. deforms at stresses much less than yield at room temperatures over long period of time. Why wouldn't a leaf spring?

Yes, replace with new and recycle old.