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May 12, 2013 20:08:17 GMT
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a while back (about 1,5 year more or less) I bought a volvo 200 (i think it was a 240) rear axle, with a locker differential. as a cheap way to get a lsd for a kadett c project.
I did some research (obviously, after the buy) to find out it only locks at low speeds, because it was made to be able to drive away in snowy area's and stuff. as soon as you shift, a mechanism(centrifugal force) falls in place to make sure it doesn’t lockup again.
as I have no intention of driving it the snow, but to have it as a fast toy to be able to run around in it on the weekends and perhaps take out to the circuit some day, I did read it could be modified to also be able to lock a higher speeds.
while I do understand the basics of locked diffs, I do wonder what would happen when a locker diff suddenly locks up a 100mph on the high way.
is there a difference in a welded diff at that speed as a pose to a locker diff that suddenly locks up when going into a fast corner??
I believe this is the type of diff I have got:
not a 100% sure, I believe it to be a 1041 axle with the eaton g80 locker inside
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Last Edit: May 13, 2013 5:56:09 GMT by tijs
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stealthstylz
Club Retro Rides Member
Posts: 14,834
Club RR Member Number: 174
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May 12, 2013 22:31:01 GMT
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Not sure how the Eaton works, a proper locking diff should always lock both drive wheels together when under power whatever the speed, and then when you come to a corner off the power the inside wheel will be locked, whereas the outside wheel will be ratcheting and therefore spin at a slower rate. If you boot it it'd lock back up again.
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thanks, yeah while i've never really driven a lsd car, I do understand thats the way it is supposed to work. main reason for me asking is the difference in lsd diffs, as I understood, conventional plate or worm-wheel lsd gradually lockup as a posed to a locker diff, thats locks up 100& at once.
I would imagine it to be a bit of a supprise when in a fast corner and the diff suddenly locks up, instead of the diff tightening to a lock up.
did find a thread on turbobricks last night about these axles, but no real driving experience explained. (when modified to lock up at higher speeds)
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Last Edit: May 13, 2013 5:55:31 GMT by tijs
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hairymel
Club Retro Rides Member
avatar by volksangyl
Posts: 1,078
Club RR Member Number: 207
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May 13, 2013 22:30:07 GMT
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a somewhat talented chap in the avenger sunbeam owners club called james meggat has built this the club forum is members only so i have copied all the posts i could find of his mods to the eaton g80 diff Here is a better view of the mechanical centrifugal locking diff..... ...Lying between the CROWN wheel on the left and the speedometer slotted pulse wheel on the right the gubbins that operates the locking function can be seen through an opening in the differential carrier. At the top is the small rotating 'barrel'. When the half shafts are turned at differing speeds a system of step up gears between the half shaft pinions and carrier causes the 'barrel' to rotate quite quickly. In the photo a little pivot can be seen carrying a pair of tiny spring resisted leading and trailing centrifugal weights. When this happens and the weights move outwards a little rack gear close to one side of the barrel is pulled on......and that is as much as is visible! Directly below the 'barrel' in the photo is a much larger centrifugal weight which looks a bit like a curved panel beaters dolly. This moves outwards against spring pressure as the rotational speed of both half shafts increases and disengages the lock up mechanism. In standard form the disengagement is intended to take place above approximately 30mph, but I think that either the spring pressure could be increased or the mass of the weight itself could be reduced to raise the disengagement speed set point. That is the lock up control, but I still don't know what is actually doing the locking? I don't think there is room in the remaining section for any friction or clutch type device? Could there be a worm drive system or something hidden within the diff carrier on the other side? I'm finding that on tarmac this thing seems to work well enough for me to consider keeping it after increasing its disengagement speed. Has anyone seen one of these before? ... Or even know what type of lock-up it uses? AHA! ...some research has found a guy who has cut off the oil slinger plate, opened up the diff and modified the governor to raise the cut off speed along the same lines as I had been thinkng. www.turbobricks.com/mods.php?content=art0027This not only shows how the diff operates and confirms that it DOES have a clutch pack inside it, but shows stage by stage how it was modified. The only thing that crossed my mind with cutting off the centrifugal mass like that is that losing a big chunk of steel from the assembly could effect the overall balance of the differential unit as a whole? It might be possible also to simply bore and tap the diff carrier to take a retaining bolt for the governor weight, or even just weld it fixed in the 'in' position? With a clutch pack and modified governor in it, these very strong axles could be a low cost alternative on other cars with a bit of grunt? Afterthought:- As the autotest cornering would be well below 25-30mph could that explain the unexpected understeer....with the locked diff trying to push the car on?......and in that case it might be useful to be able to lock it OFF during autotests? .....which at least proves it is working? To cloud the water even more I then found this item. These diffs are actually made by Eaton and are known as type G80 units..... www.mpt.org/motorweek/autoworld2613.shtml...the write up sounds impressive, and it works well on the road, but hopeless for autotesting with. Here's an animation of how it works... uk.youtube.com/watch?v=KbMZ9vcYVSguk.youtube.com/watch?v=q-rQTHMVAuw&feature=relatedSo....do I modify it to work at high speed, disable it for occasional low speed work, or leave it well alone and first try a quick rack and skinny rear tyres (and gearbox strengthened to be able to use first gear)? Any experience or thoughts on these Nev?
I picked up the new (to me) Volvo 1041 axle this afternoon, exactly the same type as fitted to EGA. I'll have to decide if the best and easiest way to use the Eaton diff with a narrower casing for the unarched car is to use the early axle casing or just to narrow this later one. Much will depend on the half-shaft splines...... I've also bought an open 940 axle just for its 3.54:1 final drive ratio, with the intention of substituting this for the overly-high 3.13:1 ratio currently fitted to EGA. I'm still not certain which ratio will best suit the new more powerful and torquier engine once it is fitted in that car though. On SYS though, the 3.13:1 ratio is already quite low in comparison with some of the common ratios used with the big V8 in its natural home, even with bigger diameter wheels and tyres of much larger rolling circumference. Other than reducing the mass of the centrifugal speed-related diff disengagement pawl so that it operates at up to a higher speed than stock, the axle will be mechanically fairly stock... As the weather wasn't too promising this morning I decided to strip the new axle ready for modification. Here is one of the main reasons these axles have such a good reputation for strength..... 34mm half shafts.... which make the original axles shafts look like cocktail sticks..... These will most likely now be kept as spares for EGA, even if it is highly unlikely thsat they would be needed. On that note, experience of the Eaton G80 in EGA has highlighted the need to increase the diffs disengagement speed, which I think is designed to operate somewhere around 25 - 30 kph. So, the new diff was stripped down..... At the front on the blue hand towel is the centrifugal disengagement mass, which is what moves outwards against spring pressure and disengages the lock-up mechanism. Behind it are the two halves of the lock up ramps on the left, and the spinning centrifugal engagement weights 'barrel' on their shaft to the right which are responsible for rotating the lock up ramps in response to a certain difference in half shaft rotational speeds. At the rear of the bench are the plates of the clutch pack. These are not what lock the axle, they are only there to cushion the action of the engagement of the lock-up ramps. A clearer description can be found here... I found than in real world use in EGA that it is still possible to be spinning up the inside wheel on exiting corners when above the 20mph disengagement speed, so as a first experiment the stock centrifugal mass was modified from this... ...to this... Most of the guys using these axles in drag race cars just cut the heavy end of the mass off completely so that it stays permanently engaged, bhut this isn't ideal for a road car. I have no idea what the new disengagement speed will now be as it isn't an exact science and was more of a guess, so I'll just have to 'suck it and see'. The modified mass rebuilt into the diff casing again, ready for putting back into whichever axle casing I end up using.... i hope this is of some help
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whats that burning smell?
oh curse word :-(
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apart from the great info,
that looks like one awesome ride!
also found someone that just welded the flyweight stuck, seems to be less of a hassle, and when making sure you plug al the holes with a cloth seems possible without having to remove the diff.
i guess i should just go for it, and see what happens.. one of the links also had a comment on it only locking up a 100rpm difference, that would not even happen on a fast corner, as long as the traction doesn't fail so i guess it should be pretty predictable.
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a locker and a slipper are different things, the volvo diffs are discussed at length over on Turbobricks.
A slipper is better if you want actual performance increases as it will increase grip out of a corner but still allow a difference in wheel speed so you wont be forcing one wheel to spin, on a circuit slippers are better.
A locker will give you more grip off the line as both wheels are locked together, however in a corner this makes over steer much more likely as one of the wheels will already by trying to turn at the wrong speed effectively giving you less grip while cornering, this is why Volvo fit the governor.
If you do buy a new diff, have a look at viscous ones, they need less maintenance than clutched LSD and are more gentle, work really well on a mostly road car. A lot of the big manufactures fit them, Ford used them in the Cossies, i think Nissan and Mazda used them quite often as well. Not as "street cred" but they are fit and forget for years.
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Volvo back as my main squeeze, more boost and some interior goodies on the way.
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May 14, 2013 11:13:30 GMT
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yeah turbobricks has been a great to find info about the locker. as i am not really building a track car, but do like to set a car sideways of the roundabout,from what i've read so far... the locker should be sufficient as i'm not realy going for the performance, but more just to have a little more fun, and probably not if but when it'll break into pieces move up and get a slipper. maybe it is my google-foo, but couldn't really find a good write up or video's about how it is to drive (except for trucks) with the modification done.. made me wonder if everybody that did the modification ended up in a ditch
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May 14, 2013 11:51:12 GMT
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It depends how much power you have and how much grip you have, my 940 has an open diff and with the boost turned up it will easily spin a wheel in second gear, if it tries that half way round a corner with a locker it will slide simple as.
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Volvo back as my main squeeze, more boost and some interior goodies on the way.
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May 14, 2013 12:00:18 GMT
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I'm not sure yet on engine choice.... could be anywhere from 120bhp and up, have a engine knocking around that should atleast put out 120 bhp.. , but not sure if I'm going to use it. (might as wel go for some extra power as i still have to modify the car to fit anything) the original axle from the kadett c project was to weak anyway. luckily a kadett c had alot less weight as a posed to your 940, so hoping for a fun drive without turbo conversion. (although a turbo convertion obviously would make an fun drive... )
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Last Edit: May 14, 2013 13:53:24 GMT by tijs
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hairymel
Club Retro Rides Member
avatar by volksangyl
Posts: 1,078
Club RR Member Number: 207
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May 14, 2013 18:06:26 GMT
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in response to telling James i had cross-posted bits of his thread: Just to clarify though, with a 200 series axle (1030 or 1031) it will be a conventional plate type diff (made by Dana, but not the Irish singer ;D) and not the G80. Only the 1041 axle in the live axled 960 estate got the Eaton G80. I've found it works excellently in snow and muddy fields etc with the stock disengagement speed. I've yet to try the modified version, but push-on understeer is the thing to be avoided that could result from excessive mass reduction, and I don't think that any-speed lock-up engagement of one of these diffs is a good idea.
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whats that burning smell?
oh curse word :-(
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May 14, 2013 20:38:05 GMT
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I'm 99% sure it is a locker style diff and looks just like the diff in the picture (from memory) not a 100% sure it was a 200 series axle..
I guess I need to dig the axle out.. and have a look and take some pics... seems I have something that doens't exist, or I have things messed up in my head (the last option is obviously the most common)
thanks for al the help so far! I'll be back with pics shortly
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Last Edit: May 14, 2013 20:39:45 GMT by tijs
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May 15, 2013 17:36:42 GMT
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From what I have been able to ascertain on the ovlov forum I peruse All 940s with the 1041 axle were g80 lockers, early 700 series cars had plate type diffs as did the 200 series.
Don't take that as gospel though.
The above obviously only applies to those cars that had this option, not ALL cars.
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Volvo back as my main squeeze, more boost and some interior goodies on the way.
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May 15, 2013 21:02:26 GMT
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well, today i bit the bullet, and started cleaning out the corner of our lockup where the axles should be.... they where there... somewhere. but in the end it was worth the trouble... i guess it was nog from a 200 series, as the sticker says it is a 1041 axle (a 1041k would i guess one can't always hit the jackpot..) i guess the axle ratio also isn't to bad, as i'm planning to be using a ford t9 transmission but only the 4 speed, with a differenc bellhousing which is 1:1... so i should be able to get a "decent" drive on the highway... that being said... time to pull the diff cover.. twisted the axle with some force, and could easily lock it up, so it still works.. so.... i am correc to say it is a 1041 axle, with what is supposed to be a g80 locker? probably from a 900 series? (this topic really gets my mojo up to get going with this project car.....)
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May 15, 2013 21:26:02 GMT
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sounds about right, a full on volvo nut will probably know how to identify the precise car, but i doubt it matters much unless you need bearings and such.
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Volvo back as my main squeeze, more boost and some interior goodies on the way.
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May 15, 2013 22:04:41 GMT
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I guess I'll have to cross that bridge when I come to it I am some what anxious to take the diff out and modify it, but for everthing there is a first time... wondering if james meggat from the cross posted piece ever updated at what speed the lockup now is cancelled out. edit-- also... somehow i was under the assumption that this locker locked really harsh, beceause it would just jam the gears... but while reading all the posts and the turbobricks thread (again...) i noticed that it actually locks kinda similar as a normal lsd diff, with clutch plates, but they only get activated because of the whole tim like contraption. don't really see why i only understand this now... but i guess english not being my native language, and that i can be a real idiot at times didn't help with perhaps some of the more technical english therms. i understand i am probably the last person in the world to finaly understand this... it all makes sence now.. thanks !!
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Last Edit: May 16, 2013 11:03:32 GMT by tijs
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May 17, 2013 12:39:39 GMT
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ok, while searching for the 2 lower "arms" i noticed something that got me confused again... this time, not about the diff, but what car this axle is from...
as mentioned earlier in the cross-post 200 series has a 1030 of 1031 axle... as i have a 1041 axle, it should be of a 700 of 900 series,right? but my axle doens't have the mounting points that a 7 or 900 series axle should have, it has the same as a 200 series???
is there a volvo nut in the room that can reset my brain, so i can locate the last missing parts for the axle? (also need the propshaft, and perhaps some bushings etc)
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Dec 26, 2013 14:04:34 GMT
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ok, while searching for the 2 lower "arms" i noticed something that got me confused again... this time, not about the diff, but what car this axle is from... as mentioned earlier in the cross-post 200 series has a 1030 of 1031 axle... as i have a 1041 axle, it should be of a 700 of 900 series,right? but my axle doens't have the mounting points that a 7 or 900 series axle should have, it has the same as a 200 series??? is there a volvo nut in the room that can reset my brain, so i can locate the last missing parts for the axle? (also need the propshaft, and perhaps some bushings etc) Hi, I am on this site myself now so I can answer you question directly. What you have there is something very unusual I think. Firstly , your differential is definitely an Eaton G80 locker. The big centrifugal mass in these is responsible for disengaging lockup above 30mph or so, and also for preventing lockup above that speed. Otherwise, the unit would be free to engage or disengage whenever drive to one wheel is lost by more than the amount prescribed mechanically between the two rear wheels or grip is regained by both. Your axle is a 1041 with a fairly common 3.54:1 ratio, so no surprise that it has an Eaton G80. In the UK I believe that only the 3-litre 960 estate got the G80 as standard equipment. It would likely have been an option on all other 1041 equipped cars though, and maybe also standard fitment on some others in other markets. The 1041 axle is quite easily identified by the extended sections on the centre differential casting that carry the tapped receivers for the upper and lower suspension link pivots, which fix to the differential on the 700 and 900 series cars. There should also be a long thin sheet steel pressing that goes each side of the axle tube on this side to put the links into double shear once the pivot bolts are fitted, and this plate is missing on your axle. As you correctly point out, your axle also has the upper link brackets that carry the more outboard upper links of the earlier 4-linked axles as fitted to the earlier 200 series cars. That is very unusual, and I have never seen that combination before! It might be possible that someone has modified a later 1041 axle for use on a 200 series car, but I suspect that it is more likely to have been done by the factory themselves for use on a late model 200 series car at around the time of production of the 1031 axle coming to a halt? Either way, it has almost certainly come off of a 200 series car. The 1031 and 1041 axles are the same width, but the 1030 axle is about 4" narrower. If you are fitting this axle to a 700/ 900 series Volvo, the important diff casting fixings are already there, and the missing bplate could easily be copied or transferred over. If it is for another type of car, the 200 series 4-link and panhard rod arrangement is much more suitable anyway.... in fact I actually converted my 'normal' 1041 axle to a very similar 5-link arrangement by making and welding on some alternative upper link brackets. If that is the case, I think you have struck lucky in finding that axle. Jim
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Rob
Part of things
Posts: 252
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i had a 92 240glt that had a 1041 from the factory.
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Bolf
Part of things
Posts: 507
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I had a 940 Wentworth with one too , on a 1992 plate
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Push on understeer due to diff lockup can be averted by driving style, i.e don't put the boot in till the apex, or just back it in...
Its mentioned that these only fully lock with a differential speed of 100 rpm, which is a fair bit!
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