RiF Posted January 3, 2003 Share Posted January 3, 2003 What is the general consensus as to which limited slip diff is best suited to a se7en and why? Gather the Quaife is fit and forget, much quieter, best for the road, ZF is best for the track and is noisy and clonks a lot, especially in reverse! Will be with the Duratec engine that has plenty of torque. Views please. Thanks Richard in France Awaiting chassis to start building my Duratec 7 😬 Link to comment Share on other sites More sharing options...
scooby dooby doo Posted January 3, 2003 Share Posted January 3, 2003 there's the AP as well.... although i think its not in production anymore ☹️ HOOPY 500 kg R706KGU Link to comment Share on other sites More sharing options...
scooby dooby doo Posted January 3, 2003 Share Posted January 3, 2003 give Phil at Road and Race a call. havn't got the number to hand my mobile just went doo-lally HOOPY 500 kg R706KGU Link to comment Share on other sites More sharing options...
felix.klauser Posted January 3, 2003 Share Posted January 3, 2003 There was some discussion of this aat http://www.blatchat.com/topic.asp?topic_id=24429 Link to comment Share on other sites More sharing options...
STEVE GILBERT Posted January 4, 2003 Share Posted January 4, 2003 And dont forget the Tran X unit, I have one and fitted it myself, it needs no mods to the Diff Case, no clonking or banging in use, designed to be user adjustable for Ramp and preload, so I would recommend it to anyone although I guess most Plate Types(Powr-Lok) are similar as they are made under liscence from the American Thornton Axle Co My car is 190bhp Zetec and on the road it has a lovely balanced action even this time of year Current cost from Tran X is £519.75 + delivery and VAT See My Zetec Power 7 Here Link to comment Share on other sites More sharing options...
Rob Walker Posted January 4, 2003 Share Posted January 4, 2003 Fit a ZF its all rubbish about extra noise and maintenance. Talk to Phil Stewart he will tell you the same. Link to comment Share on other sites More sharing options...
RiF Posted January 4, 2003 Author Share Posted January 4, 2003 Thanks to you all. I have looked back at the suggested topic but as it was really on fitting there was only a little info on suggested pro's and con's. Quaife recommended by one person! But useful anyway, thanks Felix. I have spoken to Phil at R&R and Steve at SP together with an odd se7ener. Suppliers think theirs are the best and I have not heard from enough members to make my own mine up. So lets hear more comments please. Steve: Do you have a tel no for Trans X supplier in the UK? Rob: How many miles have you done with the ZF, type of driving, over how many months / years and have you needed to adjust it? Richard in France Awaiting chassis to start building my Duratec 7 😬 Link to comment Share on other sites More sharing options...
Rob Walker Posted January 4, 2003 Share Posted January 4, 2003 Richard I fitted it about 2 years ago and its done about 8000 miles and thats with 230 bhp 160 lb ft of torque pushed through it. I checked it last week and the static preload is still 35lb ft the same as when it was installed. So no need to adjust it yet! Makes me laugh people going on about the ZF diff being noisy. Most Caterhams are deafening and the noise the diff makes is insignificant as compared to the engine induction, exhaust and gearbox noise. Link to comment Share on other sites More sharing options...
STEVE GILBERT Posted January 4, 2003 Share Posted January 4, 2003 Richard http://www.tran-x.com/index2.html Regarding choice I did lots of research, I very much like the look of the Torsen worm and wheel type of Diff as I think it is a lovely simple solution relying on the fact that the worm gear can turn the worm wheels but not vice versa, people mention shock loading and that with enough power( should that be torque) you can make this type of diff go OPEN but I simply fail to see either from looking at the diagrams I also fail to see what it is inside the Powr-Lok type Diff that can make a banging noise since both looking at the diagrams and dismantling my Tran X to every single component part, the whole unit is pre loaded and should work in a progressive 3 stage way maybe there are lots of knackared diffs out there? Have fun in your research, I found loads of really cool books in my local library See My Zetec Power 7 Here Link to comment Share on other sites More sharing options...
F355GTS Posted January 4, 2003 Share Posted January 4, 2003 Richard I changed ot a ZF type from the AP on Road & Race's recommendation as although I don't race I do do a lot of trackdays and bouncing off curbs etc with the AP type can send shockwaves through the drivetrain, hence the sheared 2nd Gear in my 6 speed ☹️ I had a ZF type in my previous Supersport and it did clonk a bit when the car was at rolling speeds particularly in reverse, however it may not have been adjusted in it's whole life so can't comment if it was normal. The new one in my SLR is as quiet as the AP one was Mark Link to comment Share on other sites More sharing options...
STEVE GILBERT Posted January 4, 2003 Share Posted January 4, 2003 It is an interesting point to note that thr SR3 uses a Torque Bias Diff http://www.radicalmotorsport.com/frames.htm Why does this not suffer from shock loadings? can any one who understands the workings of these Diffs explain it to me please See My Zetec Power 7 Here Link to comment Share on other sites More sharing options...
EFA Posted January 4, 2003 Share Posted January 4, 2003 Richard, I have done 25K miles on a ZF in my car. All the noise ONLY OCCURS if you remove all compliance from the drivetrain (i.e. a full race small sintered twin plate clutch) and have a low inertia flywheel. Mine was first pulled apart for a CWP ratio change and the pre-load and ramp mods after around 15K and there was no wear evident to any component. All the torque biasing types will spin lifted wheels and wreck your gearbox if you drive over the curbs on track! Arnie Webb The Fat Bloke 😳 @56k Link to comment Share on other sites More sharing options...
felix.klauser Posted January 4, 2003 Share Posted January 4, 2003 > It is an interesting point to note that thr SR3 uses a Torque Bias Diff > http://www.radicalmotorsport.com/frames.htm > Why does this not suffer from shock loadings? can any one who > understands the workings of these Diffs explain it to me please Not so sure it doesn't have the same problem... there is a cush drive (A rubber doughnut) within it; that might well be enough. Link to comment Share on other sites More sharing options...
STEVE GILBERT Posted January 5, 2003 Share Posted January 5, 2003 So no one actually knows why then ? the only thing I can see is the Jamming action of the worm wheel/worm gear teeth but this occurs at the point of lost traction and not when traction to the lost side is reapplied(at which point the gears un-jam) Confused still See My Zetec Power 7 Here Link to comment Share on other sites More sharing options...
Rob Board Posted January 5, 2003 Share Posted January 5, 2003 Rob W. I agree with you on the noise. A fellow sevener went in my car with the hood up and thought the diff was TOO noisy. I say hey it all adds to the feel. Just get some bl***y ear plugs! 😬 Richard, for what it's worth I have no problem with it and for fast road use it seems fine to me, although I do lack experience having only had the car 3 months, others would be better informed than I. Rob, please could you explain how/why to check the pre load and how often would you recommend doing this as part of the general servicing 🤔 Cheers Rob B. Edited by - ROB BOARD on 5 Jan 2003 11:23:08 Link to comment Share on other sites More sharing options...
felix.klauser Posted January 5, 2003 Share Posted January 5, 2003 Sorry if I'm stating but the obvious but the issue, if you can call it that, is that when one wheel goes airborne on a car with a Quaife or Sure-trac LSD that wheel receives all of the torque and is accelerated very rapidly to a rotational speed significantly greater than the other 3 wheels. So far so good... But the problem is that the rest of the drivetrain has accelerated to the same corresponding speed. When the airborne wheel touches down again and quickly regains traction and the same rotational speed as the other three wheels, the drivetrain has to be decelerated to the corresponding speed again in a very short time period. This starts with the drive shaft, goes through the diff, into the prop shaft, into the gear box and finally into the engine. The majority of the excess rotational energy is in the engine. With a racing clutch without springs to absorb some of the energy, the teeth in the gear box can become the weakest link and be damaged as the engine tries to resist being slowed down so abruptly. I suspect the Quaife straight cut gearboxes are much less susceptible to this than the Caterham 6 speed. The ZF diff doesn't notice the difference between an airborne wheel and a wheel with less traction that the other side so it prevents the sudden acceleration of the airborne wheel and the problem is greatly reduced. This same effect can happen to any diff when both rear wheels go airborne like at the Mountain at Cadwell, Dingle Dell on the Brands GP circuit or several places at the Ring. Link to comment Share on other sites More sharing options...
STEVE GILBERT Posted January 5, 2003 Share Posted January 5, 2003 Felix I agree with your eplanation with regard to open diffs but that is not as I understand how a Torsen diff works, I see it thus..A wheel loses traction(slips or is lifted) it transmits drive from its worm gears(fixed to the driveshafts) to the worm wheels then via the spur gears (that connect the two halfs of the diff) to the side with traction. Bascically every time a wheel loses traction it jams the mechanism directing drive to the wheel with traction. I just dont see a lifted wheel ever accelerating in a ATB type diff Praps its the worm gear jamming action that causes the shock loading but I cant see how this can be more sudden than the action of the bevel gear seperating/ramp wedging action in a plate type Still confused See My Zetec Power 7 Here Link to comment Share on other sites More sharing options...
RiF Posted January 5, 2003 Author Share Posted January 5, 2003 Well thanks for all your comments and experiences. I think I shall go with the ZF as it has been recommended to me with the Duratec, but needed some feed back to confirm it will be livable with and the wife won't complain all the time Richard in France se7en weeks to go before delivery of chassis to start building my Duratec 7 😬 Link to comment Share on other sites More sharing options...
felix.klauser Posted January 5, 2003 Share Posted January 5, 2003 For a good description of different types of diffs and their pro's and con's, see http://www.audifans.com/archives/1998/03/msg00618.html I don't confess to understand the nuances of torsen and Quaife diffs! Even Quaife themselves state "The QUAIFE Differential powers both drive wheels under nearly all conditions..." They don't state what the exception is! Link to comment Share on other sites More sharing options...
Area Representative Richard Price Posted January 5, 2003 Area Representative Share Posted January 5, 2003 Richard, If you get a ZF LSD make sure that it is modified to suit a 7 first! My ZF LSD is as supplied with my kit and has a preload of 65lb ft. I assume from this that the ramp angles are also the original settings to suit the Sierra. This preload and ramp angle issue leads to low speed understeer and snap oversteer. Neither desirable and both made me wonder if I'd done the right thing specifying an LSD with my kit! I plan to have mine modified as soon as I'm out of warantee! Link to comment Share on other sites More sharing options...
felix.klauser Posted January 5, 2003 Share Posted January 5, 2003 I thought Caterham ensured all ZF diffs were set-up correctly from the factory? Or perhaps that's a no-cost option that doesn't show up on the order form?! Link to comment Share on other sites More sharing options...
Rob Walker Posted January 6, 2003 Share Posted January 6, 2003 Rob, The preload to which I refer is the spring clamping force as applied to the clutch plates within the diff. When my diff was installed new it required a torque of approximately 36 lbft to overcome the clamping forces . Therefore it is a good indicator that no wear has taken place and all is well if this torque has remained the same. If the clutch plates had worn the clamping force would have reduced, if the spring had degraded the same would result. To check the pre-load leave one wheel on the ground, jack up the other and make sure the handbrake and pads are not dragging on this wheel, you can then put a socket and good quallity torque wrench on the drive flange/ driveshaft nut and check what torque is required to overcome the clamping force as applied to the clutch plates. How often should you check this? not really sure the unit is very robust and I would think once a year or 10000 m should be enough. Link to comment Share on other sites More sharing options...
Peter Carmichael Posted January 6, 2003 Share Posted January 6, 2003 Caterham specify the race series ZF differentials under section 5.9 of the regs (http://www.caterhamracing.com/downloads/2002Superlightregs.pdf). What actually happens is that caterham source standard ZF units and then send them to Phil Stewart in order to get them modified to 30 degree ramp angles and an appropriate preload. If you get a road car diff or a diff unit from Caterham you probably need to get it sorted by Phil. Link to comment Share on other sites More sharing options...
Rob Walker Posted January 6, 2003 Share Posted January 6, 2003 To add to my previous posting Peter is correct it is advisable to have the ramp angles and preload modded for the seven application. I am told that running with the ZF LSD unmodded makes the car understeer. Edited by - Rob walker on 6 Jan 2003 17:01:35 Link to comment Share on other sites More sharing options...
Tonycaterham Posted January 6, 2003 Share Posted January 6, 2003 Richard, I have a Tran-X plate type diff in my ford live axled 7. Once bedded in they do become noisy at low speed, especially turning, it is more the type of noise than the volume. They do clank and clonk so initally I assumed that I had a problem so proceeded to take mine apart took it back to Tran-X only to find this was all normal . This has been verified by Steve Perks at SPC (well respected name on this site) who used to work at Tran-X. Yes I did feel a bit stupid!!! I went for 35/90 ramp angles with a 35ftlb pre-load based on advice from this site and I have since done 2 sprints and 32 track days and it is brilliant with no adverse handling!!! I think you will find the noises more disconcerting than the wife hope this helps. Tony Link to comment Share on other sites More sharing options...
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