Diff and suspension

[lew]

AE 547 is once more mobile.As told in previous posts I found the rear suspension geometry to be at some variance to optimal! 3 1/2 deg neg one side and 1 1/2 the other.
   I stripped the entire back end out.Made up a new main leaf and tried to get the "eyes" 3/8" further apart .Very difficult,at the same time I increased the inner diam of the "eyes" from 3/4" to 1" thus allowing more meat in the bush. I then drilled the centre bolt hole offset to compensate for the camber error for one side. The additional meat in the new eye diam allowed me to machine eccentric bushes from Vesconite.Re assembled and Voila! 1 deg neg both sides exactly what I was wanting.Very lucky,and what a transformation to the driving.
   All bushes now converted to Vesconite so no more greasing required
   
   The clonks are a little better but on the next strip I will convert the sliding spline drive shafts to CV joints.
   Has anyone done this?
   When I pulled the diff apart I saw it was a 4.3,surely a Bristol car with o.d should have a 3.9 as standard??
   So does anyone have a good diff to sell me?
   I have found that a number of vehicles used ENV diffs,such as Rover, Land Rover,Volvo,early Jag 120 etc,does anyone know what vehicle used a 3.9 as that would help me

[Robin A Woolmer]

Hawk Cars should have some 3.9 diffs soon, talk to Gerry.
   
   Robin

[tim isles]

Lew,
   
   Standard fit by the factory for an Aceca with 16" wheels was always the 4.3:1 diff when overdrive was specified, although I guess one could request a different one. I'm told that the 4.3 diff is the optimum ratio for an Aceca-Bristol with O/D. The car is heavier than an Ace, plus it seems the car can pull the gearing - John Bolster recorded 128.5 mph in O/D top with his Aceca-Bristol.
   
   I'd be interested to know too what other cars used the 3.9 ENV diff. ACs used the 3.6:1 diff for the Ace. When I researched ENV diffs fitted to LRs, Volvos etc I didn't get very far, other than determining that none of them shared the AC ratios (3.6/3.9/4.3), which made me wonder if they were a different size/type?
   
   I have a (retro-fitted) J type O/D fitted to my Ace-Bristol. Reduction is a claimed 25% but I'm told in reality it's closer to 22%. I kept the standard 3.9 diff. It gives it long legs on a motorway - an indicated 85 mph results in an indicated 3,300 rpm - but I'm sure the car would be faster in direct top than O/D top, for it does make it feel pretty lazy.

[lew]

Very informative .Thanks.
   I know very little about these cars and am happy to learn
   My assumption that it should have a 3.9 comes from a remark made by a friend of mine in Zimbabwe who has an original 100D2 engined car .He tells me his has a 3.9 with od.
   In theory I would be very happy to leave the 4.3 in as it's a pain in the @#$#@ to get that diff housing out for an old man. I fully intend keeping the rim size at 16" as 1) I think its looks correct and 2)the cost of getting the 15" to South Africa would be prohibitive.
   I eagerly await other comments
   Thanks
   
   Lew

[AC Ace Bristol]

Lew.
   
   Interesting that you have used Vesconite Bushes, any chance of a article in ACtion Magazine regards work involved and transfomation of handling,
   Bonus .. reduction in number of grease points..[;)]
   
   BEX333 being a USA import was fitted with a 4.3 diff, I was led to believe many Aces bound for USA
   were fitted with 4.3 diffs for short circuit racing plus the fact that USA had speed restrictions compared to  UK and Europe.
   
   If my memory serves me well, I blieve we discussed alternative manufacturers who fitted various ratios of ENV Diffs, one being Daimler in the 1950s. ( Mike Mansergh ..  Your input required here please )
   
   Tim, there are a few different ratios for O/D units,  Bertrand Leseur produced a tabulation of different percentage ratios to different diff ratios for both 16 inch and 15 inch
   wheels prior to last years Le Mans Classic.. .. ..   Must give him
   a call and see if he is willing to share his findings and conclusion..
   
   Last but least having rebuilt my 4.3 and refitted, then removed and replaced with a 3.9 unit which is less stressfull on the engine and my hearing. I certainly would not volunteer
   to change diffs again, have too agree a real sod of a job. Especially when laying under the car when the diff jams and you know you can't leave it suspended,
   Your arms ache and its literally  inches from your cheek bones and jaw.
   Get a friend to help or better still get a friend to do it for you.
   
   Not sure if I'm  ever going to fit my NOS Quaife LSD .....  [;)]
   
   Keith..[:)]..[:)]

[Aceca289]

Lew,
   
   In case you decide to change your rear end... My Aceca started out with a 3.9:1 ratio and I had it rebuilt to 3.6:1 using an old "ACE rear end" (not 100% sure) that my dad picked up in the 70's (longer legs needed for the hipo 289). The gears were directly transferable into the Aceca casing. Gears from other ENV rear ends of that era may be transferable as well. I understood that the same rear end may have been used in Jags of that era. Btw - Ron Leonard has a complete bearing/seals kit available to rebuild the rear end. Good luck on resolving your Clonk.
   
   John

[lew]

Keith,
   More than happy to write a short article but
   1) I am not very articulate
   2) wouldn't know how to submit it
   3) I wonder if it would be seen by the correct radiance ?
   
   My reasons for 3 is that as far as I know the forum is viewable by anyone on the web(good thing), and the Mag only by members.
   I wonder how many, like myself, wonder why we should pay the annual subscription when all we realistically get is the
   mag. Due to where we live we can't participate in anything. I wonder how many owners out there are not members for this reason?
   Perhaps it should be written into the forum

[mike m]

Lew/ Tim,
   Keith has put me "in the frame " for this one, knowing that I managed to locate and purchase 3 ENV diffs that fit directly into ACE ACECA. They all came from Daimlers, Regency, Regina, Majestic, 104 and DK400A. I have inspected a couple of very late Daimler disc braked rear axles and they were also 3.9. At that stage I presume Jaguar had bought out Daimler and might have used their own axle? but probably the last Majestics. Lea Francis also used ENVs post war but used 4.875 ratio except for the 14 Sports at 4.55. I have also worked on a 2.5 Ltr sports special with 3.9 diff. As a last thought my info suggests that the 18HP Saloon 49/54 used 4.1 along with the Lynx prototype! Cautionary note at this point, Daimlers are very heavy and may have been used and abused during long service and although the diffs are over the top for AC work they can and do suffer neglect and wear. Just a last word, having changed both ACE and ACECA diffs after conversion to O/D I think the ACECA is the most time consuming. Best of luck with your searches.
   Mike.