Overdrive in 2+2

Technical advice Q&A

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DT
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#1 Overdrive in 2+2

Post by DT » Tue Feb 28, 2012 9:03 pm

Advice please. Looking at adding an overdrive to my manual 2+2 series 2. Spoken to many people - is it simple to do with no body modifications as some have said - others have said bodywork mods needed even in a 2+2. If mods needed it will be a 5 speed box! All information and pictures welcome

David

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PeterCrespin
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#2

Post by PeterCrespin » Tue Feb 28, 2012 11:13 pm

For a manual, remove four speed, swap E-type top cover onto XJ overdrive box, instal overdrive box. Wire up overdrive and enjoy relaxed cruise in electric 5th gear. The end. If you get the MOD box from an S-type you don't even need to swap top covers.

NB any other Jag overdrive box will not fit. It has to be the 'Compact Type A' overdrive.

Have fun.

Pete
1E75339 UberLynx D-Type; 1R27190 70 FHC; 1E78478; 79 S2 XJ12L; 97 XJ6L

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garrycol
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#3

Post by garrycol » Tue Feb 28, 2012 11:35 pm

Can this overdrive handle a V12?

Garry
1971 Series 3 E-type OTS

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christopher storey
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#4

Post by christopher storey » Wed Feb 29, 2012 9:47 am

Very unlikely to do so successfully. You could try changing the springs for stronger ones if you could find them, but I can think of no car larger / with more torque than the XJ6 which used the Laycock OD

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garrycol
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#5

Post by garrycol » Wed Feb 29, 2012 12:15 pm

Ok - thanks
1971 Series 3 E-type OTS

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MarekH
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#6

Post by MarekH » Wed Feb 29, 2012 12:32 pm

Dear David,

David Lacey in Malaysia has this setup and reports no problems with it. As pointed out, the overdrive is also used in heavier cars than the etype. I have fitted one to my v12, details of which are on the Jaglovers.org site. The car should be back on the road this summer. I would counsel you to install a relay to operate the solenoid so that it takes its current from a fused brown wire directly and not via a green wire through the ignition switch:- the solenoid has normal working current of just one amp but takes 16 amps to "fire", so any malfunction will fry the ignition switch if it jams whilst in the process of switching on.

See
http://www.jag-lovers.org/snaps/snap_vi ... 1170885932
http://www.jag-lovers.org/snaps/snap_vi ... 1326286185

Aside from the gearbox top cover, it was a drop in replacement. Another slant on this topic is to change the differential ratio - the v12 has plenty of torque to be able to accommodate a 2.88 if you are wanting to reduce the revs.

kind regards
Marek
Last edited by MarekH on Thu Jul 16, 2015 9:54 am, edited 1 time in total.

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PeterCrespin
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#7

Post by PeterCrespin » Wed Feb 29, 2012 1:39 pm

christopher storey wrote:Very unlikely to do so successfully. You could try changing the springs for stronger ones if you could find them, but I can think of no car larger / with more torque than the XJ6 which used the Laycock OD
You would think so (and I held the same view) Christopher, but that is not so.

Overdrive Services near Sheffield is a company made up of ex-Laycock people so one would have to accept they know what they are talking about. When I took an overdrive there I told them I wanted the competition upgrade and they asked me why? I told them I might be fitting it to my Series 3 E-type but they said not to bother. To cut a long story short I had to cajole them into taking more money from me for the upgrade and they were not at all interested in flogging me anything extra to make handle the V12. From memory they talked about the weight of an E-type being relevant and a lot lower than a 420G for example. The upgrade includes upgraded friction linings and a higher release valve setting/running pressure for the clutch. I think there was something else. The normal Jag fitment is for overdrive only to operate on top gear of course, which is all you need to get a fifth gear.
1E75339 UberLynx D-Type; 1R27190 70 FHC; 1E78478; 79 S2 XJ12L; 97 XJ6L

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DT
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#8

Post by DT » Mon Feb 24, 2014 3:56 pm

Just fitted the overdrive gearbox with its bell housing and new high torque starter motor without any spacer plate. The motor will not engage as it appears the overdrive box was off a 2.8 XJ6 ( it has no dowels on the plate behind the starter motor). I am told bell housings are different and I need to put the original 4.2 housing on the gearbox. The odd thing is that the original starter motor works. Anyone else had any of these issues? It is a late 4.2 series 2

Thanks

David

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tinworm
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#9

Post by tinworm » Mon Feb 24, 2014 4:47 pm

Hi - martinus is looking for a 2.8 bell housing - and I think he may have a 4.2 one as he has a similar problem but in reverse ! - you guys should get together . See his post under 3.8 engine ,correct clutch housing ? from a week or so back.

regards Barrie
1962 E-type roadster, 1964 E-type fixed head 1995 Ferrari 355 1980 Ferrari 308 1987 V8 90 Landrover 1990 BMW 325 touring 1988 Bedford rascal van

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#10

Post by Moeregaard » Mon Feb 24, 2014 5:02 pm

Just my two cents, but I'd scrape and save for a five-speed box. I had OD in my Healey 3000 and it was a pain in the ar*se., which is why so many Big Healeys in the U.S. are converted to Toyota 'boxes. I'm not going to pull the lid off of the"who makes the best five-speed" debate, but any of them will give you the OD top gear with slicker shifting throughout, and you'll save some weight over the factory unit.
Mark (Moe) Shipley
Former owner '66FHC, #1E32208
Former owner '65FHC, #1E30036

Planning on getting E-Type No. 3 as soon as possible....

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JaggyWag
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#11 V12 Overdrive

Post by JaggyWag » Mon Jul 13, 2015 9:29 am

OK, please can anybody let me know if they have fitted the overdrive gearbox to a V12 AND successfully run it for some serious miles rather than just potter about? Looking at previous threads that might have been Pete C and MarekH?

Thanks folks!

Pete
Peter

Series 3 2+2 1973
21 years off the road...until now!

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MarekH
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#12

Post by MarekH » Mon Jul 13, 2015 12:45 pm

Dear Pete,
I have run it successfully for some serious miles. Despite others' reservations, it hasn't fallen apart yet.
kind regards
Marek

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JaggyWag
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#13

Post by JaggyWag » Thu Jul 16, 2015 8:55 am

Thanks Marek, I have joined a little club with you! Do you have any words of wisdom on the best way to wire it up, I seem to remember some words of caution but cannot find the thread!

Regards

Pete
Peter

Series 3 2+2 1973
21 years off the road...until now!

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MarekH
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#14

Post by MarekH » Thu Jul 16, 2015 9:56 am

Click on "previous" for the advice.

kind regards
Marek

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Maxa
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#15 Re: Overdrive in 2+2

Post by Maxa » Mon Nov 12, 2018 10:42 pm

Hi Forumites, some help please from someone who has done it preferably. I am fairly happy that I have the correct short tail o/d box and sitting it alongside the original non o/d (mnod ?) gearbox it appears straightforward, even the original propshaft will fit. The o/d is slightly bulkier than the long taper on the non o/d box and I have heard some lump hammer attention is required. Is this so? My shell is painted, undersealed and has the KoolMat thermal insulation glued in so I would like to know if there is any cutting and welding to do. If so I will have to fit the box to it’s rear mount and offer it up, sans engine, to see where to cut or bash.
Also is it early mod xj6 s that have the gearstick with the o/d switch in the top? I will have to find one of these. It seems a good way of switching the o/d .

Thanks in anticipation Michael.

Willow green s2. 2+2

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mgcjag
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#16 Re: Overdrive in 2+2

Post by mgcjag » Tue Nov 13, 2018 9:15 am

Hi Michael.....i havent done it but got a box and o/d then changed my mind......from all i read there was no cutting/welding....its the speedo o/p that can cause a problem and catch the body.....the lever with the switch is early xj6 not sure if it was on other models.....you can fit a dash switch if strugling to find a lever.....is your existing car a manual or auto....what car is you gearbox from....it will need an e type top cover if you want the lever in the correct E position....just a bit of help someone who has actually installed one im sure will add.......Steve
Steve
1969 S2 2+2 & Building a C type replica

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1954Etype
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#17 Re: Overdrive in 2+2

Post by 1954Etype » Tue Nov 13, 2018 10:13 am

We've done a couple of these in S2 2+2s. You have to create a space in the transmission tunnel (RHS towards the rear) in order to clear the (I think) speedo drive. You then have to put a 2" cut at the back of the tunnel (top where the propshaft exits) as the overdrive unit is slightly wider at this point than the standard gearbox. This area is where the 2 panels meet and is welded originally. No big deal to weld in a strip once you know how much you need (about an 1").

Great mod and beats a 5 speed box hands down!
Angus 65 OTS 1E11497. 67 FHC 1E33656

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Durango2k
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#18 Re: Overdrive in 2+2

Post by Durango2k » Tue Nov 13, 2018 1:28 pm

In fact, it depends wether your car was either auto or manual before. If it was auto, the tunnel which the factory welded in will be large enough, google Jos Raaven for pictures.

If your car came as a manual car, my guess is that they put the standard manual tunnel from the SWB cars in them, because it is too narrow, and as said above, it involves some hacking, and some minor conflicts with the seat edges.

I have done it myself....

Carsten
Jag E '66 S1 2+2, Citroen DS 23 Pallas iE, Citroen SM 3.0, Concept Centaur MK1, Citroen 11 BL '54, Sinclair C5, Velosolex

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