The 'E' Type Forum

Just want to share my excitement!!

Tomorrow work starts on converting the 3.31 diff in my S3 to 2.88. Now the revs will sit at 2900rpm instead of 3300rpm at our legal cruising speed. The Speedo should also be MUCH more accurate under reading by only 2%.

This will make cruising long distances a lot more pleasant. Of course an overdrive 4th would be marvellous....

Very interested to hear how this goes Philip. Full update after road test please!

I'm assuming you have the factory 4 speed?

Double Six wrote:Very interested to hear how this goes Philip. Full update after road test please!

I'm assuming you have the factory 4 speed?

My mechanic became scared of not meeting the deadline to have the car finished by Wednesday next week - when I need the car of a road trip. We don't have the access to spares like you in the UK. Although I gave him all the bearings needed, he was scared that he needs shims and that may stall the conversion if not available in SA. So, it will be done some time after that.

My car has the 3sp BW auto.

Hi Phillip.
My car has the 2.88 plus a getrag 5 speed. At our speed limit 100km/hr it shows 2000rpm, this makes it great cruising still with leisurely overtaking.
The best thing about this combination is the need for plenty of gearchanging to drive the car properly, especially when things get twisty.
Happy motoring.

That sounds nice!!

With our long distances between destinations of interest, the more overdrive in top gear the bettter. My 7.2L Jensen (and my XJS) is doing 2000rpm at 120km/h and I feel that is still too high for steady cruising.

I test drove a 2011 Range Rover TDV8 recently and that car is doing 1500rpm at 120km/h in 8th. NICE!!

If this BW just gives the slightest hickup, it will be replaced with a GM 4L60e (hoping that it will fit). Then I will have 1900rpm at 120km/h! (1600 @ 1000km/h). The V12 will have no complaints about this!!

Hi,

Having also done something similar you have every reason to be excited, I moved from BW Auto to Getrag 5 Speed both using the 3.07 Auto Difff.

I then fitted the 2.88 diff with the Getrag 5 Speed & have now moved to 4 Speed with OD whilst retaining the 2.88 Diff.

I have kept all the original parts but it must be said the high speed cruising is now absolutely effortless & also made last year's 2500 mile road trip from Bristol to Le Mans, via Gibraltar, a far more (relatively) efficient affair!

You should certainly enjoy it when it's completed.

Regards,

Dave

I have a 2.88 dif with a rebuilt standard 4 speed 'box. The car is unique in having a factory fresh 6.0 litre fuel injected XJS engine, and the Roger Bywater's (AJ6 Engineering) Torque Plus conversion with different ECU and larger throttle bodies. With approximately 365bhp, and even more torque, it is fabulous, and very quick. It is 3000rpm at 70mph, but the speedo is still not reading accurately. The car is also on 7" x 16" wire wheels and 235/60 x 16 tyres. Not sure what difference that actually makes to the gearing.

Barry wrote:The car is also on 7" x 16" wire wheels and 235/60 x 16 tyres. Not sure what difference that actually makes to the gearing.

Not much. Those 235/60/16s are 0.8" (20mm) larger in diameter (10mm in radius) than standard. Your speedo should thus read 60mph when in fact you will be doing 61.4mph actual speed.

I thought of going to 215/70/15 (+7mm in radius) when my car is due for replacement.

Hi,

If it helps I'm running 215/65 R15 tyres (V Rated) all round & these appear to be a good alternative.

The thing to be very careful of is to ensure you get 'V Rated' Tyres as there are very few 205/70 R15 tyres that comply with this as many were produced suitable for vans?

Whilst I don't have a desire to use them I believe there are lots of 'White Wall' tyres that aren't compliant with the V Rating & as such it's likely that insurance may be invalidated if ever you were unfortunate enough to have an incident.

Cheers,

Dave

Hi guys,
very interesting topics for me inded.
My long term restoration is on going step by step.
The engine with a light weight flywheel is connected to a Getrag 5 speeds gearbox, the 5th has a 0.8 ratio. All is back in the car connected to a 2.88 diff.
I m happy to see that this kind of configuration sounds good !
Michel

Dave123m wrote:Hi,

If it helps I'm running 215/65 R15 tyres all round & these appear to be a good alternative.

The thing to be very careful of is to ensure you get 'V Rated' Tyres as there are very few 205/70 R15 tyres that comply with this as many were produced suitable for vans?

Whilst I don't have a desire to use them I believe there are lots of 'White Wall' tyres that aren't compliant with the V Rating & as such it's likely that insurance may be invalidated if ever you were unfortunate enough to have an incident.

Cheers,

Dave

Dave are you sure that in case of an incident you will not have trouble with your insurance because of the tires size.
I mean not only the v sounds to me important but also the dimentions.
cheers
Michel

People assume the tyre rating is solely to do with top speed whereas it is actually a test of several things including tyre wall strength, vehicle weight and the effect of all these factors on road holding and cornering. This is why the "but I never go that fast" argument on VR tyres is incorrect. Jaguar and Dunlop worked together to produce a tyre specification for all driving circumstances and conditions specific to the E-Type. So technically using anything other than V rated (or superior) tyres could be grounds to invalidate an insurance claim. When E-Type values were hovering between £20k and £50k the Insurance company loss adjuster would not be overly concerned but with values of £200k and up they will start looking seriously at accident claims.