Hello Friends,
I need a new crown wheel and pinion for my MKIV as the original is beyond being serviceable. I have found a New Old Stock original Jaguar set but can’t identify what car it ought to fit? It has 39 teeth on the crown wheel whereas mine has 49. The Part Number on the box is 3922 with 522 stamped on the Crown Wheel.
Any assistance would be appreciated.
Cheers,
Tim
How many teeth on the pinion? Crown (39) divided by pinion (?) equals the ratio.
Hi Rob,
The part is with the seller but going on the photo I have it looks like it could be 8 teeth on the pinion? The would be a 4.88:1 diff fitted to a 1 1/2 Litre car. Is there any reason why you couldn’t fit it to a 3 1/2 Litre car? I’m sorry to say that I have never really understood diff’s and ratio’s.
Cheers,
Tim
Hi Tim,
Don’t even think about fitting a 1.5 litre axle to your 3.5.
The Salisbury axles fitted to Mk4s are normally bomb proof. Are you sure it needs replacement?
What’s wrong with it? Photos please.
Peter
The 4.88 , or similar ratio will be hopeless in a 3 1/2 litre and thet are a different HA between the 2 cars AS Peter said they are very strong , unless left with water n them. I’ll ask locally for you.
Hi Ed,
The diff is with Ivan S at his farm. I have seen the crown wheel and pinion and during a previous rebuild the two parts were not aligned correctly resulting in them now being unserviceable, sadly. KB and Ivan are also asking around for a serviceable set. I’m sure that someone with a 1 1/2 Litre would like to have a new gear set!
Hi Peter,
Thank you for the information. As you can see from my response to Ed, the diff was set up incorrectly leading to the dramatic wearing, mostly on the pinion. Would you mind asking your sources in the UK for me please?
I will need to read an article explaining gear ratio’s, especially diff’s in order to understand them.
By the way, with the help of a kindly Jag Club member out here, I was able to view Lavender Grey on an un-restored bonnet which coincidentally perfectly matched the original colour found underneath paint on the boot hinges. That means that I will have the car in the correct, original colour. Very exciting!
Best wishes to both of you,
Tim
Hi Tim,
The axle ratio is very simple. Just divide the number of crown wheel teeth by the number of pinion teeth. So if your pinion had 9 teeth and your crown wheel 36 teeth then the ratio is 4 :1.
This means that with your engine running at 2000 rpm your wheels will be rotating at 500 rpm. If the ratio had been 5 : 1 then for the same engine revs your wheels would only rotate at 400 rpm. So the larger the axle ratio the slower the car.
Peter
Hi Peter,
Thank you for that explanation. I have just been reading a lengthy article about diff ratios so now I understand what it all means. I guess you don’t know about such things until you need to?
Cheers,
Tim
The parts book says you should have a 11 x 47 set, which was also used on 3-1/2 Liter Mark V. Look for this tag.
Hi Tim,
I have experience of two cars with horribly noisey axles. My SS was a real grinder but with the meshing set correctly it is a nice quiet axle. A friend’s MG was similarly transformed by just replacing the bearings. Set your axle up correctly and try it before swapping the gears.
Peter
Rob, is he looking for a 4.27:1 Salisbury 2HA gear set?
I think so.
Tim, can you check that your crown is 47 teeth rather than 49?
Does it have a rear cover like this>
A 4.27 Salisbury Hypoid 2HA Model is what is in my Mark V. Late Mark IV is probably the same axle other than being set up for different shocks and mechanical brakes vs hydraulic as the Mark V has.
Hi Rob,
The car is with my restorer about two hours away. I’ll have to send him this message and see what he says.
Thanks for your help, it’s always appreciated.
Cheers,
Tim
Hi Rob,
I’m told that the 47 tooth crown wheel is for a 2.5 Litre. Whereas the 49 tooth is for the 3.5 Litre. Both have an 11 tooth pinion.
= 4.27:1
Cheers,
Tim
Mike
Yes that’s the correct one. he needs
Thank you Ed!
I have a brand new in its original Jaguar box, crown wheel and pinion set for a 1.5 L if someone would like to trade? You never know…!
Cheers,
Tim
Not quite right, according to the parts books. The 3.5 Litre Mark IV and V used the 47 tooth crown with 11 tooth pinion for a 4.27 ratio. The 2.5 Litre Mark IV and V used a 50 tooth crown with 11 tooth pinion to give a 4.54 ratio.
Is it possible your car has been running around with a mismatched gear set? That would explain how they got chewed up.
Or could there be an error in the parts books?
The part number of the 11x50 set is given as 2HA-100/1 in the Mark IV book, but as 2HA-100/2 in the Mark V book.
The part number of the 11x47 set is given as 2HA-100/2 in the Mark IV book, but as 2HA-100/4 in the Mark V book.
Tim
I spoke to IM who says he has a back end 3 1/2 he would sell.
Hi Rob,
I’ve read un the MKIV & MKV Service Manuals that the Crown Wheel ought to be 47 teeth with the Pinion 11 for a 3.5 L. No doubt that is the the case. I’ll recount the Crown Wheel teeth next time I get to it.
Best wishes,
Tim
Tim
That’s correct and what the parts book also says ,
