Hi New to this site. When doing a web search I thought I had found the solution to my problem but having registered I can't find the info I registered for :-(
I am rebuilding a Trike I have had for a couple of years. I was told it had a Ford Sierra sapphire diff and axle (rear)
I would like a higher cruising speed. I have gone down the route of increasing road wheel diameter, twice, with little improvement.
The diff has these numbers/idents stamped on it.
Ford oval plate
10-1-83
838840275BE
Could anyone please identify this diff for me please?
Does anyone know if I could give her longer legs.
Cheers Frank

http://www.locostbuilders.co.uk/forum/9/viewthread.php?tid=85080


Have a look here
And welcome to the forum
Jacko

has it got a little metal tag on the back ? that's where the code is written


otherwise you'll need to count the number of turns on the input for one turn of the outputs
(or open up the back - its often stamped/written on the ring gear)

Thanks Jacko That was the link I was looking for when I registered

And also to mcerd1 I am taking the diff to be blasted tomorrow so hopefully I may find the rest of the idents
Cheers Frank
these were dam fine quick answers

i'm sure my atlas diff has 3.44 written (in white paint, by hand) on the crownwheel? got no reason to believe it wasn't done at the factory too. have you taken the cover off to look? might be worth a shot?

Try here....

http://www.super7thheaven.co.uk/Sierra_Rear_Differential

If you blast the diff casing the little tin tag held on by top left diff cover bolt will disappear
Then you will have to take the diff cover off and read crown wheel
What bike engine do you run?
Most need 3.38 to get top speed some get 110 with 3.62 others need the 3.14
The 3.62 is common the others rare and will cost £250

Thanks for that info Snapper.
If there was a little tin tag on the back plate it is long gone.
The bike is a Yamaha XVS 1100 Dragstar with a few minor engine tweaks.
On its original Trike wheels I did get 95 indicated on the sat nav in Germany but she was near the rev limiter.
Actually I didn't consider that too bad since the quoted top speed for the bike is 110 and at the time she was almost double the weight of the basic bike. I've had one short run on the 17" wheels I am now fitting and it doesn't seem to have affected the acceleration at all but because I had not calibrated the "Speed Healer" or had the sat nav on I don't know if the top end has been affected.
She will hopefully have lost considerable amount of weight over this winter.
Thanks again
Frank

As previously noted in the thread and as you have the diff out, turn the input shaft and count how many turns it takes to turn the output shaft once.

Whats the rev limiter on this engine, I don't think its a screamer so 95 would be about right with a 3.62 diff. Its a fairly torquey engine so should pull a 3.38 without an issue.

Here is a link to a calculator you can use.

Linky

why 17" inch wheels ? Are large diameter wheels more popular for trikes than locosts where even 15" wheels are considered big ?

Thanks Guys Great info.
Diff cleaned up well and the little tin tag was! there after all tells me it is a 3:14.
Its all glossed up black now and looks great.
It has to be mounted upside down in the frame and actually looks better for it.
my only problem now is that I don't know how much oil and what grade I should use.
If anyone has the info I would be very grateful
Cheers
Frank