anyone running a 4.0:1 diff?

[anthony1956]

besides me.

[Jason Plato]

not if it's a ford 7" they won't be .ford didn't do a 4.0 , the closest is a 3.92.

[Englishmaninwales]

Next closest is a 4.1 (although I think the CWP is an aftermaket gearset )

[Paul Deslandes]

I have a 4.11:1 using a cwp set supplied by Raceline some years ago. Its a compromise between road driveability and hill climbing with a c/r Quaiffe box 2.04 1st and 0.87 5th. Unfortunately its much noisier than the original 3.92 cwp, but that's down to the after market quality of the cwp rather than the ratios.

 

I plan to change the g/box to SPC semi helical innards to include a 0.82 5th for quieter cruising without sacrificing lower gear acceleration.

[EFA]

The 4.1.and 4.4 Ford Sierra crownwheel/pinion sets were made by Kam Differentials.

 

I had a 4.4 in K2RUM.

[anthony1956]

I'll see how many wheel turns I get to one prop turn in 4th tomorrow.

Someone was telling me they were in a Ford Estate of some sort.

 

4.4 sounds a bit quick.

[Gary Stone]

I ran a 4.1 diff in a Ford Escort live axle 7 for a while. I think they came out of 1100cc Escort vans. I originally built the car with the RS 2000 3.54 diff but settled for a 3.89 diff in the end.

[Paul Deslandes]

Anthony,

 

its prop turns per wheel turn you'll be measuring. The 'higher' the ratio, e.g. 4.11 v. 3.92, the more prop turns per wheel turn you'll get. i.e. 4.11 prop turns or 3.92 prop turns per wheel turn respectively.

 

Therefore at 4.11 the car will be going slower at, say, 2000 engine rpm than with 3.92.

 

I'm sure you know this but I was a bit uncertain from a couple of comments made as to whether this was clear.

 

Paul

[anthony1956]

hi Paul funny you should say that. I just spent a happy hour under the car counting prop and wheel revolutions. Eventually someone took pity and told me to spin both wheels at once.

 

edit: I gather I may have written the turns count the wrong way round in thus next para

 

Spinning only one I was getting two wheel turns to one prop turn. With both wheels, after some co-ordination practice I was counting 4 wheel turns to one prop turn.

 

edir and from here on back on track

 

Or one quarter wheel turn spun the prop once.

Then I tried twenty turns and that gave me five prop turns, this last to check I wasn't seeing 3.92 as 4.

 

Finally, my garagist was suitably disdainful saying "I have already counted the teeth on the crown wheel, it is 4 to 1." So.

 

As to the donor car if any; enquiry continues.

 

Edited by - anthonym on 1 Aug 2012 20:14:35

 

Edited by - anthonym on 1 Aug 2012 21:34:45

[DaveMorris]

Anthony(M) - I don't think that you were getting 2, or even 4 wheel turns per prop turn

 

As stated by others above above - it's the other way around. Number of prop turns per one rev of the rear wheel.

 

Try putting one wheel on the ground so it can't move, turn the other wheel around 1 full revolution and see how many times the prop goes around. This will (IIRC) be twice the ratio of the CWP set.

 

Dave

[anthony1956]

maybe I need to edit my post... whichever way round it should be I was getting 4 of one to one of the other. car is still jacked up I will do it again in the morning.

 

thanks for spotting my error.

 

Edited by - anthonym on 1 Aug 2012 21:38:21