Winter Job 1 - Differential (Advice Needed)

[Welly Jen]

Sorry, what do you mean Terry?

I had two full turns of the prop to nearly one full turn of a wheel. Think that put's my diff ratio at something like approx 2.1 which sounds a very high ratio? I may be completely misunderstanding here. Will try and find a good source to read up.

I want the car to be at it's best on track therefore, I guess, a healthy balance between acceleration and top speed, not interested in motorways. But I guess it's not as simple as what diff ratio do you use? i.e wheels sizes and gearbox ratios come into play as well. This has the potential to hurt my head.

A bit more detail on working out the diff ratio. The diff splits the drive from the prop shaft to the left and right hand wheels. It allows the wheels on the inside of a bend to go round slower than the wheels on the outside, so in a left hand bend, the left hand rear wheel is going round slower than the right. If you lift just one wheel and turn the prop shaft and count the number of turns of the prop shaft for one of the wheel, the ratio you get will be half the diff ratio as the other wheel is stopped. So if the prop shaft turns twice for every once of the wheel, then the diff ratio will be 4:1. If you have both wheels off the ground and turn the prop shaft, then on a non limited slip diff, you can't be sure that the two wheels are turning at the same rate. My car has a 3.89:1 diff, which is a common ratio for an English axle. The easiest way once the diff is out is to count the teeth on the two gears and divide.

A simulator to estimate the effect of changes on performance is this one. There are also on line gear ratio calculators where you can play with the effects of gearbox, wheel size and diff changes. You can make your own too if you are handy with spreadsheets.

Jen

[Young Pretender]

Thanks Jen, that's useful info, as is the calculator. Hopefully I'll have the diff out soon enough to know for sure.

Cheers

[Dodgey]

I kinda need a photo to understand where you are stuck - but you mentioned the possibility of a brake shoe sticking so I'll assume you have one brake drum that won't come off? (I don't understand what thread has gone, and you mention the "bolts through the holes" - but you can't see them until the drum is off.)

You removed the one small philips screw (or is it 2 - can't remember?)

Then, the trick I found (one was very stubborn) was to hit the edge of the drum (you have to be careful that it's the edge of the main drum you are hitting and not the thin back plate right next to it) hard with a rubber mallet - do this in various places, going round in a circle. I really had to thump it a fair few times. Had a break. Tried again, then all of a sudden it fell off.

Make sure you handbrake cable is slack (I found no need to adjust or undo any of the braking).

To free the drive shafts I did the same - rubber mallet on the edge of the hub - hitting it sideways, not towards the diff, in a circle. it'#s about shocking the splines free.

I would not put a metal mallet any where near any of it. Your drum is cast so it is brittle.

A few links that i used:

http://z7.invisionfr...?showtopic=2526

http://www.locostbui...d.php?tid=99414 (click the link until the page works - it does eventually)

http://www.locostbui....php?tid=118931

http://streetrodstuf...r_End/index.php

http://www.turbospor...d-tips-and-info

http://locostbuilder....php?tid=106579

http://www.englishdiff.co.uk/

[Young Pretender]

Thanks Dodgey, will have a good read of these.

I now have one problem - I can't get the brake hub off on one side. Think the brake shoes are still engaged so I need to adjust the brakes and I think the adjuster is on the rear of the hub and looks like this:

From the inside it will look like this (bottom right of pic below):

So I guess my question is: Is it possible to adjust these brakes externally (as per pic 1) or would they need to be adjusted internally which is obviously not viable for me. If the latter how can I get this hub off?

In other news, the shaft on the other side is out so I'm feeling semi-accomplished

The rubber mallet didn't work for me although I tried patiently for some time. What did work, and hopefully this might come in handy for others who don't want to purchase a puller, is to use a screwdriver from the axle side and come through the bolt hole (as per pic below). When the screw driver is up against the face of the drive shaft you can just use a mallet to tap it out.

[Dodgey]

You have different version of brakes from mine, I have a toothed wheel at the base of the hydraulic cylinder / brake actuator. You put a screwdriver through a hole in the back to rotate the wheel.

Those copper studs on yours are just the back of the rivets holding on the shoe spacer . Well that's my guess anyhow .

Can you turn the brake drum? I'm guessing not. How about with a wheel on? If you can turn it it will come off.

I have read that the shoes can eventually wear a "trench" into the drum making them tricky to remove.

P.s. looking at your brake setup I can't see where they adjust. Look at my earlier photo and its obvious where mine adjust ( toothed silver wheel)

[Dodgey]

I'd do a separate thread in the technical section specifying your brake model in the subject and someone will help you get the drum off in no time.

[Young Pretender]

The diff is finally off.  Don't worry I haven't been working on it solidly 

 

Brake hub had corroded on, one drive shaft was a pig (even with a slide hammer) and had to unbolt both suspension arms on both sides and undo the panhard rod so I could rotate the axle in order to drop it out.  But it's out.  It's a 3.89 diff.

 

So will be having the diff rebuilt (hopefully just bearings as the crown and pinion look ok to my untrained eye), new wheel bearings, probably do the brakes, all seals, bolts, and bushes replaced.  

 

But don't worry, I'm sure I'll have plenty of questions when it's time to put it all back together! 

[Dodgey]

Nice one :-)  Now you have done it once it's a doddle to put back together. I put copperslip round the inner lip of the brake drums - had to take them off the other day and it was way easier this time.

 

Couple of interesting links:

 

If you phone the guy h'll prob knock off a further 10% - most people who put their number on the ebay add do.

 

http://www.ebay.co.uk/itm/ford-escort-mk1-2-english-3-89-diff-lots-of-other-ratios-available-/271118152253?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item3f1fe6b23d

 

Or.:

 

This guy will rebuild your diff for £130

 

http://www.ebay.co.uk/itm/english-diff-differential-bearing-rebuild-service-cwp-lsd-escort-elan-anglia-3j-/281020559861?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item416e2171f5

[Young Pretender]

Cheers mate, I've got a place called 'Road and Race' not far from me that have been recommended earlier in this thread.  Price is very similar so taking it in there on Wednesday morning.

 

One question, did you go for any specific wheel bearings or just the best price you could find on the net?

[Dodgey]

I got the ONLY bearing I could find that came with the collar at the time! There seems to be a drought at the moment.. I ended up getting the ones with the small rubber o ring running round the outside.

I think I used burton power. There are two models. The width of your bearings is the deciding factor.

My advice is dont change them unless you need to!

[Young Pretender]

Well, I finally got around to putting the whole lot back together again after a full and cold day in the garage lol..

 

Didn't really get a proper run out because of the weather and my seat (and seat belts) aren't fitted.  A short blast, however, confirmed that it's all quiet 

 

Will look forward to an extended blast in the near future.

[Dodgey]

Sweet. Which bearings did you use in the end?

[Young Pretender]

The engineering firm I used ordered the same ones.. I think they were Mk1 escort.  I asked him if they were mk1 one or mk2 and he said 'pre'.