Diff upgrade

[SteveRST]

I suppose it's almost like a traction control system - but it doesn't control traction, rather the opposite - but it probably is 'safer'. An open diff will divert power to the unloaded wheel, which is 'safer' in a situation where the power being applied is overwhelming (or close to overwhelming) the available grip/traction.

With an open diff the power is still obviously being delivered by the engine, but it will take the path of least resistance.

So if you are trying to do a standing start and one wheel is on on the dirt, then this wheel will spin up and very little power will be delivered to the wheel that has traction. Not a fast getaway!
If you are cornering and applying power, then the unloaded (inside) wheel may overcome the available traction and spin. In this case the open diff will feed power to this wheel because it's easier than driving the wheel that actually has traction, but it's not going to make for fast progress.

So the LSD limits the slip of the unloaded wheel. It restricts how much of a difference there can be speeds of the two wheels, and tries to apply torque more evenly between them.

Many drifters would lock or weld the diff, so that each wheel HAS to turn at the same speed. Great for skids but not good on the road. I tried a welded diff in my Westfield and it was weird. Promotes understeer when cornering as the rear wheels are turning at the same speed, and they just want to drive the car straight ahead.

[DJ.]

I tried a welded diff in my Westfield and it was weird. Promotes understeer when cornering as the rear wheels are turning at the same speed, and they just want to drive the car straight ahead.

You have my respect Steve!

[SteveRST]

I tried a welded diff in my Westfield and it was weird. Promotes understeer when cornering as the rear wheels are turning at the same speed, and they just want to drive the car straight ahead.

You have my respect Steve!

Have it in the garage still Duncan if you fancy a go with it

Need to get around to eBaying it.

[Matth93]

I used to run a welded diff when I was racing (lsd wasn’t allowed) and on the front wheel drive cars it would wind the driveshaft up going round the corner which would then kick a little as it unwound coming out of the corner but if you had put too much camber on the car it would shatter the cv joints. To help with that we would run a Astra shaft on the Novas (it’s longer)

[locost220]

I used to run a welded diff when I was racing

Ditto, ideal for grass track, mud. But can catch you out.

[b33fy]

Colin, hopefully your query has been covered. In a nutshell you gotta think about the throttle and steering a bit more with a slipper as the power just doesn’t waste away through a spinning wheel. As Steve said get it right and you get great launches and faster exit speeds from corners, nice controlled drifts and donuts. Forget it’s there, apply too much go pedal and before you know it you’re facing the wrong way.

Loads of car meet “fails” video clips showing exactly this on you tube with cars leaving meets and getting all out of shape.

I’m not an expert on diffs at all, though I understand that an ATB is more progressive than other types.. eg. a plate diff. In so far as there are varyings degrees of locking up depending on levels of grip, power turn in, etc. So they are easier to live with than the disadvantages suggest. I can understand the pros and cons as Duncan describes, a slipper is a “must” in my book. The disadvantages only really became an issue with driver error, including my own..

[Wingco]

Thanks Mike, a great reply tbh. Thanks to everyone for the input, I am just thinking at the mo, got to start saving again after paying out for the head, also need to be sure I need one really, I'm not a fast driver quit happy to drive at my own speed and have fun so we will see.
Thanks again everyone, thanks Matt for using your thread.

[Matth93]

Cleaned all the bits up this morning and changed the bearing runners in the castellated nuts which were in a bad way

Then fitted the new bearings onto the lsd unit and swapped the crown wheel over from the old unit. When I went to fit it into the housing I found it wouldn’t go in due to being a bit bulkier so had to file the casing a bit to allow it in. Then I had to set up the diff on the bearings and adjust the backlash using a dti gauge on one of the teeth of the crown wheel to get it to the correct setting. Once that was done I read that you have to turn the nut 4 teeth tighter to put some preload on the bearings so with that done I fitted the locking plates.

Then it was just refit the rear cover with new bolts and fit new driveshaft oil seals. The diff is now back in the car and just needs oil and the prop shaft bolts doing up which I’ll probably do tomorrow

[nelmo]

I'm pretty sure it would take me a week just to get the diff out the car

Great work, Matt...

[b33fy]

Nicely done Matt.