Hi all, another noddy question I'm afraid.

I've found someone breaking a Sierra xr4x4 and I have expressed an interest in its rear running gear (from lsd to brake calipers).
What would be a "reasonable" price to pay for this lot?
I don't want to pay over the odds just because it's available now! As an aside - are these parts readily available from breakers?

Thanks in advance

Rich

About 120 is fair enough for the complete back axle including the brakes and handbrake cable.

Liam

They aren't readily available but difficult to source. How many 4x4's did you see on the roads in their heyday? Not many I'd wager. We have an LSD on Hellfire - there's not much opportunity you get to use it for it's intended purpose TBH.

We're going open for the next one - save some weight!

So what you're saying is that unless you're building a track car don't bother going for a lsd?
Would it not make general road driving better/safer?

Rich

There is much divided opinion on this subject

It's debatable whether an LSD is necessary with a bike engine, but the benefits will be more noticable with a torquey car engine. With anything low really low powered it probably aint worth it either.

i'd go for an LSD rear end anyway for the disc brakes if anything, then you have the LSD if you ever go for big power. Also, if you have any interest in controllable progressive sliding/drifting or donuts, then an LSD is a must!! Search for posts on LSDs and have a read. I'd say its better to have one that you dont really provoke than not to have one and be longing for one.

Liam

The sierra LSD is basically an open diff with a viscous coupling. If you spin one of the wheels then the viscous coupling "locks up". This has the effect of slowing down the spinning wheel and transfering power towards the wheel that has grip.

The uses of this are:

When pulling away on slipery / wet roads or at full throttle, the wheel spin will be controlled somewhat, allowing some acceleration rather than hugh wheel spin.

On a tight bend when putting on lots of power, the inside rear wheel can be made to spin. An LSD can reduce this alowing a faster get away

LSDs have their bad sides as well:

When an LSD is working, they can cause an increase in understeer. Remember that a sierra diff is basically "open" until one of the rear wheels starts to spin. In that tight corner, the LSD will allow you better acceleration at the expense of running wide out of the turn.

The sierra LSD and bolt on shafts weigh about 10kg more than an open diff with push in shafts. That will increase you 0-60 time from 4.00 seconds to 4.08 in a 425kg car.

I suppose that you could also construct an arguement that a change from rear wheel spin oversteer to rear end grip and understeer may be a little less predictable than on open diff which will just have the rear wheel spin oversteer.