Advice on fitting LSD

[Sabbot]

So here's the answer to any of you who were perplexed by the "mystery object" reply in the Northeast events NJMP track day thread.

 

I recently took delivery of a new Titan LSD for a 7" Sierra diff. I now need to figure out how to install and set it up. Any advice on disassembling and reassembling the Sierra diff would be greatly appreciated. I've built a few of Triumph, Imp, Elan gearboxes and a fair number of engines in my time (any most them even worked afterwards) but I've never set up a differential. The Elan workshop manual comes with lots of advice on how to set bearing float etc. and I assume most of it will apply to the crown wheel settings on the LSD.

 

Any and all advice will be gratefully received.

[S1Steve]

Hi Stewart,

I thought LSD was a bolt in . Feel free to explain how it's done when we

 

are down at NJMP. Good luck with it....

[scannon]

Setting up the bearing preload and the tooth engagement takes some skill. Just taking apart the diff and putting in the the new ring and pinion gears is fairly simple. It's getting it set up right that is tricky.

 

My Caterham came with an open Sierra diff. Knowing what kind of HP I was going to get from my engine I put in a Quaiffe LSD.

 

I took a class way back in the '70s on drivelines while in college and have set up a number of diffs but that was a long time ago. I elected to take out the diff and take it to a driveline shop and have a professional do the install and set up. I probably could have done it myself but my skills in that area were rusty and I didn't want problems down the line.

[xcarguy]

  scannon said:

Setting up the bearing preload and the tooth engagement takes some skill. . . . . My Caterham came with an open Sierra diff. Knowing what kind of HP I was going to get from my engine I put in a Quaiffe LSD. . . . . I elected to take out the diff and take it to a driveline shop and have a professional do the install and set up.

 

Ditto on having the diff set up properly. I did rear end rebuilds/diff changes on three of the last five cars I've owned and had a professional set up the diff each time. It's money well spent. :cheers:

[dallasdude]

Good advice. The reason everything has be set up when you put in a lsd is the lsd replaces the open carrier...which is what holds the ring gear. The precise position the ring gear had to the pinion gear is lost. There is a certain amount of science to doing this correctly but a little art also, so better to have someone install who had done it before.

[rzempel]

I don't know about the Titan, but when Installed my Quaife unit, I found that it was a straight bolt in (and so were all the others I've heard about). No spacer changes necessary. I would suspect the same should be true with the Titan, unless for some reason they don't have similar quality control.

 

Randall

[bsimon]

Here is the manual for the 7" diff.

 

A nice quiet diff is the sign of proper setup. If your current diff is quiet, chances are the swap will be easy.

Swapping the carrier is a piece of cake. Backlash and carrier bearing pre-load are the only adjustments to make. In this case you won't even remove the pinion shaft.

 

Pattern the crown wheel and pinion before dis-assembly to verify condition.

[BusaNostra]

I also have a 7" Sierra diff but mine is a quaife atb.

I just dropped the quaife like a plug and play. Didn't do any special procedure or

shim.

[bsimon]

That's the way it's supposed to go.

Swap parts, set backlash, set pre-load, button up and done.

 

It gets more involved when the pinion has to be removed, e.g., diff came with the wrong pinion depth, bad bearings, etc.

[James A]

The one issue I have seen several time with these diffs is that when you remove the bearing housing (part 13 on the diagram) the threads can gall (it is aluminum on aluminum threads), and then you have a real issue. Use lots of penetrant go slow and good luck.