Quaife diff

[alunwill]

I acquired a quaife diff to double check suitability of fit to replace my damaged unit. Overall this is a great looking unit.

Dimensionally it will take the standard diff case bearings and the jag crown wheel would physically fit.


The problem is that the flange which the crown wheel bolts to is almost 2mm closer to the non drive end compared to the original salisbury case.

When I removed the original unit it had 3 x 0.037 (3mm) shims on each side for preload and alignment so first off you'd think just remove 2 shims to compensate!

My question to those members who have far more experience on diffs than me is would 37 thou typically allow you to adjust the crown / pinion relationship enough to achieve correct backlash and gear mesh pattern. I know every set up is different but what does you exprrience indicate.

If not this units not for me.

[mgcjag]

Hi Al....I did mention that some conversions require a large diameter shim /spacer between crown wheel and carrier....you may need to look into it....Steve

[alunwill]

Hi steve,

The use of spacers with this Quaife diff will make the problem worse. The spacers normally fit between flange and crown wheel.

I know that Blackline diffs use spacers with the crown wheel but I've not been able to get hold of the mechanical drawings for their diffs to understand the implications. I hear mixed messages about blackline regarding manufacturing quality standards although they are 40% lower cost compared to Quaife.

Quaife really is a nice unit.

[angelw]

Al Wrote:

When I removed the original unit it had 3 x 0.037 (3mm) shims on each side for preload and alignment so first off you'd think just remove 2 shims to compensate!

Hello Al,
Your car being an S1, the differential assembly should be a Type 1 where the Backlash and Bearing pre-load is set via shims between the Output Shaft Bearing Housings, and the side faces of the diff housing. When making these settings, you do so with all shims removed and adjust the trail backlash by loosening the bolts that secure the bearing housing to the crown wheel side of the diff housing, if you want to increase the backlash, and tighten them if you want to decrease the backlash. The bolts securing the opposite side bearing housing are moved in same direction so as to maintain zero end float of the diff centre bearings while the backlash setting is being determined.

Backlash and Pre-load setting is relatively easy with a Type1 diff, for there is no requirement to remove the diff bearings from the diff centre each time a modification to the shim stack is required. Given the size of your original shim stacks, they seem sufficient to be able to adjust to the correct backlash. Accordingly, even if you're not up to the final assembly of the diff, it wouldn't take long to drop the assembled diff centre in, and carry out a rough backlash adjustment to confirm that you still have scope to on each side of the diff for final adjustment of the backlash.

Regards,
Bill

[alunwill]

Hi Bill,

I do have a series 1 but unfortunately the diff is a replacement dated 1990, which puts it in the xj6/xjs category. As such the shims are between diff bearings and case. With the Quaife this would mean I have 37thou to make any adjustments due to the Crown flange position.

[mgcjag]

You could look at possible thinner bearings as an option...or machine the carrier slightly...Steve

[alunwill]

Hi Steve,

Yes I think those are the options if I want to fit the Quaife in a salisbury shell. I also checked the blackline and it's exactly the same as the Quaife,. That is the crown wheel flange being 2mm closer to the non drive end.

I borrowed the Quaife diff, so at this stage I wasn't in a position to do much with it other than bench measurements.

I'll get the rest of the diff sorted and come back to this.

Alun