Okay, i'm trying to decide what tranny, and quaife, flywheel and clutch. It sounds like to avoide the 21 spline tranny you should get a 89-91 si tranny, BUT, I was looking at quaifes, and the 90-91 si uses a 35mm bearing, but like every other si and ex from 88-99, except the 90-91 uses a 40mm bearing.

Is it better to have the 40mm one, or does it not matter? What bearing are they exactly talking about here? Does this affect which axles you can use?

My plan now is to go with my 89 si tranny with 90-91 flywheel and clutch, with a quaife 40mm bearing.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Killa-X &raquo;</TD></TR><TR><TD CLASS="quote">Is it better to have the 40mm one, or does it not matter? </TD></TR></TABLE>

If you do not have the tranny yet, I would look for one with the 40mm bearings. I think they are a little better, but have no factual or actual proof. Just a gut feeling kind of thing.


<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Killa-X &raquo;</TD></TR><TR><TD CLASS="quote">What bearing are they exactly talking about here?</TD></TR></TABLE>

The bearings they are talking about are the ones on either side of the differential.


<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Killa-X &raquo;</TD></TR><TR><TD CLASS="quote">Does this affect which axles you can use?</TD></TR></TABLE>

It should not affect which axles you can use.


<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Killa-X &raquo;</TD></TR><TR><TD CLASS="quote">My plan now is to go with my 89 si tranny with 90-91 flywheel and clutch, with a quaife 40mm bearing.</TD></TR></TABLE>

That sounds like a good setup!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by keithv &raquo;</TD></TR><TR><TD CLASS="quote">

The bearings they are talking about are the ones on either side of the differential.
</TD></TR></TABLE>

So if the bearings are on either side of the differential, does that mean the differential housing is larger? And so the input shaft splines on the differential are unchanged, just that the 88-89 has larger bearings for the axle input?

I'm not a tranny guy, and know jack about them. Thanks.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Killa-X &raquo;</TD></TR><TR><TD CLASS="quote">So if the bearings are on either side of the differential, does that mean the differential housing is larger?</TD></TR></TABLE>

I am not 100% sure if the differential housing is larger, but the shafts where the bearings go are larger since the bearing has a larger ID. Also the larger ID bearing has a larger OD, so the tranny case opening where the bearings sit is larger.


<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Killa-X &raquo;</TD></TR><TR><TD CLASS="quote">And so the input shaft splines on the differential are unchanged, just that the 88-89 has larger bearings for the axle input?

I'm not a tranny guy, and know jack about them. Thanks.</TD></TR></TABLE>

I wish I had a pic of an opened tranny case, but I don't. That would probably explain alot.

 

If you find a pic of an open tranny case that would be awesome. Please post if you find one.

 

The Quaife website is *WRONG*. Most 88-91 Si transmissions use 40mm bearings, and all DX's and HF's use 35mm bearings. The info on the Quaife website that states that 90-91 Si's use 35mm bearings is BS. There is no strength difference between the 35mm Quaife and the 40mm Quaife unit since the shafts on each end are not a high stress area of the differential. Other than the shaft size on each end, the 2 quaife units for d-series are identical. I bought a 35mm Quaife because their website said that a 91 Si uses 35mm bearings (wrong), and now I'm stuck having to get an adapter because my transmission uses 40mm bearings. The adapter from KAAZ is supposedly just a sleeve that increases the size of the end shafts on the differential to 40mm so you can use the larger bearings.

 

So for one to check what size bearing they have, do they have to take the differential out of the tranny? Or can you check somehow by yanking out the axles, and checking there somehow?

 

You could probably pull the axles and axle seal from the tranny to find out what size differential bearings you have.

 

Pull your axles out and measure your bearing size with a set of calipers. No need to remove the seal, it should be obvious which size you have.

BTW, I am not positive that the Quaife site is wrong, this could very well be a Canadian model / US model difference. At least up here in Canada, almost all the trannies I have seen of Si's and even DX's are 40mm. I can't say the same about the USDM trannies.

 

okay. And the differential bearing has nothing to do with the axles? As in any si axle will work with either the 40mm or 35 mm bearing-ed differential?