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Nick Jones

Diff carrier bearings

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Calling diff experts.......

I'm not a diff expert but I've have decided it's high time I taught myself how to assemble diffs.  This has been provoked by the recent purchase of a Blackline Torsen LSD carrier.  It's a Quaife copy at roughly half the price and as the Vitesse diff is whining rather loudly.......

So, the donor diff was going to be a late 3.63:1 (thanks Alan!), ex-spit 1500.  This is now dismantled and as I also happened to have a rather earlier Mk2 Vitesse 3.89 in bits (duff scrapyard purchase some years ago - water damage to CW/P) I was working up a set of bearing numbers and noticed that the carrier bearing numbers are different.

The older carrier has 31.76mm spigots for the bearings and the bearing OD is 62mm

The newer carrier has 35mm spigots for the bearings and the bearing OD is just under 60mm.

I then measured the LSD and found that has the older style 31.76 spigots.  This is all a bit unexpected and has the effect of preventing me from using the 3.63 casing - which is irritating as it's clean and the 3.89 one is horrible...... and also, more significantly, by moving the 3.63 pinion into a different casing as I understand it,  what was a fair chance of the spacer under the pinion head bearing still giving the correct pinion height with a new bearing falls away to zero and I'm not sure how to get this to where it needs to be.

On the flip side the older style bearing looks rather chunkier, albeit with 15 rollers rather than 23.... I've not looked up the load ratings yet.

It's also possible that there is another bearing inner/outer combination that allows the smaller spigot centre to go in the later casing.....

Looks like I can interchange the solid spacer from the earlier diff onto the 3.63 pinion and do away with the horrible crush tube thing, which is definitely good news.

Anyone know what the options are (if any) and the pros/cons?

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Disclaimer: Not an expert, but I've looked into this before and have one to do myself (Marina 4.11 into a Spitfire Mk.4 casing, maybe with ATB...). So, interested to hear how you get on.

Looking at the Spit 1500 parts catalogue page there was a change when the RKC1983 carrier was introduced (standardised/rationalised with 3.27 diffs?). When this happened the bearings changed too, but casing stayed the same. I assume Quaife/Blackline use the original size as it can be made to fit any casing if you use the right bearings.

Form yorkshire_spam's helpful thread:

Quote

GHB105 - diff carrier (to commission number FH106101 equiv. to UKC169?):

LM67048 - LM67010 
(31.75x59.13x15.88mm)

UKC4805 - diff carrier (from commission number FH106102)
 L68149 - L68110
(34.99x59.13x15.88mm)

So the simple solution is to get LM67048/LM67010...

This is a guess, but if you want to swap casing (If the earlier, bigger bearings are considered better): According to the WSM Pinion heads should be marked +/- some number which is the height difference from a nominal reference pinion. If both your CWP have the same +/-, providing you keep the head spacer with the casing it should work? But what are the chances of them being the same... Or could you use this information to calculate the thickness of the head spacer you need?

 

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Thank you for that - not least for finding Sam's excellent thread which I knew was there but could not find!

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Definitely not a diff expert, but I did fit a Blackline LSD this year and, touch wood, so far it seems like a good purchase.  I did two sessions on it at Zandvoort (quali and race 1) before the engine gave up and it behaves exactly as I remember a Quaife doing - very smooth and quiet and it didn't seem to get too hot either (which Quaifes sometimes can), but that could just be me going slow :) But happy with it so far..

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I have one of those i was going to use in my Vitesse,but i was told afterwards that it won`t fit into a 3:27 because of the carrier.

Maybe my Herald with 3:63 will work.

S

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They can be made to fit with a 3.27.  2 Spec did one for Tim Ward.  Not quite sure what is involved but only quite minor machining I think.....

Anyhow......

Some research and measurement suggests that David is quite correct and there is a simple way around this.  I think it is in fact possible to use any carrier with any body by choosing the right bearing, though I haven't yet looked for the bearing that allows the later 35mm carrier in an early body.

There are probably other variations out there (the 4.11s certainly have some differences) but among the parts I have:

Early (Vitesse Mk2) 3.89 has 62mm carrier bearing saddles with a maximum width of 130.6mm
The carrier with this has 31.75mm bearing spigots and uses 15123/15245 bearings with a width of 18.16mm
The carrier width between bearings is assumed* to be the same width as the Blackline one @ 91.5mm and adding two bearing widths gives 127.82mm which will fit within the 130.6mm housing width with just under 3mm for shims

Late  (Spit1500) 3.63 has 59.13mm carrier bearing saddles with a maximum spacing of 126.17mm
The carrier with this has 35.00mm bearing spigots and uses 68149/68110 bearings with a width of 15.875mm
The carrier width between bearings is assumed* to be the same width as the Blackline one @ 91.5mm and adding two bearing widths gives 123.25mm, which will fit within the 126.17mm housing width with just under 3mm for shims

Using the LM67048/LM67010 bearing gives the smaller 31.75 ID in combination with the smaller 59.13 OD wioth the same 15.875 width.  It has a marginally higher (+3%) strength rating than the larger ID bearing.  The early 15123/15245 combination is +30% though....... which is interesting.  However, I don't think the carrier bearings are noted failure points, so probably not worth wrestling with the pinion height issue for.

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Thanks for the info Nick.I want to get this built but i don`t want the car off the road,I have at least 1 3:89 and a 4:11 in the garage,will start looking for another 3:27.

Steve

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