Diff backlash

Talk about the E-Type Series 1

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Mick
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#1 Diff backlash

Post by Mick » Sat Jan 25, 2025 8:10 pm

Hi

I replaced the bearings and oil seals to the output shafts and reassembled them to the diff using the existing shims between bearing caps and diff. I then measured the backlash on the crown wheel as 10 thou, I was hoping to compare this with the engraved marking on Crown wheel but I am unable to make sense of it.
Is anyone able to decipher it?
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Mick

1967 Series 1.5 DHC (1E15721)

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mgcjag
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#2 Re: Diff backlash

Post by mgcjag » Sat Jan 25, 2025 9:46 pm

Hi...is that the original crownwheel....it looks like the engraving for the matching number to the pinion..they come in machined pairs....search for other engraved numbers on the crown wheel....Steve
Steve
69 S2 2+2 (just sold) ..Realm C type replica, 1960 xk150fhc

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#3 Re: Diff backlash

Post by Mick » Sun Jan 26, 2025 5:23 pm

Crown wheel has not been changed during my one year of ownership but it has quite likely to have been changed in the past as the car is a USA import. I have checked again for engraved marks and can only find the 1382 numbers followed by the two illegible symbols. The diff was working fine apart from leaking oil, so in the absence of backlash settings would the best option be to check tooth contact with original shims and leave it alone?
Mick

1967 Series 1.5 DHC (1E15721)

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angelw
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#4 Re: Diff backlash

Post by angelw » Sun Jan 26, 2025 8:29 pm

Mick Wrote:
The diff was working fine apart from leaking oil, so in the absence of backlash settings would the best option be to check tooth contact with original shims and leave it alone?
Hello Mick,
The final arbitrator is the contact pattern on the Drive and Coast side of the Crown Wheel teeth. More times than not, if the Pinion Height to Crown Wheel centre line relationship and Backlash has been set correctly, the contact patter will be correct.

0.010" backlash is at the very high end of what is deemed to be normal, but it may be correct. The engraving of both the Serial Number and the Backlash amount can be very hard to determine at times; I find the best way is to take a picture with a High Pixel count digital camera and then zoom in on the resulting image.

If you simply can't determine the design backlash for your particular Pinion/Crown Wheel set, ultimately set it via the Crown Wheel Tooth contact marks.

Regards,

Bill

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#5 Re: Diff backlash

Post by Gfhug » Sun Jan 26, 2025 8:30 pm

Alan Slawson is the go to man for anything about diffs. Search for his surname on here and you’ll soon find lots of positive comments and I believe he is not unwilling to give technical advice.

Geoff
S2 FHC Light Blue
S2 OTS LHD - RHD full restoration

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#6 Re: Diff backlash

Post by Mick » Tue Jan 28, 2025 3:10 pm

Had another look today and tried checking tooth contact with engineers blue, results were variable and difficult to interpret. I have to accept that in this instance I need to seek expert help.
Mick

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#7 Re: Diff backlash

Post by mgcjag » Tue Jan 28, 2025 3:46 pm

Hi Mick...you've got Bill in a post above answering....There won't be anything he dosnt know about setting up Jag diffs he runs a professional Jag restoration business.....Steve
Steve
69 S2 2+2 (just sold) ..Realm C type replica, 1960 xk150fhc

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#8 Re: Diff backlash

Post by Mick » Tue Jan 28, 2025 8:53 pm

Hi Steve,

I have read Bills post, much appreciated and easily understood even by a simple plumber. It’s just that the tooth contact marks don’t easily translate into anything I am seeing in the manual.
I have only tried the test with the original bearing housing shims in place, maybe at the weekend I will experiment without any shims and varying the backlash.

Thanks
Mick

1967 Series 1.5 DHC (1E15721)

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#9 Re: Diff backlash

Post by angelw » Wed Jan 29, 2025 12:32 am

Mick Wrote:
I have only tried the test with the original bearing housing shims in place, maybe at the weekend I will experiment without any shims and varying the backlash.
Hello Mick,
I'm not sure which shims you're referring to by "bearing housing shims", but if you're referring to the shims under the bearings each side of the Differential Centre, it will be practically impossible to have no shims under each of the bearing and be able to vary the backlash. For a start, the tapered cone component of the bearings will want to slide down the taper of their corresponding cups.

In any event, given that you may be playing around with the Backlash, that means that you will have to remove the Diff Centre from the housing. That being the case, I suggest that you check the Pinion position relative to the centre line of the Crown Wheel, so that you know that set up is correct. The deviation from the base value is marked on the end gear end of the Pinion Shaft.

Regards,

Bill

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#10 Re: Diff backlash

Post by mgcjag » Wed Jan 29, 2025 8:52 am

Hi Mick/Bill....As we know there are different types of diff...but are we talking here about the early type of diff as shown in section H of the service manual...."carrier" is the big cast houseing that has everything inside it and bolts to the IRS..."Diff case" is the part that the crown wheel/side gears/friction plates fit into.......Iv never worked on this diff and backlash is adjusted differently to the other diffs......on this one no shims are show between case and bearings.......backlash is adjusted by shims between "gear carrier" and output shaft bearing housing shown in the service manual useing feeler guages....
Mick can you confirm this is the type of diff you have...identified by the large nut on the end of each output shaft
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Steve
69 S2 2+2 (just sold) ..Realm C type replica, 1960 xk150fhc

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#11 Re: Diff backlash

Post by Mick » Wed Jan 29, 2025 1:15 pm

Hi Steve

I believe that is the type of diff I have but I have a different design of output shaft with the nut on the inside. I have been unable to find a manual covering the diff with this type of output shaft but I am working on the assumption that the backlash adjustment is achieved in the same way.
I have found mention of the output shafts with the internal nut in other threads and it appears they offer a slight advantage in that they eliminate the possibility of oil leaking along the splines to the external securing nut.
Mick

1967 Series 1.5 DHC (1E15721)

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44DHR
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#12 Re: Diff backlash

Post by 44DHR » Wed Jan 29, 2025 2:05 pm

Mick,
If your car is a 1967 model, it is unlikely to have the early diff output shafts with an external nut, as shown in the photo above at post #10, as those types of output shafts on these differentials finished around 1964.
You should have an output shaft with no external nut - just a dished surface - but these use a large internal nut to set the bearings. I use a 47mm ring spanner on those nuts.
Out of interest, when you replaced your bearings in the output shaft housings, were they ball bearings or taper roller bearings - and what sort of bearings did you fit ?
Cheers,
Dave
Last edited by 44DHR on Wed Jan 29, 2025 3:34 pm, edited 1 time in total.
Dave Rose
1967 Series 1 4.2 FHC

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#13 Re: Diff backlash

Post by mgcjag » Wed Jan 29, 2025 2:19 pm

Hi Mick.... you need to identify your diff and output shafts......some adjusts the backlash with shims between the output shaft bearing houseing and the "carrier"... the other diffs use shims on the "diff case" before you slip on the bearings...therefore to adjust the backlash you need to pull out the Diff case, pull off the bearings to alter the shims on both sides.....Best if you can post photo's of your o/p shafts but answering Dave,s question re roller or taper bearings will help....if you have the roller bearing then these are the ones that are difficult to prevent oil leaks but the diff is detailed in the S3 E type manual...diffs with taper bearings are detailed in later xj6 manuals....Steve
Steve
69 S2 2+2 (just sold) ..Realm C type replica, 1960 xk150fhc

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#14 Re: Diff backlash

Post by angelw » Thu Jan 30, 2025 1:52 am

Hello Mick,
There were 3 Types of differentials used with the E Type. Salisbury Type 1,2 and 3. What I was referring to with regards to not being able to determine lack lash with shims removed, referred to a Type 3 Diff used in S2 and S3 cars.

Both Type 1 and 2 used Taper Roller Bearings and both Pre-load and Back Lash adjustment was made by shims between the inner face of the Output Shaft Bearing Housing and the Differential. The main difference between Type 1 and 2 differentials is that the the Output Shaft and the mounting Flange for the Rotors and Half Shafts are a two piece arrangement for the Type 1 and one piece for the Type 2.

The method to adjust the Back Lash for Type 1 and 2 Diffs, is to install the Output Shaft Bearing Housings, as shown in the picture below (as an assembly with Output Shafts, or just the Housings) with no shims and snug the securing bolts up firm, but not overly tight.

Image

It's best to have a circa even gap between flanges and diff housing to start. with. The correct Back Lash is then obtained by shifting the position of the Crown Wheel relative to the Pinion Gear, in or out by loosening the securing bolts for the Output Shaft Housing on one side of the diff housing and tightening the bolts on the other, When the correct Back Lash is obtained, the gap between the Bearing Housing flanges and the diff is measured and a shim stack equal to each gap, less 0.0015" each side is then assembled between the diff housing and the respective Bearing Housing assemblies. The less 0.0015" in shim stack is to result in a 0.003" pre-load of the diff centre bearings. This is a far better system for adjusting Backlash and Pre-load than with the Type 3 diff, in my opinion, for a number of reasons. 1. The diff centre side bearings are an interference fit on their journals, with backlash and pre-load being adjusted via shims located between the bearings and the diff centre. 2. Once the correct shims for pre-load have been established in the assembly, a diff spreader is typically required to assemble the diff centre with the housing; this is not the case with Type 1 and 2 differentials.

Type 3 differentials used Double Row, Angular Contact bearings, where the centre race of the bearing was in two halves. When the centre race was assembled with axial hand pressure, there exists a small gap between the inner faces of the inner race. When assembled with the Output Shaft and the nut securing the bearings was torqued up correctly, the faces of the inner race are pressed to make intimate contact and the correct pre-load resulted. These bearings haven't been available for many years and the bearing being offered is a very poor replacement. It has the same ID/OD, the centre race is one piece with the bearing having some end float that can't be adjusted. It's 2mm narrower, requiring spacers to be used. The sealing system, where the inner face lip of the seal was supposed to seal against the face of the out race is the wrong size and ends up partially on and off the bearing face.

Later differentials reverted back to using Taper Roller Bearing for the Output Shaft. The Output Shaft/Bearing Housing assemblies of the later differentials using the Taper Roller Bearings will assemble with the differential and replace the Double Row, Angular Contact bearing system without any modification to the diff housing whatsoever. Accordingly, when refurbishing a Type 3 Differential, its better to replace the original bearing system with the later Taper Roller Bearing system. Unfortunate, the Output Shaft assemblies from later differential are becoming hard to get. Accordingly, I now manufacture the Bearing Housing and as there is a "Metal On" condition with the earlier Type 3 Output shafts, an original Type 3 Output Shaft em to be re-machined to the specifications of the Taper Roller type Output Shaft; I supply these on an exchange basis.

Regards,

Bill

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#15 Re: Diff backlash

Post by Mick » Thu Jan 30, 2025 7:44 pm

Hi Steve, Dave

I have the type 2 differential with the one piece output shaft (see Bills post #14) and pic.
Image

Image

The bearings are the taper roller type, not fully fitted yet as I have been waiting 3 weeks for shims, I have ordered some more from another supplier and they should arrive tomorrow.

Bill

Thanks for your detailed reply, I now fully understand what I have and how to adjust. I will have another attempt at checking tooth contact repeating my attempt with original shims, if results are not good I will remove shims and adjust backlash as described. I guess that as my backlash is at the high end of acceptable I would be best to adjust in a downward direction. (I have tried deciphering markings with high resolution pics but no success)

Thanks everyone

Mick
Mick

1967 Series 1.5 DHC (1E15721)

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#16 Re: Diff backlash

Post by angelw » Thu Jan 30, 2025 9:07 pm

Mick Wrote:
I guess that as my backlash is at the high end of acceptable I would be best to adjust in a downward direction. (I have tried deciphering markings with high resolution pics but no success)
Hello Mick,
The 0.010" will be quite acceptable if it's correct for when the Crown Wheel and Pinion set was lapped. It's whatever the Backlash is after lapping that determines what is acceptable. I stated that it's at the high end, as mostly the value is somewhat less than that. There is more so a minimum value that the Gear Set shouldn't be set less than.

Are you having trouble seeing the Tooth Markings, or just interpreting how to change them to go in the right direction? When making the mark, you need to resist the rotation of the Crown Wheel in the direction that will result in pressure between the Pinion Gear and either the Drive, or Coast side of the Crown Wheel Tooth, whichever side of the tooth your working with at the time.

The Pinion Height position and the Backlash work in unison to get the correct Tooth Contact pattern. Accordingly, as I suggested in an earlier Post, I would check that the Pinion Position is correct, so that you should mainly be working only with the Backlash setting to get the correct tooth contact. For your Type 2 Diff, removing the diff centre to be able to take the measurement of the Pinion position is easy, compared to a Type 3 diff, because, if you remove the Output Shaft assemblies, which you must to be able to remove the diff centre and clearly you have already done that, there is no pre-load on the diff centre side bearings.

When you get to the point of being able to measure the Pinion Shaft position, I would also check the pre-load of the Pinion Shaft Bearings and even replace the bearings and the Pinion Shaft Seal. The pre-load check should be done with the seal removed anyway and there is a better than even chance that the seal will be damaged when removing it.

Lack of pre-load on the Pinion Shaft is one reason a diff howls when the car is under acceleration. The action of the engagement of the Gear Set teeth is to try and diminish the pre-load and if the pre-load is out of tolerance at the bottom end of the scale, the pinion shaft can move axially to the extent that the tooth contact shifts.

Regards,

Bill

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#17 Re: Diff backlash

Post by mgcjag » Fri Jan 31, 2025 10:12 am

Hi Mick..I see you have no bolts fitted to your o/p shafts for attatching disc/drive shaft....we discuss those bolts here... viewtopic.php?f=3&t=5843&start=20 Steve
Steve
69 S2 2+2 (just sold) ..Realm C type replica, 1960 xk150fhc

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#18 Re: Diff backlash

Post by Mick » Sat Feb 01, 2025 7:59 pm

Hi Bill

Thanks for your help. I hope to get back on it tomorrow, I will pay particular attention to your advice to resist the the rotation of the crown wheel. I certainly did not do that on my initial attempt, I allowed the crown wheel to freewheel and was probably turning the input shaft erratically which would explain the random markings I was achieving.

Thanks

Mick
Mick

1967 Series 1.5 DHC (1E15721)

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#19 Re: Diff backlash

Post by Mick » Sat Feb 01, 2025 8:05 pm

Hi Steve

I have just read that post and checked the new bolts I purchased, they are not a tight fit. I will reuse the original bolts.

Thanks
Mick

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#20 Re: Diff backlash

Post by Mick » Mon Feb 03, 2025 9:08 pm

Hi all

I have repeated the tooth contact test taking care to keep resistance on the crown wheel and have obtained results that I am happy with, now happy to proceed with reassembling IRS.

Thanks for your help.
Mick

1967 Series 1.5 DHC (1E15721)

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