Front hub bearing replacement

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blue_bluewater
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Front hub bearing replacement

Post by blue_bluewater » Thu Jan 09, 2020 9:00 pm

The last couple of MOTs (even before I got it) on my GTC mention small amount of play in the front hub bearings. The workshop manual mentions tightening the nut then backing off 1/16 of a turn. But there's no instructions for replacing them. Is tightening the nut normally enough? Or should I replace these, and if so is there a thread on doing that (I couldn't find one) or other instructions? thanks in advance.
Ged



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Front hub bearing replacement

Post by philhoward » Thu Jan 09, 2020 9:05 pm

There should be a little play - a strange concept to most NoT testers under the age of 50 unless they’re familiar with (what is in effect) a 1950’s design of front suspension..

I’d say carry on with it to be honest - if there’s no play the bearings don’t last very long at all!


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Front hub bearing replacement

Post by blue_bluewater » Thu Jan 09, 2020 9:49 pm

Thanks Phil, I should have checked on here before buying the new bearings :cry:



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Front hub bearing replacement

Post by Old and Slow » Fri Jan 10, 2020 12:18 pm

Check t'internet for a couple of suppliers of spacer tubes and shims (for Triumph TR4 etc) ; these go between the bearings and allow the nut to be fully tightened, the shims set the clearance better than turning back the nut, IMHO


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Front hub bearing replacement

Post by Propshaft » Sat Jan 11, 2020 10:35 pm

the outside bearing is a VW part, not TR6



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Front hub bearing replacement

Post by Dennis Nicholas » Tue Jan 14, 2020 2:33 pm

Propshaft wrote:
Sat Jan 11, 2020 10:35 pm
the outside bearing is a VW part, not TR6
Sorry, not being awkward but bearings are a fairly standard specification. The bearings for 6,6a,6b/GTC are a standard size for the bearing part number. They were not specifically made for VW, it just happens that VW may have used that spec bearing . Everyone, let'!s not perpetuate this horrible modern disease where one has to specify the car rather than the part parameters. For example there is a propshaft part that was used on 1930s Austin 7s that is exactly the same as used in a 4 wheel drive Ford Sierra.....but you try asking a Ford spares place for the Austin 7 part :lol: (the 4 hole connecting flange to axle pinion flange :wink: )

The bearings for the GTC front are tapered rollers. They require .002" to .006" end float to allow for the expansion in length of the rollers when hot.(see workshop manual) This translates to about 1/16" inch movement at the outer diameter of the tyre which to a non engineering type MOT tester may seem a lot. Using a DTI to measure end float tells you exactly what you have and if necessary you can take the DTI with you to the MOT and demonstrate the bearings are within spec :D .

Hope you have got the correct inner felt grease seal and its carrier? (GW insisted the only one they sell, the earlier 5 small ID, thick one fitted all Scimitars....wrong).
The bearings are seated on faces within the hub so the rear one comes out of the rear of the hub so pushing out the seal/carrier and the front bearing comes out of the front of the hub. There are cut aways in the bearing locating surfaces inside the hub to allow for using a special bearing remover or just the normal drift (but with drift be careful not to mark the bearing outer diameter housing.). QRG have the correct seal/carrier size (also used in one of the TRs). The split pin nut is 1/2" X 20 tpi UNF so one full turn of the nut will move the nut in/out by 0.05 inches....I leave you to work out what fraction of a turn is required to achieve what end float. (workshop figures by guessing - 1/12 turn = 0.083 x 0.05 = 0.0041666" which is between the 0.002 to 0.006 spec).
If looking at the Reliant workshop manual you may see the vertical link and hub drawing (Figure 3) has "item 13 - cup, inner bearing" That is not applicable to the 6b/GTC which has the later vertical link which has the larger diameter bit that sticks out that the felt seal fits around. The earlier VL had a smaller diameter and hence needed the item 13.
You can see full size details and spec for the bearings on the NTN website, amongst others. Small outer bearing = LM11949 inner cone/LM11910 outer cup: Large inner bearing L44649 inner cone/L44610 outer cup.
Split pin 1/8" (3.175mm); I found stainless 3.5mm would fit snugly.
Note workshop manual says use No. 10 self tapper to remove hub cap.....my stub axle had a hole in the end!!!! so self tapper just went down hole!! Gentle taping with hammer and drift/screwdriver removed hub cap without distorting.
The TR spacer tube method mentioned as made by 2 TR companies will only fit earlier, 5?, Scimitars. As far as I know there is not one that fits the 6b/GTC...If anyone has found one I would like to know......perhaps something for the club to have made as I think it is a better engineering solution. One of the kits produced would seem to be useable by having a small amount turned off the ID of the spacer tube but I felt that it would leave the tube too thin at that point.......Structural engineering professional - please comment, what is minimum thickness for such a spacer/tube in this case??
Dennis


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Front hub bearing replacement

Post by Old and Slow » Thu Jan 16, 2020 5:15 pm

Hi Dennis,
Thanks for the bearing details - I'm planning to service my front hubs so this info could prove very useful.

These came in the post yesterday; ought to fit easily but I wonder what dimension you'd like at one end of the spacer? I can measure these if you like and see how much metal remains - this would enable a calculation of the possible resulting strength (or lack of it?).
Wheel_spacers.jpg
Wheel_spacers.jpg (160.45 KiB) Viewed 399 times


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Front hub bearing replacement

Post by Old and Slow » Tue Jan 21, 2020 7:35 pm

I tried to fit the spacer tubes pictured above and found the hole at the outer end is too small. It is 0.700" and the shaft is 0.750" Perhaps the TR3 used smaller bearings - does anyone know?
I have a scrappy bit of paper that came with the Sabre Six, implying that during the rebuild 30 years ago SE5 hubs were used, with SE6 discs and calipers.
My first question is - which model has 0.750" ID taper rollers at the outer ends of the front hubs?
Second question - the discs are 10.5" diameter, picture below. Are these SE6 ? - the calipers are marked Lockheed (and if so, are Mintex MLB40 pads the correct ones?)
I put the spacers in the lathe and increased to outer hole size to 0.765" and there's still a lot of metal left so I'm happy to install these.
Lastly, is it usual for the whole of the hub cavity between the bearings to be packed with grease? About a full can's worth, it seems! How else does grease get to the inner bearing?
Front hub.jpg
Front hub.jpg (98.12 KiB) Viewed 331 times
Any help in this area will be appreciated, thanks!


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Front hub bearing replacement

Post by AJL Electronics » Tue Jan 21, 2020 7:42 pm

Grease packing should be no more than about half full. Otherwise it can end up in unwanted places when hot.


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Front hub bearing replacement

Post by SJM » Wed Jan 22, 2020 9:32 am

Dennis Nicholas wrote:
Tue Jan 14, 2020 2:33 pm
They require .002" to .006" end float to allow for the expansion in length of the rollers when hot.
The end float is principally to allow for the expansion of the hub shell when heated due to braking, not expansion of the rollers. If you are going to use a clock gauge to check the end float, it is essential to mount it on some immediately adjacent high-stiffness component in order to get a reliable reading. Make sure the grease used is a high melting point type; otherwise it may melt and find it way all over the hub and disc.



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Front hub bearing replacement

Post by gtcse8 » Wed Jan 22, 2020 1:08 pm

Old and Slow wrote:
Tue Jan 21, 2020 7:35 pm
which model has 0.750" ID taper rollers at the outer ends of the front hubs?
All cars after SE5# 454030
Prior to that they were 5/8" IIRC.
Old and Slow wrote:
Tue Jan 21, 2020 7:35 pm
the discs are 10.5" diameter, picture below. Are these SE6 ?
SE6A onwards ALL used Lockheed brakes and smaller, wider Discs.


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Front hub bearing replacement

Post by Dennis Nicholas » Fri Jan 24, 2020 9:26 pm

Old and Slow
sorry delay in getting back....rather a lot of problems this end (non Scim).
Inner and outer bearing inner race (cup) end surface size as far as I can measure with a micrometer in freezing hands -- small outer bearing 0.133 inch; larger inner bearing 0.127inch. That is the surface the end of the spacer/shims will bear against
Ref the TR spacer, is it tapered internally so a near fit on the stub taper?? I am having difficulty visualising how it will fit the stub and stay central to its axis but still be able to move back and forth with the shimming to achieve the end float. However it looks like you have achieved a fit?

Ref the brake disc for Lockheed 6a/b the disc is 10.51 inch dia. and 0.568 inch thick.
TR6 disc dia. is 10.812 inch and 5a ( Girling) is 10.82 so both can have diameter turned down to fit 6a/b otherwise will not fit in Lockheed calliper. So 5a and TR6 can be made to fit by turning down Diameter. Measurements from new items I have in spares box.

The attached document on brakes may be helpful.
Brake pads Scimitar 6a GTE and 6b.docx
(4.84 MiB) Downloaded 6 times


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Front hub bearing replacement

Post by Dennis Nicholas » Fri Jan 24, 2020 10:23 pm

Old and Slow

My GTC stub axle my measurements :- inner large bearing surface 1.0625; then tapers down for a length of 1.5 inch (TR spacer length??) then small step of about 0.0235inch to outer small bearing surface 0.750 inch.

Which kit did you order and is it specific to one of the TR models? It sounds as if your stub (What car are you fitting to??) is the same as the 6/6a/b/GTC.


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Front hub bearing replacement

Post by gtcse8 » Sat Jan 25, 2020 9:19 am

Old and Slow wrote:
Tue Jan 21, 2020 7:35 pm
during the rebuild 30 years ago SE5 hubs were used, with SE6 discs and calipers.
So the stub axle will have been changed too, which is bigger than the OE Sabre, even later SE6b/GTC/MB uses a bigger INNER bearing again.
As in an earlier thread I pointed this out.
I don`t know how to add the link on here, but it was a question by SJM on the differing Vertical links that were used (X4), with Three different stubs. :w


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Front hub bearing replacement

Post by derekoss » Sat Jan 25, 2020 12:41 pm

The spacer can't fit the taper other than clearance. Anyone that's tried to match machine tapers on a lathe will know the problems far less in the field !
The parallel ends for the bearing have enough extra to hold the spacer and allow a certain amount of end float for shimming. The act of clamping up the spacer provides the stiffness. The tapers won't touch.
Derek



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