Original Lucas radiator fan repair / upgrade.

Have you documented a Scimitar related procedure and would like to share it with others? Pictures are most welcome!
Threads here also contain previous “stickies” from other sections, as a central location for quick reference information.

Moderators: scimjim, erikscimitardemon, Lukeyboy46, Roger Pennington, philhoward

Post Reply
larrylamb11
Posts: 27
Joined: Thu Nov 08, 2018 2:15 pm
Has thanked: 2 times
Been thanked: 3 times

Original Lucas radiator fan repair / upgrade.

Post by larrylamb11 » Tue Nov 20, 2018 9:29 am

Having just completed a mini-restoration on my original radiator fan, I though I would share an upgrade I did to overcome the wear in the old Lucas motor.

Like a lot of Scimitar owners I found my radiator fan was pathetically feeble, slow and asthmatic..... Keen to preserve the originality I decided to whip off the old Lucas fan and take it apart to see what was what before deciding whether to change or upgrade it. These couldn't be more simple and once off the car, it was apparent the motor was stiff and there was more end float than one would normally expect. As we know, these are 'pusher' fans, pushing air through the radiator with the fan thrust loads taken on the alloy motor cap (that contains the brushes) using a simple pack of thin spring steel washers, bearing on a circlip on the motor shaft to take the thrust. I suspect originally these Lucas motors were never intended to be run with a thrust loading, as none of the bearings in it are really up to the job. Not surprisingly given their operating environment and with a lack of lubrication the thin thrust washers wear out, leading to stiffness and ultimately damage to the housing, if left. I could see the old motor was repairable as the running bearings were hardly worn, I just needed to improve the thrust bearing......

That's where these came in, specifically a AXK1024 (10mm i.d, 24mm o.d.):-
Image

This is a very thin thrust bearing - the whole assembly measuring just 4mm thick. I reckoned if I could get one of these in place of the old washer pack on the end of the motor I would have a really effective solution, so I ordered one and set to work...... With the original Lucas motor effectively 'worn out' (the running bearings were perfect, but the thrust bearing caput) I had nothing to loose in modifying and with some careful measurement I was able to determine that by cutting two new circlip grooves in the motor shaft I could get the new thrust bearing in place, restore functionality and not have to modify any of the other parts. I had to move the inner circlip closer to the windings by about 2mm and the outer one closer to the fan by about 3mm, but basically it was done by eye and feel to get it to sit right. I also took a gnats whisker off the motor shaft where the new thrust bearing was to sit to give running clearance. I'm lucky in that I have access to a lathe to do this, but you could do it all using a pillar drill - holding and spinning the armature in the drill chuck, using a hacksaw blade to cut the new circlip grooves and a file to clearance the motor shaft while it's spinning. The motor shaft is mild steel, so it's easy to cut the new grooves (which happen to be just about the width of a hacksaw blade) and reduce the diameter a touch where required. The net result was that, with a bit of time, I was able to install the new thrust bearing into the motor, retain the original fan position (meaning the grub screw still engages in it's detente on the shaft), retain the original look of the Lucas fan motor but dramatically improve it's performance - it now spins very freely and shifts a very decent quantity of air when running. If it isn't on a par with a modern replacement, it isn't far off and it doesn't need to run for long to bring radiator temps down enough to cycle off again. I'm very satisfied to have retained one of the original parts, improved it's functionality and completed the job for minimal outlay.

This is how it looks now....

Image

..... and here's a close up showing the new bearing in position

Image



User avatar
Nigel Clark
RSSOC Member
Posts: 522
Joined: Thu Oct 23, 2014 12:57 pm
Location: Market Harborough, Leicestershire
Has thanked: 18 times
Been thanked: 46 times

Original Lucas radiator fan repair / upgrade.

Post by Nigel Clark » Tue Nov 20, 2018 10:58 am

What a great fix, thank you for sharing.

I removed the old Lucas fan from my SE6A a couple of years ago and replaced with one from a Citroen BX, mounted on a suitable bracket. I'm tempted now to dig out my old fan and fit the thrust bearing as you've done.

The French fan is effective enough but it's noisy and vibrates more than the Lucas did.


Nigel



willholderogri
RSSOC Member
Posts: 994
Joined: Sat Aug 21, 2010 10:47 pm
Location: chippenham
Has thanked: 158 times
Been thanked: 28 times

Original Lucas radiator fan repair / upgrade.

Post by willholderogri » Tue Nov 20, 2018 12:12 pm

Do you have a link to the bearing supplier please


1962 mini, bedford CA , KR200. morris 1000, mini pickup.several escorts,ford grandad.ford cortina X2 ,astra, SE5A x 2 ,ford focus.

larrylamb11
Posts: 27
Joined: Thu Nov 08, 2018 2:15 pm
Has thanked: 2 times
Been thanked: 3 times

Original Lucas radiator fan repair / upgrade.

Post by larrylamb11 » Tue Nov 20, 2018 12:46 pm

The bearings are widely available, internal diameter 10mm, external diameter 24mm, thickness 2mm - I bought mine on eBay HERE but you can search for or ask your bearing supplier for "AXK1024" which is the standard code for the bearing and ensure you get the two "AS1024" 1mm washers too. The total assembly measures 4mm thick and it needs a touch of free play / clearance in it's assembly to work properly - i.e. the circlip holding it on shouldn't be rammed up tight against the bearing washer and should allow a hair of clearance.

Just to add, if you find that the new bearing pack is slightly too thick to allow the fan to engage far enough onto the motor shaft to align it's grub screw with the shaft detente, you can drill a new detente further up the shaft on the opposite side to the original or 'machine' a sliver off the back of the fan hub. You can DIY this by mounting the fan back to front on the motor, running the motor to spin the fan whilst using something like a finger file or grinder to gently shave down some of the hub - be careful of the spinning blades though!! Symptoms of the fan not aligning with the detente will see the motor 'tighten' as you do the grub screw up - the fan boss starts to load the new thrust bearing as the grub screw acts on the shoulder of the detente to force the fan further down the motor shaft, binding up the bearing. If it all goes together correctly the repaired motor should spin and coast freely when turned by hand.



Post Reply

Return to “How To Guides/FAQs”