Does anyone know where to find an overdrive relay for a XK150S I have checked with all the regular sources wih no luck
Tony,
There are (at least) 3 different Overdrive Relays you can use. Jaguar switched several times as Lucas updated their Relay designs, but they all should work.
Lucas SB 40-1 part number 33157
Lucas SB60 part number 33174
Lucas 6RA part number 33213
The first one was used on the XK 140, the second on the XK 150 and the final one on the later Jags, but also on many other British cars with an Overdrive.
Also have a look at eBay etc.
Bob K.
Hi Tony,
Lookup part 542-170 from Moss Motors in the Austin-Healey section. Check the “Fitment” tab on the description page. Numerous Jaguars are mentioned including the XK150, so that might work for you. $ 22.00.
XK150 Parts Lists indicate that you need a Lucas 33174 (SB.60 style) or 33199 (6.RA style) depending on the Serial Number of your car. I suspect, but can’t confirm, that they are the same electrically, but that the earlier SB.60 style uses screw terminals, whilst the later 6.RA has push on lucar terminals. The relay needs to be of the dual contact type (C1, C2 and C4 contact terminals), so that the Throttle Switch function will work. The one suggested by Bernard does not seem to be of that type. eBay may be your best bet - I see a Lucas 33174 here:
David,
The earlier SB-40 Relay with only 4 connections works well on the XK 140. Not that you will find one easily…
The wiring connections may differ between the SB-40, SB-60 and 6 RA but is basically of course the same.
The only reason to use these special Overdrive Relays is that they can (thermally) cope with a continuous current, whereas most other relays are meant for short use only (like the Horn).
Bob K…
I read in the XK140 Service Manual addendum that the Throttle Switch (which prevents the overdrive from being switched off when decelerating with a closed throttle) was introduced part way through XK140 production. The revised wiring added a second SB-40 (33157) relay to incorporate the feature. As I understand it, on the XK150 which the original poster has, the two SB-40 relays were replaced by a single SB-60 (33174) and later a 6.RA (33199) which have dual contacts to perform the same function. If the dual contact relay can’t be found (33174 or 33199) it could be replaced by 2 single contact relays as per the later 140 design. The dual contact Lucas 33199 was used on several Rootes models of the era (Sunbeam Alpines and Rapiers, as well as Commers), so Googling Lucas 33199 yields several Rootes forums that discuss how the NLA 33199 can be replaced with alternative designs to achieve the same functionality. I agree that the relays used must be designed for continuous operation.
David,
You are fully correct but my XK 140 (see pic above) was the earlier version without the Throttle Switch and the second Relay.
I still think that the XK 150 could be wired using two of these SB-40 relays, thereby helping Tony answering his question where to find an overdrive relay.
Personally, I never had any problems switching my Overdrive without the Throttle Switch, which (in my opinion) was only required for Jaguar drivers that didn’t (want to) understand how to operate an Overdrive.
Bob K.
For the early type, there’s a Lucas SB 60 on eBay, listed as a Rover part.
Else, if you want one of the later ones, there are quite a few options.