I just finished restoring a 1956 xk140 which included upgrading to disc brakes on the front. I’m not happy with the brake pressure required to stop so am considering installing the Delphi brake booster kit. Has anyone done this or have pictures of the installation? I’m wondering where to mount it. The only place I can see is between the reservoir and the master cylinder but it looks pretty tight. Also, where to tap into the vacuum. The only place I know of is where the windshield washer taps into the rear of the intake manifold. I suppose a different fitting with two ports could be used there but maybe there is a different port available. Looking for some help, anyone?
Dick
The 150 booster and Reserve tank is underneath the Left hand fender, do you have the same area as the 150, they sit on top of the battery shelf.
The inlet manifold has a 90 degree elbow fitting at the rear and on top of the inlet manifold, you could tap and install a fitting, I will try and get a picture for you.
Hi Morris, I’m not familiar with the 150, but from what I’ve seen the firewall looks different so I’m guessing the spacing in front of it might be as well. I have a LHD so the battery is on the right side. From what I’ve read Jaguar came out with a service bul. 235 in 1958 which showed how to install the 150 booster on a 140. I’m thinking that would probably give me enough info. but not sure. I know the elbow your referring to on the rear of the intake manifold. That feeds to the windshield washer. I suppose I could make up a fitting with a tee for a duel tap and that would probably be the easiest. There is also a large brass nut on the bottom side of the intake manifold but I don’t know it this would access the vacuum chamber or coolant and I’m reluctant to take it out and find out it is coolant. Thanks for the help.
Dick,
There was an “optional” Jaguar brake booster for the XK 140. I did some research in the past, which you can find here.
There are also some indications regarding the location as Jaguar did it. Hope this helps.
I do have the original Jaguar/Lockheed servo system for the XK 140, but it needs to be checked. You can see some photos in the article as well.
Bob K.
Hi Bob, I appreciate the information. I’ve been searching for Jaguars Service Bulletin 235 (1/58) for instructions on how to install the booster. These instructions are helpful but I think the coupe must be different because they say to mount on the LH side above the battery compartment (for LHD coupes). The OTS battery box is on the right hand side. I’m looking at using a new aftermarket replacement offered my Moss (Delphi unit).If someone has a picture of where and how they mounted a booster on a LHD xk140 OTS that would be helpful. I’m wondering if they mount inside the sheet metal panel above the master cylinder or outside the panel next to the master which would require some shielding from the tire. Thanks again Bob for information.
Dick,
I understand that the OTS (and DHC) have a different battery box configuration. But even for the FHC it’s quite a struggle to get it in the LH battery box (even without a battery placed).
I came up with the following basic set-up (see photo with the first experiments; the master cylinder is on the left side of the photo) also to keep sufficient space for the brake and clutch pedal movement. Note that a “lengthwise” position of the brake-servo, as recommended in the mounting instruction, seems impossible as there simply is too little space for that (at least in case of the FHC).
I cannot judge whether the Delphi unit could be positioned in the same manner. May be others have more experience with the Delphi unit.
Bob K.
Bob, Thanks for the picture. It does help. It looks like mounting sideways like you show between the master cylinder and the reservoir is the way to go. I think mounting the servo to the outer sheet metal with a stabilizing strap to the frame should work. The Delphi is offered as a modern replacement of the original servo for the XK150 so I think it is very close to what you show here. It looks tight but it should fit. Thanks again.
I recently did this on a 1956 DHC. Put the servo under the left fender on the fire wall - quite easy. Change the circuit to put the servo actuating the front disks only unless you have rear disks too. The rear drums are self actuating. I then installed a “shield” to prevent road spray damage. Best to keep the 1/4 inch pipes to the front disks and reduce size at the servo if necessary. Welsh Ent has a UK made servo with the correct pressure - avoid Asian stuff! I used the Coopercraft disks and now have total safe stopping power on our mountains here.
Dick,
Just as a reminder: the XK 140 servo has a 5½” diameter whereas the XK 150 measures 6 7/8".
I don’t know what the difference in “boost ratio” is between the two, but the XK 140 servo was made to help drivers that “prefer less effort to operate the brake pedal”. The XK 140 servo only operated the front brakes.
The stories about the actual required pedal pressure if the front drum brakes are being replaced by discs, give a “scattered” picture, varying from “no servo required” (as also some suppliers indicate) to “as much as possible”.
Bob K.
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Thanks. I intend to use the servo offered by Welsh (Delphi made in UK). It comes with a bracket to keep it at the desired angle. My problem is where to mount it. I wasn’t sure if there was enough room to the left of the clutch pedal on the fire wall, but now that you mention your installation I think that might be the way to go. Adding a shield to protect it from the front tire shouldn’t be too hard. A lot of people say to just hook up to the front discs. I still have the original drum on the back but would like to enhance the braking on this car as much as possible. I was thinking of boosting both front and back with a proportioning valve on the line to the rear brakes. That way I should be able to adjust the right amount of pressure on the rear vs the front. This car was my Dad’s car (2nd 0wner) and I inherited it when he passed. I intend to leave it to my daughter some day so safety is my motivation. I would welcome anyone’s thoughts on this.
Bob, The Delphi servo is 6 1/2" with a 3 to 1 boost. So I think I need to boost both front and back utilizing a proportioning valve for the rear feed to get the proper relationship front to back.
Dick,
If you do front and rear brakes I guess a regulating valve to the rear brakes would be a good idea as 3:1 boost is a lot and your rear brakes might lock up right away
Bob K.
Dick
Jolly Roger Motors make all the metal coverings for under fender areas for XK’s, battery boxes and shields etc.
Check out Rogers Motors or Jolly Roger Motors.
Thanks Morris. It’s always good to learn about a new source. I’ll check with them.
Was this the original set up on the xk140 with drums all round? I have never heard that. I have a 140DHC with fresh shoes and drums all round and my brakes are dangerous. They require far more pressure than reasonable and I don’t think I can lock up the brakes in an emergency . any advice. I have purchased a servo but have not installed it yet.
William,
The XK 140 Servo was offered only after production of the XK 140 had stopped. Service Bulletin 235 of January 1958 gave a description. I understand that this was done on the explicit request of the US dealers.
I apologize for the confusion: Jaguar never said that only the front brakes should be connected to the Servo, although in practice that might have happened.
Bob K.