Throwback: David Godfrey's 94 Thunderbird Master Cylinder Upgrade for XR4Ti

David Godfrey's '94 Ford Thunderbird Master Cylinder Upgrade

David Godfrey is somewhat of a legend in the XR4Ti circles. He was one of the first to figure out a bigger front disc brake option using off the shelf discs, as well as a rear disc brake conversion. He also figured out that the 94 T-bird master was a better option for XR4Ti brakes than, certainly, the early '85-'86 master, and even the improved '87-'89 master.

David no longer makes this and his site is no longer maintained, or even available. I pulled this out of the Internet archives to give it a new place to live, so people can see it, and hopefully start making them again some day. 

Chris

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David has developed a master cylinder upgrade for the Merkur XR4Ti that utilizes a lighter and less expensive unit from a 94 T-Bird.  Regarding the master cylinder, David writes:

"I wanted to find one with a bigger diameter piston bore if possible as well as a lighter one since the XR cylinder is cast iron. Never liked the XR cylinder as it is heavy and expensive.  Ended up using a cylinder from a 94 T-bird, non-ABS with a 4.6.  The T-Bird cylinder has a 1.062 in bore vs. the XR's 1.00 in. "

Below are some photos highlighting this modification:

94 T-Bird Master Cylinder with adapter plate installed - View 1

94 T-Bird Master Cylinder with adapter plate installed - View 2

Master Cylinder on brake booster - View 1

Master Cylinder installed on brake booster - View 2

Master Cylinder adapter plate and hardware

"The only trick part is the "slug" that goes in the end cylinder where the booster push rod presses on the end of the piston. The slug makes up the difference caused by the adapter plate and the interface between the XR booster and T-bird cylinder."

Master Cylinder adapter kit "slug"

"The brake lines need to be changed as the XR had two ports for the front line where the t-bird only has one. This worked out in my favor as I want to install a line lock (for drag race burnouts) and I need one line common to both front wheels to do this. The rear line was going to be changed anyway since the stock proportioning valve was going to be removed."

So, you want to buy and install Euro Ford Sierra Mk1 Lucas/Cibie headlights in your Merkur XR4Ti

Soon after buying my first XR4Ti (in the header picture of this blog), I noticed how good the European headlights looked on Ford Sierras, and, when properly fitted, how great they look on the XR4Ti. Here's an example found on the Internet. Based on this, I started my investigation into what it would take to obtain and install them.

First, the differences between XR4Ti and Sierra headlights

The Merkur XR4Ti had adequate headlights when this 30+ year old car was new, using classic incandescent bulbs with deep reflectors to throw light ahead of the car. The XR4Ti also had fairly useless, separate, inboard light pods that were turned on with the parking lights, serving as sort of daytime running lights, given that concept was just getting legs in the late 80s when these cars came out.

The XR4Ti's European cousin, the Ford Sierra, received large, one-piece headlight/driving light units, with glass faces. Not all Sierra headlights are created equal however, which I'll get to in a minute.

Second, what I learned from looking at two sets of Euro lights

There are two manufacturers of Ford Sierra headlights: Lucas and Cibie. 

I have one pair of Cibie housings that came already fitted on a car I bought, and I have one pair of Lucas housings that I bought separately, with the intention of installing them on my original XR4Ti. 

Here's what I think are the differences, based on looking at two separate sets of lights. 

Lucas:

• originally made for right hand drive (RHD) markets, namely the UK
• originally available in a wide range of Ford Sierras, from estates, saloons, and 3dr coupes
• has "city lights" provision, for a 194 blade-style bulb
• driving lights (inboard "high beams") were optional (if equipped, you'll see an twist opening on the top to allow for placing/replacing the H3 bulb)
• Plastic reflectors, for both driving lights and main lights
• Black, wide steel hold down clips for the front glass
• Uses H4 bulbs in the main lights
• Connectors allow for turning of each of the lights individually, where/when equipped

Cibie:

• originally made for left hand drive (LHD) markets, many European countries, and Argentina
• originally available in  Ford Sierras, also presumably for estates, saloons and 3dr coupes
• has "city lights" provision, for a 194 blade-style bulb
• driving lights (inboard "high beams"), takes a very small H3 bulb with one wire
• Metal reflectors, for both driving lights and main lights
• Bare, smaller steel hold down clips for the front glass
• Uses H4 bulbs in the main lights
• Connectors allow for turning each of the lights on individually; city lights, low and high beams on main bulb have their own trigger, driving lights

Common:

• Same lighting connector, although pins may be missing if no driving or city light options on the housing
• Same mounting, three bolts on the top, one bracket on the bottom
• Both Cibie and Lucas left-hand (driver's side in the US) main light reflectors have lost their chrome. I assume this was from sins of the past, cooking the reflectors with high wattage bulbs. Another reason to switch to LEDs. 

Third: Wiring for the XR4Ti, for LEDs

The XR4Ti has two relevant sets of wires on each side of the car, to run the forward-facing lights you use to drive.

1) headlights - XR4Ti uses a 3 wire socket to hold the main hi/lo bulb. Mine were yellow, white and brown (ground).

2) inboard "city"/DRL lights - XR4Ti uses a pair of wires for this, one grey/red (12v, on with parking lights), one brown (ground).

The XR4Ti wiring and headlight switch worked well enough for the stock lighting, with one high/low bulb. Average bulbs, average lighting for the 80s. They didn't plan, however, for this wiring and the headlight stalk to run more than one high wattage bulb, common in the Euro headlights. 

Euro lights = 55W low; H4 high 60/55W. (H83 Hella = 85W, off road only.)

XR = 9004, 65/45W. (9004 Off-road only, 100W/80).

Looking at the other articles (here and here), they were written 10-15 years ago. They all reference using power directly from the battery, and using the factory headlight wiring to run relays, allowing you to drive the most power directly to the lights. In 202x, we can benefit from low power, high brightness LED bulbs in every shape and form factor. 

So...you don’t need relays and extra wiring to run LEDs. If you still have the super helpful factory “convenience computer”, you may need to wire in resistors to keep the computer and the display happy. 

Euro Lamp Socket (TOP)

• City Lamp (18ga, grey) --> to have them turn on with parking lights, use factory b/grey (driver side), r/grey (passenger side) from smaller running lamp inboard of original headlamp. For the factory brown wire that runs with each, run the brown to a ground. This solved a dim light issue on my XR.
• High Beam (14ga, yellow) --> factory white
• Low Beam (14ga, white) --> factory yellow
• Driving Light (14ga, yellow) --> either, factory white, or separate switch
• Ground (16ga, brown) --> use factory brown ground wire

Other Headlight Options:

1987-1993 Ford Mustang housings are bolt-in replacements for the factory XR4Ti headlight housing, which retains the stock inboard running lights. 

Chevy Silverado (year?) housings have also been used.

Throwback: David Godfrey's Manual Clutch Adjuster

DAVID GODFREY'S MANUAL CLUTCH ADJUSTER

David Godfrey is somewhat of a legend in the XR4Ti circles. He was one of the first to figure out a bigger front disc brake option using off the shelf discs, as well as a rear disc brake conversion. The clutch adjuster is one of his creations that is still highly desired. This helps preserve the plastic quadrant the clutch cable rides which is prone to break, given the repeated tension the piece is under while being actuated dozens of times every time the car is driven.

David no longer makes this and his site is no longer maintained, or even available. I pulled this out of the Internet archives to give it a new place to live, so people can see it, and hopefully start making them again some day. Last time I saw them being sold they were $120-150/ea.

Chris

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Thanks for your interest in the Merkur XR4Ti manual clutch adjuster. I have been working on this project for some time and have developed a product that will allow for the clutch release point to be manually adjusted. Benefits of this are cleaner engagement of gears, quicker shifting, and elimination of the failure prone ratchet adjustment mechanism.

 

Important to the design is to come up with an adjuster that would work for both T-5 and T-9 transmissions and either the XR4Ti or Mustang clutch cable. I can easily come up with a one off solution to fit my car, but when a design has to fit multiple configurations and be installed by a typical XR owner (whatever that is!) the constraints get a lot tougher.

 

The manual clutch adjuster works by rotating the cable cam through it range of motion. Slight modification is required to the cam and an existing hole in the clutch pedal needs to be enlarged for the adjustment screw. These are simple mods that can be done by that "average" Merkur XR4Ti owner.

 

A few years ago I conducted a survey on the IMON list of clutch quadrant failures. Of the 30 something reply's I got only one person had a failure of the cable cam. All other failures were either the ratchet teeth or the spring. The pedal mounted adjuster can use the cable cam even if it is stripped.

Contents of the clutch adjuster kit are:

CNC machined aluminum Clutch Pivot assembly

Pivot trunion assembly with set screw

Pedal trunion

Adjustment Rod

Spacer

Lock Nut

 
 

 

Installation instructions

The clutch pedal needs to be removed to install the clutch adjuster. The best way to do this is to remove the whole pedal assembly from the car. This task sounds a lot worse than it is.

Begin by removing the sound deadener panel, lower steering column cover, and lower dash from the drivers side. Release the clutch cable by pulling up on the pedal to disengage the ratchet. The end of the cable can then be pulled from the cable cam. From under the hood pull the cable from the guide tube. The hardest part is now over! 

Remove the spring clip from the end of the brake booster rod where it comes through the brake pedal. Remove the connector from the brake light switch or the entire switch by twisting it 90 degrees and pulling it from the bracket. If you XR has cruise control disconnect the hose to the vacuum switches.

With the above done the pedal assembly is ready to unbolt and remove. There are two 17mm nuts where the pedal bracket meets the firewall. You will have to pull the carpet back to see them. Remove the nuts and flat washers. There is a 12mm-headed bolt going up from the pedal bracket to the dash support structure. Remove this bolt and the pedal assembly can be removed. With the clutch pedal assembly out make sure the nylon bushing on the end of the brake rod does not fall off and get lost.
 
 

STOCK PEDAL ASSEMBLY

 

With the pedal bracket out you can see a big hair pin type clip that holds the clutch pedal on the shaft. Remove this clip and the two nuts that hold the guide tube to the pedal bracket. You can now remove the pedal from the shaft.

Remove the clip from the end of the rod that holds the ratchet in place. Remove the rod, ratchet, and ratchet mousetrap spring. Disconnect the large spring to the cable cam and discard. Remove the cable cam from the pedal.

 
 

CLUTCH PEDAL, GUIDE TUBE, CLIP

PARTS REMOVED FROM CLUTCH PEDAL

Using a hacksaw, sharp knife, or side cutters, remove the tab from the end on the cam as shown in the picture. Make sure the tab is completely removed and flush with the flat surface.
 
 

STOCK CABLE CAM

MODIFIED CABLE CAM

Place the clutch pivot on the cam and press the pre-installed roll pin in place. The cam is now ready for installation. The roll pin can easily be pressed into place using a bench vise or channel lock type pliers.
 
 

CAM WITH CLUTCH PIVOT INSTALLED

The pedal needs to be modified so the adjustment rod can be installed. There is a small slot on the front of the pedal near the pivot. Drill the slot out with a 1/2" drill. It was easier to drill the hole if the slot is made somewhat round by using a rat-tail file. When the drill is through the pedal rotate it slightly up to elongate the hole. Remove any burrs with a round file. The spacer needs to fit in the hole and be able to rock up slightly.
 
 

SLOT IN CLUTCH PEDAL

DRILL OUT SLOT TO 1/2"

 

ROTATE DRILL UP AS SHOWN

Place the adjustment rod through the spacer and then through the hole in the pedal. Thread the pedal trunion on the adjustment rod with the flat side of the trunion facing away from the pedal. 
 
 

ADJUSTMENT ROD, LOCK NUT, SPACER, & PEDAL TRUNION INSTALLED

Place the pivot trunion in the clutch pivot. Place the cam in place on the pedal and turn the adjustment screw in until the end engages the pivot trunion. Snug up the set screw using a 1/16" Allen wrench to engage the groove in the end of the adjuster. The set screw does not need to be tightened down on the adjuster, but just engage the slot to keep the adjustment rod captive to pivot trunion.
 
 

MODIFIED CAM & ADJUSTER INSTALLED

PEDAL RE-INSTALLED ON BRACKET

Place the pedal assy on the shaft and install the guide tube and the big hairpin clip making sure the clip is fully seated in the groove on the shaft. The shaft is spring loaded so it can be pressed out to make putting the clip in place easier. Install the clip before tightening the nuts on the cable guide tube. Turn the adjustment screw rotating the cam to the forward position.

And now, the most famous instruction, "installation is the reversal of removal."

With the cam rotated all the way forward (adjuster rod fully extended from the pedal) place the clutch cable through the guide tube and hook the end over the cable cam. Turn the adjuster screw to tighten the cable and set the release point. When satisfied with the adjustment tighten down the lock nut making sure the spacer is properly engaged in the pedal trunion. Install the lower dash and other parts. Once installed the clutch adjuster can easily be reached from the foot well area.

XR4Ti Steering Racks, The Definitive Guide

Given these cars are 30+ years old, the seals in the steering rack tend to go bad. And/or the plastic boots crumble, leading to contamination of the rack and fluid, destroying the seals. Based on that, you're likely going to have to deal with some steering rack issues, regardless. You may also want to change the rack, or how it works, depending on your situation. For example, there are options for powering the rack hydraulics, such as Electrohydraulic Power Steering (EHPS) pumps from several manufacturers. I'm putting together another post for the known options there.

The XR4Ti came with two steering racks as standard, the TRW early on, and switching to the ZF for most of the production timeline of the car. Given these cars are 30+ years old, power steering rack seals and boots tend to fail, so knowing the rack is probably a good idea. 

TRW

Model years: 1985 - mid-1986
Lock-to-lock (L2L): 2.7 turns (According to what I assume is specs released early in the production of the XR4Ti, the rack was 3.6 turns, https://www.carfolio.com/merkur-xr4ti-99077?car=99077). 
Suitability: average driving, cruising

Note: Identifiable by a smooth surface on the rack housing. 

Note: Interchangeable with the ZF rack.

ZF

Model years: mid-1986 - 1989
Lock-to-lock (L2L) : 2.7 turns

Suitability: average driving, cruising, racing

Note: Identifiable by the waffle pattern on the rack housing.

Note: Interchangeable with the TRW rack.

Manual Steering Rack Conversion

Manual racks are desirable for road racing and drifting since you're aggressively turning the wheel and working the rack. These racks were never designed to take the abuse a rack will receive on a race track, especially drifting. 

Manual racks aren't desirable for a daily driver because you're having to do all the work yourself at slow speeds. Makes you realize just how heavy a car can be. 

A manual rack does simplify the engine bay by removing a pump and the belt(s) that run it. Looks great!

If you're going to run a manual rack, beef up the rag joint and steering shaft mounts, since they weren't designed to take the abuse of non-power steering forces on them.

Manual racks are not recommended if you're rally racing.

How to Order a New ZF rack at AutoZone (as of 2008):

AutoZone was $139.00, Advance Auto was $350.

"For example, the way to get the ZF rack from Autozone is to have the sales person phone ATSCO at the time you place the order. I had no problem getting them to do this. The Autozone sales person should tell ATSCO they want the Type 2 ZF rack. ATSCO will then link the order and the rack type to the PO# which Autozone also supplies.

ZF Rack: ATSCO p/n 6441 Type 2 $139.99 + $90 core

TRW Rack: ATSCO p/n 6441 Type 1 $139.99 + $90 core"

Note: Oreilly brand is A1 CARDONE part no 26-1921

Steering Rack Bushings

Stock, the XR4Ti comes with rubber bushings in the rack. You might be able to get poly or solid aluminum bushings, depending on timing and vendors:

MC2 Racing, a site by avid autocrosser Chris Grayson, has had poly and aluminum steering rack bushings available from time to time, but now recommends nylon steering rack bushings, available here. 

Steering Rack Fluid Cooling

You can use power steering coolers, akin to automatic transmission fluid coolers, purchased from many places, but Summit Racing as them for $25 (Item DER-13200). 

Steering Rack Rebuilds

You can get XR4Ti steering rack rebuild kits from: Power Steering Rebuild Kits, XR4Ti TRW Rack Kit, XR4Ti ZF Rack Kit

The size of the rack end seals (2 required) for the TRW rack are: 24-33-7 referring to the inner diameter, outer diameter, and thickness, respectively, in millimeters. Most industrial/pneumatic supply houses can provide these if you're inclined to just replace the end seals on the existing, early rack.

Other options

Ford Sierra (European) Manual Rack: 

Model years: unknown, all Ford Sierra's with non-power steering

Lock-to-lock (L2L) : 3.75+ Turns 

Suitability: average driving, cruising

Where to buy: http://www.kellybraysteering.co.uk/pages/manual_steering_racks_12938.cfm 

Requires manual steering shaft, European part: https://www.motomobil.com/en/products/steering-idler-shaft-not-for-power-steering-not-4wd-lhd-60959030-1 

 

Aftermarket Ford Sierra (European) Manual "Quick" Rack: 

Model years: aftermarket only.

Lock-to-lock (L2L) : 2.7 Turns

Suitability: racing, right hand drive (RHD) only.

Where to buy: http://www.kellybraysteering.co.uk/pages/manual_steering_racks_12938.cfm 

Requires manual steering shaft, European part: https://www.motomobil.com/en/products/steering-idler-shaft-not-for-power-steering-not-4wd-lhd-60959030-1 

Throwback: Ford Sierra Euro Headlight/Lamp Wiring for the XR4Ti (old article)

This was originally distributed as a file called litewiring.bmp through the IMON mailing list. I searched for it and couldn't find it, so I recreated it here, as well as attached the scan, of the copy, of the printout, of the attachment from the email. I'm about to do this myself, so I'm going to take this, as well as what's out on merkurencyclopedia.com and combine them into a new article.

Dec 2020 update: Here is what I did in a new 23turbo article.

Chris

Wheel studs for the XR4Ti, $28@Summit Racing, ARP Wheel Studs 100-7708

For the record, this is the wheel stud that works for the XR4Ti. Sold in a set of 5, which is annoying. 4 sets to create 16, with 4 spares.

ARP Wheel Studs 100-7708

                                          Brand:    ARP

Manufacturer's Part Number:100-7708

Part Type:Wheel Studs

Product Line:ARP Wheel Studs

Summit Racing Part Number:ARP-100-7708

UPC:672036000462

Wheel Stud Style:Press-in

Wheel Stud Thread Size:12mm x 1.50 RH

Knurl Diameter (in.):0.509 in.

Underhead Length (in):2.500 in.

Shoulder Length (in):0.315 in.

Quick-Start Nose:No

Quantity:Sold as a set of 5.

Notes:Fits late model Camaro, Corvette, and Firebird applications.

Notes:

• Application: XR4Ti,Scorpio
• These studs can be too long if you want to use a closed lug nut. Trimming may be required.

The infamous blower motor resistor issue

Why is my HVAC fan only working on one speed, or blowing a full blast? OR All about the thermal fuse, blower motor, and the parts number

If you have what appears to be the low speed, that may just be the air recirc. door opening due to a non-functional door solenoid. It is uncommon for only the middle speed not to work, since the failure of a blown thermal fuse is that only the top blower fan speed works.

The resistor pack is located beneath the plastic cowl cover behind the firewall in the engine compartment. Four or five screws to remove the cowl, and two screws to remove the pack, and a connector. The pack sits on top of the heater fan box. Just look for a plate held in with two screws and a wiring connector. Once removed, you'll see two or three coiled wires and a thermal fuse mounted on the other side. The thermal fuse is the culprit. 

You can either:

A) Repair with a 291.2 degree F (144 degree C) thermal fuse. (Radio Shack part #270-1322a or newer #270-1320). Don't solder it in. It MUST be crimped in, or the heat from soldering it will blow the resistor. You can cut the body of the old fuse off and twisted the leads of the new one to the leads of the old one. All speeds to the blower should work after this repair.

OR

B) Solder in series a 10 amp fast blow fuse.