UPDATING FROM SAAB TO FORD SERVO /MASTER CYLINDER (summary)
Discussion
I know this is important to a few members. The recent 'threads' might get a bit confusing so I undertook to tidy this up and get a link sorted from the alternative parts list. All the following has appeared before, but not all on the same thread.
If you were following the recent thread on this subject you will be aware that there was a great deal of interest in sorting out a viable alternative to the SAAB set up, and to get it documented. I was very anxious that this should be 'bottomed' and that the solution should be documented in a way which could, if necessary, be justified to insurers. I am sorry but this will be a long post!
I’ve set out the current position and what I hope will be a clear statement of the option to adopt if you wish to ‘updated’ from the SAAB set up.
I would propose to ask for a link from the Alternative Parts List to this information but, before I do, I would ask you to look at it critically and let me know if you have any concerns or any other information.
All the available parts information from TRW (Lucas/Girling) has now been studied. I have also received a good deal of info from other forum members which has helped establish exactly what TVR fitted and what the exact issues are in making a change.
I am now satisfied that I know exactly what TVR fitted: Most cars have a SAAB sourced system but later cars have a particular FORD Fiesta sourced system. There doesn’t appear to be a precise change over date. It was important to establish exactly what the later system was as this system would have had 'type approval' by TVR. Therefore a change by us from a SAAB to an original but later TVR set up would be an updating in specification rather than an alternative arrangement, and not therefore a ‘modification’.
(There has been some further confusion in that at least 2 references refer to TVR fitting a FORD Sierra servo, I am now satisfied that this is incorrect).
The original SAAB sourced system (SAAB 9000 2.0ltr ) uses an 8” diameter servo fitted to a 22.2mm master cylinder. The master cylinder is of the Lucas steel type and uses a remote reservoir.
TRW part number for the Servo is PSA314 and is now listed as unavailable.
TRW part number for the master cylinder is PMH237 and is now listed as to be discontinued.
The FORD Fiesta system is that fitted to certain Mk 3 Fiesta’s. Most Mk3 Fiestas use the same 8” servo, so that is easy to identify. However a note of caution is necessary re the master cylinders: At least 6 different ones were fitted, several were externally similar but differ in bore and swept volume. I would therefore advise that if you wish to purchase second hand you restrict that to the servo, and fit it with a new master cylinder using the part number below.
I have confirmed with TRW technical staff that the following specification appears to be what TVR used (there do not appear to be records at the supplier end) and would give the same performance.
SERVO:
TRW part number for the servo is PSA 328 and is readily available new. The servo was fitted to the majority of Fiesta Mk3 models (89-95) whether ABS or not and should be readily available second hand.
The servo is dimensionally identical to the SAAB in all major respects except for a detailed change in the mounting holes and the clevis pin. Although the PCD (pitch circle diameter) of the 4 mounting holes are identical, each of the servos has two 8mm opposite mounting bolts on a 90mm PCD and two on a 102mm PCD, regrettably it is the opposite pair on the Fiesta servo!.
That means that the bulkhead does need to be redrilled. This is actually quite a simple job.
I've attached a drawing/template showing the position of the existing holes and the position or the required holes.
With the old servo off, working from the engine side, draw a line through the centre of the diagonally opposite pairs of holes. The top left and bottom right holes need to move IN by 6mm, the top right and bottom left need to move OUT by 6mm. As the old and new holes overlap, if you try to drill 8mm the drill is likely to 'drift'into the old hole so I suggest you drill about 4mm holes and file the holes out to 8mm.
The bulkhead is reasonably thick glass reinforced plastic with a steel plate on the inside. The steel plate provides the strength and is sufficiently strong for the extra holes not to be any problem. I would however recommend that you use wide thin washers, approx 20mm wide, under the nuts on the inside together with additional sealant around the holes just to ensure water cannot get in.
http://i199.photobucket.com/albums/aa102/greymrj/T...
There is also a small change necessary at the pedal connection. The SAAB servo uses an 8mm clevis pin while the Fiesta servo uses a 10mm pin. The brake pedal needs to be drilled accordingly and a larger pin fitted. On the drawing I have also put in the dimensions for the new clevis pin required. (If you leave the 8mm pin you will get increased slack in the pedal and increased wear at the joint.)
There is also a small change in width of the clevis which requires slightly different packing washers to be inserted.
The only other change is that the vacuum pipe is now on the engine side of the servo rather than the outside, and the vac pipe needs to be shortened.
This is a link to a picture of this servo (I have pictures from other aspects if they are of use to you)
http://i199.photobucket.com/albums/aa102/greymrj/1...
MASTERCYLINDER
TRW part number for the master cylinder is PMH247 and is readily available new. The cylinder was only fitted to certain non ABS models, I am only able to confirm fitment to the non ABS Fiesta 1.4 89-95 and 1.8D 89-95.
This is a four port Lucas type steel master cylinder, 22.2mm bore, externally very similar to the SAAB part but using a top mounted reservoir.
When supplied new, or as fitted in the Fiesta, two ports are fitted with external pressure regulating valves. For the TVR application these need to be removed because the S type has a separate pressure regulator (on the bulkhead above the servo).
The positioning and thread sizes of the ports match the SAAB fitment.
This is a link to a picture of this master cylinder (I have pictures from other aspects if they are of use to you.)
http://i199.photobucket.com/albums/aa102/greymrj/1...
Again, please note that there are at least 6 Fiesta Mk3 master cylinders, of which at least one is outwardly identical but is not identical internally.
(It would also be possible to use the more common Fiesta master cylinder PMH138 which has identical bore and stroke but has only two ports and would require an external T piece, but there is no advantage in doing so and as it isn’t what TVR fitted it would be a ‘modification'.
A couple of further notes;
The Fiesta servo PSA328 has a small adjuster screw on the piston rod that operates the master cylinder piston. There should be clearance between the rod and the piston when the brakes are off. This gap should be correct as set at the factory but occasionally it may be necessary to adjust the rod slightly to maintain clearance.
Do not be tempted to match the Fiesta servo to the SAAB master cylinder, it would be possible but the piston rods differ in length and the cylinder piston might not be able to return properly when the brakes are off.
I wouldn’t advise trying to fit a Fiesta top mounting reservoir to a SAAB cylinder with the remote reservoir. It may work but it isn’t an approved adaptation.
Phew!!! I sincerely hope that helps some owners. I now have a 28 page folder, CD and parts manuals on the subject!
If you were following the recent thread on this subject you will be aware that there was a great deal of interest in sorting out a viable alternative to the SAAB set up, and to get it documented. I was very anxious that this should be 'bottomed' and that the solution should be documented in a way which could, if necessary, be justified to insurers. I am sorry but this will be a long post!
I’ve set out the current position and what I hope will be a clear statement of the option to adopt if you wish to ‘updated’ from the SAAB set up.
I would propose to ask for a link from the Alternative Parts List to this information but, before I do, I would ask you to look at it critically and let me know if you have any concerns or any other information.
All the available parts information from TRW (Lucas/Girling) has now been studied. I have also received a good deal of info from other forum members which has helped establish exactly what TVR fitted and what the exact issues are in making a change.
I am now satisfied that I know exactly what TVR fitted: Most cars have a SAAB sourced system but later cars have a particular FORD Fiesta sourced system. There doesn’t appear to be a precise change over date. It was important to establish exactly what the later system was as this system would have had 'type approval' by TVR. Therefore a change by us from a SAAB to an original but later TVR set up would be an updating in specification rather than an alternative arrangement, and not therefore a ‘modification’.
(There has been some further confusion in that at least 2 references refer to TVR fitting a FORD Sierra servo, I am now satisfied that this is incorrect).
The original SAAB sourced system (SAAB 9000 2.0ltr ) uses an 8” diameter servo fitted to a 22.2mm master cylinder. The master cylinder is of the Lucas steel type and uses a remote reservoir.
TRW part number for the Servo is PSA314 and is now listed as unavailable.
TRW part number for the master cylinder is PMH237 and is now listed as to be discontinued.
The FORD Fiesta system is that fitted to certain Mk 3 Fiesta’s. Most Mk3 Fiestas use the same 8” servo, so that is easy to identify. However a note of caution is necessary re the master cylinders: At least 6 different ones were fitted, several were externally similar but differ in bore and swept volume. I would therefore advise that if you wish to purchase second hand you restrict that to the servo, and fit it with a new master cylinder using the part number below.
I have confirmed with TRW technical staff that the following specification appears to be what TVR used (there do not appear to be records at the supplier end) and would give the same performance.
SERVO:
TRW part number for the servo is PSA 328 and is readily available new. The servo was fitted to the majority of Fiesta Mk3 models (89-95) whether ABS or not and should be readily available second hand.
The servo is dimensionally identical to the SAAB in all major respects except for a detailed change in the mounting holes and the clevis pin. Although the PCD (pitch circle diameter) of the 4 mounting holes are identical, each of the servos has two 8mm opposite mounting bolts on a 90mm PCD and two on a 102mm PCD, regrettably it is the opposite pair on the Fiesta servo!.
That means that the bulkhead does need to be redrilled. This is actually quite a simple job.
I've attached a drawing/template showing the position of the existing holes and the position or the required holes.
With the old servo off, working from the engine side, draw a line through the centre of the diagonally opposite pairs of holes. The top left and bottom right holes need to move IN by 6mm, the top right and bottom left need to move OUT by 6mm. As the old and new holes overlap, if you try to drill 8mm the drill is likely to 'drift'into the old hole so I suggest you drill about 4mm holes and file the holes out to 8mm.
The bulkhead is reasonably thick glass reinforced plastic with a steel plate on the inside. The steel plate provides the strength and is sufficiently strong for the extra holes not to be any problem. I would however recommend that you use wide thin washers, approx 20mm wide, under the nuts on the inside together with additional sealant around the holes just to ensure water cannot get in.
http://i199.photobucket.com/albums/aa102/greymrj/T...
There is also a small change necessary at the pedal connection. The SAAB servo uses an 8mm clevis pin while the Fiesta servo uses a 10mm pin. The brake pedal needs to be drilled accordingly and a larger pin fitted. On the drawing I have also put in the dimensions for the new clevis pin required. (If you leave the 8mm pin you will get increased slack in the pedal and increased wear at the joint.)
There is also a small change in width of the clevis which requires slightly different packing washers to be inserted.
The only other change is that the vacuum pipe is now on the engine side of the servo rather than the outside, and the vac pipe needs to be shortened.
This is a link to a picture of this servo (I have pictures from other aspects if they are of use to you)
http://i199.photobucket.com/albums/aa102/greymrj/1...
MASTERCYLINDER
TRW part number for the master cylinder is PMH247 and is readily available new. The cylinder was only fitted to certain non ABS models, I am only able to confirm fitment to the non ABS Fiesta 1.4 89-95 and 1.8D 89-95.
This is a four port Lucas type steel master cylinder, 22.2mm bore, externally very similar to the SAAB part but using a top mounted reservoir.
When supplied new, or as fitted in the Fiesta, two ports are fitted with external pressure regulating valves. For the TVR application these need to be removed because the S type has a separate pressure regulator (on the bulkhead above the servo).
The positioning and thread sizes of the ports match the SAAB fitment.
This is a link to a picture of this master cylinder (I have pictures from other aspects if they are of use to you.)
http://i199.photobucket.com/albums/aa102/greymrj/1...
Again, please note that there are at least 6 Fiesta Mk3 master cylinders, of which at least one is outwardly identical but is not identical internally.
(It would also be possible to use the more common Fiesta master cylinder PMH138 which has identical bore and stroke but has only two ports and would require an external T piece, but there is no advantage in doing so and as it isn’t what TVR fitted it would be a ‘modification'.
A couple of further notes;
The Fiesta servo PSA328 has a small adjuster screw on the piston rod that operates the master cylinder piston. There should be clearance between the rod and the piston when the brakes are off. This gap should be correct as set at the factory but occasionally it may be necessary to adjust the rod slightly to maintain clearance.
Do not be tempted to match the Fiesta servo to the SAAB master cylinder, it would be possible but the piston rods differ in length and the cylinder piston might not be able to return properly when the brakes are off.
I wouldn’t advise trying to fit a Fiesta top mounting reservoir to a SAAB cylinder with the remote reservoir. It may work but it isn’t an approved adaptation.
Phew!!! I sincerely hope that helps some owners. I now have a 28 page folder, CD and parts manuals on the subject!
Could I ask one of those of you who is better with the technology to insert the three pictures (probably best at the end?)so they are part of the thread?
It might also be worth cross referencing to the previous thread.
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
It might also be worth cross referencing to the previous thread.
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
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