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Topic: My 85 TBird (Read 61047 times) previous topic - next topic

My 85 TBird

Reply #105 –
Mr. Sass,

One question and one comment.

Have you had a chance yet to jack up the rear of the chassis to see how much droop travel the rear suspension has with the Mustang shocks at the ride height that you have the car at?

I think you are going to have one problem with the hydroboost installation. All of the 1987-88 T-Birds have a 3.5:1 pedal ratio. That is the pedal pad moves 3.5 units for each unit that it pushes the m/c pushrod. I do not have the data for your 1985 2.3l turbo, but I assume it is the same. You can check you pedal ratio be measuring the physical brake pedal dimensions and dividing one by the other.

The Mustang that you pulled the hydroboost unit from has a pedal ratio of 4.75:1.

Since you appear to have connected the hydroboost unit pushrod to the 3.5:1 pedal pin, the required pedal effort and travel is going to be quite a bit different than what Ford designed. The brake pedal effort is going to be 36% (4.75/3.5) higher. The travel at the pedal pad is going to be reduced by the same amount.

To correctly fix this, the pin on the brake pedal should be moved upwards slightly less than 1" (0.97") and the hydroboost unit should be raised on the firewall to correctly align the pushrod so it is straight.

On second thought, since your rear brake calipers have 60% more piston area than the Mustang rear calipers the hydroboost system was designed around, I would only raise the pin on the brake pedal 0.75".

My 85 TBird

Reply #106 –
Jack,

Thank you for taking the time to check out my build thread here.

I will check into the brake pedal ratio and make the needed adjustments.

If you think the vic rear calipers are going to be an issue I am not against getting something else fitted up, or finding a better suited m/c.  Better now than later. 

I have not checked rear axle travel, I will install my shock adapters and do so.

Thanks again, Joe

My 85 TBird

Reply #107 –
I also am in the same boat and it very certain I have almost no droop travel on my 88. What is your ride height from some static point and I can compare to mine.
 

My 85 TBird

Reply #108 –
Mr. Sass,

I don't think the Crown Vic rear calipers will create a major problem on your car. There do have larger pistons than what is ideal for your application. This creates two problems.

1) Increases the amount of rear brake bias. Most of this can be dealt with through the adjustment of the proportioning valve. Since your car is going to have a staggered tire setup, that helps compensate some also.

2) It will make the brake pedal have more travel and require less effort. As noted above this is being countered by the fact that that the pedal ratio in the car is to low. It could also be corrected with a different m/c diameter, but there are no other diameter m/c that will fit on the hydroboost unit.

With the pin on the pedal raised 0.75" I think it will be fine.

My 85 TBird

Reply #109 –
Jack,

Thanks for your input on this, I will give the vic brakes a try.

I will not have any tire stagger for now, it will be 275 40's all around. I was not brave enough to order the 315's to see if they would fit.

Quote
phils88gt

I also am in the same boat and it very certain I have almost no droop travel on my 88. What is your ride height from some static point and I can compare to mine.


It will be a while before I check, but I will post what I find when I do.

My 85 TBird

Reply #110 –
Here are the mods to the L strut tower. The hydro boost just clears during installation, if it ever needs replaced the motor will have to be pulled, which may have been the case anyway.



Fabricated cap


Inside seams welded, ground, sandblasted and coated with 3M weld thru primer


Bolted and clamped, ready to weld


Welded up and finished off




Like the R side all the original metal was welded to the new.

My 85 TBird

Reply #111 –
Quote
Jack Hidley

 I think you are going to have one problem with the hydroboost installation. All of the 1987-88 T-Birds have a 3.5:1 pedal ratio. That is the pedal pad moves 3.5 units for each unit that it pushes the m/c pushrod. I do not have the data for your 1985 2.3l turbo, but I assume it is the same. You can check you pedal ratio be measuring the physical brake pedal dimensions and dividing one by the other.

 The Mustang that you pulled the hydroboost unit from has a pedal ratio of 4.75:1.

 Since you appear to have connected the hydroboost unit pushrod to the 3.5:1 pedal pin, the required pedal effort and travel is going to be quite a bit different than what Ford designed. The brake pedal effort is going to be 36% (4.75/3.5) higher. The travel at the pedal pad is going to be reduced by the same amount.

 To correctly fix this, the pin on the brake pedal should be moved upwards slightly less than 1" (0.97") and the hydroboost unit should be raised on the firewall to correctly align the pushrod so it is straight.

 On second thought, since your rear brake calipers have 60% more piston area than the Mustang rear calipers the hydroboost system was designed around, I would only raise the pin on the brake pedal 0.75".


The 85 does have a pedal ratio of 3.5:1. It measured 13" from the center of the brake pedal pad to the center of the of the pivot and 3.7" from the center of the pedal pin to the pivot which comes to 3.51. Not sure how accurate the measurements are but definitely close enough to confirm 3.5:1.

Following the above advice I moved the pin up .75" for a ratio of 4.42:1. Pretty straight forward, grind off the weld that holds the pin and drive it out. The pin is larger than 1/2" and smaller than 5/8" and since I do not own a drill bit between I drilled the hole to 1/2" and carefully reamed it out with a die grinder until the pin was a press fit. Welded it in and filled in the old hole. Had to relocate the brake light switch so that the switch pad would hit it. Still need to reinstall the pedal assy and mount up the hydro boost to see how well the pushrod lines up with the pin.





Also worked on the header to steering shaft issue. Cut the header tube and overlapped the metal to make some clearance. Not going to weld it up until I reinstall to make sure that it clears. The BBK long tubes were on the motor when I purchased it and the header was already flattened for the steering shaft, just not quite right for the bird. Thinking about sending the headers in to have them coated, possibly to Jet Hot.



My 85 TBird

Reply #112 –
I would think that the pinch in the two primaries will affect those cylinders performance. For the pain in the ass long tubes are I would try and reroute the primary do that the flow is not restricted.

Darren

83 351W TKO'd T-Bird on the bottle


93 331 Mustang Coupe - 368 rwhp

My 85 TBird

Reply #113 –
Quote
Aerocoupe

I would think that the pinch in the two primaries will affect those cylinders performance. For the pain in the ass long tubes are I would try and reroute the primary do that the flow is not restricted.

 Darren


Only one tube is pinched, but I agree it has to affect that cylinders performance somewhat. Not too much good said about the bbk headers over on some of the mustang sites. I am going to live with them as is for now. I need MUCH more practice with my tig, but would like to build a stainless steel set for it someday.

My 85 TBird

Reply #114 –
Only progress worth noting this weekend was mounting up the hydro boost and pedal assy to check for alignment. I was expecting to have to move the hydro boost on the firewall but it turned out that with the pedal pin raised .75" and the prior mods to the booster mounting plate that the rod lined up almost perfectly straight. I knew  the rod was at an angle prior to changing the pin height, but thought it was better than it was, and I quote,
Quote
I moved the holes in the mounting plate upward 1 inch, this moved the booster down so that it was more in line with the brake pedal rod mount and lined up with the hole in the firewall. Could have moved it down a little farther so that the rod was better lined up with the pedal mount, but it did hook up.

To be correctly aligned I should have moved it down much further. Hard to believe that doing a poor job of doing it wrong worked out for the best.





My 85 TBird

Reply #115 –
Beautiful work Bodyman.  Seeing your car progress makes me want to get out and work on my Bird.

My 85 TBird

Reply #116 –
Thank you. Mine has been in a steady holding pattern the last couple of months.

My 85 TBird

Reply #117 –
Bit of an update. Over the Christmas holiday I was able to reinstall the motor/trans. Unfortunately the mods to the right lower firewall for header clearance, and the header tube for steering shaft clearance were not enough. The plan today was to pull it back out and try again, but I got side tracked and started building the strut tower brace. I used some elec conduit for a couple of test runs and then bent up the 1 1/4" tube and built some mounting plates. There is 3/8" between the tube and blower and about 1/4" between the tube and the hood, hopefully that is enough. If not I will have to make one from 1" tube. I will use some 1" tube to make the braces back to the firewall.





My 85 TBird

Reply #118 –
Are you going to solid mount the motor?  I would worry that there is not enough clearance between the blower case and the 1-1/4" rod for when you have the motor wound up and trying to tear out the driver side motor mount.  Other than that the brace looks fantastic!

Darren

83 351W TKO'd T-Bird on the bottle


93 331 Mustang Coupe - 368 rwhp

My 85 TBird

Reply #119 –
Quote
Aerocoupe


Are you going to solid mount the motor? I would worry that there is not enough clearance between the blower case and the 1-1/4" rod for when you have the motor wound up and trying to tear out the driver side motor mount. Other than that the brace looks fantastic!

 Darren


 I am concerned about the clearance. Going to try some good polyurethane mounts. Something like these,  http://www.energysuspensionparts.com/proddetail.asp?prod=4.1127  I was going to build it from 1" tube, which would have given me 5/8" clearance, but liked the look of the 1 1/4" tube so much better. I used 3/8" spacer between the rails and the k member, I might just make that 1/2". 

Also considering cutting the bottom of the tube out above the blower case and welding in a flat piece. If I did this and move the k member down the extra 1/8",  I might be able to get somewhere near 3/4" and 7/8" clearance. Thoughts on how much is enough?