Adding Caster to a 69

[jgkurz 52]

Hi All, I am putting in rebuilt control arms and ball joints in my 69 Mach1. I am doing the Shelby drop at the same time. When I pull the engine this winter I plan on putting in Borgeson steering box. These require 3-4deg of positive caster to work properly. I don't have a baseline but I'm fairly certain the car would not have the needed caster if I assembled as is.

 

I have read that adding washer(s) to the front post of the UCA's will add caster.

 

1) Is this true? If so, how many washers should I add to get the 3-4deg?

 

2) Is it possible to add washers with the control arms and springs fully assembled?

 

3) Is there a better way to add caster?

 

Thank you!

Edited June 23, 2014 by jgkurz

[Hoover 12]

http://www.themustangshopaz.com/Products/ClassicMustangs/ClassicMustangs.html

 

The above web site mentions addng an adjustable strut rod will provide additional caster. I don't have their products, so check the link out and go from there.

[det0326 179]

Hi All, I am putting in rebuilt control arms and ball joints in my 69 Mach1. I am doing the Shelby drop at the same time. When I pull the engine this winter I plan on putting in Borgeson steering box. These require 3-4deg of positive caster to work properly. I don't have a baseline but I'm fairly certain the car would not have the needed caster if I assembled as is.

 

I have read that adding washer(s) to the front post of the UCA's will add caster.

 

1) Is this true? If so, how many washers should I add to get the 3-4deg?

 

2) Is it possible to add washers with the control arms and springs fully assembled?

 

3) Is there a better way to add caster?

 

Thank you!

 

jgkurz Its like you read my mind I too want to do the Borgeson set up and have been reading about the 69 with factory set up not having enough caster, I think I even applied to a post concerning this issue. I have often thought about while doing the Shelby drop to incorporate the added positive caster but I am not sure how to tell exactly how you would know how much to move the bolt holes rearward. If you knew a way to calculate this you could actually move the holes down for the drop and rearward to gain caster. I'm not sure it would even be possible but would nice to not have to fool with the shims on the upper control arm.

Dave

[jgkurz 52]

http://www.themustangshopaz.com/Products/ClassicMustangs/ClassicMustangs.html

 

The above web site mentions addng an adjustable strut rod will provide additional caster. I don't have their products, so check the link out and go from there.

 

Looks like a quality part! Thank you for the link.

 

I'm guessing caster can also be adjusted a bit using the stock strut rod?

[jgkurz 52]

jgkurz Its like you read my mind I too want to do the Borgeson set up and have been reading about the 69 with factory set up not having enough caster, I think I even applied to a post concerning this issue. I have often thought about while doing the Shelby drop to incorporate the added positive caster but I am not sure how to tell exactly how you would know how much to move the bolt holes rearward. If you knew a way to calculate this you could actually move the holes down for the drop and rearward to gain caster. I'm not sure it would even be possible but would nice to not have to fool with the shims on the upper control arm.

Dave

 

It looks like the strut rod is the best place to do the caster adjustment. I will assemble without shims and see if I can get the alignment to the following specs after the Shelby drop. I wont have the Borgeson box in until the winter. At that time I may add more caster.

 

.5 neg camber

1/16-1/8 toe in

2.0-3.5 pos caster

[det0326 179]

It looks like the strut rod is the best place to do the caster adjustment. I will assemble without shims and see if I can get the alignment to the following specs after the Shelby drop. I wont have the Borgeson box in until the winter. At that time I may add more caster.

 

.5 neg camber

1/16-1/8 toe in

2.0-3.5 pos caster

 

Keep us informed, I am very interested in this set up also. There's lots of people that has tried this with stock adjustments and came to the conclusion that there were just not enough built in caster in the stock set up to get the required caster angle. I could be very wrong but it seems to me that trying to adjust that much caster with the strut rod would put the

lower control arm in a bind.

Dave

[3pedal 95]

Wellll...Let me say this about that...steering is tight,no return to center,No bump steer,had to cut app inch and a half off bottom of column...Running 70 steering pump with custom hoses run under car and up to box...the kit hoses are too short and will cause hell if you want to change the spark plugs as they will be directly in the way...I must say I am totaly no happy but car drives super and laser straight and may have to live with it...not sure what my caster reading is right now as no allignment has been done , but it is already cranked to max positive,all brand new suspension parts...alignment shop next....joe

[det0326 179]

Wellll...Let me say this about that...steering is tight,no return to center,No bump steer,had to cut app inch and a half off bottom of column...Running 70 steering pump with custom hoses run under car and up to box...the kit hoses are too short and will cause hell if you want to change the spark plugs as they will be directly in the way...I must say I am totaly no happy but car drives super and laser straight and may have to live with it...not sure what my caster reading is right now as no allignment has been done , but it is already cranked to max positive,all brand new suspension parts...alignment shop next....joe

 

Joe

 

Then ur saying as right now with all the stock positive caster you can get out of it your steering still does not return to center?

I've heard a lot about bump steer, what is this condition? Is it sort of like a wondering condition if you hit an uneven place or something?

Dave

[3pedal 95]

What bump steer is like is when you hit a rut or pot hole the wheels will quickly turn one way or the other...luckily I don't have that problem.I will increase the caster once I know where it is.In the past I have cut the rear strut rod nut in half to squeeze out more +caster ,I even switched the lower control arms on my 67 f/b to Global Wests with spherical ends to eliminate bind for more +caster...on my 70 with the Borgie, shimming the upper control arms may be the way to go for more +caster also, time will tell,Borgeson should be more transparent with their info....joe

Edited June 23, 2014 by 3pedal

[det0326 179]

What bump steer is like is when you hit a rut or pot hole the wheels will quickly turn one way or the other...luckily I don't have that problem.I will increase the caster once I know where it is.In the past I have cut the rear strut rod nut in half to squeeze out more +caster ,I even switched the lower control arms on my 67 f/b to Global Wests with spherical ends to eliminate bind for more +caster...on my 70 with the Borgie, shimming the upper control arms may be the way to go for more +caster also, time will tell,Borgeson should be more transparent with their info....joe

 

I agree Joe they should be trying to help us figure this out and they would probably sell more power steering kits. If you were doing the Shelby drop anyway do you think you could just move the drilled holes rearward enough while moving them down for the drop if you could calculate how much to move them rearward. It shouldn't be hard to figure out how far to move them just to get a couple of more degrees positive caster. I don't know if this would cause other problems tho.

 

Dave

[3pedal 95]

You will run into a problem with the zerk fittings hitting....joe

[det0326 179]

You will run into a problem with the zerk fittings hitting....joe

 

I agree Joe that at the stock position the zerk fittings don't have a lot of clearance but if your doing the 1 inch drop the farther down you go the wider the distance in the shock tower. You also would not have to move it that much to get a couple of degrees. the distance between the upper and lower ball joint is less than 9 inches so the circumference of a 9 inch circle is about 28 inches divided by 360 is .078 times 2 equals .157 of a turn in the clock wise position.

[jgkurz 52]

Great comments everyone. My plan was to do the 1" drop without the holes being moved but maybe the best approach is to move the holes back a bit to get the needed caster. This would lessen the need to use the strut rod to add caster which would aslo bind the UCA.

[shaun071 62]

Some info from the Australian Mustangtech site on adjustable strut rods and alignment in general.

 

http://www.mustangtech.com.au/Content/pid=10.html

 

Info on Shelby drop with offsetting holes rearward

 

http://www.mustangtech.com.au/Content/pid=4.html

 

Hope this helps. Guys here in Oz are more into corner carving than drag racing so there's some good info on making a Mustang handle with modern radial tyres.

[jgkurz 52]

Outstanding info on this subject. Thank you.

[jgkurz 52]

I read through the Oz site and I now think caster needs to be added using 3x 1/8 washers on the front post or the 1" Shelby drop with a 3mm offset to the rear. The author has probably forgotten more than I will ever know about Mustang suspensions so I trust his advice.

 

What I still am trying to figure out it which method I should use or whether I should do both.

[jgkurz 52]

Just spoke to the folks at Mustang Plus. They advised that improving caster via the Shelby Drop is not advised on the 67 and later Mustangs and that I should use the strut rod. This seems to validate what I'm seeing vendors offer for the Shelby drop templates. The 67 and later templates drop the holes directly down without movement toward the rear. Unless I get new information I will add washers to the front post of the UCA then fine tune the caster with the strut rods.

[jgkurz 52]

What bump steer is like is when you hit a rut or pot hole the wheels will quickly turn one way or the other...luckily I don't have that problem.I will increase the caster once I know where it is.In the past I have cut the rear strut rod nut in half to squeeze out more +caster ,I even switched the lower control arms on my 67 f/b to Global Wests with spherical ends to eliminate bind for more +caster...on my 70 with the Borgie, shimming the upper control arms may be the way to go for more +caster also, time will tell,Borgeson should be more transparent with their info....joe

 

Joe, as I re-read your post I am wondering if the P/S pump may be contributing to your bad experience. Borgeson told me I need 3-4deg positive caster and a P/S pump that provides 1150-1350psi to work properly.

 

I'll be shimming my UCA's so I'll report back after the alignment to help you decide on how to improve caster on your car. My shock towers are modified so I hope I don't have zerk fitting issues.

Edited June 24, 2014 by jgkurz

[det0326 179]

Just spoke to the folks at Mustang Plus. They advised that improving caster via the Shelby Drop is not advised on the 67 and later Mustangs and that I should use the strut rod. This seems to validate what I'm seeing vendors offer for the Shelby drop templates. The 67 and later templates drop the holes directly down without movement toward the rear. Unless I get new information I will add washers to the front post of the UCA then fine tune the caster with the strut rods.

 

 

Yea that's what I gathering from all this also. There must be an unforeseen problem that some ran into that we don't know about, but for the life of me I can't see what it would hurt, it seems like a perfect way to add caster. Some articles that I've read advise against the Arning drop(Shelby) without shimming the upper ball joint and other places I read says its not necessary. I guess all these modifications just depend on whose article you're reading. It looks to me like tho that if you move the holes down on the same angle that there are would actually move the U/C forward a little increasing negative caster. It seems you would have to move it back some to maintain what positive caster you have in the stock setup.

Dave

[3pedal 95]

I have a 67 S code fastback I did a Shelby drop to, I am using stock Power steering, NO Problem there and all I could get was 2 degrees +...I have not had the 70 with the Borgie aligned yet but I played with the toe in yesterday wow it was toed out approx. 3/4 " I corrected it to -0-...made a nice difference... now i am looking foward to More +caster...I f you want to add shims to the UCA add to the front bolt only, that tips the top of the spindle rearward for + caster....joe

[det0326 179]

I have a 67 S code fastback I did a Shelby drop to, I am using stock Power steering, NO Problem there and all I could get was 2 degrees +...I have not had the 70 with the Borgie aligned yet but I played with the toe in yesterday wow it was toed out approx. 3/4 " I corrected it to -0-...made a nice difference... now i am looking foward to More +caster...I f you want to add shims to the UCA add to the front bolt only, that tips the top of the spindle rearward for + caster....joe

 

If I understand this correctly the holes in the shock tower as referenced to the plane of the frame rail the front hole would be a little higher than the rear hole is this correct, which means it is on an angle. That being said when you did the drop on the 67 S code did you drop the holes on this same angle keeping the front hole a littler higher than the rear one. And if that is the case would this not set the top of the spindle more forward or more negative caster. Did you shim the top ball joint or is this just suggested only for the 69 and 70?

I know nothing about suspension and just trying to cover all bases before doing the Borgenson set up. In your opinion was the 1 inch drop to any advantage that was really noticeable as for as street driving? I understand too from some other people that on the 69 and 70 anyway (don't know about the earlier ones) that the new hole drilled, I think the rear one, will actually be off the reinforcement plate for the frame motor mount a little, is this true? Sorry for the short novel but just trying to find answers.

Thanks for any info you can share on this and please keep us informed on your progress.

 

BTW I do agree on the method you are using to increase caster on the top rather than pulling the LCA forward with the strut rod.

Dave

Edited June 24, 2014 by det0326

[3pedal 95]

You do need to pull the strut rod as far foward as possible,yes the bolts will be off the support a little ( use thick washers),do the drop a 1000 Frenchmen can't be wrong LOL, both of my cars handle grrreat, look on Tony Brandas site for Shelby drop diagram...have not used the washer spacer trick yet,I would try it....joe

Edited June 24, 2014 by 3pedal

[stangnet33 88]

Curious to see how this shimming the uc works, because now you are also starting to mess with your camber. You were aiming for -.5 deg and you are now heading toward the positive. As this was not a designed adjustment as where you can move both the front and rear bolts "in" or out. Hopefully you have enough adjustment available with the lc arm eccentric adjustment bolt to compensate the camber for this added washer. Also the lc arm strut rod is designed to help adjust you caster.

Edited June 24, 2014 by stangnet33
spell

[Midlife 814]

I believe you can also change caster by rotating the UCA bolt multiple times relative to the UCA itself: essentially moving the UCA arm forward or backwards relative to the pivoting shaft with the two bolts. I may be wrong, however.

[det0326 179]

Curious to see how this shimming the uc works, because now you are also starting to mess with your camber. You were aiming for -.5 deg and you are now heading toward the positive. As this was not a designed adjustment as where you can move both the front and rear bolts "in" or out. Hopefully you have enough adjustment available with the lc arm eccentric adjustment bolt to compensate the camber for this added washer. Also the lc arm strut rod is designed to help adjust you caster.

 

I agree with you on the spacer on the UCA hole this would be messing with the geometry of the suspension. I also agree that the strut rod was originally designed to add or decrease caster but there is not enough factory caster built in the 69's and 70's to get the wanted 4 to 5 degrees for the Borgenson power upgrade and trying to force more than it was designed to do seems would be a bad thing. That's why I was asking about when doing the Arning drop move the holes rearward to compensate for a little more caster, but some are saying not to do this but are not explaining why not to do it.

Dave