Bump Steer remediation

Chris Taunton

Daily Driver
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Here you can see the springs and struts that I removed and the ride height I settled on. It is 1/4" lower on the left and 3/4" lower on the right (same on both sides now). Camber is set at -1.75 and toe is 1.5 mm out. The front springs are 225 lb/in. It is much firmer and more capable. The front tires (Achilles 122's) throw in the towel before the car does. There is definately bump/roll steer at this ride height. But the car is much more fun and more together than before. I highly recommend the coilovers from MWB.

Once I have the bump steer hardware in hand, I will swap to the modified spindles, big front brakes, rear disc brakes, 14" wheels, A052 tires, and deal with the bump steer all at once. For now, Gus is a much happier car.

Chris
 

Chris Taunton

Daily Driver
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I picked up the wheels from the painter Friday morning and the front brakes, wheel studs, wheel bearings and hubs for the modified spindles arrived Friday afternoon. I'm still waiting on the 20 mm spacers, the rear disc setup, the strut brace, the chassis stiffeners, the heim jointed tie-rod ends, and I still need to source the pins to attach the new tie-rods to the bottom of the steering arms.

Wheel offset with spacers will be 18 mm. Current wheel are 7 mm.

Chris
 
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Dr.Jeff

True Classic
Chris, your car looks great. And I love all of the custom parts you have for it, especially those wheels. It should be a blast to drive and look fantastic.

I see that you are getting heim jointed tie rods. The heim joints will have "straight" holes through them for the mounting hardware (to attach them to the steering arms). The stock tie rod ends have "tapered" mounts that match the taper on the steering arm holes. That will be changed to mount the heim joints. So you won't need the insert adaptors I posted earlier. Your new heim joint rods will use hardened bolts and the steering arms will need to be drilled the same size (and straight rather than tapered). You can also use longer mounting bolts and add spacers to adjust the bump steer. Look back at the other picture I posted for an example.
 

Chris Taunton

Daily Driver
Chris, your car looks great. And I love all of the custom parts you have for it, especially those wheels. It should be a blast to drive and look fantastic.

I see that you are getting heim jointed tie rods. The heim joints will have "straight" holes through them for the mounting hardware (to attach them to the steering arms). The stock tie rod ends have "tapered" mounts that match the taper on the steering arm holes. That will be changed to mount the heim joints. So you won't need the insert adaptors I posted earlier. Your new heim joint rods will use hardened bolts and the steering arms will need to be drilled the same size (and straight rather than tapered). You can also use longer mounting bolts and add spacers to adjust the bump steer. Look back at the other picture I posted for an example.

Hey Dr. Jeff,

I haven't decided on the best way to approach this. Here is an example of an "upside down" tapered pin for Porsches:
https://www.pelicanparts.com/More_I...tm_term=RENS01009P&utm_campaign=Shopping+Feed

There are lots of "right side up" choices like this:
https://www.speedwaymotors.com/Adju...MIjuXJ3oHl6wIVUtbACh1oDQjtEAQYAyABEgJzrPD_BwE

The tapered sleeves could be used with the "right side up" pins, if I can find matching tapers. I am exploring options. When the tie-rod ends arrive, I will decide on the best approach.

Thanks for your help.

Chris
 

Dr.Jeff

True Classic
Hey Dr. Jeff,

I haven't decided on the best way to approach this. Here is an example of an "upside down" tapered pin for Porsches:
https://www.pelicanparts.com/More_I...tm_term=RENS01009P&utm_campaign=Shopping+Feed

There are lots of "right side up" choices like this:
https://www.speedwaymotors.com/Adju...MIjuXJ3oHl6wIVUtbACh1oDQjtEAQYAyABEgJzrPD_BwE

The tapered sleeves could be used with the "right side up" pins, if I can find matching tapers. I am exploring options. When the tie-rod ends arrive, I will decide on the best approach.

Thanks for your help.

Chris
Both of those examples are for utilizing the tapered bore in the steering arms. But you don't necessarily need to do that. Straight holes and straight pins (bolts) can be used instead. The Fiat tie rod end ball joints have such small tapered pins that depending on what size the heim joint hole are, you might not need any adapter - just drill out the holes.

But if you prefer the tapered hole approach, then the ones I referenced earlier are for early water cooled VW's (Mk1 and 2 Rabbits, Golfs, Jettas, etc - from the mid 70's through the 90's). They used to go for around $100 as a complete kit, including the correct size drill bit, etc. But then you would need the pins (bump steer adaptors) to match that taper. The taper for American cars is much more common here in the US, and I'm sure they have the same options to fit them. You can even get a tapered ream to redrill the holes.

Here is an example that uses a straight hole and bolt, but includes an insert to convert the taper on the steering arm to a straight bore:
 
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fiatfactory

Steve Cecchele
Both of those examples are for utilizing the tapered bore in the steering arms. But you don't necessarily need to do that. Straight holes and straight pins (bolts) can be used instead. The Fiat tie rod end ball joints have such small tapered pins that depending on what size the heim joint hole are, you might not need any adapter - just drill out the holes.

Sorry but I think that is very bad advice.

Ball joints and tie rod ends have TWO methods of securing them for a reason.... apart from the fact that it is legislation and a safety requirement for vehicles driven on the road... if one method fails (nut comes off) the taper will hold ... modern ball joints without a taper pin will have a locking cotter pin that wedges into the joint pin, as well as the nut... there is ALWAYS two methods to securing the joint... always. Using a straight bolt/nut gives you just one.

most of that equipment is not designed for on road use, for good reason.

SteveC
 

Agnelli

True Classic
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Here you can see the springs and struts that I removed and the ride height I settled on. It is 1/4" lower on the left and 3/4" lower on the right (same on both sides now). Camber is set at -1.75 and toe is 1.5 mm out. The front springs are 225 lb/in. It is much firmer and more capable. The front tires (Achilles 122's) throw in the towel before the car does. There is definately bump/roll steer at this ride height. But the car is much more fun and more together than before. I highly recommend the coilovers from MWB.

Once I have the bump steer hardware in hand, I will swap to the modified spindles, big front brakes, rear disc brakes, 14" wheels, A052 tires, and deal with the bump steer all at once. For now, Gus is a much happier car.

Chris
Off topic, but enviously looking at your new struts, it occurred to me to ask how old your flex lines are.
 

Chris Taunton

Daily Driver
Off topic, but enviously looking at your new struts, it occurred to me to ask how old your flex lines are.

Agnelli,

They are less than 20 years old, but near the end of their lives. See picture of the front brake kit from MWB. New braided stainless front brake lines are in that box. The rear disc brake kit is coming from Croatia, sadly, with rubber lines. I will have braided stainless lines made up locally using the lines in the kit as a pattern. I bled the brakes and cleaned and lubed the wedges after I drove the car to Georgia from Portland, OR last November.

I'm glad that you are recommending to people to check their lines. It is a commonly overlooked item on classic cars.

BTW, love your wagon and have been enjoying your posts.

Chris
 

Chris Taunton

Daily Driver
Tires arrived yesterday. Still waiting on the rear brakes and the wheels spacers. But... the head gasket has failed. I'll be removing the head next weekend. Here is a picture of the tires:
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Chris
 

Agnelli

True Classic
Agnelli,

They are less than 20 years old, but near the end of their lives. See picture of the front brake kit from MWB. New braided stainless front brake lines are in that box. The rear disc brake kit is coming from Croatia, sadly, with rubber lines. I will have braided stainless lines made up locally using the lines in the kit as a pattern. I bled the brakes and cleaned and lubed the wedges after I drove the car to Georgia from Portland, OR last November.

I'm glad that you are recommending to people to check their lines. It is a commonly overlooked item on classic cars.

BTW, love your wagon and have been enjoying your posts.

Chris
Chris -

keen to hear about your rear disks, sounds like you sourced from Andrea, Stole or Jupiter. Sorry about your head gasket. On the other hand quite the opportunity given your excellent suspension upgrades.
 

Longitudinal

True Classic
Those would not pass engineering certification for road use in Australia, at very minimum not without x - ray and other crack testing, and then probably only after proving strength with a destructive test... personally I would not have a part modified in that manner on one of my vehicles... sorry, just my opinion, YMMV.

For track use only, sure.

SteveC

I'm with Steve here. I am a skilled and experienced welder, and I would not perform that operation even on my own car. On a stamped and welded steel part such as some cars have, maybe. But not on a cast part, even if it is cast steel and not cast iron, and especially not after grinding the face reinforcement off the welds.
 

Chris Taunton

Daily Driver
I'm with Steve here. I am a skilled and experienced welder, and I would not perform that operation even on my own car. On a stamped and welded steel part such as some cars have, maybe. But not on a cast part, even if it is cast steel and not cast iron, and especially not after grinding the face reinforcement off the welds.

Hey Logitudinal

Thanks for weighing in. How would you go about making a different upright for a 128? Have you been involved in a similar project? If so, what was done and what was the cost?

Thanks,

Chris
 

Chris Taunton

Daily Driver
Chris -

keen to hear about your rear disks, sounds like you sourced from Andrea, Stole or Jupiter. Sorry about your head gasket. On the other hand quite the opportunity given your excellent suspension upgrades.

Agnelli,

The rear disc brake parts are from Andrea (classicperformance-parts.com). The calipers and carriers are still at the powder coater. I will post pictures when the parts arrive. Everything else I've bought from him has been great, it just takes a long time in shipping.

The other snag is the studs I got were too short. A longer set is coming from a supplier in the UK.

Chris
 

Longitudinal

True Classic
Thanks for weighing in. How would you go about making a different upright for a 128? Have you been involved in a similar project? If so, what was done and what was the cost?

Good question. I have seen machined ball joint spacers that take the place of the ball joint in the knuckle and provide a new, lower mounting point for the ball joint. None of that would work for you because of design constraints--integrated BJ, placed at an angle, and facing the wrong way for a spacer to work. And you can't flip the arm because of the taper and the cast-in angle.

Making a whole new knuckle is possible, but also very expensive.

Maybe moving the tie rod upward could accomplish a similar result? Machining parts to do that would be a simpler task.
 

Agnelli

True Classic
Agnelli,

The rear disc brake parts are from Andrea (classicperformance-parts.com). The calipers and carriers are still at the powder coater. I will post pictures when the parts arrive. Everything else I've bought from him has been great, it just takes a long time in shipping.

The other snag is the studs I got were too short. A longer set is coming from a supplier in the UK.

Chris
Chris -

Same experience for me from Andrea, got my rear arms from classicperformance.

Do you plan for a fixed valve to adjust front to rear brake bias?
 

Chris Taunton

Daily Driver
Good question. I have seen machined ball joint spacers that take the place of the ball joint in the knuckle and provide a new, lower mounting point for the ball joint. None of that would work for you because of design constraints--integrated BJ, placed at an angle, and facing the wrong way for a spacer to work. And you can't flip the arm because of the taper and the cast-in angle.

Making a whole new knuckle is possible, but also very expensive.

Maybe moving the tie rod upward could accomplish a similar result? Machining parts to do that would be a simpler task.

Longitudinal,

The modified upright was intended to bring the camber gain curve closer to stock and raise the front roll center. Macpherson strut suspensions have very limited camber gain and do not work well when lowered. In a race car, you can compensate with very stiff springs to limit suspension travel and set static alignment where you want it. On Gus, I want good geometry with reasonable suspension travel. The 225 lb/in springs I am currently using are at the edge of reasonable for a street car, IMHO.The steering geometry will have to be corrected separately.

I think someone could use finite element analysis and cad to design a part that could be machined from billet, but I don't know THAT guy. If any of you do, I'd love to talk to him.

Chris
 
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Chris Taunton

Daily Driver
Chris -

Same experience for me from Andrea, got my rear arms from classicperformance.

Do you plan for a fixed valve to adjust front to rear brake bias?

Agnelli,

I plan to drive the car before changing brake bias. I might be able to adjust the original limiting valve or even use a different length link to correct the balance, if necessary.

Chris
 

Chris Taunton

Daily Driver
Chris -

Same experience for me from Andrea, got my rear arms from classicperformance.

Do you plan for a fixed valve to adjust front to rear brake bias?

Agnelli,

Which arms did you get and how do you like them? That will be on my list soon.

Chris
 
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