Cutting strut rod bushings for correct geometry?

[MopaR&D]

I read an article on a site detailing a road-racing '68 340 Barracuda about how most replacement strut rod bushings are too thick and push the strut rod back, putting strain on the lower control arm and reducing available caster. I want to cut mine and rearrange them so they work at the right angle but I'm not sure how. I have polygraphite bushings from PST and they seem like a pretty hard material, I can't think of any way to cut them that is safe besides a band saw and I don't have access to one of those.

 

[rednesss]

http://www.summitracing.com/parts/HSS-14385

Problem solved.

 

[autoxcuda]

I read an article on a site detailing a road-racing '68 340 Barracuda about how most replacement strut rod bushings are too thick and push the strut rod back, putting strain on the lower control arm and reducing available caster. I want to cut mine and rearrange them so they work at the right angle but I'm not sure how. I have polygraphite bushings from PST and they seem like a pretty hard material, I can't think of any way to cut them that is safe besides a band saw and I don't have access to one of those.

That's my car or Matt Grubel's.

I cut it on a lathe. But you could use a hacksaw. Problem solved. Cost: $0.00

Here's some picture of the setup. I ran it from about 1995 to 2010.

 

[autoxcuda]

Matt Grubel did a how to article on his website using this info. The picture of all the bushings is my (Steve Wall) picture.

http://www.heritech.org/cuda/bushings.html

 

[rednesss]

I see you have a set of the Hotchkiss installed there in your picture even if the cost wasn't $0.00 :happy2:

 

[autoxcuda]

I see you have a set of the Hotchkiss installed there in your picture even if the cost wasn't $0.00 :happy2:

The piece I'm holding in my hand has the poly bushings cut for $ 0.00. And I ran that very piece in my car from 1995 to 2010.

It's pretty hard to see them when they are installed in the car. The picture is an example of what they look like after 15 years of use (not much different than when installed).

On my old website 68 Cuda Autocrosser I talked about cutting the poly bushings. But AOL dumped the site a few years ago.

Yes, I don't run them right now, but that doesn't mean they won't work for what the original poster is asking for. I was looking for a higher level of performance and precision than a factory setup and willing to sacrifice some dampening the bushings provide.

 

[Oldmanmopar]

73 and up strut rods are shorter. They should be used when instaling the two piece poly strut rod bushings. When I got my suspension kit i called and they sent me the correct one piece poly's to use my early strutrods. I posted pics awhile back xhowing the difference

 

[sireland67]

I have a set of 73 up strut rods if you need them.
PM me if interested.

 

[rob_robinson87]

I cut mine when I rebuilt my front end.. It was pretty easy using a molding/trim saw and then cleaning it up on a flat surface with sandpaper. Then I cut the metal insert using a cutoff wheel so the nut would screw on enough to get the cotterpin in. I did it a little at a time to make sure I didn't take off too much. Obviously the back one will need a lot more cutting then the front one. Pretty easy mod and much better to have the harder poly bushing there instead of the rubber one that gives a lot more.

 

[MopaR&D]

Thanks for all the great replies, suppose I'll try a hacksaw. Trimming the metal insert is a good idea too, I remember how the nut wouldn't go on far enough to use a cotterpin the first time they were installed.

This is the site I found the info, it's actually a '67... http://users.erols.com/mathewg/mgcuda.html

 

[Oldmanmopar]

I don't know if you guys realize that the strutrod bushing locates the control arm to center it on the pin bushing that the torsion bar goes into . The arm should be perfectly square to the pin. Cutitng the strut bushing to make the roll pin fit is a real idiotic way of doing this. They make poly bushings for both early and later struts. Where did you get the measurments telling you how much to cut the front and or rear. These bushings are made to locate the strut with the bushing squeezed to a specific amount guaged by the sleeve. Like I said I had the same problem and I called PST and they sent me the correct bushings. The early bushings do not take a sleeve. They are usually one piece. Moog makes two piece without the sleeve for early cars. One piece are easy to install if you have early bars.

 

[MopaR&D]

I understand the bushing's effect on alignment and how they have to be the correct thickness. Which is exactly why I need to cut mine in the first place, the back bushing is too thick and pushed the control arm back which threw off the alignment and put strain on the roll pin that you're talking about. My car originally came with two-piece bushings BTW they were just much thinner. I need to cut the front bushing and shorten the sleeve a bit so the nut on the end of the strut rod will screw on far enough (like stock) to insert a cotterpin for safety. And that site I linked has specs on exactly how much to cut to get correct geometry.

 

[Oldmanmopar]

I understand the bushing's effect on alignment and how they have to be the correct thickness. Which is exactly why I need to cut mine in the first place, the back bushing is too thick and pushed the control arm back which threw off the alignment and put strain on the roll pin that you're talking about. My car originally came with two-piece bushings BTW they were just much thinner. I need to cut the front bushing and shorten the sleeve a bit so the nut on the end of the strut rod will screw on far enough (like stock) to insert a cotterpin for safety. And that site I linked has specs on exactly how much to cut to get correct geometry.

I went to the parts shed and grabbed a set of strut rods for a 72 back (top in pic) and a 73 up (bottom in pic) You can see the difference in length flang to flange And also the room for the bushing between the washers . The washers on the 72 back canot be reversed to mimmic the 73 up. On the 72 back the nut bottoms on the sholuder. no sleeve like the 73 up. There is no way a 2 piece for a 73 would work on the on a 72 back correctly. This is just some info you all might want to know. Pictures do not lie the rod lengths are different.

 

[Oldmanmopar]

I cut mine when I rebuilt my front end.. It was pretty easy using a molding/trim saw and then cleaning it up on a flat surface with sandpaper. Then I cut the metal insert using a cutoff wheel so the nut would screw on enough to get the cotterpin in. I did it a little at a time to make sure I didn't take off too much. Obviously the back one will need a lot more cutting then the front one. Pretty easy mod and much better to have the harder poly bushing there instead of the rubber one that gives a lot more.

Another engineer here . The harder you make the strut rod bushing is not better. The bushing is suppose to allow the control arm to move up and down freely but not front or back. If not the strut rod will break as the problem they had with the early a-body cars. That is why they went to a thicker bushing in later years. Did you also know that you should never tighten any bolts that secure any busings until the car is at ride hieght getting aligned. If you do you will rip the bushings and they will be permantly destroyed. Upper and lower control arm bushings with inner and outer attached sleeve are made to travel the same distance in either dirrection. If you tighten them when the car is raised and then bring it to ride hieght you already put it at half its travel. As soon as the car dips when driven the sleeves will rip from the poly or rubber, This is not the case with lower poly because you leave the original sleeves in place and lube the bushing. But all uppers and OEM lowers this mus be done.

 

[daredevil]

Another engineer here . The harder you make the strut rod bushing is not better. The bushing is suppose to allow the control arm to move up and down freely but not front or back. If not the strut rod will break as the problem they had with the early a-body cars. That is why they went to a thicker bushing in later years. Did you also know that you should never tighten any bolts that secure any busings until the car is at ride hieght getting aligned. If you do you will rip the bushings and they will be permantly destroyed. Upper and lower control arm bushings with inner and outer attached sleeve are made to travel the same distance in either dirrection. If you tighten them when the car is raised and then bring it to ride hieght you already put it at half its travel. As soon as the car dips when driven the sleeves will rip from the poly or rubber, This is not the case with lower poly because you leave the original sleeves in place and lube the bushing. But all uppers and OEM lowers this mus be done.

Did not know this. Well time to loosen everything back up.

 

[autoxcuda]

I don't know if you guys realize that the strutrod bushing locates the control arm to center it on the pin bushing that the torsion bar goes into . The arm should be perfectly square to the pin. Cutitng the strut bushing to make the roll pin fit is a real idiotic way of doing this. They make poly bushings for both early and later struts. Where did you get the measurments telling you how much to cut the front and or rear. These bushings are made to locate the strut with the bushing squeezed to a specific amount guaged by the sleeve. Like I said I had the same problem and I called PST and they sent me the correct bushings. The early bushings do not take a sleeve. They are usually one piece. Moog makes two piece without the sleeve for early cars. One piece are easy to install if you have early bars.

I got this measurement from original bushings and 72 down strut rods. That's where the top picture I took on Matt Grubel site comes from. It compares factory and aftermarket bushings. You shorten the inner sleeve down the same amount as you do the rear poly bushing part. So the nut will clamp against the sleeve like the later style.

The idea is to just put it back in it's factory position.

Even though, the factory bushing doesn't always perfectly 100% position the lower control arm (LCA) on the pin. Also when the suspension travels up and down the strut rod has some arc to it moving the end of the LCA forward and back. The strut rod does not pivot on the same arc as the LCA. There's even some slop in the LCA shell to height adjuster connection.

The cutting the rear poly bushing deal worked 16 years and 80,000 miles for me and I got great alignment numbers. I ran rubber LCA bushing from 1994 to 1998 and when I took them out they were perfectly fine. I just removed my LCA's to put on the Hotchkis parts last year and the poly LCA bushing I ran from 1998 to 2010 looked fine and we even reused them even though I had new ones.

The one piece rubber early bushings aren't very good. Even in poly. And they tend to tear in the middle. They are mushy and allow the LCA to move back and forth high loads. That's why Moog sells and improver bushing two piece version part number K7040 for 63-72 A-bodies. We are just shortening the poly two piece bushing to match.

 

[Oldmanmopar]

That moog bushing is for easy instalation and allow more motion. One piece bushings have to be pulled in from the rear with a installation tool. The cupped washers on the one piece incase the bushing which dose not allow enough movement. The washers on the later two piece only sqeeze the inner part of the bushing stoping back and forth mottion and allowing alot more up and down motion. If you were to put a swivel on as hotchkis did you would not even need the bushng. The bushing is to allow movement so the strut rods do not snap under severe driving conditions. If you only drive your car on smooth roads or don't have the power to flex the suspension under acceleration. You will never have a proplem. My first poly bushing kit ended up on the street in pieces after a couple of launches and puting alot of pressure on them from the roll control. When you break your first strut rod from binding and the wheel destroys your fender. Don't say I didn't warn you all. Yes you want to get rid of as much forward and rear ward motion as possible but you want to increase its motion of pivot up and down to protect the rod. One of the reasons for upper a-arm bumper extensions and tie cables on early a-body race cars. I have been doing this for many years and have seen what happens to those who think they know because they got away with it for awhile. What do you think causes struts to break? Or Bend? They always break at the end where they are attached

 

[autoxcuda]

...If you only drive your car on smooth roads or don't have the power to flex the suspension under acceleration. You will never have a proplem. My first poly bushing kit ended up on the street in pieces after a couple of launches and puting alot of pressure on them from the roll control. When you break your first strut rod from binding and the wheel destroys your fender. Don't say I didn't warn you all. Yes you want to get rid of as much forward and rear ward motion as possible but you want to increase its motion of pivot up and down to protect the rod. One of the reasons for upper a-arm bumper extensions and tie cables on early a-body race cars. I have been doing this for many years and have seen what happens to those who think they know because they got away with it for awhile. What do you think causes struts to break? Or Bend? They always break at the end where they are attached

I've done it for many years too.

You lube that poly bushing to the later/replacement type washer connection as well as the Use very thick grease or that snotty clear-like grease they give you with poly kits. You can see the lube still on those poly bushings on the picture I showed.

And there are cases where the strut has broken with rubber bushings too. Struts get rusty in there. Threads get stripped. And struts that have previous worn bushings that beat on the K-member hole. Or owners or mechanics that have jacked the car on the strut rod. Or cheap POS transportation cars for high schoolers imitating Dukes of Hazzard.

I've driven in 13 different states with that poly setup I showed above. Iowa winters, trips to downtown Chicago, Minneapolis, St Louis. I've driven it 1, miles straight trips back and forth from L.A. to Ames, IA SIX TIMES. Autocrossed it many times in Iowa and Nebraska. I loaded my Cuda to 5300 lbs on grain scales after finishing school and cracked the K-member on the way back. Strut rods were fine.

Then I drove it back and forth commuting to work from metro L.A. to Thousand Oaks everyday for work 80 miles round trip through the most trafficed freeway stretch in the world (I-405 between I-10 and CA-101)

I've also ran it at Willow Springs and Buttonwillow race tracks. And I've been off track a few times too. Once I even bent a steel 15x8 rim and dimpled up my shock tower.

All of that and not a bent strut rod with that same cut poly setup shown in the picture above.

Examples of various other extremes of punishment, power, and flexing that my cut poly strut rods have taken... First tow pictures are of bent rim, shock tower hold dimpled up a little, bent valance a little. Had to dismount tire to get the rocks stuck between the rim and tire out.

 

[Oldmanmopar]

The bottom line is there is the correct way to do the job. Not saying your rigging didn't work for you and maybe others . But if they have to be modified to fit your using the wrong parts. They do make the correct bushings for every application. If you are that cheap That you insist on cutting and using missed matched parts to make it work you, Go for it. I on the other hand know what bushings go with what application and can install them correctly without cutting them. I gave you the pics and you can clearly see there is a difference and why your bushings have to be modified. Your just one of those people who are proud of your engineering to overcome something that you didn't understand in the first place. So you just keep on cutting your parts to fit . If you can get them a little thicker you might be able to get two sets out of one pair. I should have known not to try and explain the reason there is a problem with these bushings. There is always a custom fix it guy who's been there.

 

[mikedevore]

If I understand this, as long as you match the correct bushing set to the strut rod that you are using, all should match?
Can you interchange the strut rods between K-meber styles, as long as you get the correct bushings for the struts you are using.
Are the LCA to strut mount on the K-member, the same for all years.
Good info here from everybody involved, keep it coming.
Would you want to set any type of pre-load on your chassis pivot points for a drag car?

 

[autoxcuda]

The bottom line is there is the correct way to do the job. Not saying your rigging didn't work for you and maybe others . But if they have to be modified to fit your using the wrong parts. They do make the correct bushings for every application. If you are that cheap That you insist on cutting and using missed matched parts to make it work you, Go for it. I on the other hand know what bushings go with what application and can install them correctly without cutting them. I gave you the pics and you can clearly see there is a difference and why your bushings have to be modified. Your just one of those people who are proud of your engineering to overcome something that you didn't understand in the first place. So you just keep on cutting your parts to fit . If you can get them a little thicker you might be able to get two sets out of one pair. I should have known not to try and explain the reason there is a problem with these bushings. There is always a custom fix it guy who's been there.

I understand clearly what you are talking about. I have a very complete selection of A-body suspension pieces stock and aftermarket less that 30 feet from me. Those early one piece bushing blow. Especially in poly. Moog only sells the improve two piece style and it not just because they are easier to install.

Not many people want to locate a pay for 73-76 strut rods. And most of the people selling them can't ID what they have. And the poly bushings are still too thick for those. I've run the cut poly bushing on the 73-76 strut rods too.

I understand suspension design and tested and been part of championship oval track cars enough to know what matters and what doesn't. You are one of those guy that believes the factory suspension is 100% perfect to the 0.001" for everyones needs and wants. A factory design has all kinds of compromises in regards to anti dive, scrub, bump steer, ackermann, parts sharing, economics of scale, liability, etc.

Geez shouldn't modify a motor either. Leave it all stock. But that's ok to modify, because you understand that.

 

[autoxcuda]

If I understand this, as long as you match the correct bushing set to the strut rod that you are using, all should match?
Can you interchange the strut rods between K-meber styles, as long as you get the correct bushings for the struts you are using.

Yes or match the position the bushing meets the K-member.

Are the LCA to strut mount on the K-member, the same for all years.

67-72 strut rod

73-76 strut rods are shorter shoulder to shoulder

Good info here from everybody involved, keep it coming.
Would you want to set any type of pre-load on your chassis pivot points for a drag car?

I'm not a drag guy, but I would really think no.

You'd want to preload you chassis with the front torsion bar adjuster or moving the rear wheel up/down on a leaf spring car. Or on a coil spring rear you adjust weight jackers, spacers, or coil overs.

 

[MopaR&D]

That's good advice on tightening the bolts when the car is resting on the wheels but I feel like it would be tough getting to them once the car is on the ground. I'm doing all this in my garage and I'm sure I have far less tools and equipment than you guys.

I'll take some pics of my strut rods and post them so I can know for sure what type I have. I feel like it's the '72-down ones but I was definitely able to install sleeves for the bushings that slid over the rod.

 

[Oldmanmopar]

Yes K"s are all the same from Contol arm to strut rod flange length

The shorter rods are for the two piece are always coarse thread on bushing end see picks above

No matter what your car is used for Bushings should be tightened at correct ride hieght when alligned.

I use early SS rear springs . Everyone that uses these knows they make the car lean after installed. The reason is to accomendate for torque to the left rear. On most of the older SS cars using these springs If you look at picture you will notice their front wheels do not drop out on launch. This is because they either are cabled up or have Upper a arm bumper extentions. which helps eliminate bump steer

Preloading the right rear does help with those uneven SS springs. I am not going to get into why but here is what I do.

First most mopars are not built or welded together correctly. How many of you go to burn out contests and see cars that want to spin around when doing a burnout. this also effects the launch.

Where the leaf spring bracket bolts to the front of the car. The flat surface with the four holes where the studs go through. Alot of cars especially non perfomance models that were auto/open rear cars were not straight. Mine was 1/2 inch off. and seen worse. An easy check is where that is welded to the frame rail there is a tab that is welded to the bottom of the rail. In front of that tab is a hole about 3/4 inch . Measure from that tab to the hole. you will see a difference if your car is not built straight . Mine was 3/8 difference from side to side. you can shim the short side back to correct this. Measure from K-member mounting bolt back to the pad to get the correct thickness of the shim needed. I made a 1/2 inch plate with four holes out of aluminum and put it in front of that spring that had to come back. After putting in longer studs.

Then preload , With car setting on level surface jack the car in the center of the rear. This lets the car sit on three points . adjust your front bars to sit approximately 1/4 inch above lower Control arm bumpers. Make sure your bumpers are new or the same hieght. This levels your suspension without sitting on the uneven SS springs. When you leave the car down the car will lean to the left front. Jack weight to the left front with the bar adjuster until both rubber bumpers are the same. Usually the bumper space will raise to about 1/2 inch before it levels This differs from car to car. somethig you'll have to play with. Always do this without the stabilizer bar attached. Then reattached it when done. Remove left link from stabilizer bar when drag racing for even transfer.

I owned several Dana cars that used these springs from the factory. and always used this method on those cars also. It works for me.

Put a spacer under upper a arm bumper to shorten the distance the front drops out when launching. If yo have a deep pan or headers that hang. On a drag car you can add a spacer under the lower arm bumper just to make up the space between the frame and the rubber bumper. This will prevent your pan or headers from scraping when coming back down. six cyl. bars cause this travel to be excessive and quicker but are weak coming down. mine still sqashes the rubber and just touches the one tube I have to move up. Poly bumpers are stiffer and give more control but you will have to keep an eye on them .They do not take as much abuse as the rubber. I have poly on mine and have spares.

My front shocks are 90/10. my backs are QA-1's I have the right rear 2 clicks tighter then the left But again this is what works for me. I do not road race my car. My front wheels are 3 inch the rears are 12 inch. With a spool it doesn't like to turn. I run a tightened up clutch suregrip on the street. One reason I stayed with a 8 3/4 easy gear and chunk change for different uses.

I will be going to Cal-tracs soon with monos. This will probably change things for me and then I will be asking some questions.

 

[Oldmanmopar]

I understand clearly what you are talking about. I have a very complete selection of A-body suspension pieces stock and aftermarket less that 30 feet from me. Those early one piece bushing blow. Especially in poly. Moog only sells the improve two piece style and it not just because they are easier to install.

Not many people want to locate a pay for 73-76 strut rods. And most of the people selling them can't ID what they have. And the poly bushings are still too thick for those. I've run the cut poly bushing on the 73-76 strut rods too.

I understand suspension design and tested and been part of championship oval track cars enough to know what matters and what doesn't. You are one of those guy that believes the factory suspension is 100% perfect to the 0.001" for everyones needs and wants. A factory design has all kinds of compromises in regards to anti dive, scrub, bump steer, ackermann, parts sharing, economics of scale, liability, etc.

Geez shouldn't modify a motor either. Leave it all stock. But that's ok to modify, because you understand that.

If I was involved with championship black top oval racing as you are . I wouldn't be using stamped steel arms and struts from the 60's. With whats on the market today there is tubular arms and coil overs. also cambered spindles. and suspension built for evey application. I am not saying I am the professional here. But I am stating facts on how the average person can resolve a problem without a saw and a hammer.

That sprint car in my profile is not something I pulled out of a book. Its here and my sonand I take it apart and put it back together weekly. set ups are different for every track and track conditions. Every change is kept on file. for every race. We are still learning this car and take all the advise given to us and try it. Mayby that is why we have the sponcers we have. I never shy away from good advice.

My list of racecar mechanical experience goes from Top fuel to modified nascar. But I stiil take any properly explained advice to heart.

Please don't tell others to modify their steering components beyond there design specification. This can become dangerous and liable. There is a engineered specification for all parts. and yes you can modify any at your own risk. I am telling you that altering these bushings can cause the ends to break on the rods. I have seen it . The results are not usually good. If you do it without a problem then that is fine. But who is to say the person following your advice has your professional knowledge and skills. The right saw or hammer size. These are steering components. Not engine parts.

My son and I discuss all changes we make among ourself and other freinds who race in all classes of the sport . Before we make the change to our race bikes , cars , and trucks and sleds advice is used from all input . We are always building new toys for him to race. Saftey is always the first conideration before the change is made. Maybe thats why he is still with me. I love him and it is my upmost duty that he out lives me. .

Now all that said Use the correct parts and feel safe. Why put a question mark after safety.