Is a Panhard Rod Necessary?

[steveg]

Just noticed my panhard rod mount at the axle has broken the welds and is non-functional.

In normal (non-race) driving, does the panhard rod provide any benefit? I know what it's supposed to do, just not sure I noticed any difference with it broken.

This is a Cape International "uprated bar" with a Heim joint at the axle end. This may have caused the break, as the stock setup has rubber bushes at both ends.

 

[DerekJ]

I drove my first Healey for 4 years without a Panhard rod including an ascent and descent of the Stelvio pass. In normal driving it's not absolutely necessary, not all cars with live rear axles had them. However it is there for a purpose, to 'locate' the axle, so probably best to have one, but its not an emergency.

 

[HealeyRick]

Steve,
No first-hand experience on how it will affect handling, but I'd also consider that if you're running wider tires than stock the panhard bar will aid in keeping the tire sidewalls from contacting the inner fenders. Given how thrifty the Healeys were in designing the cars and BMC was in producing them, I can't imagine they wouldn't have jumped at the idea of saving a few quid per unit by leaving the bar out if they didn't consider it a necessity. And although the bar was deleted when the BJ8 was introduced with redesigned rear suspension, they still provided for lateral axle location with trailing arms.

 

[DerekJ]

Rick, those are torsion bars not trailing arms. They prevent the axle from winding up which the Panhard rod doesn't do. I don't think the MGB had a Panhard rod.

 

[HealeyRick]

Rick, those are torsion bars not trailing arms. They prevent the axle from winding up which the Panhard rod doesn't do. I don't think the MGB had a Panhard rod.

Thanks, Derek. I stand corrected and found this explanation from Marty Jansen:

The panhard rod was detrimental in the handling of the car on the early year
suspension design. On the early cars, the rear springs ran parallel and the
rod was used to hold the rear axle stationary - to limit the side movement of
the rear axle. The suspension also needed to be softened because the chassis
was flexing too much . This resulted in the axle travel up and down to be
increased. This design caused the panhard rod on hard cornering to pull the
car into a spin out. The design was used for cars up to the BJ7 and early
BJ8- 1964.
On the BJ8 65 and newer design, although chassis rigidity was still a problem
Healey realized by toeing the springs in at the front, the rear end would be
stable eliminating the panhard rod.Due to the fact the chassis problems were
not resolved , soft springs were still used and as a result the increase
horsepower caused the springs to windup -going into a S pattern. To resolve
this problem the radius arms were installed. Radius arms do not offer any
assistance in the side movement of the rear axle. A better design would have
been a Watts link.

 

[DerekJ]

Rick,

It's a small world. I didn't mention that my first Healey was built by a close friend of Marty's using one of his new chassis. On the advice of Marty he left off the Panhard rod! Marty was the first person I met in the Healey world when I asked him to view a car I wanted to buy.

 

[RAC68]

I also believe Marty (Frameman) to be quite knowledgeable.

Re: BT7 Handling

I have been following this thread for a few weeks now. The Austin Healey chassis was never structurally sound.
I have several items I wish to address- suspension mounting bushings-these are mounted in rubber for very good reason. It is to reduce road shock and lower stressing of the chassis supports. All auto manufacturers mount their suspension components in rubber insulated bushings. Road and Track and other car magazines tested Healeys when they were brand new and found the car had handling issues and suffered scuttle shake. They also suffered from doors fly open on hard cornering due to torsional loading. sound structures do not have these issues. It was not until 1965 that Healey realized if he was to toe in the rear springs the car would be more stable in the back. On the earlier cars he ran the rear springs parallel. It utilized the pan hard rod for rear end stability but because the chassis suffered from torsional loading issues softer suspension was used to control the twisting of the chassis. The end result was a car that would spin out on a corner as we have read in many articles over the years.
Rally cars and competition cars were equipped with roll cages which added rigidity to the car. These cars suffered from structural issues as well. Applying race technology to an every day driver is not a good idea because of the different environments. A race car is inspected after every race and generally torn down and rebuilt after every race. A regular car does not have this happen.
My suggestion would be to put heavier front and rear sway bars in and toe rear springs in and remove your pan hard rod. These are low cost items. I think this would provide the most bang for your buck. Keep the insulated rubber bushings and stay away from the hard bushings.
I respect the forum's members but this is an area I have a very strong understanding and was concerned when I read some of the suggestions.
Marty​

As you can see, rubber bushing, heavier sway-bars front and rear, to-in rear springs, and get rid of the Panhard rod.
Steve, I can see eliminating the Panhard but I also think that it would be important to also toe in the springs at the same time if you want to tighten up the rear suspension and gain some handling improvement.

Rick, sorry for repeating what you has already quoted but I thought his suggestions (in context) would be pertinent to this discussion.


Happy New Year,

Ray (64BJ8P1)​

 

[BN2guy]

Very interesting! Thanks, Rick (and Ray) for passing on Marty Jansen's explanation. I think that this explains why my BN2 was missing the Panhard rod when I bought it in 1961; and further, explains why it had been fitted with a set of Traction Masters (anti-tramp bars). I have since acquired and installed an original Panhard rod, and also mounted a DWM rear anti-roll bar.

Since the car is still undergoing restoration and isn't yet drivable, I don't know how it will handle. It will be interesting to see. I suspect that I may still have some work to do.

Bill

 

[steveg]

I also believe Marty (Frameman) to be quite knowledgeable.

As you can see, rubber bushing, heavier sway-bars front and rear, to-in rear springs, and get rid of the Panhard rod.
Steve, I can see eliminating the Panhard but I also think that it would be important to also toe in the springs at the same time if you want to tighten up the rear suspension and gain some handling improvement.

Rick, sorry for repeating what you has already quoted but I thought his suggestions (in context) would be pertinent to this discussion.


Happy New Year,

Ray (64BJ8P1)​

Rear spring toe-in isn't an option. Will re-weld the bracket and either re-install my stock panhard (if I can find it) or modify the end of the Cape item to again use the rubber or poly bushings.

 

[DerekJ]

A rear anti roll bar isn't really necessary and can cause problems. As the rear axle is a live beam set up and has longitudinal leaf springs there is already a lot of roll resistance inherent in the rear suspension set up. They are often used with cars that have rear coil springs as coil springs are less resistant to roll than leaf springs. Similarly if you removed several of the leaves of the leaf spring thereby making it softer then an anti roll bar might be required.

 

[John Turney]

Rear spring toe-in isn't an option. Will re-weld the bracket and either re-install my stock panhard (if I can find it) or modify the end of the Cape item to again use the rubber or poly bushings.
View attachment 30789

Yes. Suggest the poly bushings.

 

[John Turney]

Rear spring toe-in isn't an option. Will re-weld the bracket and either re-install my stock panhard (if I can find it) or modify the end of the Cape item to again use the rubber or poly bushings.

Steve,

I assume since you broke a poly bushing on your Panhard rod, you must have repaired it. I discovered this afternoon that mine has broken the same place yours did. We're you able to repair without removing the axle, or did it have to come out? Did you do any reinforcement?

 

[steveg]

Steve,

I assume since you broke a poly bushing on your Panhard rod, you must have repaired it. I discovered this afternoon that mine has broken the same place yours did. We're you able to repair without removing the axle, or did it have to come out? Did you do any reinforcement?

I had to modify my rear shock mount to add the "ear" for the panhard rod. See:
https://www.pbase.com/stevegerow/image/154242713

Was not able to re-weld the stock mount without removing the axle.

 

[Genos2]

Derek, they are not torsion rods on the BJ8, they are radius rods, big difference. My '53 100 has round traction type bars on her, left-over from when she had a Corvette V-8, they almost look like a copy of the MK3's seem to work fine, think it still has pan-hard rod also. cheers

 

[John Turney]

I had to modify my rear shock mount to add the "ear" for the panhard rod. See:
https://www.pbase.com/stevegerow/image/154242713

Was not able to re-weld the stock mount without removing the axle.

Thanks!

 

[andrea]

From this interesting discussion I assuming that if I add my REAR sway bar, I must eliminate the Panhard rod,
this is my question, unsolved, before Marty thread publication, I agree with Marty !
https://picasaweb.google.com/lh/photo/QUiBNkLcutzByWdgKutEXNMTjNZETYmyPJy0liipFm0?feat=directlink
The other problem is that on 100/6- the rear sway bar can go on only with SIDE EXHAUST !!

 

[steveg]

From this interesting discussion I assuming that if I add my REAR sway bar, I must eliminate the Panhard rod,
this is my question, unsolved, before Marty thread publication, I agree with Marty !
https://picasaweb.google.com/lh/photo/QUiBNkLcutzByWdgKutEXNMTjNZETYmyPJy0liipFm0?feat=directlink
The other problem is that on 100/6- the rear sway bar can go on only with SIDE EXHAUST !!

Andrea,
Wouldn't it be fairly easy to put a dip in the exhaust pipe to clear the sway bar?
I tried a side exhaust once and it was too loud for non-racing use. Others have said the same.

 

[JAV]

I made a dip in one exhaust pipe to clear my rear sway bar. It did hit ground on some hi crowned roads, but normally was fine.

 

[andrea]

Hi Steve
my new Stainless pipes are so fair that I am hesitant to make the dip - the last, romantic mechanic-
I agree with you side exhaust are too loud for longs trips

 

[Legal Bill]

Rick, those are torsion bars not trailing arms. They prevent the axle from winding up which the Panhard rod doesn't do. I don't think the MGB had a Panhard rod.

Actually, torsion bars are used in a twist configuration to serve as springs, like in the Jaguar E-Type. The Phase II BJ-8 used radius arms that define and limit the swing of the live axle.