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TR4/4A TR4 Sway Bars

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Bob_Muzio

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I'm looking for input on using a rear Addco sway bar with a front factory style bar on a TR4. My previous TR4 had Addcos front and rear. My current TR4 has a factory style front bar and since I have the bars from the previous car, and liked the handling, I was considering installing the rear bar.
Has anyone read if the combination is compatible? Does anyone one have personal experience with this mix?
Thank you,
Bob
 
Addco's rear bar is 5/8" in diameter. A concern might be that since it's thicker than an OEM front bar it might create too much rear roll stiffness.
 
I noticed that but the factory bar appears to attach to the suspension more outboard than the Addco thereby having greater leverage...that might offset the difference in thickness.
Bob
 
Bet you'll need to experiment. My comment was based on fitting their 5/8" rear bar on my '64 Corvette. I just didn't care for the result. I then added the larger front bar from a later year big block (1" vs. 7/8" - Addco's was also 1") and that 1/8" difference made all the difference.
 
I've got a 5/8" Addco bar on my 4A but I added a 7/8" TR6 Addco bar on the front. Still haven't driven the car though so I am probably no help for how the results are. I expect a slight over-steer but controllable with steering and brakes.

The front bar mounts to a TR6 radiator guard.
 

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I do not have experience with exactly that mix. Here is my experience. I put a front bar on my 63 TR4 about 40 years ago, I wanted to auto x. Went to the wrecking yard and took one off a wrecked small Buick, it is 13/16. Anyway it is still on there. Many years later I added an addco to the rear, really didn't see much difference until I decided to get rid of the original rubber mounts and use whatever the hard plastic stuff is called on the front and rear bars. Glad I tried an autocross before getting to deep into a corner on a wet road. Couldn't keep the car straight got real tail happy. The addco is in the shop somewhere. If you want it, I'll sell it.
 
TRMark said:
I do not have experience with exactly that mix. Here is my experience. I put a front bar on my 63 TR4 about 40 years ago, I wanted to auto x. Went to the wrecking yard and took one off a wrecked small Buick, it is 13/16. Anyway it is still on there. Many years later I added an addco to the rear, really didn't see much difference until I decided to get rid of the original rubber mounts and use whatever the hard plastic stuff is called on the front and rear bars. Glad I tried an autocross before getting to deep into a corner on a wet road. Couldn't keep the car straight got real tail happy. The addco is in the shop somewhere. If you want it, I'll sell it.
Click to expand...

You can adjust the rear somewhat using long springs that fit over the mounting bolts where it mounts to the rear spring plate. Use a longer bolt so that the spring is tensioned as you tighten the bolt instead of having the bolt snugged down all the way. Addco sells a kit to accomplish this on other cars so it's something I'm going to try.

btw- I enjoy a tailhappy car in autocross. If you get the feel of it, you can use it to your benefit in hairpins and the like by braking at the right time to stop the rear swing and point you straight into the exit of the corner. Worked on my little Formula F500 car anyway.
 
I say go for it, Bob. It's a fairly easy install, the only tricky bit is fishing those funky U-bolts through the frame. There are lots of things you can do after it is installed to tune the front/rear balance, like using hard bushings up front & soft in the rear. I believe Addco even offers end links with springs in them to cut way down on sway bar action (in an adjustable fashion).

I had Addco bars front & rear on my TR3A and felt that the rear bar was too strong using the supplied links. But with hard nylon bushings in the front, and rubber installed kind of loose in the rear, I felt it was a definite improvement over no rear bar at all; when on the street. On the autocross track, the rear bar didn't seem like an improvement at all; my best time at the VTR 2000 autox was with the rear bar disconnected.

Of course, the TR3 is narrower, and Addco supplies a narrower bar for the front (but the same bar as the TR4 for the rear), so you may have less of a problem with your TR4.
 
I liked the Addco bars on the front and the rear. If the "mix" doesn't work I can always replace the front factory style with the Addco I have.
Bob
 
I think a rear Addco and stock front bar will give you too much understeer.

On a related note, has anyone fitted the Addco bars from a TR6 to a TR4 or TR4A? The Addco bars for the TR6 are the same for the TR250, so I imagine they would work well on an IRS TR4A and possibly on a live axle TR4 or TR4A.
 
TRMark said:
I do not have experience with exactly that mix. Here is my experience. I put a front bar on my 63 TR4 about 40 years ago, I wanted to auto x. Went to the wrecking yard and took one off a wrecked small Buick, it is 13/16. Anyway it is still on there. Many years later I added an addco to the rear, really didn't see much difference until I decided to get rid of the original rubber mounts and use whatever the hard plastic stuff is called on the front and rear bars. Glad I tried an autocross before getting to deep into a corner on a wet road. Couldn't keep the car straight got real tail happy. The addco is in the shop somewhere. If you want it, I'll sell it.
Click to expand...


Mark - when you said "small buick" and 40 years ago; I assume you are referencing one of the early/mid 60's uni-body Buicks and/or Pontiacs of that era? Buick Special, Tempest, Lemans, etc?

thks -w
 
TR4A_IRS said:
I think a rear Addco and stock front bar will give you too much understeer.

On a related note, has anyone fitted the Addco bars from a TR6 to a TR4 or TR4A? The Addco bars for the TR6 are the same for the TR250, so I imagine they would work well on an IRS TR4A and possibly on a live axle TR4 or TR4A.
Click to expand...

My solid axle 4A has an Addco TR6 7/8" bar on the front attached to a TR6 radiator support. Rear is 5/8" spec'd for the 4A live axle. It's different than the TR4 because the frame is different.

Instead of using the Addco square u-bolts to mount the rear up throught bottom layer of the frame channel, I made up 1/8" steel plates tacked to the top of the frame channel and drilled holes through the plate all the way through the top and bottom frame channel to attach the bar. MUCH stronger and less prone to rip out the frame.
 
Mark - when you said "small buick" and 40 years ago; I assume you are referencing one of the early/mid 60's uni-body Buicks and/or Pontiacs of that era? Buick Special, Tempest, Lemans, etc?

thks -w [/quote]

Long time ago, but I think a Buick Special. I really should install a proper one designed for the car.
 
Regarding the TR6 Radiator Guard upgrade (ie - putting it on a TR4); what modifications need to be made to the TR6 rad guard in order for it to fit on the TR4?

my assumption is that it does not bolt directly to the TR4. from what I can tell it does not "bolt right up".

FYI - at this point I am in possession of a stock TR6 sway bar and a stock TR6 rad guard. ...and a bare TR4 frame.

thanks.
 
Willie_P said:
Regarding the TR6 Radiator Guard upgrade (ie - putting it on a TR4); what modifications need to be made to the TR6 rad guard in order for it to fit on the TR4?

my assumption is that it does not bolt directly to the TR4. from what I can tell it does not "bolt right up".

FYI - at this point I am in possession of a stock TR6 sway bar and a stock TR6 rad guard. ...and a bare TR4 frame.

thanks.
Click to expand...

...did a quick eyeball of it, looks as if I could slice the TR6 rad guard in the middle and take out the extra width (as the rad guard fits directly to a 4a, right?/wider) and then after rewelding the new/narrower tr6 rad guard "simply" slip on over the tr4 frame ends and bolt on...make sense?

...anyone want to poke a hole in my thought balloon?
 
I've recently come into possession of a TR6 front sway bar and was hoping to mount it to my 64 TR 4 as well. I don't have the rad guard, yet. Anybody successfully made this work?
 
on the last page somebody asked about running the addco front and rears on a TR250 or 6, my 250 has the addco front and rears, I have autocrossed it, it is cery well balanced, pretty darn neutral and very flat in the corners, I have bigger rubber too, 205/65s.

I had a solid axle 4A too, the solid axle cars are so much stiffer in the rear to start with my guess is the effect of front and rear bars would be different on a solid axle car.

But just a guess, no bars on the old 4A
 
@doughairfield:

Over the weekend, a friend of mine and myself did a cardboard mock up of the TR6 rad guard so as to fit BETWEEN the frame ends of the TR4 ('62 in my case).

this is accomplished by cutting about 4 inches out of the center of the rad guard and rewelding. it is mounted by 2-3 bolts per side drilled directly through the frame and secured with washers, etc. (at least that is my plan). this won't interfere then with the bumper outriggers.

here are the initial observations:

1) the overall front to back length of the rad guard is NOT long enough to extend outward to support the TR6 sway bar as it would on a TR4a or tr6.

1a) however, it does extend out far enough such that it's still a much more secure mounting for the TR6 sway bar than using the flimsy and (not extending at all OEM tr4 rad guard).

1b) basically, you'll still need to fabricate steel sheet stock outriggers that extend out from the tr6 rad guard to the sway bar.

2) my further justification for all of this is that you get much more rigidity from the tr6 rad guard in the frame end itself, plus it's robust enough to handle the thicker sway bar torsion AND you also get the luxury of the oil cooler mounting (which I want to run an oil cooler as I do like to drive long distance in my car).

3) there is still the very slight possibility I might fabricate a near replica as above from scratch ONLY the scratch-build rad guard would be longer such that the outriggers (as above) would not be needed to support the sway bar - however, the concern is that this scratch build model might extend out too far and thereby interfere with the body work.

3a) I did some measurements and it would be very close. (ie body interfering with scratch built/longer rad guard).
 
Guys - the TR6 radiator guard should mount right up on a TR4A. Have done that once, about to do it again.

Keep in mind you need the TR6 brackets for the lower A-arm as those don't come in any of the kits.
 
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