Re-arching leaf springs

[Pete Haburt]

I just re-arched the left rear spring on my 61 BT7 3000, as it was sagging about 3/4" lower than the right side. When disassembled, with the main leaf on flat table/ curve up, there was 4" from table to top edge of leaf. I re-arched main leaf to 5 3/4", then re-arched three supporting leafs to match the main. This was done on a rolling machine at my work's shop. The car now sits nice and level, with about 2 finger widths between tire and fender opening on both sides.
I intend on wrapping the exhaust pipes in that area with header insulating wrap, in an effort to keep the intense heat off the spring.
It will be interesting to see how long the re-arched spring retains it's current height.
Anyone have any experience or history with this?
Pete H.

 

[Dave Russell]

As a reference the generally accepted "standard" for big Healeys is 27" from ground to the fender openings. The BJ8 phase 2 is 28". In the real world people seem to set it at anything that strikes their fancy.

Spring manufacturers & some spring shops say that the only way to make a spring hold it's arch is to set it to the desired dimension & then re heat treat & temper.

Other shops feel that cold bending to desired arch will hold the new arch. The force required to cold bend the spring is much higher thay any road loads will be. I have found that cold bending seems to hold the arch for a few years if not longer. Maybe not for forty years though. I would say, do it any way you are comfortable with.

I doubt that exhaust heat will get the spring anywhere near hot enough to affect it. I think it would take at least 700 degrees F to bother it. Probably more like 900 to cause any problems.
D

 

[Bob Claffie]

I suspect the tailpipe wrap will do more harm than good. As mentioned above, the heat effect on the spring would be negligible but trapping rain water!!! or condensation inside the wrap would not be beneficial to the pipes. Bob

 

[aeronca65t]

I re-arched the rear leaf springs on my racing Spridget (cold). It's been a couple of years, and so far, so good....ride height has remained the same.

 

[Pete Haburt]

Thanks for all of your input. I think I'll save the money from the header wrap. Thanks for the reference dimensions Dave, I have 26 3/4" at the moment, but willing to bet the tires need some air from the looks of it.
The Healey is happy again. Now, if it would only dry up outside for a day or two!
Pete H

 

[Johnny]

<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by Dave Russell:
As a reference the generally accepted "standard" for big Healeys is 27" from ground to the fender openings.
D<hr></blockquote>

Just went out and measured my 60' BN7 and found the left side rear at 25.5", right 26.25." Since I installed new, from MOSS, rear springs is there a problem here? The tires, on new wheels also, seem to fill the wheel well just fine. I can see the top of the tires when viewed from the side.
What do you think? Would having the new springs arched be worth the effort?
Thanks for replying.

 

[Dave Russell]

Hi Johnny,
There is a pretty good discussion here;
https://www.team.net/html_arc/healeys/200309/msg00643.html

I don't know if it would be worth the effort. The considerations would be - Does the car look straight side to side? Does it look level front to back. It's really hard to tell what is out of level. These cars were basically hand made & there is quite a variation of parts & their mounting. Eg. the chassis could be level but the fenders (wings) are not all mounted at the optimum heights. The fenders may not have the same dimensions. The bumpers may not be level with the chassis or with the body. There is some adjustment in the bumper bars to frame mounts for up & down.

I guess that I would do a few more measurments to determine exactly what is not the same. Measure from axle to frame on both sides. Measure from level ground to bumpers. Measure all four wheel wells to ground. Measure front frame to ground for level. After all of this, if the car looks straight & level to you, the one inch lower than normal should not really be a problem. If the car looks level side to side & is not obviously dragging it's tail don't bother it.

Be aware that the front springs have an effect on the side to side level of the rear also.

On my car, I changed rear spring arches three times, lowered one side on the front, & moved the bumpers up & down several times before I had the desired car appearance & suspension travel. Probably not needed unless a person just wants it perfect.

The only other consideration that I can think of would be that the "new" springs may continue to take a set & change some more as you put miles on the car.
D

[ 02-11-2004: Message edited by: Dave Russell ]</p>

 

[Jim Weatherford]

Bob Claffie said it pretty well, I do know that heat wrap around a new set of headers on my Cobra brought a grown man to cry in about 16 months.

I had to write a check for the new set of headers to replace the rusted out set caused by the heat wraps. When I replaced them I ceramic coated the new headers and as far as I know they are doing just fine.

 

[littlecars]

I was just reading through this thread and was surprised that nobody mentioned the fact that people sitting in the car will change how it sits, as well as how the springs will change. If frequently driven with just the driver that spring will sag sooner than the other, the weight of the passengers will also have some impact on this as well. I personally haven't seen my car on all four wheels in so long that I can't remember how it sits. Got to get taxes done so I can get back to work on it. Cheers

 

[Randy Forbes]

<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by Jim Weatherford:
I do know that heat wrap around a new set of headers on my Cobra brought a grown man to cry in about 16 months. <hr></blockquote>

At WOT, that number can be as low as sixteen hours (of actual run time)!

The people that sell that "crap" should have the decency to tell their customers about the pitfalls. This has been known information in the circle/dirt track arena for about ten years.

One week ago today, I sent the headers for my Healey to Jet Hot for metallic-ceramic thermal barrier coating. I've been out of town this whole week so I'm hopeful that they'll be returned in time for reinstallation the weekend after this. A far better solution in the effort to maintain higher velocity gas flow through the header (primary & design purpose) with the added benefit being reduced underhood temperature, corrosion protection and least of all, better appearance. And why do we want higher gas velocity in the header? For improved scavenging of spent gasses in the combustion chamber to assist the incoming fuel/air charge in the cylinder filling for the next power stroke! Exhaust gas velocity will slow down as the gasses cool.

 

[Johnny]

<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by Dave Russell:

I don't know if it would be worth the effort. The considerations would be - Does the car look straight side to side? Does it look level front to back. It's really hard to tell what is out of level. These cars were basically hand made & there is quite a variation of parts & their mounting. Eg. the chassis could be level but the fenders (wings) are not all mounted at the optimum heights. The fenders may not have the same dimensions. The bumpers may not be level with the chassis or with the body. There is some adjustment in the bumper bars to frame mounts for up & down.
Be aware that the front springs have an effect on the side to side level of the rear also.
<hr></blockquote>
Points well taken. I think I'll leave it alone for awhile and check after I put a few miles on it. BTW the springs in the front are also new, and if memory serves were slightly off when measured on the work bench. Thanks for responding.