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Chassis Checking: With a new chassis one may be confident that it is straight and square. But mounting it on saw horses in the garage lead to an alarming discovery: It rocked as if warped. Before any further work could be done the chassis needed to be checked. This shows how that was done.
Chassis Strengthening: A number of points on the Healey may be strengthened. This shows additional bracing that may be added to the engine mount pedestals, the wishbone mounts, the rear shock mounts and the chassis rails below the axle.
Chassis Rustproofing: Given the effects of rust on the previous chassis I intend to preserve this one rather better. This shows the products to be used and their application.
Chassis Checking
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The tube is moved until the level of water in it just reaches the top of the saw horse- which is also the bottom of the chassis rail.
The other end of the tube (held by a pair of vise-grips under a brick- sophisticated high technology solutions to simple problems a speciality!) is then checked.
The first was then raised using "shims" of old carpet until the two matched exactly.
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With a new chassis one may be confident that it is straight and square. But mounting it on saw horses in the garage lead to an alarming discovery: It rocked as if warped. Well, all else before that seemed to go wrong.
But suspicion fell on another culprit: the garage floor. The saw horses too could be wonky, but I had more confidence in my building them than in my "professional" builder's ability to lay a floor flat. It could have been a quandary: the Healey manual gives all sorts of useful measurements for determining the straightness of a chassis, but it makes having a flat floor a pre-requisite. So here I am, with a suspect floor, sawhorses that I'm pretty sure of (and quickly measured floor to top surface for certainty), and a chassis that I wonder about....
The solution:
All I needed was to ensure that the tops of the saw horses were level. The chassis rested on them, so if it were warped that would show itself as a gap between a rail and the saw horse it should rest on.
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In this photo the sawhorse is a little high relative to the first. The sawhorses were the same height, so the floor sloped.
Rather than cut the sawhorse to match the slope it was easier (and more sensible) to raise the lower one to achieve a level base on which to set the chassis.
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A "bubble" level could be laid on a straight board between the saw horses and along them. I wasn't confident in the accuracy of such a crude measure. It might look level but considering all the niceties of suspension performance I could see a lot of hard work and a considerable investment compromised by a "bubble". Thus an absolutely accurate approach was required.
The no cost solution! (A Healey FIRST) I had a dehumidifier. It used a length of clear plastic tubing to drain. That tube could be taken off and into its 20 foot length have sufficient water poured to fill up 15 feet. One end could be tied so that the tube laid against one saw horse's top. The other end could be moved across to the other saw horse and raised until the level of water in the tube was just even with the top of that saw horse.
If the sawhorses's tops were on a level then the water in the tube would match them.
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If the water were level with only one, the saw horse would need to be raised, or lowered to bring the two water levels even with the sawhorse tops.
Simple... Cheap... Absolutely and always accurate.
Now knowing that the surface on which the chassis rests is itself level the chassis may be checked for straightness, squareness and warp.
More importantly, ANYONE can use this method for their Healey too. Attach one tube end so that the level is "fixed" at the datum point you wish to measure against. Then the other end may be moved where necessary and the water level used to judge the difference +/- relative to the original datum (check them simultaneously!). A ruler can then provide a "fine" measurement.
Chassis Strengthening
This section will discuss the various modifications made to the chassis to strengthen it. These include reinforcing the wishbone mounts, motor mounts, and the rear shock mounts.
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Wishbone mount reinforcements
Bending one to fit.
Left reinforcements for rear wishbone and engine mount tower.
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Wishbone Mounts
The wishbone mounts were reinforced following the guidelines at:
www.team.net/www/healey/tech/big_hly/chassis/chassis_strgth.html
and the appropriately shaped gussets fabricated from 2 mm thick mild steel, and welded into place. The first step was to measure and cut paper patterns and fit them to the spaces to be reinforced. The steel was then cut to the pattern and bent or folded as required. The braces were then ground and trimmed to a close final fit for a neat placement. They were then welded into place, and the welds ground to present a smooth appearance.
These were put in before any of the inner body panels were mounted to take full advantage of the ready access available.
Engine Mounts
The engine mounts were also reinforced following the guidelines at the site noted above with the gussets fabricated from 2 mm thick mild steel, and welded into place. The basic procedure was the same as for the wishbone reinforcements, though the limited clearance forward of the engine mount towers meant the braces used in that area had shorter bases than the rear ones. These may be seen in the photographs.
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Shock mount reinforcements, the one closest has since had to be reduced in width to allow enough clearence for the inner body panels.
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Rear Shock Mounts
The old shock mounts at the rear showed signs of stress and cracks along the chassis rail. To help keep these vertical and rigid triangular reinforcing pieces were fabricated from 3 mm thick mild steel and welded in place. Paper patterns were cut, and closely fit to the area to be reinforced. The steel was cut to pattern and then the fitting required minor machining to allow for the chassis rail ridges and weld beads on the original brackets.
Note: the bracing originally intended has had to be modified. When the rear panel was trial fit to the chassis this brace interferred with it. So, rather than extend the full width of the chassis rail it was cut back to the middle.
The tubular shock conversion for the rear was also reputed to impose additional loads on the shock brackets. This made the reinforcements even more desirable, and discussions with others lead me to seek additional bracing for them. One idea was taken from the "nasty boys" site where a home made shock conversion used similar mounts with a brace. (ntahc.org/modifiedhealeys/Technical/RearTower1.JPG) The basic idea being that upward pressure on the two brackets would then be transmitted through that brace and the shock mounts would not be subjected to so severe a sideways strain. This brace and its fitment are also shown in the photos.
Rear Chassis Rails
The site also suggested that the tops of the rear chassis rails beneath the axle be reinforced too. Rally cars needed this to strengthen and protect the rails from damage in rough terrain. This was one modificiation that didn't seem entirely applicable. Its simple enough- just a plate fit to the tops of the chassis rails beneath the axle running the length of that flat section
Additional bracing for tubular shocks:
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Chassis Rustproofing
The susceptibility of the Healey to rust is too great to be ignored and any restoration effort should attempt to remedy those problems and forestall any future difficulties. Certainly starting with a new chassis is a major benefit, but even in this case the chassis had sat idle for some years previously developing a modest rash of surface rust to remove. This section discusses the various things done to remove the surface rust and treat the exterior chassis with a rust-resistant coating prior to it priming and painting, and the efforts then made to treat the internal surfaces of the outriggers and main rails to prevent problems in those unseen areas. Most of this work was done after the chassis strengthening had been completed, but if there were areas that were being sealed off they were rust proofed first.
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The sand blasted chassis:
and the scuttle:
both in POR-15 anti-rust primer.
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Surface rust treatment
I had considered doing this all manually and had outlined the whole process: 1) strip the chassis of its existing primer, Once that was done the extent of the surface rust could be seen and dealt with, 2) heavier spots of surface rust would then be mechanically removed using both composition and twisted wire wheels, 3) then the chassis would be phosphate treated using Metal-Ready and the chassis washed with hot soapy water and dried. Once all that was done it would be primed with two coats of POR-15.
As it happened I decided to have the chassis sandblasted to removed the light rust and to provide a better base for the primer that would then be immediately applied. The chassis was sent (along with the inner body panels and a few other parts) In October, 2004 with a desire to have everything returned by or before Christmas. This turned out to be overly optimistic and the Chassis was returned only in late April, 2005 and some components remain even now (early July, 2005) and I hope to have it all by the end of the month....
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Internal Rust Treatment
The surface rust treatment was relatively straight-forward since the whole area was accessible. The interior surfaces of the chassis were not. I was reluctant to use the phosphating method for rust removal. There were two reasons: first, the acidic solution could not be cleaned from the inside surfaces and some concern about its long term effects existed, and secondly, it might be difficult to ensure an even, effective coverage of the top and sides with such a thin solution. For this reason a rust converter was used for the open outriggers- it would still leave the concerns with evenness of coverage, but its longer term impact was neutral. Once the treatment had dried, then Waxyoil or Dinitrol would be sprayed into all of the cavities to be protected. Each of the closed box sections will have a small access hole drilled to allowed rust preventative fluid to be injected, and then plugged. A heavy coating is to periodically applied. With the new chassis the amount of rust will be minimal.
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