Jaguar XKE Tech Tips
Many of following tech tips were compiled from the member's of e-type Digest from jag-lovers.org. There are no implied guarantees. These suggestions are from other XKE owners on how they solved similar problems or challenges and may illustrate varied and occasionally contradictory conclusions to the same problem. Please forward any questions, comments, criticisms, or suggestions firstname.lastname@example.org. Commercial use is strictly prohibited. Ó Copyright 1998 by Mark Hicks. Legal Restrictions
Tires & Wheels
TIRE RUBBING - INCORRECTLY INSTALLED BUMPER STOP
There has been much discussion over the months as to whether the 205/70/15 tires will fit a Series 1 without rubbing the rear rubber bump stops. Some say they fit, others have removed their bump stops due to rubbing. Well my 205/70/15 Goodyear Comp T/A's fit my old '66 OTS, but the same tires didn't fit my new ' 66 OTS. Both cars had replacement bump stops. It turns out that the replacement bump stops I purchased from BAS have a 15 degree angle, and they have to be turned inward. Sure enough, I had them both turned inward on my old car, and I mistakenly had them turned outward on the other. A quick turn to the inside, and now the tires clear the bump stops on both cars. The 15 degree angle isn't noticeable unless you look for it. I suspect that all dealers supply the angled product, we just have to pay attention.
ARE YOUR TIRES TO OLD TO BE SAFE?
Always replace your tires every 5 years even if they look good. Rubber does not age well and hardens, dry-rots, cracks, and otherwise decomposes over time. A perfect looking tire can destroy itself at highway speeds. Don't Risk It!
To find out the age of your tires, look for the letters "DOT". On the end of the same line, you'll find three numbers, for example "417". This means that the tire was manufactured in the 41st week of the year '97. (Remark: Don't know how to tell "1987" from "1997" etc., but as far as I remember, it has something to do with the little sign which follows the three digits. On my '97 Dunlop tires, it reads like a < (small arrow/triangle, pointing to the left).
The "Offical" JCNA National Concours D'Elegance Rule Book lists the following as the correct tire size for E-Types:
I) XKE Series 1 3.8 & 4.2 -- 6.40x15
II) XKE Series 2 185 x15
III) XKE Series 3 E70x VR15 (205/70xVR15 -- under old system an "E"
Aspect ratio tire is a 185, but 205 is correct, as the industry standards changed in the 70's...only a 205 tire is correct. If you order tires and ask for an "E" ratio, they will try to order 185...thatís wrong, use only a "205")
The "Red line" tires are O.K. for Series II cars. However the "rule" book notes that 185 x 15 radials "did not come with a side aspect ratio molded into the tire. It was however a 75 side aspect ratio tire. The 75 aspect ration is no longer an industry standard. Use either a 70 or 78 aspect ratio. Goodrich and Michelin are sources.
The "book" also notes that "Wall or stripe/color is optional." On the other hand, if you aren't concerned with being perfectly "authentic" then try radials on the older models...you will "lower" the car slightly and as has been noted, get a misread from you speedometer. But, the car will probably handle much better.
WHAT KIND IS BETTER?
It is my belief that wider tires are better on dry roads, narrow on wet. I think that wide or narrow, a tire puts roughly the same number of square inches of rubber on the road. The important difference is the shape of the patch. Wide tire, wide patch, better lateral control for dry handling. Skinny tire, long patch, better traction for the wet.
Radial tires give it up all at once, bias tires lose grip a little at a time. This is why bias tires work in a drift: you have aural input to help you through the curve. Try Hoosiers or Mickey Thompson's if you want a
high-performance bias ply tire. Mickey Thompson Indy Profile's have been made in the same molds since 1966, so you have a modern tire with a vintage design.
New tire should have the same circumference as the old tire to avoid speedometer error. My favorite tire size calculator is at:
Most old-style tires were 75 or 80 profile. Don't assume that your new tires are new. Tires can sit on the shelf a long time waiting for a buyer, especially the specialty tires many of us use. In the United States, every tire has a Department of Transportation code, which looks something like: DOT DBUA A44 414 GCD 415. The last three digits are the date code. In this case, 415 means the 41st week of 1995. Don't pay for a new tire which has already spent half it's useful life in the back room!
Tubes suck, unless they are punctured, in which case, tubes blow!
Check your spare. A lot of us are carrying vintage spares, which would probably be worse than useless if you actually had to use them. Save the old spare for show, get something safe for the driver.
WIDER IS BETTER?
OK, I guess you want more rubber on the road. So do I. Here goes: I currently run 225/60 x 15's on the car. Not a problem. I want to get sticky high performance rubber, but no can do with a 60 or higher profile.
I'm not talking about really good tires, but ultimate tires. However a 50 profile makes the Jag a low rider. Does not fill the wheel well, looks gross. So, I ordered ONE wheel 7" wide. Now, this wheel is a 16" wheel, so it will look pretty close. You can fit a 45 profile 235, possibly 245 tire in there. Very tight fit. The wheel needs 1/4" offset exterior and 3/4" offset internally. Certainly a 6.5" x 15 wheel fits.
VARIOUS 2 CENTS ABOUT TIRE CHOICE
I'm assuming that 1 "atmosphere" = 14.7 lbs at sea level. Then 2.3 atmospheres = 33.81 pounds of pressure. I believe most of my car's service manuals say around 32 - 34 pounds for high speed driving so this sounds about right. Use the 14.7 number to convert to atmospheres.
TO SLIDE OR NOT TO SLIDE?
Recently I was conversing with a very knowledgeable Jaguar technician and professional race driver. He swears that the E-type with bias-ply tires will easily outhandle one fitted with modern radial tires. Furthermore, he says that the wider tires often recommended today actually hinder handling in the XKE. His opinion is based upon years of experience on the track and on the street and, while too complicated for me to follow, is rooted in the premise that the E-type was meant, for optimum speed around a curve, to slide through the curve. He points out that wide radial tires make the rear end stick in the curve which does
not allow the oversteering Jag to use its torque to push the car on through. I have done a pitiful job describing his elaborate explanations of the physics involved, but I must say that I was both impressed and confused. It goes against current belief.
The handling superiority of bias-ply tires re E-types has been cited in various articles and books, most notably in mags such as Classic Car & Automobile. At straight-out speed, though, I should think the radial tire would have a greater margin of safety. If Dunlop 6.40X15 bias tires were available at a reasonable price (Coker lists them for a king's ransom), I'd put them on in a minute. My car originally had the Dunlop bias-ply tires and handled much better on twisty roads than the Michelin Xs that replaced them.
Never use grease on your wheel splines. When heated the grease liquifies and proceeds to leak through the hub to your spokes coating them and collecting dirt. Instead use anti-seize compound, the same silver substance you use you your spark plugs. It won't liquify, won't make your wheels dirty and guarantees ease of removal in the future. A very small amount gets the job done.. Rule of thumb, about the time you think you've put on enough anti-seize, you've probably applied too much.
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