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View Full Version : TR2/3/3A When will the rear spring start to compress TR3



mallard
04-18-2011, 07:57 PM
I was wondering when the rear spring will start to compress so I can install the rear axle buffer. I did not install it before thinking it would be easy to install after I had the body on and all the other parts. I have a gap between the axle and the frame wide enough for a piece of paper. I even had someone weighing around 240 pounds standing in the trunk and the gap hardly changed. Could I have the wrong springs in the car? They looked just like my originals.

tdskip
04-18-2011, 09:57 PM
If the car is stripped of everything else it probably will take more than 240 pounds to do it Keith - that is only a slightly educated guess however.

vivdownunder
04-19-2011, 08:24 AM
Keith, check if you've been mistakenly supplied with later TR4 deep dish springs, designed to be used with a 3" lowering block.

They are shorter in length at 39.5" eye to eye, against 40.5" for TR3/early TR4 leaf springs.

Or perhaps you have been supplied with competition springs.

If you find you have the correct springs, you could disconnect to rear hangers and lift the diff housing to fit the bump stops.

On a fully weighted car, the bump stops sit about 1.25" - 1.5" above the frame.

Viv

Don Elliott
04-19-2011, 09:41 AM
After about 120,000 miles from new, the rear springs on my 1958 TR3A were resulting in the rear end of the TR to sag to the point that when I would drive over a bump, the axle would hit the frame. Then at 130,000 miles from new, the rear spring on the RHS broke. So I relaced them with new springs marked "Made in England", installed two new ones and right from that day, the height was correct - as the car had been when I bought it new in 1958. I never used to grease the old springs nad I think that is what caused every leaf to wear thinner - to the point when they sagged - then one broke.

I have driven 55,000 miles on these new springs - never greased them and they are still the correct height.

TR3driver
04-19-2011, 12:33 PM
Seems to be a common complaint with new TR3 rear springs. I haven't figured out if they are arched wrong, or the wrong rate, or both; but I've heard lots of similar complaints.

The stock springs should have only a slight curve when unloaded, they actually bend "backwards" when loaded. And adding 265 pounds should have increased the gap by about 1". I would pull them back off and compare to the dimensions in the manual.

Note that the springs are supposed to be painted with "old engine or rear axle" oil every 6,000 miles. I agree that neglecting their lubrication is what leads to broken leaves.

https://i258.photobucket.com/albums/hh260/TR3driver/TS13571L/DSCF0007_reduced.jpg

mallard
04-19-2011, 08:04 PM
It's hard to get a good measurement with the spring on the car but it looks like 40.5". How can you tell if it was a competition spring or not? I would guess buy the number of leafs. I think once I heard you could tell by the number of clamps. This one has six leafs, and four clamps.

TR3driver
04-19-2011, 08:37 PM
Stock springs had 6 leaves (not counting the little spacers on the passenger side), and 4 clamps. But I have no idea what the 'competition' springs have.

The ends of the leaves are also tapered on the original springs. Might be a trick of the light, but your bottom leaf looks like the end is cut off square?

Not real clear, but maybe you can see how they taper both in thickness and from side to side in this shot:

https://i258.photobucket.com/albums/hh260/TR3driver/TS39781LO/Rearswaybarendlinkreduced.jpg

vivdownunder
04-19-2011, 09:03 PM
Another thing, it's hard to tell from the pic, but do the leaves vary in thickness ?.

Original springs had a 7/32" main leaf, the next four leaves were 3/16" and the 6th leaf was 11/64".

If all your leaves are the same, that along with the non tapered ends could account for increased stiffness. If you have any way of checking, the original laden camber was 7/8" negative, static deflection was 4.04" and the spring rate was 515 lbs.

Viv.

mallard
04-19-2011, 10:00 PM
There is no taper on the ends of the leafs, and they are all the same thickness end to end. It looks like these maybe competition springs (arghhh).

bnw
04-20-2011, 06:11 AM
Stock springs had 6 leaves (not counting the little spacers on the passenger side), and 4 clamps. But I have no idea what the 'competition' springs have.

The ends of the leaves are also tapered on the original springs. Might be a trick of the light, but your bottom leaf looks like the end is cut off square?

Not real clear, but maybe you can see how they taper both in thickness and from side to side in this shot:

https://i258.photobucket.com/albums/hh260/TR3driver/TS39781LO/Rearswaybarendlinkreduced.jpg

LOVE THE HAY!

mgedit
04-20-2011, 08:24 AM
Not sure of the specs of the springs on my 56TR3, but here are a couple of pics that might help. 6 leaves and tapered.

https://i146.photobucket.com/albums/r268/mgedit/56TR3Spring.jpg

https://i146.photobucket.com/albums/r268/mgedit/6Leaves.jpg

Cheers, Mike

sp53
04-20-2011, 03:26 PM
Do you have an old set to compare with?

mallard
04-20-2011, 07:53 PM
Not any more I gave them away. My springs don't look like Randall's or Mikes, thanks for the pictures.

mallard
04-06-2012, 06:36 PM
Back to an old topic. I removed the the rear springs from the car because I determined they were competition springs. I have the original old set back and was thinking of having them re-arched. After 87000 miles they were starting to get weak. The factory manual has a nice diagram of the spring but does not show a measurement for the arch. Also it says the springs should have a center hole measurement eye to eye of 41" Mine is 40 1/2". Making the spring longer would result in compressing the spring even more. Does anybody have the arch measurement or what the height of the spring should be if measured from a flat surface to the top or bottom of the spring.

I know I could get new springs, but I second guess the quality.

TR3driver
04-06-2012, 09:34 PM
Actually there is a measurement for the "arch", except the book calls it "camber". The problem is that it (and all the other measurements) are to be taken with the spring loaded with 515 pounds. The "arch" measurement is taken from a line through the center of both eyes, to a line tangent to the top of the main leaf. The book gives 7/8" nominal.

I was talking to Steve Hedke the other day (who very successfully built and drove a TR3 in The Great Race a few years back, placing first in class); and he feels that re-arching doesn't last very long. He felt that new springs from Moss were the way to go (but added that he gets a discount as a Moss dealer).

mallard
04-07-2012, 09:52 AM
Thanks Randall I should have noticed the laden measurement on the spring. That would explain why my spring is shorter than the one in the specs. The springs I have for the car are in good condition without rust or cracks. One is about 3/8" taller than the other. I do not see any extra plates on the taller spring. Maybe they were not putting them on that early in production.

TR3driver
04-07-2012, 12:50 PM
Right, the extra spacer didn't come in until early 58. My TR3 didn't have it either (until I installed the springs from the 3A).

PS, I'm guessing that internal friction has a largish effect on free height. I'd try rechecking with some nominal load applied (like having someone stand on the spring). The real "proof of the pudding" is to measure corner weights with the car assembled; but I haven't gone that far yet.