Changing leaf springs, potential issues/ driveshaft angle? - Vintage Mustang Forums
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post #1 of 11 (permalink) Old 06-22-2019, 09:16 AM Thread Starter
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Changing leaf springs, potential issues/ driveshaft angle?

Hello everyone,
I recently got my 1970 Mustang (has a T5, might be relevant) back together after fixing rust, rebuilding the front suspension, installing a 4 barrel carb, and a few other things. It's driving great, but the original rear leaf springs are soft and sagging so my next project will be installing the Eaton 138# 2" lowering springs I have.

I'm leaving on a road trip next Friday morning, and I'll be working Monday to Thursday until then, so I just have this weekend if I want to change the leaf springs before the road trip. I think it would be good to change them if I can, I'm concerned about scraping over bumps with three people and a bunch of luggage in the car. However, I'm nervous that I might run into an issue such as the change in driveshaft angle leading to vibrations. If that happens I probably wouldn't have time to sort it out before the trip.

Realistically, if I go under there and just slap on some new leaf springs (which I think will raise the rear of the car a little) what are the odds that it will cause some kind of problem?
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post #2 of 11 (permalink) Old 06-22-2019, 09:35 AM
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As long as it really raises the car, you shouldn't have any problems. If there is anything to worry about it would be with the T5 install depending on how on the edge you are with the drive shaft angle. If you have driven the car with three adults with the old springs and didn't have issues, you should be golden. If you are exposing the system to new steeper angles than the system has experienced before, you could have an issue. The bigger issue will be getting the front bolts out of the old springs. Expect a hassle and the use of destructive tools to solve that one once you get tired of trying wrenches...


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post #3 of 11 (permalink) Old 06-22-2019, 11:08 AM
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Removing the bolts can be a big hassle and turn a simple afternoon project into a 2 day project. If you want to do it start soaking the bolts immediately with good penetration oil. If you start the project have a air hammer ready and a sawzall or a >5'' grinder. Worst case you have to cut the bolt which is no fun and takes some time.



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post #4 of 11 (permalink) Old 06-22-2019, 01:46 PM
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Being you're i the rust belt, expect the worst. I had a couple cars that I had to cut the spring away from the front eye, cut the eye in half and peel that away, then cut the shell and burn out the rubber bushing and finally the inner sleeve and the bolt. Having an oxy-acetylene torch makes short work of this, but it can be accomplished also with a 4 1/2" angle grinder and a handful of cutting discs.

IMO, partaking upon a major project prior to a trip is asking for trouble. Better to do the repair and verify everything is good without 3 other people in the car.
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post #5 of 11 (permalink) Old 06-23-2019, 09:35 AM Thread Starter
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I actually had no trouble getting the front bolts off! This is a Texas car so that helps. Unfortunately now I'm stuck trying to find replacement U bolts, the ones Eaton sent are too narrow.
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post #6 of 11 (permalink) Old 06-23-2019, 10:54 AM
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What rear axle do you have? Or what is the diameter of the tube?


You are a lucky man the front bolts come off easily.
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1966 Convertible (Plant: San Jose, CA)
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post #7 of 11 (permalink) Old 06-23-2019, 11:39 AM Thread Starter
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I have an 8 inch rear axle. I need U bolts with 2 and 7/8" inside width. Eaton sent ones that seem to measure about 2 and 5/16". Given the high cost of the Eaton parts, combined with the surprising difficulty of acquiring a correct U bolt locally, this has really soured my experience with Eaton.

But yeah at least the front bolts came off. I used "easily" a little liberally, they were quite tight, but it was nothing a hydraulic floor jack underneath a breaker bar couldn't handle!
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post #8 of 11 (permalink) Old 06-23-2019, 11:51 AM
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You should be able to get the correct U bolts at almost any car parts dealer. An 8 inch rear axle is nothing out of this world.



Good luck



1966 Convertible (Plant: San Jose, CA)
289 2V, PS, AC
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post #9 of 11 (permalink) Old 06-23-2019, 11:56 AM
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Id think any NAPA store would have the U bolts you need. If it turns out you cant find them at an auto parts store, look for a truck spring shop in your area.

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post #10 of 11 (permalink) Old 06-23-2019, 12:18 PM
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Quote:
Originally Posted by Feethurt View Post
..., the ones Eaton sent are too narrow.
Didnt see this in the other thread. It makes me wonder if your rear has been changed. All the ones i tried from the parts stores where a few hairs too wide. Also none will have flattened parts to be correct.

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post #11 of 11 (permalink) Old 06-23-2019, 01:40 PM Thread Starter
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I don't care about "correctness," if it works it works. Do the flats have any functional impact? My old U bolts are 2 and 7/8" wide, which from what I can tell is what all 1970 Mustangs used?
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