checking rear end housing straightness

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Rapid Robert

Rapid Robert

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7&1/4 in the stock car that wrecked (came down on another car). I want to add some 4:10's but I will get another one to work with if this one is bad. how do I check the housing for straightness? Your thoughts please. thank you for your time. RR
 
If the axle is out of the vehicle, put it on a pair of jack stands on a level garage floor. Mark the tubes at three evenly spaced intervals and measure at from the bottom of the tubes to the floor. Use another jack stand to hold the center section at the pinion and rotate the center section 90 degrees and repeat. If you need a slightly heavier duty replacement with much better parts availability, find a 7.5 inch axle out of a ford ranger.
 
OK so I measure the tubes 3 intervals on each side ? with the pinion nose down toward the floor then raise it 90 degrees to horizontle & repeat?
 
As man, ford guys don't even recommend a 7.5" rear axle to their enemies. LOL

They are pretty delicate.
 
413 said:
As man, ford guys don't even recommend a 7.5" rear axle to their enemies. LOL

They are pretty delicate.
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Like the 7-1/4, the spiders are the weak link. But, being a dirt circle track car, use a mini spool in it, and 4.56 gears are available. I can't imagine it being weaker than the 7-1/4 axle with welded spiders...
 
with the axels and the sg pin out run a STRAIGHT bar in one side through the center and out the other tube then see how far off each tube is off , if your axels will go in or out easily it's probally good enough .
 
If your reared is complete and out it is very easy. Put tires on it and run a tape measure across the tread ( like checking toe ) rotate the housing 1 complete turn and watch your tape. Best if you have a helper. You may have to put the tires on top of blocks for clearance of pinion, brake lines and so forth. This is how we did all our rearends, even welding on the housing can warp it.
 
excellent info/help & very much appreciated. I know what I need to do now. I do have some 4:11 gears. where do I source a mini spool? We did go with welded spiders & no issue but I'd like to be proactive. RR
 
Oh I misunderstood I was thinking that there was one for the 7&1/4. You were talking I'm assuming about the Furd one. I will weld the hell out of the spiders. Garrett you have enlightened me tremendously on this issue & I very much appreciate your time/help. RR
 
Rapid Robert said:
Oh I misunderstood I was thinking that there was one for the 7&1/4. You were talking I'm assuming about the Furd one. I will weld the hell out of the spiders. Garrett you have enlightened me tremendously on this issue & I very much appreciate your time/help. RR
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Lincoln Locker. You got it, buddy.
 
actually I Googled it & it came up with some good utube vids on prepping the spiders before you weld em, mainly getting em clean/dry. RR
 
I measured the height of the tube & on (on side of the pumpkin) 3 measurements along that length were equal but on the other side the measurement at the outer end (near the perch) was 1/8" off and I pullled both axles & one went back in easily but the other one needed some tapping. is it time to source another one? RR
 
For a roundy-pounder, I'd run it.... and keep an eye on the axle bearing on the bent side.
Needing "some" tapping is not a deal breaker for me, in your situation.


A ten pound sledge and a swing, would be a different answer.
 
Honestly I would direct the energy to finding a stronger rear end like an 8 3/4 . By the time you verify straitness and buy gears/ pay for the to be set up you are 3/4 the way to an 8.75 . Since you want 4.10s I have to assume you are making some power and plan on using that power .
I recommend 8.75 because both housings and pumpkins are readily available ad you won’t have to pay to get the gears set up if you buy a functional pumpkin . A good ford explorer rear end would work as well but I am not sure about gear availability.
 
you can measure all you want the ONLY way to know what you have is to read post 7 and follow what is said . that's how it is done .
 
excellent info. Actually I have an 8&3/4 and a 5:57 pumpkin (probably deeper than I need) with welded spiders but the dr diff axles will not go in all the way. still haven't figured out what is wrong there.
 
Rapid Robert said:
excellent info. Actually I have an 8&3/4 and a 5:57 pumpkin (probably deeper than I need) with welded spiders but the dr diff axles will not go in all the way. still haven't figured out what is wrong there.
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Had the same problem with Dr. Diff axles, took a triangle file to splines to remove any burrs, then they slid right in.
 
Rapid Robert said:
excellent info. Actually I have an 8&3/4 and a 5:57 pumpkin (probably deeper than I need) with welded spiders but the dr diff axles will not go in all the way. still haven't figured out what is wrong there.
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I have a gaging tool for an 8-3/4. Consists of 2 bushings to be clamped into bearing saddles of the carrier along with tubing extending to both ends of the housing. From there use calipers to figure centeredness of the axles relative to housing ends. You can make this stuff easily using a local machine shop.

scan0009A.jpg
 
Rapid Robert said:
I measured the height of the tube & on (on side of the pumpkin) 3 measurements along that length were equal but on the other side the measurement at the outer end (near the perch) was 1/8" off and I pullled both axles & one went back in easily but the other one needed some tapping. is it time to source another one? RR
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Is the rear end in the car? Is the rear end locked? If you answer these two questions I can explain which method to use to check the rear end for straightness.
 
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