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Cost of Cutting Down an American Rear

RAC68

Darth Vader
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Hi All,

A friend is finishing his BJ8 and has always wanted to use it as a highway cruiser (travel back and forth down the Shore). He has installed a 3.54 rear but believes a lower ratio (i.e. 3.12 or so) would be better for his objective. Since there is very limited ring & Pinion choices for a Healey rear (3.54 being the lowest), I have noticed that some of those Healey owners choosing to install a V8 conversion have also installed a cut down rear from the same manufacturer of the engine with a more consistent rear with added features.

So:
What Would It Cost to Cut Down an American REAR for Installation in a Healey?

Thanks All,
Ray(64BJ8P1)

 
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I think the cost would be all over the place, depending on what rear-end you select, where the work gets done--California is gonna cost more than Ohio--and who does it. I do know the rear-end of choice is usually a 'Ford 9-inch.' I think they were used on pretty much every rear-drive Ford in the last century and are favored for strength and easy 'swappability.' Here's one off-the-shelf, and I'd bet this outfit would do a custom width for the right, er, 'encouragement:'

https://www.speedwaymotors.com/Spee...MIgtGEkbiA2wIVj6_sCh1pfgq5EAQYASABEgJQwvD_BwE

Also:

https://www.hotrod.com/articles/9-inch-ford-rearend-strongest-rearend-due-hypoid-distance/

I'll add that the Austin rear-end is similar in that third members can be swapped in and out just about as easily.

Now that I've (sorta) answered the question, I gotta ask why he doesn't just convert to a 28% OD, and save some of his acceleration? Also, changing the OD would not require speedometer conversion or, at least, a ratio adapter.

 

HealeyRick

Yoda
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In addition to narrowing the rear end housing, the axles will have to be shortened and splined if he wants to continue to use his wire wheel hubs. Then the spring brackets and shock brackets will have to be welded on and add on either a new rear driveshaft flange or new driveshaft fabricated. OTOH, it's a good time to do a rear disc brake conversion if you buy a rear already set up for them.
 

maxwedge5281

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i have been quoted 2600 dollars for a 8.8 rear end with disk brakes and with posi and proper spline axles...best shop in our area for this. that would include a new carrier with gears of choice. i prefer an automatic transmission so i have a built four speed aod 200 4r transmission. the fourth gear is overdrive and gives me good cruising rpms on the interstate even with 3.90 rear gear. i also have a lockup converter that reduces rpms in overdrive by almost 500 rpms over non lockup in overdrive gear. it also gives me much more foot room without a clutch pedal.
 
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Another consideration is whether the engine will "pull" the car when not at highway speeds including being able to accelerate at a reasonable rate.
 
Last edited:

Bob McElwee

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When i put a Toyota 5 speed (W55 i think and i have no idea where the paperwork is now) i was doing close to 80 mph at 3K rpm with a 3.54 rear end. Seeing as most of the time i was doing 75 mph on the interstate it was just right for me. Still had plenty of grunt in the lower gears also.
 

Patrick67BJ8

Darth Vader
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I think the cost would be all over the place, depending on what rear-end you select, where the work gets done--California is gonna cost more than Ohio--and who does it. I do know the rear-end of choice is usually a 'Ford 9-inch.' I think they were used on pretty much every rear-drive Ford in the last century and are favored for strength and easy 'swappability.' Here's one off-the-shelf, and I'd bet this outfit would do a custom width for the right, er, 'encouragement:'

https://www.speedwaymotors.com/Spee...MIgtGEkbiA2wIVj6_sCh1pfgq5EAQYASABEgJQwvD_BwE

Also:

https://www.hotrod.com/articles/9-inch-ford-rearend-strongest-rearend-due-hypoid-distance/

I'll add that the Austin rear-end is similar in that third members can be swapped in and out just about as easily.

Now that I've (sorta) answered the question, I gotta ask why he doesn't just convert to a 28% OD, and save some of his acceleration? Also, changing the OD would not require speedometer conversion or, at least, a ratio adapter.

I have a BJ8 with stock engine, Toyota 5-Speed with the 28% 5th gear ratio and a 3:54 rear end ratio. IMO, unless a V8 is installed it’s a very good combination. Anything with a higher gear ratio would affect acceleration. As an option, how about a 6 Speed Tremec transmission?
 
OP
RAC68

RAC68

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Thanks All for your responses and suggestions.

The engine was rebuilt and well oiled after installing that and the Toyota 5 Speed and sitting for the next 10 years without ever starting. As mentioned, he has a 3.54 and I would be very happy with a 3K RPMs @ 80 MPH as Bob Mc indicated but he had been talking about a lower rear and something less then 2.5K. As far as weak acceleration, apposed to my occasionally aggressive shifting at 5K RPMs, I don't think he ever shifted his Healey past 3K.

Again, thank you All for your responses,
Ray(64BJ8P1)
 
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Unless your friend is going to attempt a Land Speed Record or one of those 24 Hr runs on a closed circuit I would not recommend he put in a different rear axle to get a numerically lower differential ratio. I would bet that any rear axle he is considering would add weight and bog down the car's acceleration even further. Of course, one of the nice things about owning a Healey is that one can do whatever he wants to it....
 

steveg

Yoda
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Thanks All for your responses and suggestions.

The engine was rebuilt and well oiled after installing that and the Toyota 5 Speed and sitting for the next 10 years without ever starting. As mentioned, he has a 3.54 and I would be very happy with a 3K RPMs @ 80 MPH as Bob Mc indicated but he had been talking about a lower rear and something less then 2.5K. As far as weak acceleration, apposed to my occasionally aggressive shifting at 5K RPMs, I don't think he ever shifted his Healey past 3K.

Again, thank you All for your responses,
Ray(64BJ8P1)

Has your friend been driving his Healey at all? Sounds like he's considering this option theoretically, rather than practically. Driving the 3.54 with a Supra 5-speed or 28% OD is pretty sweet.

He'd lose the BJ8 radius arms as well. Plus it looks like the Ford axle is beefier (heavier) so his handling and ride might suffer.

Looks like a couple grand easy.
 

HealeyRick

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Has your friend been driving his Healey at all? Sounds like he's considering this option theoretically, rather than practically. Driving the 3.54 with a Supra 5-speed or 28% OD is pretty sweet.

He'd lose the BJ8 radius arms as well. Plus it looks like the Ford axle is beefier (heavier) so his handling and ride might suffer.

Looks like a couple grand easy.

I have to agree with Steve, Seems like a solution in search of a problem that doesn't exist. I think there's a real risk of undergearing the car with a 3.12. Not only in terms of acceleration but in grade climbing. My 5th speed is .063 with a 3.54 rear and even with 350 hp and plenty of torque climbing a steep grade or passing is going to be better with a downshift to 4th.
 
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RAC68

RAC68

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Hi All and thank you for your responses.

My friend has a number of Healeys, XKEs, and other British cars and did mechanical work on British cars makes for a small number of customers and is quite knowledgeable. Although all of his cars are in some stage of resurrection, he has finished a small number for sale and now, at his advanced age, wants to complete his favored Healey BJ8 Phase 2 as his Down the Shore Cruiser (highway driving). A friend for the past 35 years, he differs from my occasional brisk 5K RPM shifting in that I don't think he has ever shifted any of his cars past 3K RPMs.


Steve, although I thought he had not experienced his 3.54 rear and it was installed along with rebuilding the engine and installed a Toyota 5 speed, in fact he actually experienced the 3.54 rear for some time in combination with his original trans/OD and expects it will be similar with the 5-speed. As far as having slow acceleration, he feels he can always drop down a gear with the 5 speed if extra get-up-and-go becomes necessary. However, since there is no higher rear for the Healey to experience, he is drawing his thoughts on an understanding of how a high rear worked in the non-US version of the XKE phase 1. He feels the Healey's engine can handle a higher (then 3.54) rear, and as Steve suggested, theoretically but without any verification.

Again, thanks to all for your input,
Ray(64BJ8P1)
 
Last edited:
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