Rear End Upgrade Advice for 1983 Mustang GT

EBW83

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Jul 10, 2017
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I am considering a moderate upgrade to my 3.08 7.5” Traction-Lok rear end. My initial thought was to “simply” swap out the gear set (to 3.55 or 3.73) but there are other considerations:
  • This rear end is original and has around 230k miles on it. I’d bet that there are other items which should be serviced such as the Traction-Lok clutches and bearings and/or bearing seals. Currently, this rear end seems to be working fine and doesn't leak but I have put more HP to the rear end with some engine performance upgrades.
  • Experience level required. I have the 1983 Ford shop manual set which has detailed instructions but have limited experience doing something like this. There are a number of specialty tools (dial indicator, pinion depth gauge, shims, gauge blocks and depth tools) and calibrations (bearing preload, ring gear backlash, ring gear runout) required. I was hoping to get a high-level recommendation of the job and then assess whether or not I should tackle it myself.
  • Can this be done without removing the rear end? It looks like the gear set swap out could be done without removing the housing assembly from the car. I’d be doing this using jacks and jack stands while laying on my back.
  • Availability of 7.5” rebuild parts and/or kits (carrier, bearings, seals, etc.).
Any insight or advice is appreciated.
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John Dirks Jr

there is enough sticking out to grab on to
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I think for the time, effort and money involved in rebuilding the 7.5 including new gears and all, your better bet would be to swap out the 7.5 for an 8.8 out of a later year foxbody. With a little patience you can find one with the gears you want. Then just swap the whole rear end.
 
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revhead347

Just rub Vaseline all over
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You can do gear swaps with marking compound instead of special tools. It just takes longer; it's more of a trial and effort process. If you have a factory engine, or near factory power, and you aren't running sticky tires, the 7.5" rear end will probably be fine. If you intend to do anything with the car power wise, I would go ahead and upgrade to an 8.8" rear end. Last I checked, MPS sold a Fox 8.8" for about $250, and an SN 8.8" (5 lug with disk brakes) for about $550. It really depends on how far you want to go with the car.

Kurt
 

rgsauger

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You can also pull the diff and take it to a shop that does gears. Very simple to set up on a bench. Will not be much $.

Or check eBay and Craig's for a differential with your desired gears and limited slip already.
 

EBW83

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Jul 10, 2017
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Thanks guys for the inputs. I have upped the rear wheel HP by 80-90 and have wider, stickier tires on it. It seems I've outgrown the 7.5" so I will pursue the 8.8" rear end option. This also gives me a good excuse to replace the rear end control arm bushings.
 
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