Fox Need Advice On 3.73 Gear Installation

cdurbin · Aug 15, 2014

My 91 vert has a 98 GT rear end setup used during the 5 lug conversion. It currently has the stock 3.27 gears. I would like to install some 3.73's to wake this thing up a bit. LMR has the full Ford Racing kit for around $260. My question is this: Is this something I should pay a shop to do or is it something I can do myself? I've got excellent mechanical sense and have done a lot of wrenching on this car but I've never attempted gears. I've read mixed reviews on attempting this. Just looking for some input from the experts.
I don't want to bite off more than I can handle and jack something up. Thanks in advance.

Noobz347 · Aug 15, 2014

If you're asking the question then I would suggest that you have a shop do it. Not because it's particularly hard but because you do not possess the tools necessary to do it yourself.

My suggestion would be this:
Find a shop that can do it and will allow you to watch/help. Then you will know exactly what you need and how to do it for the next go around.

In the meantime, you can search up some youtube vids on gear swaps to see what I mean.

mikestang63 · Aug 15, 2014

This job requires patience, attention to detail, some special tools. It is not something to tackle unless you are confident that you can do the job correct. Even experienced mechanics mess this up. There are many videos online that will show you how to do it.

As Noobz said, if you are unsure, best to ask around locally who has done this numerous times and done it right. The cost is going to be anywhere from 300 -500 depending on where you are. LMRS sells the same kit and you get a stangnet discount. I would highly recommend using the kit with the upgraded gt500 bearing.

84Ttop · Aug 15, 2014

Agreed with the others. This is more than likely a job that you should not tackle without all of the special tools required. 300$ for the install is the going rate in our area and using all new parts, the setup is guaranteed.

cdurbin · Aug 15, 2014

Thanks for the info guys.
Taking it to a shop was the direction I was leaning anyway.
I just wanted to get confirmation that I would not be wasting money.

hoopty5.0 · Aug 15, 2014

cdurbin said:
Thanks for the info guys.
Taking it to a shop was the direction I was leaning anyway.
I just wanted to get confirmation that I would not be wasting money.

If it helps any, LMR has install videos, gear installation included. I watched it myself the other day actually. I'd watch it, make your decision based on that video. I have some whining ass 4.10s that I can't wait to replace when funds allow.

revhead347 · Aug 15, 2014

I am an ASE certified technician with years of experience, and I don't mess with gear changes on any car but my own. It requires special tools and know how. The gears have to be shimmed and adjusted just right. When a car comes in for a gear change, I pull the axle and truck it down to the gear shop.

However, I do specialize in transmission rebuilds. There is something you need to know about doing a 3.73:1 gear swap. The stock 91' cars come with an 8 tooth drive gear for the speedo, which requires a 23 tooth driven gear. The 23 tooth gear is an aftermarket bandaid, and doesn't work well. Usually that driven gear comes apart within a month dropping shards of plastic in your tailhousing. the correct fix is to pull the tailsection and install a 7 tooth/21 tooth combo.

Kurt

cdurbin · Aug 15, 2014

revhead347 said:
I am an ASE certified technician with years of experience, and I don't mess with gear changes on any car but my own. It requires special tools and know how. The gears have to be shimmed and adjusted just right. When a car comes in for a gear change, I pull the axle and truck it down to the gear shop.

However, I do specialize in transmission rebuilds. There is something you need to know about doing a 3.73:1 gear swap. The stock 91' cars come with an 8 tooth drive gear for the speedo, which requires a 23 tooth driven gear. The 23 tooth gear is an aftermarket bandaid, and doesn't work well. Usually that driven gear comes apart within a month dropping shards of plastic in your tailhousing. the correct fix is to pull the tailsection and install a 7 tooth/21 tooth combo.

Kurt

Thanks
Great information to know.

revhead347 · Aug 15, 2014

I should add that this only applies to manual cars. The drive gear on auto cars is part of the output shaft, and you can't change it.

Kurt

cdurbin · Aug 15, 2014

revhead347 said:
I should add that this only applies to manual cars. The drive gear on auto cars is part of the output shaft, and you can't change it.

Kurt

Yeah, It's a 5-speed.
I think the drive gear might be why my speedo bounces around from 0-30 and then smooths out.

RangerJoe · Aug 16, 2014

I've done two. I got lucky with the first one. The second one I ended up having to pay someone to redo. I hate to say that I cannot do something myself. Would I tackle it again? Not sure,it is a very precise job and was somewhat frustrating. Sometimes the piece of mind is worth letting someone else do it.

Joe

A5literMan · Aug 16, 2014

I just bite the bullet and let a shop do both of mine. I thought about trying it the second time but decided to let the same shop(many years apart) do it. Both jobs were perfect. No noice. No problems. It also cost 300$ 2 years ago fwiw.

Fox Need Advice On 3.73 Gear Installation

cdurbin

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor

mikestang63

84Ttop

They make new pistons every day, so why worry?

cdurbin

hoopty5.0

mechanicus terribilis

revhead347

Apparently my ex-husband made that mistake.

cdurbin

revhead347

Apparently my ex-husband made that mistake.

cdurbin

RangerJoe

I leave the horn on while driving

A5literMan

At least it is lumpy...

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Fox Need Advice On 3.73 Gear Installation

Stangnet Facilities Maint Tech... Er... Janitor

They make new pistons every day, so why worry?

mechanicus terribilis

Apparently my ex-husband made that mistake.

Apparently my ex-husband made that mistake.

I leave the horn on while driving

At least it is lumpy...

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