Well, ****...

D

DieselDan

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That statement kind of sums up how I feel right now. My transmission crapped the bed last week, I lost third gear. I put this transmission in when I bought the car, at 86K because I bought it with the blown transmission. The car now has 164k, so I guess the used transmission did me good.

The old transmission was j-modded and had all its springs, but if I recall, I used F-150 springs in it. Well, anyway I installed a transmission out of a 2000 Mustang GT yesterday. I filled it up with fluid today and took it for a drive. This transmission got the light blue/purple springs and the 2/3 spring stayed in. I found that the Mustang trans already had holes larger than a pre98 would have.

So, I knew in the back of my head that there was a minor change to the speedometer teeth on the output shaft, but also had read that a member here had done a direct swap of a 99 GT transmission and it was a direct swap for him. I drove the car, and the shifting is so nice. Firm but not too firm, like my old transmission. Short story Long, the speedometer is off 5-10mph. It must have the different number of teeth on the output shaft. Now to figure out how to fix it. The car does feel faster, although I'm not sure if that's possible...?

Any Suggestions? My best bet I guess is a SpeedCal.
 
Speed cal is the best bet. You can also take out the VSS, see what gear it has on it and go up/down one tooth depending if your speedo is reading high or low.
 
DieselDan said:
That statement kind of sums up how I feel right now. My transmission crapped the bed last week, I lost third gear. I put this transmission in when I bought the car, at 86K because I bought it with the blown transmission. The car now has 164k, so I guess the used transmission did me good.

The old transmission was j-modded and had all its springs, but if I recall, I used F-150 springs in it. Well, anyway I installed a transmission out of a 2000 Mustang GT yesterday. I filled it up with fluid today and took it for a drive. This transmission got the light blue/purple springs and the 2/3 spring stayed in. I found that the Mustang trans already had holes larger than a pre98 would have.

So, I knew in the back of my head that there was a minor change to the speedometer teeth on the output shaft, but also had read that a member here had done a direct swap of a 99 GT transmission and it was a direct swap for him. I drove the car, and the shifting is so nice. Firm but not too firm, like my old transmission. Short story Long, the speedometer is off 5-10mph. It must have the different number of teeth on the output shaft. Now to figure out how to fix it.

Any Suggestions?
Click to expand...

Dan, the normal that I have always run with is 4mph per tooth. You did not mention to fast or to slow. +or-. I work at Ford of Clermont down the road from here you work. I have been the Service manager for about a year(been in Ford Service since 86). In order to get it right I have to tell most employees what to do (even the managers) It is sad but fact here. Let me know +or- 5-10mph and what you currently have, if available, I will get you the gear you need. PM me and I will send you my phone #.
Thanks Claude
 
Last edited:
Thanks for the info guys! Hey Claude, I used to work for Jarret-Gordon and Weikert, before I moved to NC, then back to FL again. My car currently has 3:73s with the purple speedo gear. The speedometer is off about 5mph initially around 20mph, and grows to about 10mph off around 55-60. I did not realize there was a selection for speedometer gears, I just thought there was a gear for each rear gear ratio. My bet would be that I need 1 less tooth on my speedometer gear, does that sound right, and is that an option?

Thanks!
 
Now that I was thinking about it again, I would have to go up in teeth, make the speedo gear spin slower.
 
That trans should be an 8 tooth output. With 3:73 I don't know if you can there from here.. lol.
Speedcal maybe.
 
Too many little teeth.

2013-03-02_23-21-19.jpg
 
That sucks Dan!

I'm getting ready to send mine back off to the trans shop hopefully once and for all!!
 
When KK built my car he did a direct swap of a transmission from a 99 GT Mustang and he also did a Jmod to it before he put it in.
 
When swapping transmissions, most swap out the output shaft. I have an '03 GT trans in mine, output shaft has been swapped to keep the speedo correct. Until I had put the 4.10's in at least.

You should be able to swap the output shaft and save yourself loads of headache on speedo gear selection, and save money from buying a speedcal.

The thing about speedo gears on the vss.... the more the teeth, the easier they shred.
 
Yea... the old transmission has been back to the JY for the core charge. I'm kinda "eh" on the whole thing. With the amount of time I had to do all this, I wasn't really keen on the idea of pulling the transmission completely apart. Besides, the output shaft I have now is stronger than the one in my old transmission. I am looking into a speed-cal now... I sure as hell am not R/Ring the trans in the driveway again, that can kiss my ass lol.
 
i forget which gear i used, orange one sounds right, 5 minutes to install, and my 2002 gt trans is same mph as gps reads.
 
So I did some simple thinking on this and here is what I came up with...

Original speedo gear ratio was:
(speedo gear) : (OS teeth)
21:7 = 3

New ratio is:
21:8 = 2.625:1

Potential Ratios:
22:8 = 2.75:1 (no good)
23:8 = 2.85:1 (no good)
24:8 = 3:1 (good!)

However, there is no such gear and even the 23 tooth gear has a short life expectancy.

Back to where I was I guess...
http://m.summitracing.com/parts/dak-sgi-5

Using this as reference:
http://forums.tccoa.com/showthread.php?p=1364032

Hey Mike! Could you possibly change the title of this thread to something useful so it can be searched for? Something like "2000+ 4r70w transmission swap" or something?

Thanks!
 
Dan, the white Jeep gear Mike has would work but only last about 3 to 6 months, if that long. I would either go with the speed cal or the universal one you mentioned and you could also swap out the 8 tooth output gear to a 7 or 6 and that would give you more options to choose from for the speedo gear. Yes, the tail shaft would have to come off. Might not hurt to find out if the JY still has your tail shaft and see if they'll let you swap them out. Unless you're pushing 400hp or more, I doubt you have any worries about the other tail shaft breaking. Maybe the long style would be prone to it but not the short.
 
The old transmission I'm sure is gone... In a giant pile of scrap somewhere. I'm not too concerned about swapping it out at this point, maybe one day down the road. For now, I'll look into buying the DD converter module. This is one of those times where I look at how much my time is worth, and how little I really want to pull that transmission again.
 
I can't blame you at all. Pulling the trans, especially for something simple would be annoying. If you were to loosen the motor mounts and drop the trans mount, would that be low enough to get to the tail shaft? Been a while since I have been under one and really looked at it. If that thing you're looking at is cheap enough and works accurate, go for it. Honestly if it was me, I would find out exactly how much I was off with someone beside me at 60 mph and then 50, 40 and then bury that in my head and know exactly how fast I'm going. :p That way I'm not spending more money. Just roll with the flow and you shouldn't get a ticket.
 
I have a GPS app that has shown me I am about 10mph off. I would have to completely remove the transmission and then remove ALL of the guts from inside the transmission. The tail shaft is the very last part to come out of the case.
 
DieselDan said:
I have a GPS app that has shown me I am about 10mph off. I would have to completely remove the transmission and then remove ALL of the guts from inside the transmission. The tail shaft is the very last part to come out of the case.
Click to expand...

Wait, I mean the tail housing, not shaft. It bolts on and would need a new seal /gasket put on when replacing.

Back here..

98tranny-1002.jpg
 
When I installed the trans, I installed a front pump seal, a rear seal and a tail housing gasket. There is still nothing I can do though with the tail shaft because it is removed out the front of the transmission...

The only solution I have, without removing the trans and removing the internals entirely is a speedo gear or a converter box.
 
Just get a speed cal or equivalent and be done with it Dan. That way you can run a speedo gear that isn't going to eat its self.
 
Converter box then because going up to fine teeth with an 8 tooth output gear will only last 1,000 to 10,000 miles and then they'll end up grinding themselves down and wearing thin and not reading at all. Tail housing comes out the front?:confused: New one on me. Anyway, the converter sounds like you're best option to solve the speed problem.
 
The tail shaft comes out the front during disassembly. Yea, I'm not going to bother with speedo gears.
 
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