Finally getting the new transmission

[HerMajestysMechanic]

Well the time has finally come. After 6 months of slipping, shaking, and questionable shifts, ThatOneGirl has finally agreed to get a new tranny for her GM. We went to our trusted family mechanic and began the process this Friday. We're getting the standard, warranteed AOD replacement, with the added Shift Kit and clutch pack upgrade. The whole package will be covered for 3 years or 70k miles. Goes in a week from this Monday. Both her and I are pretty excited that her baby will finally be able to completely channel the added power of the HO kit that Nitro put on before she bought it from him. It's going to be like a whole new car. As an added bonus, when my mechanic, TIM, installs the new tranny, he's going to order one with the correct speedo gear, so the 140 speedo that Matt installed will be accurate. This is gonna be so frickin sweet!

Now if only I can convince her that since they have to pull the cats and crossover out to drop the tranny, that she should let them put in the mustang X pipe that Nitro gave us. The car is registered in Michigan, so it doesn't need the cats for emissions, she's just not sure if it's gonna make the car too loud. I say go for it, but I'm the kinda guy who likes em a bit loud.

We'll keep y'all posted as the process continues.

The Admiral

[interceptor1985]

X pipes are known for making stuff too quiet but I like the power so....

[nitroracer]

Sounds like a good upgrade. Im happy the car never left you stranded anywhere. As long as you use the gear from the original transmission the speedometer should read right, I never changed the gears out back.

I ran it with that H-pipe for a while, the car wasn't too loud. I just hated getting to the bolts on the header flanges!

Take a picture of the olde' car for me!

[Blaze86Vic]

Yeah, which speedometer you have does not matter. Both are accurate with the same grears. Only changing the gear in the rear axle will through the speedometer off.

[HerMajestysMechanic]

The problem is, the Speedo is currently off. It varies in "offness" by as little as 1 or 2 MPH at low speed, to 10MPH above 80. All of the "offness" is on the high side. so 70 on the Speedo can mean anywhere from 70-80, and its not consistant in its "offness" It still has the 15inch rims and Avid ST tires that Nitro had on it, so I doubt the tire size is the issue. Which leaves either the Speedo-Cluster, or somethin in the tranny. Least thats what Im figurin at this point. If the new Tranny set-up doesnt fix the Speedo, Me and ThatOneGirl will just have to go to the junkyard and dig up another 140MPH speedo I guess. Need one anyways, since apparently ya cant just replace the fuel guage, ya gotta do the whole cluster. Either way, Im lookin forward to the new tranny, should make the trek to SF alot nicer this summer, thats for sure.

Admiral

[nitroracer]

That sounds like an internal problem with the speedometer, and those tires are slightly oversized compared to stock. I wanted to fit as much rubber on the car as I could.

[1987cp]

I've had good luck with an offroad X-pipe and decent shorty headers being pretty quiet with replacement-type mufflers and 2.5" over-the-axle tailpipes. Good luck with the speedo issue. Have fun!

[gadget73]

If the speedo isn't consistently inaccurate, I'd say either VSS problem since its an electronic speedo or a bad speedo. Check it for codes and see if you get anything about the VSS signal. It should get more and more off the faster you go, but it should always be the same percentage off. For example if 77 means 70, it should always be 1 mph off for every 10 mph. If 70 actual shows anywhere from 70-80 without any consistency, there is some other problem. A slight amount off is probably the tires, but it shouldn't be a large amount.

[1987cp]

A slight amount off is probably the tires, but it shouldn't be a large amount.

Right on. You can calculate the amount the speedo should be off based on the circumference of the tires; it should be a pretty small error. If it weren't nearly 1am with me needing to be up for church in the morning I might be all rigorous and work out an example just for my own amusement.

Which reminds me ... Happy Easter everyone!

[mrltd]

Speedometer error is a percentage. As the speed increases, so does the error. As Gadget said, if it's inconsistant, it's a VSS or speedo issue. Also, if you are going by those radar trailers, they are not all calibrated. I've passed some on trips that had a 10mph difference between 'em. The same goes for mile markers. If you are pacing off around turns it will be incorrect, due to the way they install them. They mark by the middle of the road, not the outside or inside lanes.

[HerMajestysMechanic]

The inconsistencies were initially evaluated by using a pace car, but then re-affirmed by Dyno. And it is an inconsistent amount, so y'all may be right that its the speedo itself. As for the VSS, I just checked the codes this afternoon and nothing at all is throwin codes. Looks like I might as well go to the yard next weekend and pull another cluster, since I need one to fix the fuel guage prollem anyways.

I've dealt with incorrect speedo's before, but only on mechanic ones. At first I just assumed that it would be a simple percentage based calculation like y'all have said. But the Speedo needle itself also doesnt move smoothly as it should under controlled acceleration. Despite knowing by my senses that I'm accelerating, the speedo needle moves in slight fits and starts. Sometimes it'll read 70 for a full "1 Mississippi" then move up to a more believeable speed. Sometimes it seems oto be corresponding with Actual speed more accurately. Basically it sounds like I need a new cluster. Just a quick question though.

When pulling the cluster, other than the ribbon cables in the back, what is that tube that goes down into the dash. And do I have to remove it at the cluster end, or the other? Or can I just clip it and use the tube thats in the GM now? Im gettin to learn alot about these beasts, but still so much left uncovered yet.

Thanks again,

Admiral

[gadget73]

Thats for the shift indicator. You'll need to pull the collar off the column itself. Its held in with a screw (or nothing since they commonly break). The cable hooks onto a crank arm on the shift linkage. Excuse the blurry pics but this is essentially what you'll be looking at. Dash and column trim is different on a later model but the collar and shift indicator ought to be pretty similar.

The collar installed inside the column. The crank arm that the cable inside hooks to is visible here as the black dealie with the peg on it. You can see the wire looped over it.


The collar itself and how its cabled into the cluster. Thats a Towncar one so its a bit different visually, but same concept.



This is what state you'll normally find the clamp in.



If its like this, ream out the screw hole and use a wire tie to clamp it in place so the shift indicator works properly.