North American Turbocoupe Organization



auto tranny problem , not downshifting?
GT350R Offline
Senior Member
#1
Ok, the tranny in the wifes TC is acting funny. When it is a freeway speeds (light cruise) it has a loud rumbling sound to it. It has a similar sound when you are braking when coming up to a stop light. It sounds almost like a manual tranny does when you forget to push the clutch in and try to stop. Of course being an auto it does not have the jerking feeling of a manual when this happens.

Could this be do to a bad/blow vacuum modulator?

Or is it time for a new tranny? If its time for a bew tranny the car will be parted out. The body s just not worth saving anymore. It would need doors and new quarters to be worth it. But if it can be fixed without new tranny, it will be.

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GT350R
#1978 20th 2.3 Turbo T-top
#3608 20th 2.3 Turbo T-top
WAY too many TC's and other mustangs!

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GT350R
(sold Sad ) 87 5speed, Motorsport head, [email protected]+2, [email protected], gutted or ported everything & all the typical junk.
84 Gt350 2.3T T-top
84 Turbo GT 418rwhp

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86tc Offline
Member
#2
I'd go ahead and do a fluid and filter change first (only costs about $10 for the filter and pan gasket and another $10 for fluid, depending on how much it holds). If that doesn't work, try the modulator. I know on my '62 Ranchero the modulator went bad, and it wouldn't shift into 3rd gear after awhile of driving like that. That's what it sounds like to me, too. Not positive, but sounds right. [Image: smile.gif]

Rick
'62 Ranchero (in progress...again)
'72 Gran Torino Sport (for sale/trade)
'76 Honda CB750 (for sale/trade)
'88 Yamaha Blaster Race 4-wheeler (for sale/trade)
'89 Lincoln Town Car (for sale/trade)
'92 GMC Safari Conv. Van (for sale)
'94 Pontiac Bonneville
'96 GMC Jimmy
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segfaultxr7 Offline
Posting Freak
#3
I'd start by checking the U-joints and wheel bearings for play. New front wheel bearings cured a rumble I had at freeway speed.

Or, do you mean it's actually lugging the engine, like you give it some gas and expect it to downshift, but it doesn't? If so, I once saw a shift kit somewhere for the A4LD, it specifically said one of the problems it addresses is the tranny causing the engine to lug. You might want to go to the Ford dealer and have them look up TSBs on the subject as well. Another tranny-related thing it could be is the torque converter clutch slipping or not unlocking when it should. You can test that by unplugging the TC solenoid (sorry, I know it has one but I have no idea where it is!) and see if the problem goes away. It's not good for the tranny to drive it like that permanently, but for diagnostic purposes it's fine.

[This message has been edited by segfaultxr7 (edited 05-19-2002).]
88 TC 5-speed
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GT350R Offline
Senior Member
#4
This sounds like a loud humm but not like a wheel bearing rumble (sorry my fault on discription still trying to get a grasp on it). When it first started it was loud inside the car, really loud. Now it seem that as I kept driving it today, it got quieter.

I got under it and checked out teh hose for the vac mod and it seems fine. I also checked the u joints and they seemed fine. The driveshaft weight seems to move a tiny bit if I try to move it with my hand. It does not appear to be broken free at all, but I was able to detect that it moved as I watched the ends. I dont have my TC here to be able to compare them. How stiffly should that weight be mounted to teh driveshaft? It is mounted on rubber and it just seems that the rubber is resilant as it should be. So it seems fine without being able to compare it.

There are no leaks and teh fluid level is where it should be if not high, and it does not smell burnt.

I played with it on the freeway and I believe I can tell when it is shifting to all 4 gears as well as feel the TC lock up. The sound is reduced when the TC locks up. WTF?

I am not a big fan of doing fluid and filter changes on high mileage trannys (99k) if I dont know for sure that it has had them n the past. I have seen too many trannys die that way. One of them was a parts car I bought.

Oh yeah, I hate slush boxes! I swore years ago that I would never own another one. I did not remember that I would be married one day and might possibly need one. The funny thing is that just as she really really wants a stick we also find that we night need something with 4 doors instead [Image: biggrin.gif]
GT350R
(sold Sad ) 87 5speed, Motorsport head, [email protected]+2, [email protected], gutted or ported everything & all the typical junk.
84 Gt350 2.3T T-top
84 Turbo GT 418rwhp

My Garage
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bigred Offline
Member
#5
After a year of auto trans problems I would say the trans in yours is getting ready to go. The a4ld is junk and a serious money pit.Find a 5 spd and spend the money you save from not rebuilding the auto on the body or some other part of the car..........Scott
1988 TC T-5 swap,New Head,Wiseco .030 pistons ,5.5 Crower rods ,balanced ,24x12x3 intercooler,T-3 .60
Ranger Roller Cam,New brown tops.
New 3"cat and 3"single SS exhaust
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segfaultxr7 Offline
Posting Freak
#6
Yeah, I've heard about fluid+filter changes killing trannies too. However, it's a lot less risky if you take it to a garage that hooks a machine to the trans. cooler lines and pumps new fluid in that way; they run about 20 quarts through so all the old varnish and stuff is freed and collected by the machine (hopefully!).

I can't help you with the driveshaft weight, but if it's mounted with rubber than what you describr sounds about right. I've seen cars with dying torque converters make some really weird noises. Like grinding, thumping, screeching, and clattering--all at once. Try listening to that area at idle, put a broomstick up against it and hold your ear to the other end.

I don't like slushboxes much, either. I drove my dad's Grand Cherokee the other day and I damn near forgot about driving an automatic. I kept feeling around for the clutch and trying to downshift around turns, etc. [Image: smile.gif]
88 TC 5-speed
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Pete D Offline
Administrator
#7
"we also find that we night need something with 4 doors instead "
Hark! does this mean there is little GT junior on the way? Or is the wife hinting that you MIL is coming to live with you ?

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NATO Member. it's not a vice, it's an obsession
"The nice thing about each new day is nobody ever used it before" Barnaby Jones
88 TC X 2, 86 SVO, mods list at
http://www.turbotbird.com/showroom/pd_88tc.htm
Pete Dunham


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GT350R Offline
Senior Member
#8
I get the feeling the tranny is on its way out also.

I tried a few things. While at freeway speed I sliped it into neutral and the sound stayed the same. So that should rule out the TC or a cracked flywheel. I am wodering it the sound could be the rearend transmitting though the driveshaft.......

If the tranny goes I will transplant the motor into a 87-90 Mustang convertable for my wife. She would love that since she misses her old 89 GT convertable. Her only rule is that it has to have NO rust. This car looks pretty turdy and she has been a real sport about driveing it for so long.

Pete, we need to hook up about when you are driving out to Carlise. It looks like the Dusk till Dawn crew is headed out with Gator early Friday and I cant go till Early Saturday morning. Oh and,,,,,, [Image: biggrin.gif]
GT350R
(sold Sad ) 87 5speed, Motorsport head, [email protected]+2, [email protected], gutted or ported everything & all the typical junk.
84 Gt350 2.3T T-top
84 Turbo GT 418rwhp

My Garage
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