Thanks to all that have posted on this board. A lot of the posts have already helped me!!!

OK... now for the meat... I have an 87 GTA that came with the 10 Bolt Drum Brake rear. I have switched to the Borg Warner 9 Bolt with a 3.45 gear ratio. Want to see? Go to http://www.seven-of-nine.com/gta.htm

Now for the quesitons... I replaced all of the bearings and seals. Checked all of the gears, etc. I put a new Panhard bar and new control arms on as well. Since putting the 9 bolt in, I have a vibration at 55 - 70 that I didn't have before. Thought maybe I had thrown a tire weight on one of the wheels... balanced them... still have the vibration. Any ideas?

Next question... I need to change the gear for the speedometer. Where do I find info on what part number to order?

Last one! Anyone know where to get a 9 bolt differential cover? I have tried and tried. I don't care about chrome (would actually prefer black). Mine has a very small crack and it leaking some. I could weld it, but prefer getting a new one...

Thanks in advance!!!!


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James

1987 Pontiac Trans Am GTA - 305 TPI - 700R4

http://www.seven-of-nine.com/gta.htm

 

i'd weld the crack and then look for another cover, have you tried gm parts? if they don't have one try the local junk yards. vibration might be hard to track down. are you sure bearings are good, correct preload on pinion? correct back lash and pinion depth? u joints good? drive shaft bend?

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ICON Motorsports
1st & 3rd
MM Black Diamond 538 F&AM

 

make sure the driveshaft is centered in the pinion yoke and the caps are pushed tightly together before tightening the straps down. had the same problem when i replaced the u-joints. loosend the straps and pushed the caps together. then tightened down the straps. the yoke does not center the u-joint. you have to do it yourself. voila! he vibration was gone.

 

Thanks for the replies!

The most pressing issue for me is the speedometer gear to set the speedo to read acurately. Anyone know the part number for a 700R4 with the 9 bolt 3.45 ratio rear?

Where do I get it?

Thanks!

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James

1987 Pontiac Trans Am GTA - 305 TPI - 700R4

http://www.seven-of-nine.com/gta.htm

 

3.45 did not come with the auto....only the 5spd. I don't know what gear to get but just FYI.

 

Thanks! That sounds bad... didn't think to check whether or not the 3.45 came with the auto... now I'm concerned...


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James

1987 Pontiac Trans Am GTA - 305 TPI - 700R4

http://www.seven-of-nine.com/gta.htm

 

What tire size?

 

Tire size is 245/50/16...

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BorgX (James)
1987 GTA - 305 TPI - 700R4

 

How close would the speedo gears for 3.42 get him?

 

15T Gray (8642620) Drive, 42T Green (25513049) Driven
or
16T Blue (8640518) Drive, 44T Dark Gray (25513051) Driven

 

We can help. Please send complete request to houser@rearman.com . We may still have 9-bolt covers on hand. (We usually blast and paint rear housings and covers with black enamel.) Include phone number. Contrary to someone's rude remark, I want to help. I prefer to get the details and refer to a pro mechanic than to tell you what I think I remember from my car...