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If you want a numbers marching vehicle, used 5th gears for that vintage transmission are plentiful (at this time). I''ve got several on the shelf.
If you don't care about a marching number car, used transmissions of that vintage are also plentiful. I've got several of these, also.
Unfortunately, finding a used transmission that is in good enough condition to install is virtually impossible....they all seem to have worn synchros (and worse) after 40 years of use.
Are these the two correct Part# for the 5th gear set for my US '78 #412?
928.302.905.08
and
928.302.905.09
Just the 08. The gear set comes as a pair (the PET shows both of the gears joined by a line, so it's a paired assembly). You've got a G28.03 transmission, the 09 part is for the G28.05.
Also, pardon my ignorance but are the synchros that everyone says go bad on these early cars a separate part ? or part of the 1st and 2nd gear set?
Oh, and the synchros are separate parts. Listed as 'synchroniser ring' in the PET. You'll only need to replace gears if the teeth are bad. Hopefully you can keep one of your kidneys now!
Just the 08. The gear set comes as a pair (the PET shows both of the gears joined by a line, so it's a paired assembly). You've got a G28.03 transmission, the 09 part is for the G28.05.
Thanks Jeremy. Is the .09 part for a Non Limited slip car? I guess I do not understand the difference between my G28.03 and the G28.05...What is the difference?
Thanks Jeremy. Is the .09 part for a Non Limited slip car? I guess I do not understand the difference between my G28.03 and the G28.05...What is the difference?
They revised the whole transmission for MY80 for ROW, and '81 in the US. The 09 part is for that newer one. If you've got the Morehouse CDs, the change is described in the MY81 Service Info document (basically, stronger box and some revised parts because the transmission got mounted a little differently when the central tube changed dimensions). One of the biggest changes was the length of the input shaft, so the two 5th gear assemblies are definitely not compatible between the two.
There's enough of these pieces still available used in good condition. Buying new has not been required.
You will require synchros (and other pieces) to accomplish a high quality rebuild.
Thank Greg, can you give me an idea what I am looking at $$ wise to get this done right? I have someone who has the correct 5th gear set from Porsche for $800 and a 1st and 2nd gear set as well for an additional $1200 if those should be replaced. I am thinking those are pretty good prices for factory new parts. I know synchros are a good idea, what "other" pieces are required?
Early 928 transmissions are like a box of choc'lates- you never know what you're going to get' - Forrest Brown
Which is to say that after 40 years there are enough variables of driver habit/skill, gear oil changes, mileage, and use that every transmission's rebuild needs are variable enough that it's impossible within $1K (to make up a number) to guess at what a proper rebuild would cost. The decision point is whether to commit to pull the tranny and ship it to Greg so he can read its tea leaves or not.
Early 928 transmissions are like a box of choc'lates- you never know what you're going to get' - Forrest Brown
Which is to say that after 40 years there are enough variables of driver habit/skill, gear oil changes, mileage, and use that every transmission's rebuild needs are variable enough that it's impossible within $1K (to make up a number) to guess at what a proper rebuild would cost. The decision point is whether to commit to pull the tranny and ship it to Greg so he can read its tea leaves or not.
Good point.
I Imagine Greg is backed up 'til the cows come home.
Thanks Rob, and everyone else for their help. At this point is a later Borg W swap a reasonable alternative?
Either way I will call Mary and see what my options are.
Your car is nice enough and original enough and early enough that my vote is to keep it correct/matching numbers. Any B-W transmission is also 30 years old and probably needs to be gone through as well. Do it like you mean it.
Thank Greg, can you give me an idea what I am looking at $$ wise to get this done right? I have someone who has the correct 5th gear set from Porsche for $800 and a 1st and 2nd gear set as well for an additional $1200 if those should be replaced. I am thinking those are pretty good prices for factory new parts. I know synchros are a good idea, what "other" pieces are required?
Here are the gears sets i am talking about
Jump all over that 5th gear set for that price. New is going to be a lot better than anything that is 35 years old. (Almost all of these things have spline wear/damage to a certain extent.)
I'd hold off on the 1st and 2nd gear set, until you know if they need to be replaced....unless the transmission has been crunching 1st and/or 2nd gear for quite some time. (Every crunch you hear is those tiny engaging teeth being ground down.) If you've been driving around with a crunch at every upshift or downshift....odds are you will need 1st and 2nd gear engaging teeth. These can be robbed from other gears, but are far more long term reliable if you use a new gear with new teeth.
Labor to do a non-limited slip box is $1200. Everything else is parts....and what parts you need are impossible to predict. (What Rob said.) That being said, it's been quite a few years since I did one of these that was under $3000.00......and that price is without replacing gear sets. (Almost all of these transmissions need both synchros and sliders, at this point in time....and that tears up $1500 in a big hurry!)
05-24-2017, 12:52 PM
