1979-1993 & 94 Conv [Subscribe to Daily Digest] |
 | [Main C900 Bulletin Board | BBFAQ |
Prev by Date | Next by Date | Post Followup ]
Member Login / Signup - Members see fewer ads. - Latest Member Gallery Photos
Re: Engine Rebuild Tips (w/out knowledge of engine condition) Posted by Cmyles [Email]  (#1126) [Profile/Gallery]
(more from Cmyles) on Sat, 13 Jul 2024 10:01:38
In Reply to: Re: Engine Rebuild Tips (w/out knowledge of engine condition), mb  [Profile/Gallery]
, Sat, 13 Jul 2024 08:23:20
Members do not see ads below this line. - Help Keep This Site Online - Signup
|
The GM55602 was used in C900's from 1986 through 1988 and is a fine unit. After rebuilding hundreds of C900 five speeds I've concluded that the mean mileage for wear necessitating rebuilding is 150,000 miles regardless of the variant. I've seen them fail sooner and run farther but the mean seems to be that figure. So you'd be well served to try and determine the history of the unit before installation. The need to rebuild an otherwise well functioning unit is typically telegraphed by developing bearing whine that can be heard by the driver. Difficulty shifting or selecting gears, popping out of a gear, grinding, noise related to a specific single gear etc. are also common indications that rebuilding is required although all causes external to the unit (e.g. bad motor mounts, shift linkage adjustment) should be explored first. Pre-1989 five speeds had the rear cluster gear needle bearing rolling directly on the hardened layshaft which slowing wears away the layshaft on the thrust side allowing the cluster gear to roll off center. This seems to happen at about the same rate that the pinion shaft bearings wear out but occasionally I disassemble units that have advanced layshaft wear and still serviceable pinion bearings or vice-versa so symptoms of a worn out unit don't always include bearing whine. Such layshaft wear should cause growling but I believe that it's virtually inaudible.
As far as I know there is no single source for all the parts needed to rebuild the C900 five speed like there was many years ago. Bearings and seals are all generally available but my shop relies on a massive stock of good used parts along with gaskets, shims, pre-89 layshafts, 1-2 shift forks and other items that I either produce or recondition in my shop. As all of these transmissions have now been to the moon and back and often been rebuilt one or more times we have moved beyond the days when just replacing a few bearings would ensure another 150k miles usage. In the '90's I could easily rebuild one of these in a short day. Now I usually spend 4-5 days on each unit as every single tiny part must be thoroughly cleaned and checked for defects (and I'm not 25 years old).
One more thing you might consider for the engine besides gaskets and seals is a new timing chain unless records indicate it's already been replaced. Much easier to do with the engine out. That engine will probably already have the late improved chain tensioner but if not replace that too.
, Thu, 11 Jul 2024 17:53:01
, Fri, 12 Jul 2024 09:07:09
1, Fri, 12 Jul 2024 08:33:311, Sat, 13 Jul 2024 08:23:20, Sat, 13 Jul 2024 10:01:38 <-- Viewing This Message, Sat, 13 Jul 2024 17:23:36
No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.
 |
 |
 |
 |
 |
