The X1/9 5 Speed Transaxle Service Notes
There is a really good 5 speed transaxle re-build guide written by Steve Hoelscher for and Ulix Goettsch who compiled it. It is located at: http://www.seattlex19.org/data/5s101/
And the shop manual at this link: http://www.fulton4thward.us/Pages/x19.htm
These service notes come from my years of working on these transaxles, my ideas of why these problems occur and what was done to address these problem areas.
The first years of this transaxle has a rather fragile reverse gear. Part of this problem is due to the long 16mm diameter shaft for the reverse idler gear. This shaft tends to bend under load and the gear tooth contact is reduced resulting in damaged gear teeth on 1st and 2nd gear sleeve, the reverse idler gear, input shaft gear and possible damage to the transaxle casing boss that supports the reverse gear shaft. In later production years of this transaxle, FIAT changed to an 18mm diameter shaft to help prevent this problem. With the knowledge this is a problem area for these transaxles, engage reverse gently, rowing the gears from 1st to 2nd before engaging reverse can help to engage reverse gear. It will also help if the driver does not launch from a stop like speedy Gonzales or the Road Runner in reverse gear. There are several photos of what happened to the reverse gear, 1st, 2nd sleeve and reverse gear shaft and transaxle reverse gear support boss. The previous owner of this transaxle tried to “fix” the cracked boss with J.B. weld which is epoxy glue. A totally unacceptable repair for this problem.
3rd gear tends to be the most abused gear in the x1/9. 3rd, 4th and 5th gear uses “Porsche” type syncros which consist of a floating ring, sliding stop assembly, tapered engagement sleeve and pointed, tapered engagement teeth. 1st and 2nd uses the more traditional cone type syncro except these are steel instead of brass on this transaxle. When gear engagement is forced beyond the syncro’s ability to match gear speed difference, this results in grinding or chipping of the engagement teeth and over time, the points on the engagement teeth become rounded or broken and no longer engage properly. Preventing this problem from happening is not difficult, simply allowing some time for the syncro to match gear speed difference before engaging 3rd gear or any other gear. Don’t jam the shifter into 3rd gear like a battering ram with the idea of getting the gears to shift faster. Trying to force the gears to shift faster beyond the ability of the syncro’s design will only cause problems. A bit of finesse make a world of difference when shifting into gear and doing so will increase the service life of the syncros. There are different versions of this gear depending on which year the transaxle is made. Count the number of gear teeth and have this ready when ordering a replacement gear. This also applies to other gears in the transaxle as there are variations of gears used over the years of transaxle production. There are photos of a worn out 3rd gear, 3rd and 4th sleeve, and worn out syncro ring in the transaxle photo section. It is possible to remove the syncro ring and flip it over if the gear slider side is not overly worn. The slider side of the syncro ring receives most of the wear and gear side less wear. There are also photos of a new 3rd gear and sleeve for comparison.
The shifter centering spring used in 1979 and very early 1980’s transaxles have a 3.2mm and early 1980’s have a 2.1mm diameter centering spring wire with two coils on the end, diameter spring wire and later 1980’s have a 2.6mm diameter spring wire with three coils on the end. This is the U shaped spring on the shift linkage housing that is held in place between a spacer and sheet metal washer with rolled edge. The arms of this spring can snap off and the broken off end of this spring floating around in the transaxle can get stuck between gear teeth resulting in damaged or broken gear teeth. This happened to a 1979 x1/9 I owned years ago which resulted in a broken tooth on the final drive shaft gear. Use the spring with 2.6mm diameter wire and three coils on the end instead of two coil springs as a replacement if possible. These tend to be less prone to snapping off in service and results in a better shifter centering feel. This spring should be replaced when ever the transaxle is serviced. The M6 bolt that holds this spring assembly to the housing is staked in on the back side. If the M6 bolt is removed without grinding the staked threads flat, the threads in the aluminum housing will be severely damaged. The threaded hole is too close to an edge on the back side of the housing and makes installing a nut on the back as a fix for cored out threads very difficult. Remove this M6 bolt by grinding off the expanded, staked down threaded section flat to the housing with a small grinding stone on a die grinder and remove the M6 bolt with a 10mm wrench. If the original spring has the 3.2mm diameter spring wire with two coils on the end and the replacement spring being used has the 2.6mm diameter spring wire and three coils on the end is use to replace it, the spacer which fits inside of the spring coils will be ~1mm too short. The solution is to get the proper spacer or shim up the old spacer with a ~1mm thick washer with the same diameter as the spacer. Use Loctite removable (#246 or #243) thread locker during re-assembly of the spring assembly. Re-staking the threads on this bolt insures this bolt will not come un-done.
The plastic flanged sleeve bearing that supports the clutch release shaft tends to break off at the flange joint. When this happens along with a worn out bushing, it tends to make the clutch engagement less than precise. One solution to this problem is to use a
industry standard sintered bronze flanged sleeve bearing. It is 0.750” outside diameter, 0.625” inside diameter, 0.125” thick flange and 1.00” long (Mc Master Carr# 2938T18 or similar from a local industrial bearing suppler). The hole for the clutch shaft in the transaxle housing is about 19mm or 0.748” and the 0.750” FSB does a nice press fit into this hole. Once the FSB is pressed in place, an adjustable 5/8” hand reamer is used to enlarge the inner diameter of the bearing about 0.006” or slightly more than 16mm (0.630”) for bearing to shaft clearance. The clutch release shaft is 16mm in diameter. Oil the bearing with synthetic motor oil before installing the clutch shaft. The sintered bronze bearing should last longer than the original plastic bearing. US
If the differential tapered roller bearings are replaced, then pre-loading of these bearings needs to be checked or re-set. Follow the instructions in the FIAT factory manual. A special tool is specified in the FIAT manual for seating the diff bearings, this can also be done by using extra shims under the cover, temporally installing the cover and toque the 4 retaining bolts to not more than 10 foot pounds in a uniform cross pattern. Remove the bolts and cover once this is done and measure the depth of the diff bearing and height of the cover with a depth micrometer. The FIAT spec for clamping space is 0.003” to 0.005”. In addition, the diff bearing cover that is held on with 4, M8 bolts tends to bow inwards due to the pressure from holding this assembly together. Factor this into the measurement when selecting a new shim to pre-load the diff bearing. Don’t forget to install the O-ring between the cover and the transaxle case. Failure to do this will result in oil leaks from this cover assembly.
Helpful tips and tools for servicing this transaxle.
· Make an input shaft holding tool from the clutch disc spline center hub. This tool is used to hold the input shaft while loosening or tightening the M20 lock nuts in the far side of the input shaft.
· A 0.25” or thicker steel plate with two or more clearance M8 holes drilled and mounted to a good size slide hammer used to remove the stub axles.
· Use a small cape nose chisel (~4mm) that will fit into the M20 lock nut slot. The locknut staking can be removed usually with less damage and fewer problems this way. It also works on the 30mm hex wheel axle nuts.
· Use Hylomar blue on all paper gaskets and seal edges to prevent leaks. IMO, it works better than most silicone sealers.
· Replace all oil seals including the tiny one located on the speedo drive gear assembly. Replace all O rings, they are located on the reverse gear idler shaft, speedo drive assembly, Diff tapered roller bearing cover.
· The gear selector rod seal can be removed by drilling a hole thru and using a slide hammer with an eye bolt on the end. It is a good idea to replace the gear selector rod bellows since they are often damaged from service.
· Give the magnet located near the gear selector shafts a good cleaning before re-installation. It is usually buried under a pile of metal debris.
· Use the factory manual for bolt torque specification and follow them.
· I have used Redline MT90 in this transaxle with good results in the past. I’m going to try Neo-Oil 75-90W synthetic transmission oil this time as they have become one of the preferred choice for a good number of F1 and other race teams.
· Photos are located in a separate file in the group transaxle folder.