g-force transmissions
Frequently Asked Questions









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1.   The transmission kicks out of gear when shifted.
2.   The transmission has a "tight" spot when spinning over by hand.
3.   The transmission only has high gear.
4.   The transmission "vibrates".
5.   The transmission makes a whinny sound, similar to a supercharger.
6.   The transmission shifted from first to fourth gear when I pulled second gear.
7.   The transmission shifted from second to fourth gear when I went for third gear.
8.   The slider and shift fork appear to be "burnt" or worn. They appear to have heat cracks.
9.   The transmission "grinds" heavily when going into reverse.
10.   The transmission "clunks" when shifting into gear at a standstill.
11.   The transmission leaks oil.
12.   The yoke is extremely tight when installing the driveshaft into the transmission.
13.   The transmission is constantly throwing springs off of the 1/2 slider set only.
14.   The transmission is constantly throwing springs off of the 1/2 or 3/4 slider sets.
15.   How to Adjust the V-Gate Shifter.

 
1.   Symptom: The transmission kicks out of gear when shifted.
Cause: The slider or faceplate is worn heavily.
Solution: Replace the slider and faceplate assembly.
 
2.   Symptom: The transmission has a "tight" spot when spinning over by hand.
Cause: Either there is dirt between a pair of meshing gear teeth or a tooth is bent.
Solution: Take transmission apart (for G-101, remove side door) and inspect gears. Wash off all gear sets with solvent or brake cleaner and rotate input shaft. If the problem persists, rotate transmission slowly until tight spot is felt. At this point, check backlash (wobble) on mainshaft gears. The gear set that does not have any backlash is the one that contains a bent tooth or embedded debris. If the gear set contains debris, simply clean with appropriate measures. If the gear set contains a gear(s) with a bent tooth, the set must be replaced.
 
3.   Symptom: The transmission only has high gear.
Cause: The "head set" gears are broken. This is the gear set at the front of the transmission.
Solution: Replace the gear set.
 
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4.   Symptom: The transmission "vibrates".
Cause: The transmission is most likely not the culprit. Check the following chart.
Solution: Fix the problem with appropriate measures.
1. Is the driveshaft in a bind at any point?
2. Is the yoke engaged far enough on the splines?
At least 2 inches of spline length should be engaged.
3. How long is the driveshaft and is the diameter and wall thickness adequate?
4. Check the universal angles for extreme bends.
5. Check the bellhousing alignment and flatness. This will misalign the transmission and driveshaft when under load.
Note: The transmission should ALWAYS be rubber mounted.
6. Check the clutch disk(s) for cracks and/or runout.
7. Mark the driveshaft when taking it in and out to see if the rotation angle has any effect on the severity of the vibration. If the vibration goes away at a certain marking on a consistent basis, then the driveshaft/yoke assembly is probably not balanced properly or is bent.
8. Check the runout and balancing of the wheels. Because they are running on a large diameter circle, any runout can cause a severe vibration.

 
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5.   Symptom: The transmission makes a whining sound, similar to a supercharger.
Cause: Because you have a straight-cut gear transmission, they do tend to be a little noisy. It is most likely the reverse idler gear and is not important as far as performance of the transmission is concerned.
Solution: Try running a thicker synthetic oil or get some GF-2000 oil from our sales department. This oil is specially formulated to work with G-Force transmissions and their internal components.
 
6.   Symptom: The transmission shifted from first to fourth gear when I pulled second gear.
Cause: Most likely you pulled the shifter handle too slow and/or got into severe tire spin or shake. When this happens, the selector pin in the shifter can fall down prematurely and will result in a missed shift. Even though it appears that you pulled second gear, you actually pulled fourth. The transmission WILL NOT go from first to fourth unless you shift it that way on the stick. A clutchless transmission MUST be held in gear (except 5th on some models) or it could come out of gear. It is even a good idea to hold a clutch-assisted transmission in gear at all times.
Solution: Ask about our safety plate option to prevent this. It takes less than ten minutes to install and will be provided FREE to you if you have a Long shifter. Unless the buyer requests that it NOT be installed, all new Long Vertical Gate shifters come with this plate already installed (as of 1995).
 
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7.   Symptom: The transmission shifted from second to fourth gear when I went for third gear.
Cause: The three coil pins (similar to roll or 'split' pins) in the third/fourth slider hub are either sheared off or missing. Some buyers eliminate these pins for no apparent reason because they appear to do nothing.
Solution: Replace the three coil pins, but ONLY in the third/fourth slider hub. They are not necessary in the first/second slider hub, even though some very early model G-Force transmissions had them.
 
8.   Symptom: The slider and shift fork appear to be "burnt" or worn. They appear to have heat cracks.
Cause: The transmission is overshifting too far into gear.
Solution: Check the shift stops and reset if necessary. Click here for more information concerning the adjustment of the V-Gate Shifter.
 
9.   Symptom: The transmission "grinds" heavily when going into reverse.
Cause: Most likely the problem is with the air gap setting in the clutch. The clutch is not fully disengaging when the pedal is depressed.
Solution: Increase the air gap setting in the clutch and see if that fixes the problem.
 
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10.   Symptom: The transmission "clunks" when shifting into gear at a standstill.
Cause: The clutch is probably not disengaging properly.
Solution: Increase the air gap setting in the clutch and see if that fixes the problem.
 
11.   Symptom: The transmission leaks oil.
Cause: The o-ring between the case halves (GF-5R and GF-2000 only) is worn out.
Solution: Replace the o-ring or use silicone instead to insure a tighter seal. Also re-silicone the front cluster plug
 
12.   Symptom: The yoke is extremely tight when installing the driveshaft into the transmission.
Cause: The mainshaft may be bent severely or the bushing/bearing is worn out or crushed.
Solution: Check the mainshaft between centers and use an indicator to see if it is straight (within .010 TIR is acceptable, .003 preferable) or replace tailhousing bushing or bearing.
 
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13.   Symptom: The transmission is constantly throwing springs off of the 1/2 slider set only.
Cause: The transmission slider is still in a lower gear when starting the burnout.
Solution: When doing the burnout, try pulling into the water in 1st gear and then putting the transmission in neutral just before entering the water (i.e. coast the last few feet when entering the water.) Then put the transmission in the appropriate burnout gear and start the burnout.
 
14.   Symptom: The transmission is constantly throwing springs off of the 1/2 or 3/4 slider sets.
Cause: The sliders are most likely worn too heavily and/or the shifter stops are out of adjustment.
Solution: Replace the slider and faceplate assembly and reset the shift stops.
 
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15.   Adjusting the V-Gate Shifter

To properly adjust the Vertical-Gate style shifter installed on your G-Force transmission, follow the following simple steps. This will help ensure extended service life of your transmission.

1. Adjust all shift rods (stainless steel tube rods or solid steel) so that .250 diameter alignment pins falls easily through the neutral hole (.257 diameter hole just below 5/R gate on side plates)
2. Tighten all nuts on rods and be sure rod ends are free (not bound up when pivoting)
3. Shift transmission into 1st gear - make sure it is all the way in gear and not "dead heading". (This can be accomplished by turning the input and output shafts opposite directions from one another.)
4. Loosen the 1st gear stop bolt on the bottom of the shifter. Turn bolt towards the stop plate (as if you were going to tighten the bolt), until there is an air gap between the bolt head and the 1st / 2nd pivot plate.
5. While holding the shifter tightly in 1st gear, (slightly tighter than you would when going down the track - this varies among different drivers), turn the stop bolt until the head of the bolt meets the 1st / 2nd pivot plate.
6. Tighten bolt by using the locking nut.
7. Repeat for all five gears.
8. If your shifter has a reverse stop, turn the bolt all the way towards the stop plate, "click" the transmission in reverse (it is detented), and turn the stop bolt until the head of the bold meets the 5th / Rev. pivot plate.
9. Check all stop adjustments by shifting through all gears. There should be VERY SLIGHT drag on the input shaft when the transmission in held tightly into gear. Generally, it is important to hold the transmission tighter into gear when setting the stops than when going down the racetrack. This ensures the virtually no drag when actually using the transmission for racing.
10. Repeat this procedure EVERY TIME the shifter is unbolted from the tailhousing.

Service Recommendation: Do not unbolt the shifter from the tailhousing. If possible, just unbolt the tailhousing from the transmission case and take the rod ends off of the black shift levers (3 bolts/nuts). This will eliminate the need to readjust the shift rods and stops every time the transmission is taken apart.

*Note: Generally, the more drag felt on the input shaft when holding the transmission into gear, the longer the sliders and faceplates in the transmission will last. However, this is only true to a certain degree. You do not want EXCESSIVE drag when turning the input shaft, as this will create premature shift fork wear and cracked sliders.
 

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