Grinds into reverse

**EndressAuto** · August 1, 2015, 06:34 AM

Customer of mine has a 2007 Atom 2 that was in for limp home mode and code P0101. Worked that out and drove the car for 3 days now no issues. Went to back out of the garage to deliver the vehicle back to the customer and it grinds into reverse. Has never done that before.

I have manually bled, pressure bled, vacuum bled from the throw out, and vacuum bled from the reservoir all no dice. Pedal feels the same as i remember it always has.

Some sort of clutch drag going on here. Not enough to move the car once in gear but enough to put a load on the gear train that seems to be overcoming the ability of reverse syncro. Put the car in a forward gear and then reverse, no grinding and shifts like butter.

All play is adjusted out of pedal linkage.

Am i missing something here with the bleeding to make it special then any other car? No leaks, no noises from the clutch, no nothing. Well figure out how the air got into the system if this reoccurs but at this point i just want to get the car to stop grinding.

Unless some sort of reverse synco failure all of a sudden but thats kind of hard to imagine to have happen in just one shift.

**MadMaxAtom** · August 2, 2015, 02:30 AM

No synchronizer for reverse. Sometimes when cold,my Ecotec will do this as well. I am now using Ford 75/90wt synthetic gear oil and cold reverse grind issue is much less frequent.

Synchromesh transmission discussion:

"The previous discussion applies only to the forward gears. The implementation of the reverse gear is different, implemented in the following way to reduce the cost of the transmission. Reverse is also a pair of gears: one gear on the countershaft and one on the output shaft. However, whereas all the forward gears are always meshed together, there is a gap between the reverse gears. Moreover, they are both attached to their shafts: neither one rotates freely about the shaft. When reverse is selected a small gear, called an idler gear or reverse idler, is slid between them. The idler has teeth which mesh with both gears, and thus it couples these gears together and reverses the direction of rotation without changing the gear ratio.
In other words, when reverse gear is selected, it is in fact actual gear teeth that are being meshed, with no aid from a synchronization mechanism.

**EndressAuto** · August 2, 2015, 06:48 AM

I was getting both responses when searching and asking if reverse is synced. I came up mostly with regular cobolt transmissions are not but SS transmissions are.....if it in fact is not synced then that makes sense to be setup and act just like a GM or Ford T5. Select a foward gear then reverse with them.....

Can anyone else conform reverse is not synced and I am chasing shadows here of a symptoms I just just never realized before?......somehow.....

**EndressAuto** · August 2, 2015, 07:18 AM

And why Ford gear oil and could I have the part number? Well give it a shot Monday morning.

**s2kseven** · August 2, 2015, 09:01 AM

I had similar issue on my Lotus Esprit V8: I had a feeling that the clutch dragging (friction plates dragging)
causing the splined shaft to rotate while trying to engage in reverse. I replaced it with new oil and adjust my transmission selector didn't do me any good.
I adjusted the rod of my clutch master cylinder and did the trick. Maybe the master hydraulic clutch needs a little push. Try to adjust one full turn and see.

**MadMaxAtom** · August 2, 2015, 05:13 PM

I like the Ford synthetic as it makes shifts smoother than anything else I have tried,including the GM recommended fluid. I don't have the part number off hand..will post it tomorrow when I'm in the shop. (I was away this weekend at a time trial race event at Whiskey Hill raceway..took first place in Super Unlimited..and set a track record!)

**EndressAuto** · August 2, 2015, 07:50 PM

Already adjusted the master enough to where I was conformable it wasn't going to not release the hydraulic system fully.

Let me know that parts number and we'll try the fluid. If not it'll just be a foward gear being selected before reverse from here on out.

**MadMaxAtom** · August 3, 2015, 05:51 AM

Ford part number XT-M5-QS , which is a full synthetic 75/90wt with NO friction modifiers.Do not add any friction modifiers, as the F35 uses a Quaife ATB posi-traction differential unit,which is all gears,and no clutches and does not need additives(which will deteriorate the bronze synchro rings.) The Ford synthetic fluid has a GL-4 rating. You will need to buy 2 qts and it takes about 1.7 qts. to fill the transaxle. I have tried many other gear lubes and have found the Ford stuff to work the best.

**EndressAuto** · August 4, 2015, 11:48 AM

I got that exact part number from Ford and it says manual transmission fluid on it, but your saying its gear oil? Just want to make sure i got the same stuff that your recommending. No weight rating on it, just says synthetic manual transmission fluid.