Par gears

K

kevmc

Member
I bought a set of Par gears 1st to 4th got the gearbox rebuilt with new gears, seals & bearings etc reversed the car out selected first gear and let the clutch out and the end casing is now split and broken, now i am led to believe that these gears are there to stop this happening or do you still have to get the support brace for the end casing??
Regards
Kevin
 
P

pulsar pete

New Member
I believe having straight cut gears produces less axial forces so should reduce the chances of this happening. So you just set off gently and the box split in two??
 
K

kevmc

Member
Thats what i thought, Yes it was reversed out the garage put into first and the end casing disintegrated. It wasn't launched and if it was it should have coped with it as i its running .7 of a bar just now.
 
P

pulsar pete

New Member
Could there have been an issue with the casing during the build? Who built it?
I've done launches without an end brace and with helical gears no problems, I have par straight cut now and an end brace....it's odd how it's split it just setting off?
Would incorrectly shimming it be a possible cause? I'm no expert at all, but just putting suggestions out there
 
K

kevmc

Member
I have owned the car for 7 years the gearbox was removed and the new gears installed then installed moved out the garage and its went, i would have seen the point if it was launching but even then the box with the par gears should handle it specially standard power.
 
fubar andy

fubar andy

Moderator & N/W Rep
Staff member
kevmc said:
It wasn't launched and if it was it should have coped
Click to expand...
"Should" doesn't mean it will.
After grenading numerous gearboxes over 11 years, fitting a Quaife and cryo treating a number of gearbox cases ANYTHING can happen with a GTiR gearbox.

I can only presume that the end if the case was significantly weakened due to some sort of wear and tear or you were too heavy handed with it!
 
Fast Guy

Fast Guy

Moderators
Staff member
Par gears are just am uprated gear. Unless they were straight cut they'll do nothing towards the longevity of your gearcase. You need a full straight cut gear set including final drive to stand a chance of your gearbox lasting.
However just driving away normally in 1st shouldn't have broke the case unless it was already badly cracked.
 
The Doc

The Doc

Moderators
Staff member
Sounds like reverse and first selected at the same time,and straight cut gears with a standard final drive is a bit pointless as the final drive will put more stress on the cases than using helical gears as the helicals are cut in opposite directions to cancel the forces out, bad advice from who ever told you all to use this combination.
 
The Doc

The Doc

Moderators
Staff member
Sounds like something i.e the return spring or detent bearing was left out to cause your issue.
 
K

kevmc

Member
The Doc said:
Sounds like reverse and first selected at the same time,and straight cut gears with a standard final drive is a bit pointless as the final drive will put more stress on the cases than using helical gears as the helicals are cut in opposite directions to cancel the forces out, bad advice from who ever told you all to use this combination.
Click to expand...
Even at 0mph surely not 5th gear gave way?
 
The Doc

The Doc

Moderators
Staff member
No it sounds like reverse was still engauged when you put the car in first, it only takes a mistake when building the gear box.
 
The Doc

The Doc

Moderators
Staff member
They should be as they have done no work as such..i.e it was not moving at any speed, inner bearing wrass on the main shaft is chipped which is peculier, input shaft bearing is old and is stained with old burned oil, that shaft spread could be first and reverse engauged at the same time, case previosley damaged or massive excess preload . Stock helical final drive and straight cut gears will do this eventually in our gearbox anywsy so maybe its a blessing in disguise for you to fit a s/c final drive.
 
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