The GMC CCKW

My 352 had a problem where it kept jumping out of 5th gear,I haven't used it for 7 months and thought I'd remove the box today to find the cause. I've found the clip holding 5th gear in was broken and the 5th gear retaining washer was completely broken up into small pieces.The grove in the main shaft has warn so I'm reluctant to fit it back into the gearbox.
Has anyone had the same problem and if so how do I go about repairing it.
Could I as mentioned before on here recut the shaft to take 2 washers?? or have it cut deeper and put a bigger retaining clip in.

Who stocks the repair parts,the toothed 5th gear retaining washer and retaining clips are needed,I will need to change the mainshaft piolt bearing as well.
Any help appriciated

regards

Steve

I seem to recall that they had a replacement (better) 5th gear mainshaft gear with more holes in it to get more oil to the bushing and clip. This of course will not do anything for you with your problem. I believe that you will have to replace the mainshaft and 5th (mainshaft) gear too.

You need to contact Rex Ward, only person I know in the UK who might hold parts and can give advice.

Rob

What I'm after now is a cross reference of the bearings used in the gerabox,If anyone could help
Bearings as listed in the manual are:
Main Drive Gear Pilot(at Crankshaft)
Type....... Ball
Number ND-7109

Main drive
Type .......Ball
Number ND 47509-A-45

Mainshaft Pilot (front)
Type....... Roller
Number HY 94322

Mainshaft Rear
Type....... Ball
Number ND 43308

Countershaft (front)
Type..... Roller
Number HY-1207TS

Counershaft (rear)
Type.....Ball
Number ND-47308


Any help would be appriciated as It's a little hard to cross reference these numbers through European distributors

Regards

Steve

Here are some of the pictures of the gearbox and some of the problems encountered,Nice interesting Data plate I found.
The 5th Gear Snap ring caused a few problems on the installation,I slipped with the circlip pliers and jabbed Robs finger

there is a fix for this problem.

I may have posted it a while back, but I cant recall.

it was told to me by a mechanic with over 50yrs GMC experience.


he said they all fail like this eventually. it is a design fault that starves the thrust washer of oil.

i believe his solution was to machine out the retaining groove and fit 2 washers as i recall. maybe some oil flow enhancement, cant remember.

he also said never lug them in 5th.

tony

Thanks for share.I have the same problem in my transmission 2-44 truck.

never LUG them? whats that mean

LUG:

Don't run the rpms down below where you should have down shifted to a lower gear already

Ahhh gotcha Thanks!

Anyone got any info on the bearings??I've just recieved the parts I got from the US via Ebay Gears and circlips,just need to find a supplier of bearings and I'm away.

regards

Steve

Hi Steve, try Wildenberg, they usually have all the gearbox bits in stock.
Email wildenberg@planet.nl

I have a problem in my fifth gear(overdrive).When my truck is stoped with engine running I can movement the shift lever to the 5th shifting position,but in motion I can't movement it.Any help for this case?

The shifting forks inside the transmission are interlocked so that you can only put it into one gear/speed at a time (move one fork at a time).

It may be that one of the other (non-4th-5th) forks is not moving completely to the neutral position and is locking the 4-5th fork from moving.

Thanks Dr.Deuce.I will write the TM10-1563 and see what and how can I do to dissolve this problem.*PS:I can movement the shift lever to the 4th shifting position with truck in motion,4th is ok.