5th gear thread (fifth gear fix) NV4500 transmission
#11
A few thousand miles back my 4500 got a rebuild... Seems the guy that owned the truck before me fixed the 4500 by welding the nut in three places. I came off the light towing a Geo Metro of all things and therer was a big bang. A real big bang. No forward, no reverse, no 4wd...dead right there. Got it on the hoist and took it apart. The output shaft had sheared off clean at the welds. Darn near perfect clean cut. You could see the penetration well into the shaft. Ran it over to the T-shop and the brought her back to life with all new guts, top plate, and updated shaft and nut. I would have to say, keep the welder out of there.
#12
The ebay nut you're showing is what we did for mine the first time. Lasted about 25k. No 5th gear lugging, no towing in 5th gear under 60 mph and it came off while towing at about 70 mph. Had LaserBob do it this time for me and it's supposed to be an improved nut, more so then the first improved nut, but not sure where to find a pic for you. I wouldn't worry about stripping the threads. Torqued it to spec, then put on a cheater bar and gave it another turn.
#13
I do believe I have the back half of the shaft on my bench in the shop. Makes quite the paper weight. I'll head out there in a bit.
#14
#15
#18
Dang.. that is some luck! Hope it remains reliable for ya.
---AutoMerged DoublePost---
I'm going to do a fluid change in the nv4500 also.
This transmission has a lot of miles on it and is starting to develop synchro problems, so I'm going to use a process to flush it in an attempt to clean up the synchronizers.
What I'm going to do is a 3 step process I've come up with since nobody seems to have a flush process for the tranny.
I'll ADD 1 quart of MMO (Marvel Mystery Oil) to the fluid that's already in there, run it through all of the gears for 5 or 6 miles until it's warm then drain.
Then I'll refill with 3 quarts Pennzoil synchromesh, 1 quart MMO, drive across town going through all of the gears, then drain. Regular synchromesh fluid is NOT okay to use in the transmission for any length of time because it will sheer down faster than the synthetic, but it will be fine since I'm only using it to flush the transmission.
Drain for the second time, then refill with 5 quarts Redline MT-85 which is a NEW lubricant from Redline designed specifically for the NV4500.
Capacity is 4.25 quarts, I'm going to over fill by 3/4 quart by using 5.
My goal is to remove all of the contamination from previous burnt gear oil and all wear metals that are present in the transmission. The MMO will thin the old fluid that's in there and break surface tension before the initial drain, then it will act as a cleaning agent when combined with fresh synchromesh the second time around.
I will report back and let you know how effective this flush is.
The Redline probably won't be here until the end of the week, so it is a project for next week-end.
---AutoMerged DoublePost---
I'm going to do a fluid change in the nv4500 also.
This transmission has a lot of miles on it and is starting to develop synchro problems, so I'm going to use a process to flush it in an attempt to clean up the synchronizers.
What I'm going to do is a 3 step process I've come up with since nobody seems to have a flush process for the tranny.
I'll ADD 1 quart of MMO (Marvel Mystery Oil) to the fluid that's already in there, run it through all of the gears for 5 or 6 miles until it's warm then drain.
Then I'll refill with 3 quarts Pennzoil synchromesh, 1 quart MMO, drive across town going through all of the gears, then drain. Regular synchromesh fluid is NOT okay to use in the transmission for any length of time because it will sheer down faster than the synthetic, but it will be fine since I'm only using it to flush the transmission.
Drain for the second time, then refill with 5 quarts Redline MT-85 which is a NEW lubricant from Redline designed specifically for the NV4500.
Capacity is 4.25 quarts, I'm going to over fill by 3/4 quart by using 5.
My goal is to remove all of the contamination from previous burnt gear oil and all wear metals that are present in the transmission. The MMO will thin the old fluid that's in there and break surface tension before the initial drain, then it will act as a cleaning agent when combined with fresh synchromesh the second time around.
I will report back and let you know how effective this flush is.
The Redline probably won't be here until the end of the week, so it is a project for next week-end.
Last edited by Gunmetal; 01-17-2011 at 02:58 AM. Reason: Automerged Doublepost
#20
I had an updated mainshaft.......most up to date nut possible.....all the works put about 600 more dollars in tht tranny includeing input shaft.....lasted 8 months nut backed off again.........dont let ne1 tell u ther is a reliable fix, that piece to slip over the splines would b the best tho, ive welded mine all the way around if u do research on metals u know how to weld them, i heated mine up to 450 deg tig welded it all the way around with some 309 and its been a year and a half and i pull my 18,000lb trailer in 5th gear bcause of my 4:10s and have put close to 50,000 miles on tht tranny, ive had my share of metallurgy classes and its my profession dont tell e i cant weld it....