TH400 issue

matt69olds

Ain’t no feeling like Oldsmobling!
Feb 10, 2008
137
0
16
A few months ago I started a thread on a th400 that goes to nuetral at WOT. I rebuilt another core, out of a 69 442. New Raybestos GPX frictions in the forward clutch, Sonnax clutch hub with bearing, new 34 element sprag, bushings, thrust washers, roller clutch, bands, etc. Took the car out for a test drive, worked flawlessly for the first 10 miles or so. Did a couple 30mph WOT, once again, felt great. Came up to a stop sign, felt a clunk, now it won’t move in any forward gear, and binds and chatters in reverse. Takes a lot of throttle to get it to move in reverse, it will roll easily forward. Obviously, it needs to come back out. Any ideas or thoughts on what might have broke? Thanks
 

matt69olds

Ain’t no feeling like Oldsmobling!
Feb 10, 2008
137
0
16
I also need to tell those in readerland I have a gear vendor in the car also. Gear vendor swears there is nothing that can cause slipping at WOT with the overdrive off. The input/output shafts are locked together by a sprag. Since I’m sitting along the road waiting on a flatbed, I decided to call them. Now they think it’s possible that the sprag to have broken, freewheeling forward, binding/chattering in reverse. I guess I know what I’m doing this weekend. . At least the engine is still running. It’s 13 degree!!!
 

dank GN

BlackArts Automotive (661)993-8277
Jan 11, 2009
3,445
398
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SoCal the high desert
Did you set the linkage properly? I believe you disconnect the linkage then set the trans to netrual then setup your linkage properly with the correct throw distance since the linkage was setup for a 4 speed it’s going to be different.
 

FASTV6HENRY

Member
Feb 16, 2012
274
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18
40
Orlando FL
I also am having the same issue you are. I have a Gear Vendors unit behind a th400 but trans does not lock up. However it does clunk into gear after i come to a stop light. I also have a rattling noise coming from what i think to be the transmission when i put it in reverse. I should mention it does not happen everytime. And i have no issues shifting its just a bad rattling noise when in reverse. I will be pulling my trans out in a week or so and taking it to my trans builder to see what the issue is. I also called Gear Vendors and they said its probably not the GV unit, but i should always shift into and out of overdrive under a load because I have a RMVB. So they don't recommend using the automatic setting because down shifting at a low speed of 35mph is hard on the cone clutch inside of the unit. I also notice the GV shift really hard/firm when going into and out of overdrive not sure if its normal.
 
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Mr.Spool

Well-Known Member
Nov 6, 2006
4,173
521
113
A few months ago I started a thread on a th400 that goes to nuetral at WOT. I rebuilt another core, out of a 69 442. New Raybestos GPX frictions in the forward clutch, Sonnax clutch hub with bearing, new 34 element sprag, bushings, thrust washers, roller clutch, bands, etc. Took the car out for a test drive, worked flawlessly for the first 10 miles or so. Did a couple 30mph WOT, once again, felt great. Came up to a stop sign, felt a clunk, now it won’t move in any forward gear, and binds and chatters in reverse. Takes a lot of throttle to get it to move in reverse, it will roll easily forward. Obviously, it needs to come back out. Any ideas or thoughts on what might have broke? Thanks
im going to give you a quote from a guy who builds some really fast 400s.dont call me till it doesnt move.from all the 400s i have seen that was a long time from original purchase,after your 10 mile problem,something was missed or setup wrong.
 
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