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78 BRONCO RANGER XLT -351M-C6-NP203 TO 205 SWAP -9IN 3.50 REAR
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98 Posts
Discussion Starter · #1 ·
Hi guys -It has always seemed in the 34 years of owning my 78 (truck came with the wife)-married into it-
I have always remembered having that dreadful "R" clunk!.

In all these years of ownership-blood sweat and tears I have had the>>
-Engine rebuilt-351M
-C6 rebuilt
-OEM SWAPOUT of 203 to REBUILT 205(all seals replaced Only)
-BRAND NEW -double Cardan JOINT with Driveshaft /Slip and U joints
-Pulled Carrier 9 inch-Sent out for Inspection and Backlash adjustment

-As of June 2020>>
BRAND NEW -Yukon Axles and Bearing Kits
BRAND NEW- Rear Shocks
BRAND NEW- All Rear Brakes /Wheel Cylinders /Hardware-Drums Turned
BRAND NEW- SUMMIT Center caps and Gorilla nuts**

-can someone PLEASE tell me why it still clunks when put into REVERSE???
Are they suppose to -the wife (original owner) says -"Oh it always did that?"

I'm thinking worn part in T-case or C6-that might of gotten overlooked???

ALL INPUT WELCOME!! (y)

164714
164715
 

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78 BRONCO RANGER XLT -351M-C6-NP203 TO 205 SWAP -9IN 3.50 REAR
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98 Posts
Discussion Starter · #3 ·
Normal to have some at the diff. Ring and pinion backlash is what you hear
no worries
So all you guys have it!!-and its just not mine only!!??- Ok lets hear from all 78 79 owners-Please chime in and let us know that you have the Clunk -and have learned to live with it😣 ---------thanks Gondal
 
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So all you guys have it!!-and its just not mine only!!??- Ok lets hear from all 78 79 owners-Please chime in and let us know that you have the Clunk -and have learned to live with it ---------thanks Gondal
Yes happens in my 78, was concerned at first but its normal


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1978 Bronco Ranger XLT, 400/C6 92 K documented miles &1994 Bronco,XLT 85K original miles
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1,069 Posts
I have a '78 with 93K on it and never noticed it. Now you got me thinking... I'll update this weekend when I'm home/drive it. Great ownership story.
 

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78 BRONCO RANGER XLT -351M-C6-NP203 TO 205 SWAP -9IN 3.50 REAR
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98 Posts
Discussion Starter · #7 ·
I have a '78 with 93K on it and never noticed it. Now you got me thinking... I'll update this weekend when I'm home/drive it. Great ownership story.
Thanks Desert!-let us know
 

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1984, 300 L6, smogless, manual 3speed with overdrive.
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My 86 one ton 2wd does it 460-C6 my FSB does not 300-manual
 
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I might add
My 78 used to clunk into R when it had the C6
When it got the np435 clunk went away
My 79 with the C6 clunks into R
Had a 70 Plymouth that clunked intoR it was an auto too
 

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78 BRONCO RANGER XLT -351M-C6-NP203 TO 205 SWAP -9IN 3.50 REAR
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98 Posts
Discussion Starter · #11 ·
Maybe it has something to do with the C6????-maybe it does have a bit of play -enough to cause the clunk?????
 

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my 302 w/ C6 does it, just posted about it today lol.
 

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78 BRONCO RANGER XLT -351M-C6-NP203 TO 205 SWAP -9IN 3.50 REAR
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98 Posts
Discussion Starter · #14 ·
Let me guess????- you have a C6?????
 
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I've had my 78 for 9 years now... it had a clunk until very recently...

Back when I had the 351M/C6/NP205 it would clunk into R, and it would clunk going back into D.

After swapping out the running gear to 4.9L/ZF5/BW1345, things got a little different... I could feel a clunk every time I got on or off the throttle, regardless of what gear I was in.

I recently swapped out the rear axleshafts and diff. The ring and pinion that I pulled out had respectably little backlash for the age. Nowhere near enough to account for the tremendous slop that the pinion had with driveshaft removed and both wheels on the ground. The probem in my case was heavily worn splines on the shafts AND in the side gears of the open diff. Having addressed that, the whole deal feels tight now, in all gears.

Just because a shop set up your gears correctly, doesn't mean that the diff is any good. 42 years of abuse can beat steel up pretty good.
 

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78 BRONCO RANGER XLT -351M-C6-NP203 TO 205 SWAP -9IN 3.50 REAR
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98 Posts
Discussion Starter · #18 ·
I've had my 78 for 9 years now... it had a clunk until very recently...

Back when I had the 351M/C6/NP205 it would clunk into R, and it would clunk going back into D.

After swapping out the running gear to 4.9L/ZF5/BW1345, things got a little different... I could feel a clunk every time I got on or off the throttle, regardless of what gear I was in.

I recently swapped out the rear axleshafts and diff. The ring and pinion that I pulled out had respectably little backlash for the age. Nowhere near enough to account for the tremendous slop that the pinion had with driveshaft removed and both wheels on the ground. The probem in my case was heavily worn splines on the shafts AND in the side gears of the open diff. Having addressed that, the whole deal feels tight now, in all gears.

Just because a shop set up your gears correctly, doesn't mean that the diff is any good. 42 years of abuse can beat steel up pretty good.
thanks for that info Derek- good to know!!!- I'd like to think its in the 205 with mine-I swapped out the full time 203 with a 205 from a 79-was told the case is bulletproof and to do just a seal kit only on it.-Maybe its a worn gear or spline???
 

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1982 FSB 302, c6, BW1356 manual, manual hubs, manual windows, 3.00 gears, 31x10.5 Kenda A/T
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I'm in the C6's do it crowd. This is my 4th (73 76 91 82) every single one of them clunked into reverse and lightly on hard downshifts.
 

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78 BRONCO RANGER XLT -351M-C6-NP203 TO 205 SWAP -9IN 3.50 REAR
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98 Posts
Discussion Starter · #20 · (Edited)
I'm in the C6's do it crowd. This is my 4th (73 76 91 82) every single one of them clunked into reverse and lightly on hard downshifts.
Thanks Harry-it sure seems to look that way-and possibly the 205 now (n)
 
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