Trans to Rear Coupler Play

[161L]

Well I put the engine in the FED this weekend.  It has been awhile since I have had a car that uses a coupler between the trans and the rear end (my RED has a four link and a drive shaft) and I am looking for some guidance on how much play I should allow when setting up the coupler.

The car is a 200" S&W FED with a long powerglide and a ford 9" rear.

Any and all help is appreciated.

Steve

[fuel749]

I usually go with an 1/8" or so

[arush]

Strange Engineering recommends 1/8" to 3/16" end play.

[rooman]

^^^^^^ Yep!

Roo

[161L]

I appreciate the replies.

I'll post some pictures once I get further along with the project.

Thanks again

Steve

[Curly1]

Thanks for that information I will be building a front engine dragster by end of year.

[Draw 3D]

Just a little note from my experience; I used to run 1/8-3/16 gap but my rear seal kept leaking out fluid and the rear bushing would show signs of burnishing and wear. Increased the gap to 1/4-5/16 and since then no runs, no hits and no errors.

[dusterdave173]

I am a novice and when I built my car from scratch that coupler worried me more than any part of the build--I wound up with about 3/16ths plus It takes a pair of channel locks to slide it fore and aft--it ain't sloppy laser perfect lined up  but...after engine trans in and out and after many runs it looks great with no odd wear or marking at all it works beautiful  I am sure it could be a little better done but it has to be about as good as any and it looks to be happy--I say who knows what it is doing with some Torque on it
Now I worry about what is really important    The Groove!

[JrFuel Hayden]

Our coupler/driveshaft slides in/out by hand, no tools needed, it could be you need to adjust/ make different motor mounts. Just try putting a jack under the front of motor until the coupler slids easy, then you'll see what needs to be modifyed with your front mounts.

Cheers,
Jon

[dreracecar]

I am a novice and when I built my car from scratch that coupler worried me more than any part of the build--I wound up with about 3/16ths plus It takes a pair of channel locks to slide it fore and aft--it ain't sloppy laser perfect lined up  but...after engine trans in and out and after many runs it looks great with no odd wear or marking at all it works beautiful  I am sure it could be a little better done but it has to be about as good as any and it looks to be happy--I say who knows what it is doing with some Torque on it
Now I worry about what is really important    The Groove!

Is that a "WORM" chassis??

[dusterdave173]

No room to get your fingers on it  it slides easy as pie just have to grab it with something--it has stayed put and worked out well even after a few in and outs and yes it is the dreaded Worm --so me and my neighbor both have one and just keep making lap after lap  service on the engine trans is a PIA but really otherwise it has been a great piece cheap as dirt since there are so many of the chassis out there bare and calling out for someone to finish  yep he sells a "dream kit"  he sold about a hundo of them so ......they are out there
I don't give a @#%& who don't like it   I love mine and yes there are many other and maybe better units out there but after finally getting it dialed in she runs like a bracket car and the car works very well, handles great and mine goes nice and straight--the .095 was easy to make nice welds and probably will hold up well as time goes on

[PSweeney]

if you have any binding on your coupler, it'll hurt something, either pinion support, tail bushing, or the coupler.  It needs to be aligned so it slides easy.  You might need to add turnbuckles to the rear of the trans for fine adjustment as it's literally half a turn on a 3/8unf thread from binding up.   If you have no trans mount, a 1/4in 6061 motorplate isn't ridged enough to hang the trans from unsupported and it won't slide free unless supported. 

[rooman]

if you have any binding on your coupler, it'll hurt something, either pinion support, tail bushing, or the coupler.  It needs to be aligned so it slides easy.  You might need to add turnbuckles to the rear of the trans for fine adjustment as it's literally half a turn on a 3/8unf thread from binding up.   If you have no trans mount, a 1/4in 6061 motorplate isn't ridged enough to hang the trans from unsupported and it won't slide free unless supported.

I disagree re the mid plate. If the motor is not bolted to the other side maybe the plate could flex enough to cause a problem, especially if the frame is excessively wide or the top and bottom rails don't have much vertical spread and are low relative to the crank centerline. I never run a trans mount in my cars and never have problems with binding. In the case of a car where the trans coupler plugs directly into the female unit on the rear end the alignment is more critical but there should not be any issues if the car is built correctly.
  I have seen issues when the mid plate is not supported correctly as in a car where the motor has been moved forward from the original location as in an old car that was not built with enough room for a transmission (right Steve? ) but in general a transmission mount is not a really good idea or necessary when you have front mounts and a mid plate. 

Roo

[hotrod316]

  who me 
let me tell you a story

[fuel749]

if you have any binding on your coupler, it'll hurt something, either pinion support, tail bushing, or the coupler.  It needs to be aligned so it slides easy.  You might need to add turnbuckles to the rear of the trans for fine adjustment as it's literally half a turn on a 3/8unf thread from binding up.   If you have no trans mount, a 1/4in 6061 motorplate isn't ridged enough to hang the trans from unsupported and it won't slide free unless supported.

I disagree re the mid plate. If the motor is not bolted to the other side maybe the plate could flex enough to cause a problem, especially if the frame is excessively wide or the top and bottom rails don't have much vertical spread and are low relative to the crank centerline. I never run a trans mount in my cars and never have problems with binding. In the case of a car where the trans coupler plugs directly into the female unit on the rear end the alignment is more critical but there should not be any issues if the car is built correctly.
  I have seen issues when the mid plate is not supported correctly as in a car where the motor has been moved forward from the original location as in an old car that was not built with enough room for a transmission (right Steve? ) but in general a transmission mount is not a really good idea or necessary when you have front mounts and a mid plate. 

Roo

I'm with Roo, never built a car with a trans mount and never had a coupler issue. For some reason it makes people awful nervous to see the trans hanging off the back of the block (especially people new to dragsters) but if they'd take a look around they'd see that it's the norm. Unfortunately, lots of people look but do not see.