FrontEngineDragsters.Org Forum
Drag Racing Discussions => Front Engine Dragsters => Topic started by: 161L on March 20, 2017, 09:50:44 AM
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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
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I usually go with an 1/8" or so
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Strange Engineering recommends 1/8" to 3/16" end play.
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^^^^^^ Yep!
Roo
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I appreciate the replies.
I'll post some pictures once I get further along with the project.
Thanks again
Steve
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Thanks for that information I will be building a front engine dragster by end of year.
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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.
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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!
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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
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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??
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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
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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.
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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
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:o who me ;)
let me tell you a story 8)
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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.
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Rear trans mount is only required for a door car (or a car with suspension) where the load on the trans is not just radial. As the suspension moves and the angle of the driveshaft changed the force puts varying load on the bellhousing
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On my four link Altered the transmission is just sitting on mount and not bolted down. My new rear engine dragster was same way.
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I run a trans mount and have no issues. I run a T 400, these are very heavy and with power, cracking the bell housing is very common. I run the JW bell attached by the pump bolts 5/16. With the heavy trans the threads can be pulled out of the case so a mount is needed. I run a bi-pod mount- stand, clamped to the X the bolts are left finger tight at the trans.
Van
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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 always thought the same Roo until this car I have now. It's a shortly glide with a straight male / female coupler (not the nice in situ version). The motor was set using a line up bar and presumed aligned. When we mocked up, whatever we did we couldn't get the coupler to slide easy. We assumed alignment was off, so it was sent away again to have it re-done on the jig, new motor plate and chassis mounts reamed to the bolt shanks (with engine weight on mid plate ears). We aligned the coupler on a scissor jack so it slid easy, then made the front motor plates with saddle mounts, using transfer punches and again reaming all holes to size to take out any slop. This was closer but again it bound up. Talking to another racer with the same set up who had the same issue, we made two turnbuckles mounted off the trans rear cover triangulated down to two brackets on the chassis. We found the range of adjustment to be within half a turn on the bars and just taking up the trans weight slightly was the difference between it binding and sliding freely.
A mount may not be needed for all cars but this was the only way we could obtain the alignment. With a shortly glide close coupled we didn't have the driveshaft length to take up any angular mis-alignment. With a full length glide and a driveshaft, I wouldn't expect to use a mount either. I should add both couplers were brand new and with used / worn couplers I imagine this might not have been so much of an issue.
Heres a pic, you can just see the rod end on the rear cover
(http://imagehosting.rodsnsods.co.uk/23258da32333c123.jpg)
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The turnbuckle deal that you used is a great idea as it does not tie the trans rigidly to the frame while still supporting it. The thing that I see problems with is a solid mount that bolts the trans to the frame rigidly. In the door car field a lot of chassis kit manufacturers supply a bracket that bolts directly to the trans with no cushion. I try not to do full bodied cars anymore but in the past I have used a factory style cush mount to support the back of the transmission.
I reworked an altered a while back where the chassis torqued up off the line and tore the rear trans mount tabs off the crossmember. The car had quite a few other issues--motor mounts out in the middle of space, well away from the uprights and only a half mid plate that allowed the frame to "diamond" under torque but in this case the owner was lucky that the crappy weld failed before the transmission housing.
Roo
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It worked well for us, but it took some figuring. We remounted the whole deal three times before we settled on this. I did speak to another guy with a similar issue and he used saddles and a heavy zip tie which allowed some compliance.
I think it's really the door car guys who suffer most in this regard. Wider rear track, more torque reaction and a solid mounted trans just becomes a stressed member. Use a stock glide with a thin bellhousing and they start cracking bellhousing. Then they hack them off for a Ultrabell, problem masked.
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I would say that if you are having problems and need more than normal clearances you may need stronger engine limiters.