We maybe getting a 11 f750 ford with a 6.7 cummins. Currently has a 6 speed eaton in it. My question is is there any 10 or 13 speeds that would be half way easy to swap in it. It has a hydraulic clutch. Thanks for the insite
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Transmission swap
- Thread starter Tyler d4c
- Start date
Mike L
Senior Member
I toyed with the idea when I was dealing with my transmission issues. Did the 6 speed fail or are you just looking for some different? I think (correct me if I’m wrong) but as long as you have the correct bell housing and input shaft size you can put anything in that you want.
Junkyard
Senior Member
It can be done....I’m not exactly sure how many variables there are. Bell housing, input shaft size (OD and spline), air to operate the trans, driveshaft yoke size, driveshaft length,crossmember location if needed, physical space for the trans depending on location of air tanks, exhaust etc, might need a different PTO if it has one. @Truck Shop knows those boxes well, he can probably rattle off two or three good options.
Truck Shop
Senior Member
For a 10 or 13 spd your looking at a 6610 or 6613 and used take outs are stupid in price-reman price is stupid also. #1 bell housing depending on what you have now which taking
a guess Eaton 6306.
a guess Eaton 6306.
Supply and demand, there's thousands of the bigger boxes coming out of "retired" or wrecked big rigs. The trick might be to find a box truck with the transmission you want in it, buy the whole truck for pennies and part the rest?
Truck Shop
Senior Member
Problem is nothing is going for pennies, those small Eaton 10's and 13's are getting hard to come by. Some years back Eaton started chipping the older gear boxes to get them
out of the system. And with everyone wanting to avoid trucks with emissions all those old parts including gear boxes the prices have climbed drastically on tier 2-1 and old.
out of the system. And with everyone wanting to avoid trucks with emissions all those old parts including gear boxes the prices have climbed drastically on tier 2-1 and old.
Yup. I suppose with all the auto-shifts these days, it's mostly the vocational rigs like dumps and loggers that are ordered with full manual boxes anymore? I've been away from the big rigs for about thirty years now so obviously I'm not up to date on trends, lol. 3406B was the last one I thrashed for a bit.
Truck Shop
Senior Member
Well the 3406B was the last of the good ones.
I jist absolutely hate the 6 speed ive drove the truck before and it way to gappy for my taste. By the sounds of it ill just have to get to lookin ill have to see what the transmission model in it now is
You will get no argument from me!
How about a two speed rear axle? I was looking for a light two or three speed Brownie (auxiliary) but damn if those things aren't scarce as hen's teeth and gold plated! I gave away a sweet three speed thirty years ago, I may have to go find it!
crane operator
Senior Member
I don't think I'd change anything until after I had it 6 months, and you see if you can possibly live with the 6 speed. It will take twice as much work and twice as much $$ as you think it will to swap.
Every issue that Junkyard mentioned is going to be a problem, and there's probably 4 more that will show up mid project.
Looks like PTO to get figured out and I don't know that that slave will handle a bigger clutch? I think I'd also look pretty close to see how the gauges are hooked up/ signal for speedo and tach.
When you go looking for trans, keep in mind that some have a more forward or rearward shifter location, and I'd kind of do some measuring before I went looking so you have a idea of bellhousing to floor opening length.
I think I still have a old small box 6613 in the back room, but I'm sure it needs totally gone through.
Any idea what the first and final ratio is on the existing box? And the rear gear set? Just to see if its some super deep OD and a 5 something rear. Or a more standard rear ratio.
Every issue that Junkyard mentioned is going to be a problem, and there's probably 4 more that will show up mid project.
Looks like PTO to get figured out and I don't know that that slave will handle a bigger clutch? I think I'd also look pretty close to see how the gauges are hooked up/ signal for speedo and tach.
When you go looking for trans, keep in mind that some have a more forward or rearward shifter location, and I'd kind of do some measuring before I went looking so you have a idea of bellhousing to floor opening length.
I think I still have a old small box 6613 in the back room, but I'm sure it needs totally gone through.
Any idea what the first and final ratio is on the existing box? And the rear gear set? Just to see if its some super deep OD and a 5 something rear. Or a more standard rear ratio.
Mike L
Senior Member
That’s the same transmission that’s in my kenworth. 1st gear is almost a granny low gear and 4th to 5th seems like the ratios are a bit far apart. I’m not in love with it but as long as it stays together I’ll deal with it.
Truck Shop
Senior Member
http://www.roadranger.com/rr/ProductsServices/ProductsbyCategory/Transmissions/PCT_486870
6610 & 6613 don't have forward covers. Your FSO 8406 has wide ratio pretty standard for those gear boxes.
even if you put a 7 speed in it top holes are 1.00 to 0.75. Just not enough balls under the hood for the split.
The clutch is a stamped steel 14" the slave would work because that's as big a clutch as it will take.
But it's a ton of work.
6610 & 6613 don't have forward covers. Your FSO 8406 has wide ratio pretty standard for those gear boxes.
even if you put a 7 speed in it top holes are 1.00 to 0.75. Just not enough balls under the hood for the split.
The clutch is a stamped steel 14" the slave would work because that's as big a clutch as it will take.
But it's a ton of work.
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I already drive the truck from time to time I hate it it so far the only major problem keeps coming back to the clutch there seems to be plenty of room under the cab to accommodate shift tower location speedo is definitely a trouble hopefully if I put study in to it it won't be to awful.
crane operator
Senior Member
I figured you would know.
So its only the big box 9 10- 13 etc. that have a forward?Isn't it in the letters of the box- instead of a RT XXXX its a RTF XXXX for the forward shift location boxes?
Truck Shop
Senior Member
Keep in mind the RTO 6610 has a top ratio of 1.00 to 0.75 roughly the same. take a good look at the link I posted.
Truck Shop
Senior Member
I figured you would know.
Isn't it in the letters of the box- instead of a RT XXXX its a RTF XXXX for the forward shift location boxes?
That is correct. The 66 series has a shorter front section than a full size box so no gain on making two covers just bend the shifter to fit.