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Not quite a year ago had my '85 240 professionally converted from auto to 4 spd/OD. Best decision ever made. One problem I noted at the time here, the manual OD is less than the auto's OD ratio (.79 vs .69). Hence, I lost about 7 mph cruise speed. At a fairly quiet 2600rpm with the auto, it was 75mph. Now with the manual it's about 68. My car has the 3:73 gears, needs the 3:31. Cruising 75 now is rather noisy at 3000rpm. The Bentley doesn't even mention changing rear gear sets, assuming it's a huge task or not possible outside a dealership. Not like US cars where you pull the axles and pull the third member and stick another in. Do I assume the only way to go to the higher ratio is to change the whole axle assembly for a 3:31? That looks rather daunting in disassembly/reassembly though probably doable in my garage just not sure I'm up to it. Hmmm. Any thoughts?
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Theres a lot of good advice on rear end mods, swaps etc. Since you have a manual shift, have you considered installing a T-5 trans? Depending on the year you can have either a .63 or .68 overdrive.
I have a T-5 with the .63 mated with a 4.10 rear (in a 122S/B230 swap) Lots of zip in the lower gears and a very comfortable 2500 rpm at 70 mph.
Gas mileage? Last spring I got 35 mpg from So Cal to Portland for the IPD show.
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TR, I've not heard of the T-5 trans. Is that a rear drive trans? How does it differ from the M47 5 speed? Is it a bolt-in replacement for the M46? With my setup just a year old and with a new clutch at the time and a new rear main oil seal, I'm not ready to go through a trans swap again. I'd rather concentrate on the rear gears. Still trying to find the time to research the parts and process to change them. As much as I like the 3.73's performance, the way gas is destined to go, I'm heading towards the gear change to the 3.31s. If I can pull it off. But thanks for responding and for the suggestion.
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Mr. D
I have an 86 245 that runs at 2800 rpm at 73 mph. I've checked the speedometer(out of a sedan) against the GPS to confirm the speed. On that car, I am using the tires and wheels from an 88 765 so 15" as opposed to the 14s that came on the vehicle(I am assuming a 3.92 on the wagon, but don't know for certain. It certainly out jumped the 765 with the same engine). You could up the tire diameter to compensate for the difference between a 3.54 and a 3.31 gear.
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Again, thanks for all your suggestions, guys. Still contemplating some sort of a gear change. Time is the problem. Too much on the "plate" as with all of us. Gas is still stable in Southern CO but I'm sure it's due to rise with the other parts of the country. If I can find a 240 in my local yard with a 3.31 I may go further into the assembly change. Or I have a local shop that is very competent that I may approach for their opinion, too. It's a work in progress, as always. Thanks again.
Roger
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hello
its not really bolt in. need a adapter at the engine side then a custom driveshaft i believe.
nice if your making more power.
then there is the getrag tranny swap some use but not bolt in either.
i suggest just swap the whole axle. driveshaft alignment is important.
good luck
Mike
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To answer your question about the T5--it a transmission made by Borg Warner--used in cars like the Mustang and Camaro starting in the mid-80's. The T5 is a very nice shifting tranny with some long and longer top gears available. It was my answer for an auto to standard shift conversion in my VolvOldsmobile V8 245. It doesn't sound like your answer.
If you would need to have a shop make your lower gear rear conversion ($$$)---why worry about what will fit your housing? Pay them instead to swap out an entire rear if you aren't sure about doing it youself. That job is very doable by a DIY'er if you decide to go that way. -- Dave
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hello
i considered the t-5 swap before i did the M-47 swap but not for very long.
went with the less expensive bolt in application.
your setup seems like a good one.
thanks
Mike
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hello
i installed a m-47 in my 940 turbo and the gas mileage went up 1 mpg.
didnt like the gearing with the 3.73 so i found a 960 w/3.31 gears and pulled the whole rear end and swapped it in my car in the driveway (4 hrs) and this added another 2 mpg. 240 will be a little more work to swap i believe.
so i can get 27-28 hyw driving easy.
my 940 turbo wagon gets 23 mpg hwy.
i drive 430 miles/week just to get to work so the savings adds up with the manual.
sold the guts to the 3.73 and the auto tranny and actually made money on the swapping of parts. labor was all me and i work cheap here at home.
good luck
Mike
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Changing a ring and pinion is not a difficult task for a good mechanic. You can probably find everything that you need by doing an internet search on the subject. I found a list of parts at http://www.ringpinion.com/Diffwizard.aspx , one of the ads that runs on this site. It seems that with the 3:73 rear axle, you could go 3:91 or 4:10 with the same carrier, but changing to 3:31 or 3.54 will require a carrier change.
If you want to make your ride jump, put a 4:10 unit in there. Not only will it be much quicker off the line, it will be easier on clutches. These little tractor motors seem to be more efficient when they are revved close to the power band.
Regards,
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Big Harry, I accessed the link you provided to the rear-end site. I can't find anywhere that they provide 3.31 ring and pinions. The lowest (numerical) is a 3.54 which isn't geared high enough to give me that RPM drop I desire. I will contact them and see what they might recommend. Also, there's a driveline specialty shop in Colorado Springs that may offer some solutions. At this point, I'd rather have pros tackle it.
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posted by
someone claiming to be volvoid
on
Wed Feb 8 09:00 CST 2012 [ RELATED]
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I've had similar thoughts because I have a 1983 245 intercooled turbo that was professionaly converted from auto to manual before I bought it, leaving me w what should theoretically be a 3.92 rear end. It's nice and spritely around town, but I've also considered moving to a 3.73 or even 3.54 for lower highway rpms. Does anybody have any thoughts about how much this would improve mpg at highway speeds? I get between 23-26 mpg driving between 60-70 (68/70 mph = 3100 +/-rpm) Assume a speedo conversion would be necessary, as well?
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Way back, during the last gas crisis (long lines at the pump) in the 1970's, there were all sorts of advice being offered. Two in particular stood out:
One was that the torque peak rpm should coincide with the speed at which you're usually driving (your comfortable highway speed).
The other is that you should drive at the lowest rpm where the engine doesn't feel like it's lugging.
I tried both when I was in my manual transmission's Honda (5-speed). The second was completely boring (I tried driving at about 40 mph in 5th), and I'd have to shift down for any little hill.
I think that the first made sense when you factored in speed (how long it took to get someplace) -- mileage was a little less than the first method, but at least it didn't seem like I was on the road for days at a time :-).
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Big Harry, thanks for the link and suggestion. Ah, a 4.10 would definitely give my 240 more dig but that's going in the opposite direction from where I desire to end up. My car is buzzy enough nearing 3 grand. That would only make it worse, though I understand your reasoning. Under different circumstances, it may be a consideration, but not at this point. A chunk of my commuting is on the freeway and I need less RPMs. I enjoy the performance of the 3.73 gears, but I need to drop the cruise RPMs at this point. I will definitely look into that link for more information. It may be a way for me to go if the job isn't too complex. The negatives center around my work schedule. My plate is full enough that I don't relish adding another project! Thanks again to all for your input. Glad to have the Volvo family around for support. It means a lot to hear from others who have "been there done that".
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Sounds like you are nervous about swapping the entire rear.
Not sure of your capabilities but you should really slide under there and eyeball what has to be disassembled and reassembled. Not a whole lot.
Laying under the car looking around will probably build up your confidence.
If you have 1/2" drive tools with a breaker bar, you should be able to disconnect everything you need to.
Jack stands at the Rear lift points and a floor jack for supporting the Axle Diff.
The scariest thing I would be worried about is IF the Brakeline will come lose.
Take the Brakelight fuse out of the car, push the Brake pedal down and hold it down with a chunk of wood wedged between Pedal and Seat. That will keep the Brake reservoir from emptying. Making Bleeding a snap.
--
'75 Jeep CJ5 345Hp ChevyPwrd, two motorcycles, '85 Pickup: The '89 Volvo is the newest vehicle I own. it wasn't Volvos safety , it was Longevity that sold me http://home.lyse.net/brox/TonyPage4.html http://cleanflametrap.com/tony/
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Tony,
I have pretty much all the tools I need, 1/2" as well as metric open ends, box, etc, compressor & impact w/sockets, jacks and stands. It's just the extensive disassembly. Mainly the parking brake cables and losing fairly new axle bearing and seal a year or so ago. I'll have to see if my local foreign salvage has a nonturbo manual, at least an '85 the same year that has a readable tag to tell me it's a 3.31. Probably won't be expensive as they treat me pretty well. I'm just not looking forward to the job! But a quieter cruise would be nice, plus slightly better mileage. No pain, no gain as the saying goes! Thanks for your input.
Roger
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Maybe you can keep the cables from the 'new' axle. Just disconnect at the Trani Tunnel.
Just a thought.
Good luck
--
'75 Jeep CJ5 345Hp ChevyPwrd, two motorcycles, '85 Pickup: The '89 Volvo is the newest vehicle I own. it wasn't Volvos safety , it was Longevity that sold me http://home.lyse.net/brox/TonyPage4.html http://cleanflametrap.com/tony/
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I'd just buy an entire rear axle from a salvage yard. Should be cheap and easy.
Otherwise, take your rear axle to some place that specializes in this sort of work. Jeeps use a very similar differential, so a place familiar with Jeeps would do.
Changing a diff is not rocket science, but there's not much room for error... and errors are costly.
-Ryan
--
Athens, Ohio
1987 245 DL 324k, Dog-hauler
1990 245 DL 142k M47, E-codes, GT Sways/Braces, Dracos, A-cam
1990 744GLE 189K 16-valve
1991 745 GL 304k
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My experience with differential gears has been limited to a bygone era (i.e., on domestic hot rods of the 50's, and some '60's, when I was a teen), but unless there's been a whole change in the way differentials are put together, changing the gear sets in a diff is not a do-it-yourself project: it requires the proper set of shims, and the use of dye indicators and someone experienced who can interpret the dye marks, to know what shims to use and where to place them, if you want it done right (i.e., one that won't cause excessive noise or wear).
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My thoughts are along the same line. Big job, not something to rush into. Changing the gear set requires precise tooling and settings. Pulling the assembly to do that next step seems overkill when I'd have to pull it anyway to put in a salvage 3.31 so I'm thinking in that direction. Less hassle overall. And I may just choose to live with it, though it's not exactly the outcome I'd expected. Still don't get why Volvo made the manual OD a different ratio from the auto. Doesn't make sense. Thanks for the input.
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I believe your rear end is basically a Dana unit much like that used in Jeep, Ford, etc. so a change in ratio is possible. However, you would very likely find that to procure the parts to do it would be more expensive than just hunting down a complete 3.31 axle at a wrecking yard. On some of the Dana's, you can only change the gear set to a certain point and then you have to switch to a different carrier, but I don't know where that break occurs. A search of some of the Jeep forums would give you those details.
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Thanks, Chris, yes it would be more expensive than I'd care to get into rather than go through the process of installing a salvage unit. Seems like a big project beyond R&R an axle unit. As I said to Ryan, I may just choose to live with it or I may dive into getting a 3.31 unit from my local Volvo salvage yard. They kid me that they keep their old Volvos around just for me, lol! I'm not looking forward to all of the disassembly of the rear suspension and parking brake stuff, but to get the end result of a quieter cruise, it may be worth it. I'll have to decide. Thanks again for your input.
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