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Differential questions

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jcatnite

jcatnite

Jedi Knight
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I've never rebuilt a differential but can't believe it is too hard. My question regards changing crown wheels and pinions. I think I would like a 3.55 but they are getting impossible to find. I did source a crown wheel and pinion from a place in the UK (for a sizable amount of money). Can I use this gear set in my existing differential? I think they will interchange but it is a lot of money to spend on a hunch.
Thanks,
JC
 
Thanks for the response Mark. Moss Europe has them in their catalogue (crown wheel and pinion only). But I was thinking of buying it from a site called autogear.co.uk. I found it last night. Today it seems their site may be having difficulty. Here is a link to a listing site that has information about them.
https://www.kellysearch.co.uk/gb-company-61030881.html

I guess I will call them next week to see what they say. I tried to email them but it got bounced back. The botchy site and the undeliverable email makes me nervous but their price was a good bit better then Moss Europe so I'll keep them in the running for now.
JC
 
Turns out this AutoGear site also has a 3.39:1 that is supposed to fit the midget differential. Now I'm seriously considering it. I can put that one in and gain about 15% speed to rpm. That lets me put some low profile tires like 185/50 13 tires to bring the torque back in line. I would still have a bit of a speed increase but I could probably live with that.
Opinions???

JC
 
3:55 and 3:39 gearing in a Spridget wouldn't leave much oomph for acceleration. It depends on your driving styles and habits. Do you normally go for pleasure cruises with little or no spirited driving?

Moss US sells a 3.73 or 3.71 that would be about right for most driving styles, and it's probably at least a couple of hundred dollars less than importing the 3.39 or 3:55 from Autogear in the UK.

Also, consider that the weak U.S. dollar makes those UK prices awfully tough to swallow. The Brit pound is at about $1.96 US or so, such heaviliy inflated pricing for UK products, plus the shipping costs, make UK stuff almost impractical.

Let us know a bit more about how you intend to drive the car, then you might get a bit more focused input from the crowd here.
 
I have no plans for Autocross. I do get on it from time to time but mostly drive it like I am going to church. I do need to be able to get up the hills here..lol. Like I mentioned, I plan to offset some of the loss of power with lower profile tires. And yes, the exchange rate is pretty rough right now. I am hoping (as we all are) that it turns around sometime in the near future. But that is a discussion for another forum...lol.
JC
 
3rd in my midget is just a bit lower than 4th used to be with my old setup. I can hang pretty good with the 3.55. Just because you have a 5 speed does not mean that you have to drive in 5th gear, or 4th for that matter. Gear down if you need torque.
 
Thanks Kim, I was hoping you would chime in. I might just stick to the 3.55 rather than going all the way to 3.39. Neither one is happening until I get enough pennies in my penny jar to afford one...lol. Spending too much money on the daughters Jeep right now.
JC
 
I don't know what kind of motor you are using. I gave a lot of thought before buying the 3.55 gears. Max torque in the 1275 is at 3000 rpms and I was shooting for 60 at 3000. I hit it about 2800 and 3000 is closer to 65, but it holds real well at that speed on the highway. Got to take me a trip and see what I get when I get all this heat, vapor thing worked out.
 
regularman said:
I was shooting for 60 at 3000. I hit it about 2800 and 3000 is closer to 65,
Click to expand...

a five speed with a 3.9 and 175/70s it just what you were after.. actually every 1000 rpm is 21 mph, but with real world tire slip, its right there.. It's what i'm running with a 1098.
 
I'm running a 1500 with the 4 speed. I've got a fast road cam but I still think my max torque is around 3500. Right now I'm running around 16.5 - 17 mph for each 1000rpm. There aren't really any viable 5 speed options for the 1500 and I've got too much money sunk into it to change to a 1275 anytime soon. Thanks again for the advice, and I might take you up on that offer Kim. I've got family in the Salisbury/Statesville area. We get up there from time to time.
JC
 
jcatnite said:
I'm running a 1500 with the 4 speed. I've got a fast road cam but I still think my max torque is around 3500. Right now I'm running around 16.5 - 17 mph for each 1000rpm. There aren't really any viable 5 speed options for the 1500 and I've got too much money sunk into it to change to a 1275 anytime soon. Thanks again for the advice, and I might take you up on that offer Kim. I've got family in the Salisbury/Statesville area. We get up there from time to time.
JC
Click to expand...
Hey, my mom and dad are from statesville.
 
Pythias said:
regularman said:
I was shooting for 60 at 3000. I hit it about 2800 and 3000 is closer to 65,
Click to expand...

a five speed with a 3.9 and 175/70s it just what you were after.. actually every 1000 rpm is 21 mph, but with real world tire slip, its right there.. It's what i'm running with a 1098.
Click to expand...
I started wiht the 3.9 and 4 speed and it was way too low. I have 3.55 and 175/70s and the five speed and 2800 is around 60. Its just what I wanted. A 3.9 would have still been two high rpms for me.
 
JC, why not a nice D-type OD unit? With a little wedging in here and there, the OD will fit right in.

Just a thought, probably more expensive than the ring and pinion swap, but something to think about.

OD in an LBC is lotsa fun, IMHO.
 
Thanks JP, I considered the T9 mod a while back. I would dearly love a 5 speed but that mod might be a little beyond my skill level. (I'm nervous about modifying the transmission tunnel). But the main reason is, I found it very difficult to source a gearbox here in the US. I looked for the Merkur XR4ti gearboxes but they were only imported over here for just a few years.
JC
 
JPSmit said:
jcatnite said:
There aren't really any viable 5 speed options for the 1500
Click to expand...

https://www.the-wizardsden.com/html/mg_home.html

https://82.44.126.36:76/convert.htm
Click to expand...
That transmission is from the Ford sierra. They did import it to the states. Here it was called the Murcury Merkur XR4TI. You see one of those in the bone yard every once in a while. Kind of an odball car here. They used to perform well in the UK, but they had no pollution control then all high octane leaded fuel.
 
I know relatively few came over - but, they seem to be common as dirt in the UK - I wonder how expensive it would be to ship - especially if one of our UK members brokers it.
 
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