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Author Topic: Spicer standard trans, change it or not ? Is there a better standard available ?  (Read 1619 times)
scanzel
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« on: September 30, 2013, 04:21:30 PM »

I have a 6 speed spicer standard trans in my conversion, it seems to always be hard to shift gears without a lot of grinding no matter how I do it. The clutch has been replaced and the linkage adjusted but I still seem to have problems at times. I don't want to go to a automatic too $$$. Is there another standard trans out there that might be a better choice to change over to. At times after warming up it seems to shift pretty good but down shifting can be a real challenge. In two years we want to hit the road and I don't want to be grinding gear teeth all across the country. The wife has even given me a go ahead to change it if something is going the be better for me.
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Steve Canzellarini
Berlin, CT
1989 Prevost XL
Lin
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« Reply #1 on: September 30, 2013, 04:38:46 PM »

I'd say to save your money until you can do the automatic.  Aside from the cost, you will love it.  Why put a couple of thousand into something that isn't as good?  If you take some time and look, you might find a good price on an Allison. 

In the meantime, do you have a tach?  If so, learn to coordinate your sifting by the rpm.  You won't even need to use the clutch most of the time.  If you do not have a tach, it is really worth having one even if you end up with an automatic.
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Homegrowndiesel
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« Reply #2 on: September 30, 2013, 04:45:03 PM »

Drain and refill the trans oil. Check the proper specs on the right oil for the right temp. Alot of time someone put 90 weight oil in the trans thinking they were doing right. Sure makes for some miserable driving.
  I do agree that if I was to change trans it would be to an automatic. I have an eagle with manual, and mci with auto. I have been in places with the auto that were impossible with the manual.
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Aerodynamic Eagle & MCI 102a3
luvrbus
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« Reply #3 on: September 30, 2013, 06:08:18 PM »

The Prevost has a very complex shifter I would check the u joints on the cable, the boots,bushing, cable for clamp downs ,stiffness of the cable and for worn parts on the shifter tower on the transmission they shift nice when everything is in good shape and that is a good transmission it beats a 4 speed Allison hands down IMO in that bus 

good luck
« Last Edit: September 30, 2013, 06:32:23 PM by luvrbus » Logged

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gus
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« Reply #4 on: September 30, 2013, 06:40:03 PM »

Six speeds are nice if you have a low first gear.

I sure would have liked that 6sp in my 4sp 4104!
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PD4107-152
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Ash Flat, AR
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« Reply #5 on: September 30, 2013, 07:15:42 PM »

Clifford is right.  We had an MC-9 with the Spicer 1062 6 speed in it and I loved it.  One sweet shifting transmission and the ratios were perfect.  Check everything from the trans forward.
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'81 Eagle 15/45
'47 GM PD3751-438
'65 Crown Atomic
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« Reply #6 on: September 30, 2013, 08:40:53 PM »

FWIW, some of our old fire apparatus had a Fuller T906 6 speed and if memory serves, the ratios were very very close to that of the Spicer 6 sp.  Excellent ratios indeed.  Darn near perfect in fact for the application.

FWIW (again?) My old Crown Supercoach ex schoolie had the Fuller RTO-910 and when I first got the old girl, shifting that tranny was an absolute pain in the rear.  Nothing like I remembered from years past.

Sossss, the corrective action was, like already said here now better, was to crawl under the bus with a hand  greaser.  Seems there were many pillow blocks and a few U-joints in the single big shift rod.  Each had a zert.

After I found all of them and greased them up, the shifting feel completely changed.  Now took about 3-5 pounds of effort and the shifter moved a whopping 2-3 inches.  Two finger shifting.   HB of CJ (old coot)
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TomC
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« Reply #7 on: September 30, 2013, 09:09:33 PM »

Can try switching to synthetic trans oil. The only change I would make would be to switch to the 7spd overdrive. I had that transmission in one of my trucks and it shifted ever so easily-and without an air splitter, was a no brainer. Could even pull it into 1st without the clutch (don't ask how I know this).
The best is an Allison auto. Look for a HT740. The ratio jumps for the top 4 gears are just about the same.
6spd direct- 8.53, 4.87, 3.00, 1.90, 1.33, 1.00
Allison 740HT- (7.38 torque converter + 1st) 3.692, 2.02, 1.38, 1.00.
Once you experience the Allison automatic, you'll be kicking yourself for not changing it sooner-and this from a truck driver that drove nothing but 13spd for over 1.3 million miles. Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
scanzel
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« Reply #8 on: October 01, 2013, 07:24:35 AM »

Is there a possibility that the trans is just worn. The Bus has 684,000 miles on it and I don't know if the trans has ever been changed or worked on. I will try the synthetic oil. What weight of oil should be used ? I really like the standard. An auto would be nice then I could instruct the wife to drive at times. With the auto wouldn't I have to go to a DDEC unit to work with the engine and trans.
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Steve Canzellarini
Berlin, CT
1989 Prevost XL
luvrbus
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« Reply #9 on: October 01, 2013, 07:37:50 AM »

No the World (electronic) transmission will work on a mechanical engine and the 740 transmission will work on DDEC engine,the 754CR and 755CR were a popular transmission for your bus

Your problem is just a wore out slider up front they not cheap to rebuild but Prevost has the parts and the transmission uses engine oil most have 15/40 I think it takes 41 pints or 2-1/2 gallons

 Prevost did have the option of the Spicer PS145-7A seven speed it has a very low and reverse ratio
« Last Edit: October 01, 2013, 08:15:47 AM by luvrbus » Logged

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Boomer
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« Reply #10 on: October 01, 2013, 08:59:31 AM »

Steve, with that many miles I would wager that the clutch cross shaft and bushings are worn out and could be the major source of some of your problems.  Need to pull the trans to fix that but no big deal. 

Edit, disregard; you say the clutch has been replaced.
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'81 Eagle 15/45
'47 GM PD3751-438
'65 Crown Atomic
Vancouver, WA USA
DaveNCari
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« Reply #11 on: October 01, 2013, 02:18:26 PM »

So.....would this 6 speed be able to be fitted to my 4104?

That would be so nice.....lol

Dave
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Boomer
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« Reply #12 on: October 01, 2013, 08:53:09 PM »

Nope, it is not an angle drive.
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'81 Eagle 15/45
'47 GM PD3751-438
'65 Crown Atomic
Vancouver, WA USA
DaveNCari
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« Reply #13 on: October 02, 2013, 07:24:04 AM »

Ahhhhh I was sort of afraid of that.....

If there were a 6 speed that would fit...I figure they all would have it by now.....

Dave
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jetart
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« Reply #14 on: October 03, 2013, 06:15:28 PM »

I Have a Spicer 6sp and REALLY enjoy it.  It's not synchronized like a car or light truck so you must match road speed to engine speed by blipping the throttle on down shifts and time your shifts perfectly on up shifts otherwise you get a little grind.  I use the clutch 1-2 (for silky smooth transition) and no clutch 2-5 or 5-2.  I usually double clutch going down 2-1.  I never use super low out on the road.  You may also check the clutch linkage and shift rod for grease fittings.  I don't know for a fact but i would guess the tranny takes engine oil (40-W) as my factory oil tank has two valves one goes to the engine and one to the transmission.  I check it frequently but have never added any and it always looks clean like it came out of the jug. If you know a semi truck driver that can drive your bus for a bit while you watch they can teach you a thing or two.  I thought I was doing ok until my mechanic and I took a ride (1.2M miles under his belt in his Pete) and I really got the no clutch shifting down quick with a little technique instruction. Give it some time before you swap it out, get a pro to teach you some stuff and practice.

82 Prevost 8-71NA 6sp spicer
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'82 Prevost LeMirage XL, 8V71NA, 6 speed Spicer, converter unknown
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