Spicer 4-speed shifting

[richard5933]

The manuals that came with the coach were Maintenance Manual X6814 with the Supplement 7014 which covers the 4108. They don't mention the parts you're talking about. How do I know if I've got the correct manuals?

[TomC]

I had a friend in the early 80's that ordered a Peterbilt with a 6 X 4 both overdrive. I got the model numbers of both transmissions and made a table for him with all possible ratios. Even though theoretically there were 24 gears, believe it or not, 10 were either repeats, or so close you couldn't really use them-so only 14 speeds progressive. I'll take an Eaton 18spd Roadranger any day with a true 18 speeds progressive. Good Luck, TomC

[chessie4905]

They don't mention it in mine either, but the individual parts are shown in trans breakdown. These parts are at the end of the countershaft toward output shaft yoke. Pull the cover to verify.

[eagle19952]

Yeah- the tap thing that you lift to adjust- at he back -I've followed procedure and its reached the limit of adjustment.

Sometimes even when stationary with clutch depressed, it doesn't want to go into first. It doesn't slip yet but I fear a new clutch will be needed soon.

does this have a clutch brake disc ?
some had a one piece that required the transmission to be removed. there is a two piece replacement  for these situations.
we used an air chisel to remove the one piece..

Haldex Midland BK313 Hinge 2" Clutch Brake



https://www.vehicleservicepros.com/directory/brake-service-and-tools/product/12084155/kiene-diesel-accessories-inc-clutch-brake-cutter-no-k1360

[Dreadnought]

does this have a clutch brake disc ?
some had a one piece that required the transmission to be removed. there is a two piece replacement  for these situations.
we used an air chisel to remove the one piece..

Haldex Midland BK313 Hinge 2" Clutch Brake



https://www.vehicleservicepros.com/directory/brake-service-and-tools/product/12084155/kiene-diesel-accessories-inc-clutch-brake-cutter-no-k1360

When I was at that place in Williams CA, the older guy said "It's a push type clutch, twin plate, 15 inch diameter with dry clutches. " if that answers your question.

I don't know if it has a clutch brake. Bevans- do you know if it has a clutch brake? I imagine it's virtually the same set up as yours

[eagle19952]

iirc most twin discs i had were equipped with a clutch brake..this is what lets you into first gear with the input shaft turning at idle.
maybe a/his bus does not have this.
just posting possibles 

[DoubleEagle]

I have an air throttle on my 1975 Model 05 Eagle with the Spicer 4-speed, and I have gone up and down the gears all over the US. It will take time, but follow RJ's guide and practice. You can shift into first while still moving as long as you are within the range of that gear, you just have match the revs needed to get in. On steep grades, there might be times you need to use it. I have not used an oil clutch, so I can not speak for the difference, but obviously it has worked for others.

[chessie4905]

If he removes the cover, he can be sure. Plates can be removed or replaced easily. One piece.I think they are held with snap rings. Several years ago, I swapped out a worn out set for a good set quite easily. There is no clutch brake. It uses a countershaft brake instead. Regular clutch uses two very large auto transmission clutch plates apply and floater plate. Whole setup runs in oil. Hard to burn unless you get crazy. Very little travel required to engage or release. Pressure plate is diaphragm style with multiple fingers. BTW, clutch looks a lot like the style that was used in 4104 Hydrashift setup.

[bevans6]

MC-5 does not have a clutch brake, or a countershaft brake.  It would solve a world of problems if it did.  It does have a 15" dry twin disc Long push type clutch.  I was looking at mine this morning...     On mine I decided the dragging/won't shift into first issue was worn splines on the input shaft to the transmission causing the plates to hang up.  Worse when the plates got hot and seemed to swell a bit and drag worse.  I spent a few hours trying to design a countershaft brake but never tried to actually do it.

Brian

[Dreadnought]

MC-5 does not have a clutch brake, or a countershaft brake.  It would solve a world of problems if it did.  It does have a 15" dry twin disc Long push type clutch.  I was looking at mine this morning...     On mine I decided the dragging/won't shift into first issue was worn splines on the input shaft to the transmission causing the plates to hang up.  Worse when the plates got hot and seemed to swell a bit and drag worse.  I spent a few hours trying to design a countershaft brake but never tried to actually do it.

Brian

That sounds like mine. Very worrying....

[richard5933]

I don't know about how things play out in an MCI, but in the 4108 I'm pretty sure that getting the transmission into first gear is a universal problem. Nearly impossible to accomplish this with the engine running - I usually make sure I'm in first when I get to an intersection. If I need to let it idle to warm up usually I have to shut down, shift into first, and then restart using the neutral switch over ride. If getting into first was my only problem I'd be happy.

All that said, today's drive went a bit better. I made a point of holding the accelerator pedal down to keep engine speed up until I'd found the sweet spot and got the downshift done. Still a bit problematic on a couple of shifts into 2nd, but slowly getting better. Again, most important thing I've done is overcome my fear of slowing/blocking traffic for a moment.

[Jon]

Screw the traffic. Everybody is in a hurry and no matter how fast you can get started there is always going to be some fool that wants you to go faster.

Get a big sign to spread across the back that says "Student Driver".

[Dreadnought]

Screw the traffic. Everybody is in a hurry and no matter how fast you can get started there is always going to be some fool that wants you to go faster.

Get a big sign to spread across the back that says "Student Driver".

Or you could roll coal to encourage them to back off- easily done on a 2 stroke Detroit!

[ol713]

   HI RJ;
       Please send me that article also.  I have been grinding gears
       for a 100k miles now and still, I might learn something.
                                    Thanks,  Merle.       (MC-7  4spd)




[qu    ote author=RJ link=topic=32528.msg367813#msg367813 date=1510191042]
Richard -

Welcome to the world of GM wet-clutch 4-spd manual transmissions!!

Over the years I've seen many an experienced stick-shift jockey brought to their knees by these Spicers, so you're not alone.

Send me your email address in a private message and I'll send you an article (in .pdf format) I wrote a few years ago about shifting these beasts.

Dan -

Thanks for your kind words, they're appreciated.  See you at Q!

RJ
[/quote]

[HB of CJ]

Determining whether you have a clutch brake is easy.  Just place the tranny in neutral.  Let out the clutch.  Then quickly push the clutch all the way in to the floor while at the same time engaging 1st rear or your starting gear. 

If the shifter goes into gear without all the grinding and horrible noises you may have a functional clutch brake.  It the tranny refuses to go into gear without a bunch of grinding then it either does not work or you do not have one.

You can also use the clutch brake to quickly shift while accelerating going up hill and needing to up shift.  Considered abusive but sometimes you have no choice.  Fire apparatus comes to mind.  The mechanics frowned.

The clutch is NOT a neutral gear.