• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

MGB MGB syncro help

Share this page

S

sparks

Member
Offline
Hey guys. New to the site. I sold my '72 TR6 a couple years ago and recently purchased a '66 mgb for restoration. Usually I restore old muscle cars, but got a deal on this mgb. She grinds everytime going into second. I'm sure the syncro is shot. I have done a couple searches here and not really found any info, schematics,etc...Can someone point me in the right direction before I disassemble the trans.
Feel free to email as well...c_lehman67@hotmail.com

Thanks,
Chris
 
Chris,
Welcome to the BCF. I could probably talk you thru it if you run into a problem. You will probably need a layshaft and layshaft bearings also.(plus seals and gaskets) I think the book says to remove the shift rods and leave the block they ride in on the case. I remove it as a unit. No springs and balls to mess with that way. I have ground down a old 7/16 wrench to fit that application. Have a manual handy and i will try to write out the steps and get them to you. I plan on reworking the box in my 67 in a few weeks and that will make it a easy task to write it out without missing anything. Bob
 
Thank you so much. I did watch a video on it last night to familiarize myself with it somewhat. I am going to be placing an order for restoration parts in a week and I am hoping to have the engine/trans out this weekend sometime. I did see that the 'scalloped' gear requires a steel syncro. I will surely order that and the gaskets at least. Shame the car only has 48k miles.
I will keep an eye out for your write-up. Greatly appreciate it.
Chris
 
Do Moss or VB still offer a "kit" for rebuild? VB had one, contained all the bearings and seals, synchros too, IIRC.

Funny, I have two laygears sitting here, found 'em the other day digging thru some boxes. Internally kinda rough, thought maybe they could be sleeved to make 'em reusable. Anyone ever attempt it?
 
I don't see a rebuild 'kit' in the catalog for Moss. Just individual parts. I knew the guy I bought the car from. He works for Moss so I can ask him. Thanks.
 
There are no steel syncros in a 66 mgb box. The late 67's had a steel 2nd gear syncro but 2nd gear also has a different part number. I redid a MGA trans that someone rebuilt using just the steel 2nd gear syncro. It did not work! Doc brings up a good point. Check inside the laygear for pits or rough areas where the needle bearings ride. I have pitched several good looking laygears over the years because of just that problem. The mainshaft bearings on these boxes are pretty stout. I have seen input shaft bearings that need replacing mainly on boxes that have been sitting out in the weather out of the car. I would also order the 3? hard to remove "C" clips that hold the needle bearings in. Bob
 
Thanks for the info. The Moss catalog shows both upto '67 depending on what type of gear is in there. Looking at the outside of the trans, it has been apart before due to the gasket sealer oozing out of all the covers. Not sure what has been done internally. It works great except for the shift into second which grinds for a second before going into gear..
 
Here is how i would do the 2nd gear syncro replacement. It from memory and a bit long. If anyone finds a step i missed or has a better way to to a task feel free to speak up. Remove shift remote(4 bolts),Remove rear flange and seal,Remove tin plate and interlock,Unbolt tail piece-be sure shift lever clears shift rods at the interlocker-rear bearing is a interference fit on the mainshaft so a large hammer and 2x4 wood block will help remove the tail piece,Remove the 1'long spacer from the mainshaft and speedo drive gear.(be sure the key is still there when reinstalling the speedo drive gear!)Take a sharp chisel and mark the center bearing holder to case location (this helps when reassembling),Remove the side cover and remove the bolts and lock washers from the shift forks,Remove the 2 bolts that hold the shift rod block to the rear of the main case.(i have a 7/16 box wrench i ground down to fit this job.The block can break if you pry on the thinner areas so be carefull!,Remove the 3 rods with the block,Remove the brass shift forks,Remove the bolt that holds the reverse gear shaft,Slide the shaft out to the rear and remove reverse gear,Remove the release fork and the front cover,Remove the layshaft and let the laygear and thrust washers drop into the case,With a long brass drift i tap out the input shaft and bearing(be sure its clear of the laygear),Needle bearings will drop into the case to be collected later,From the front of the box carefully tap the mainshaft with a hammer and block of wood to remove it from the case.You will have to slide off the sliding hub assembly along with 3rd and 4th gear syncros to remove the main shaft from the case. Be sure to note which is front on the sliding hub assembly!,Then lift out the laygear and front and rear thrusts washers,Now collect the 3/4"long needles bearings from the bottom of the case.Next step is to put the main shaft straight up in a good vise.There is a pin and spring just visable.You have to depress the pin into the mainshaft and rotate to collar to remove it.I use 2 small picks or probes to do this.Once you rotate it it takes some wiggling with the picks to remove it,Slide off brass parts and then 2nd gear to access the syncro.I have not found a easy way to remove the "C" clips inside the laygear.I put the laygear in a vise protected with wood strips and use two small picks to remove the clips.Have you pot of coffee on and be sure small children are not where they can hear you. When assembling i install the laygear and thrust washers into the case and run a small wire thru to hold the thrust washers from dropping out of place, Reassemble in reverse order,Grease the inside of the input shaft to hold the needle bearings in place while assembling. When bringing the laygear back into position i stand the gearbox on its tail and insert a long screwdriver thru where the thin wire is.Remove the wire and try to align the layshaft and thrusts with the holes in the case.Install the layshaft with the notched end toward the front.Also when you put the mainshaft back into the case the chisel marks will correctly locate the rear bearing housing so the gasket and tail piece will align. I hope this helps and thanks to AlanT (who posts here)i am able to assist others with syncro changes. Bob
 
Bob said:
Grease the inside of the input shaft to hold the needle bearings in place while assembling.
Click to expand...

Long ago learned the "trick" (see Members Articles) with regard to those bearings: A small rubber band and grease to hold the needle bearings on the "snoot" of the SHAFT and bring the two together. It works reliably.


I've "cheated" with the layshaft/thrust washers by modifying an old shaft with about a 1" "extension" added, ground to shaft diameter and a rounded point. Makes the assembly a lot easier with this "pilot" shaft.
 
Aw...something new for me to try ! The only thing i want to look at before i try that is to see if you misalign the mainshaft and do not hit the needle bearings straight on could they drop off into the box. If you screw up a bit on the alignment.. with the needles in the bore of the input shaft they stay put and the input shaft can be removed and reinstalled without hunting needles in the bottom of the box. You know i gotta try it. Wish me luck i'm goin'in. Bob
 
heh.... it was "given" to me by BMC trained tech, back in the late '60's. His da' owned the dealership, they'd done dozens of 'em.
Now I pass it on after doin' dozens more. :wink:


Read the "Tale of Transmissive Tutelage" story in the Articles section. Even a ~girl~ can do it! :wink:
 
Back
Top