• Hi Guest! Being a Paying Supporter is NOT a requirement to participate at BCF. However, subscribing will help ensure we can continue to serve the LBC community for years to come. If you enjoy BCF and find our forum a useful resource...Please consider supporting us by **Upgrading**
    (PS: Subscribers don't see this banner)
Tips
Tips

Rear end crown and pinion gear swap. 4.11:1 to 3.54:1 [long read]

roscoe

Jedi Knight
Silver
Country flag
Offline
I am making the post I wish I'd found when I searched before I began the job of changing out my 4.11 rear end gears for a 3.54:1 crown wheel and pinion. Many on this forum have had this done and I'm sure if there is someone who has actually done the work themselves they will speak up. For those that may not know, the 3.54 gear set was used in those big Healeys that came without the Laycock de Normanville overdrive.
Oddly to me, many have overhauled engines and a smaller number have done gearboxes but most folks stop at changing these parts out and take these to a ring and pinion shop or at least someone who has done this before. The BN2 shop manual I have covers both the hypoid type and earlier straight or parallel spiral bevel geared differentials and some of these processes are slightly different between the two, although they both work pretty much the same. I'm only talking about the hypoid gear sets where the pinion is not in line with the center line of the crown wheel as I have in my ‘56 BN2.


There are a few tools that you have to have or make in some cases. I fabricated an axle hub nut wrench as the axle shafts have to be removed and installed to do this as I wanted to disassemble the hubs to inspect and repair as necessary and reseal them when they go back together. You don't need to pull the hubs but it is a convenient time. Since the whole differential carrier assembly comes out of the axle housing, it is convenient to do that yourself and take it to a pro shop and it really shouldn’t be very costly to have someone else do the set up if you choose that route. I spoke to some who suggested it is much easier to remove the whole rear axle assembly and then pull the differential out of the "pumpkin" versus jacking or lifting the car and leaving the axle in place. I elected to jack it and leave it in place as the thought of bleeding the brakes gives me night sweats. Brakes have been flawless since I rebuilt them. If you have good jack stands and they go high enough, with the batteries out and the drive shaft just pushed out of the way, access was pretty easy. In retrospect I would do it this way again if I ever needed to. It was not difficult to remove or reinstall the assembly if done from underneath with the rear end jacked as high as my jack stands would go. I also made a holding tool which picks up the flange of the differential housing when removed so it can be firmly put in a vise. Last, I made a tool that lets me hold the differential coupling flange so the 140 foot pounds of torque could be applied to the pinion nut that holds the flange to the pinion in front. It just picks up two of the 4 bolt holes and I can slide a long pipe extension on it. All done in a 6 inch vise.


The tools you need that you can't make are a good vernier caliper or 0 to 1" outside micrometer, a dial indicator with a magnetic base that is machined flat ( I had a dial indicator with one of those flex neck jointed things that clamps with a vise grip but those are not able to be used for the measurements needed). There is a British tool made for this but the magnetic dial indicator base at Harbor Freight was perfect and inexpensive. Another tool you absolutely have to have is something to remove the inner (rear) bearing on the pinion. The bearing has to come off if you are reusing it and if you need to adjust pinion height. It is installed such that none of my gear pullers or bearing splitter pullers would work without destroying the bearing. I happened to have bought a grab bag of British tooling from a guy years ago and never needed any of it. Low and behold the bearing puller and adapters for this part of the job were among the many tools. They are of a type I had never seen and work elegantly as shown in my photos. They allow pressing the bearing off with no stress on the bearing cage or rollers. Last, you need a special gage block to zero the dial indicator in order to set the pinion height. I also had one of these in my bin of tools. I had always wondered what it was when I came across it in my tooling. All the tools have Churchill or Mowog numbers that are called out in the manual and etched or on data plates on the tools. You could get by with knowing the dimension of the block and machining your own but you need one or the other. The height of the gage block is (surprise!) 1.000 “. If you measure the diameter of the differential support bearings divide it by 2 and add 1.000 ”, if you set your pinion height properly it should equal the number etched or other wise marked on the pinion head. This number is the nominal distance there should be between the center point of the crown wheel diameter and the flat surface of the pinion head, called pinion height. You may have to change the height if you don’t get a useable gear pattern or backlash.


Once you get the picture of what they describe in the shop manual, it is really fairly easy to set the pinion height with the correct shims, the pinion preload with a torque werench able to read 5 to about 50 inch pounds, and the gear backlash. Although they never mention checking the gear pattern I'll be doing that to check everything else. Normally that is the last thing you do when doing this on any rear end and it can be cause to readjust backlash or pinion height.


I should add that all of the bearings and races I could see and feel were pristine and I am not one to replace these just because new is thought to be better. New bearings are not always better in my opinion. I also had no measureable play in any of the gears or thrust washers that drive the axles. The old gears had an excellent gear pattern prior to removal and showed very little wear.


One thing I did notice was some gouging on the differential carrier frame from some previous knucklehead ( me being the current knuckle head) using something evil to hold the assembly during some torque operation. It had been there for a long time and remained except for my dressing the edges.


Unlike more modern set ups, pinion preload is set with shims rather than a crushable spacer. These shims are available from the usual suppliers in a variety of thicknesses, you will likely need a small selection if you are putting in new gearing. The pinion preload is very sensitive to the shimming and one or two thousandths can put you over or under by quite a bit.
There are two other shim types that are not as readily available. The ground shims for setting pinion height were not to be found at a reasonable price or variety of thicknesses. I needed to increase the thickness of mine by .005" so simply got some .005” shim stock and made a shim.

The other shimming you might need to do is for backlash. Interestingly, these shims although they used to be available in a variety of thicknesses are not to be found but are identical to the spacers that are used to pinch the wheel bearing by .004 when you install the axle shaft. Same OD and ID but they are just one of the thicknesses that used to be available. It happens that the ones I had on my axle hub bearings were one of the thickest available so these could be used if one needed some by simply shaving them to the thickness you need. I could have easily made a shim to adjust the backlash but found I didn’t need to to get a final lash of .0085”.


Speaking of setting backlash, many modern cars have threaded plugs on each side of the ring gear carrier bearings and you can tighten one and loosen the opposite to maintain preload on the bearings to alter the position to effect the backlash you want. It isn’t a preload you can measure with a torque wrench, like pinion preload. With the shims on these set ups you have to keep the total shim thickness, adding up both sides, the same to maintain proper preload. There is a procedure which involves using the numbers factory stamped on the bearing mount and measuring the bearing races as described in the manual you must follow if you change these bearings, to have the proper preload. Lucky me, I didn’t have to do this. You would also have to do this if you changed out the ring gear carrier assembly. But in my case, if I had .010” backlash and wanted .008”, all I needed to do was measure my total shims and add a .002” fabricated shim to one side and use some 80 grit wet dry paper glued to a surface plate to shave .002” off the opposite side shim to achieve a .008 backlash. My shims were both well over an eight of an inch thick so this would be fairly easy.


My test drive was a joy. With the W58 Toyota gearbox in 5th using my gps app, at 70 mph on the freeway I was seeing about 2800 RPM and my wife and I could actually talk. Maybe not a real conversation but close.


I will add some photos but that is not my forte, so please excuse that they are not captioned. I am happy to correspond with anyone contemplating this job.



IMG_20210106_134442105.jpgIMG_20210106_153403258.jpgIMG_20210106_134203764.jpg1609992739458_1609992736006_IMG_20210106_134412150.jpgIMG_20210106_135944099.jpg1609992836056_1609992834742_IMG_20210106_140351035.jpgIMG_20210106_134342417.jpg
 
Last edited:

Healey Nut

Luke Skywalker
Country flag
Offline
Not a difficult job to do .
I did both of my BJ8s and it made a difference of about 1000rpm lower in top gear stock gearbox with OD .
I have already done the diff for my 62 Rally Recreation ,that has a sideshift gearbox with OD .
My only tip is putting the pinion gear in the freezer for a few hours to shrink it before dropping it into place works a treat and some engineers blue to check the mesh pattern on the gears once your done .
 

Healey Nut

Luke Skywalker
Country flag
Offline
Still available at AH4H in the UK or AutoFarm in CAN .
I think you are thinking about the Lempert version .
 
OP
roscoe

roscoe

Jedi Knight
Silver
Country flag
Offline
I use a heat lamp for about a half hour and get the inner pinion bearing up to about 140 or 150 deg. F and the bearing drops on to the pinion with a nice click. I use a hydraulic press to make sure it is seated. I find that the pinion is just a light hand press fit into the forward (outer) bearing. In other words, I can take the pinion out of the housing by pushing or tapping lightly to slide it out of the front bearing. The light press fit and proper preload on the inner race of that bearing keeps it rotating with the pinion.

The attached photo is of my first gear pattern using prussian blue. I ended up using some white lithium grease mixed in to make it easier to see when I did the final check.

20201230_103138_copy_1235x1235.jpg
 

Attachments

  • 20201230_103130_copy_1235x1235.jpg
    20201230_103130_copy_1235x1235.jpg
    72.9 KB · Views: 74

steveg

Yoda
Gold
Country flag
Offline
OP
roscoe

roscoe

Jedi Knight
Silver
Country flag
Offline
The gear sets are available from Dennis Welch, Moss, Austin Healey spares and possibly others. I got no response from Lempert when I emailed them so I don't know about those. I actually got mine ( labeled Made In USA) from British Car Specialists in Stockton, as they had a set in stock that had been ordered by someone but never delivered for some reason. They are a Moss dealer so I believe that is where they came from. The set looked very nice in terms of finish and fit. It did seem that the sets from the UK are less expensive without the customs fees etc., but I just didn't want to wait or have any difficulties getting them. BCS also had a good selection of preload shims for the pinion. David Nock was also helpful with a couple of questions I had.
 

Patrick67BJ8

Darth Vader
Silver
Country flag
Offline
Just a thought.
wouldn’t you be able to keep your lower gear ratio gears for quicker acceleration and just change the gearbox to a tremec 6 speed?
 
OP
roscoe

roscoe

Jedi Knight
Silver
Country flag
Offline
I don't know if there is a bell housing made for the healeys that adapts for a Tremec box. I doubt it. I paid 500 bucks for a really nice W58 I found locally and the kit for everything else including a new driveshaft and hydraulics was about $2,400.00. The Tremec 6 spped costs a "bit" more than that, without the bellhousing or clutch actuating hydraulics.
 

Patrick67BJ8

Darth Vader
Silver
Country flag
Offline
I don't know if there is a bell housing made for the healeys that adapts for a Tremec box. I doubt it. I paid 500 bucks for a really nice W58 I found locally and the kit for everything else including a new driveshaft and hydraulics was about $2,400.00. The Tremec 6 spped costs a "bit" more than that, without the bellhousing or clutch actuating hydraulics.
I know a guy who has a tremec in his Healey. I’m not sure if it’s a five or six speed.
 
Country flag
Offline
... I use a heat lamp for about a half hour and get the inner pinion bearing up to about 140 or 150 deg. F and the bearing drops on to the pinion with a nice click...

Side Note: After, for years, using my kitchen oven, heat gun, etc. to heat parts for assembly--and always wishing for something better--I finally sprung for a countertop oven. All in, it was under $80 delivered from Best Buy (free shipping). I'll use it soon to heat my BN2's rear hubs for bearing insertion.
 

dougie

Luke Skywalker
Country flag
Offline
I don't know if there is a bell housing made for the healeys that adapts for a Tremec box. I doubt it. I paid 500 bucks for a really nice W58 I found locally and the kit for everything else including a new driveshaft and hydraulics was about $2,400.00. The Tremec 6 spped costs a "bit" more than that, without the bellhousing or clutch actuating hydraulics.

Here ya go...https://drivenman.com/product/austin-healey-3000-5-speed-conversion-kit/

I'd say the the Smitty/Toyota swap is still the best for American car owners.
 
OP
roscoe

roscoe

Jedi Knight
Silver
Country flag
Offline
There you go. I thought I did pretty thorough homework but I've never seen that for the Healeys. I wonder what the kit costs, with the gearbox? Usually when you have to ask for a quote there is a good chance you might not like the answer. This is sort of why I started this thread. Thanks.
 
Similar threads
Thread starter Title Forum Replies Date
S Rear End Noises Spridgets 11
A TR2/3/3A Rear end locked up Triumph 6
John_Mc TR6 Twitchy rear end Triumph 18
maxwedge5281 Removing Complete Rear End From BN6 Austin Healey 5
Rut TR4/4A Rear end questions Triumph 8
H For Sale Rear end bearing and seal set Austin Healey Classifieds 0
R TR2/3/3A Lube for steering box, transmission and rear end Triumph 6
E For Sale Tr3 rear axle, rear end Triumph Classifieds 6
Rut MGB Rear end service MG 7
D TR2/3/3A TR3 Engine dumping Coolant out its rear end - HELP Triumph 5
Rut TR4/4A Which rear end ratio? Triumph 1
Jim_Gruber Bugsy IV - Rear End now Reinstalled - Yeah Spridgets 0
Jim_Gruber Decopnstruction of Rear End over, Reconstruction Begins Spridgets 4
Jim_Gruber Rear End almost out Spridgets 5
Scotsman TR4/4A How to fix sagging rear end. Triumph 8
PatGalvin TR2/3/3A Rear End Problem Triumph 22
SilentUnicorn 3.7 rear end Spridgets 6
Jeepster Wallowing rear end? Austin Healey 27
Got_All_4 TR4/4A TR4 Detroit Locker Positraction Rear End Triumph 6
bugedd Rear end noise [insert joke] Spridgets 11
tr7andtvr Wedge Tr7/8 rear end ID RKC0100 Triumph 4
tinman58 TR5/TR250 Very stiff rear end Triumph 27
D Posi-Rear end in a series 3 Jaguar xj6 Jaguar 12
Boggsy64 MGB Rear end washers easy MG 1
mt10flyer TR2/3/3A Rear End Klunky Triumph 7
R transmission and rear end oil Austin Healey 2
E Rear end is cocked Austin Healey 4
Jim_Gruber Reinstalling Rear End in a BE - Quick Steps Spridgets 8
J Possibly stupid question about drivetrain / rear end Spridgets 11
1 Jensen Healey Rear end / Rear Axle wanted -Texas or surounding preferably Other British Cars 6
bugedd Need some rear end education Spridgets 15
bugedd Limited Slip advice, scrapping idea of RX7 rear end Spridgets 34
Jim_Gruber Pics of how Rear End bolts into a BE Spridgets 21
J Last Step, Rear end: What is this one? Austin Healey 8
5 Uppity Rear End Austin Healey 6
M Replaced rear end, can't reconnect propshaft Spridgets 2
jsfbond My rear end Triumph 2
doughairfield Painting my rear end. Triumph 7
M looking for rear end gears for bj8 Austin Healey 25
6 HELP! something broke in the rear end... Triumph 71
A Rear end weight? Austin Healey 7
R TR4/4A tr4a irs clunking rear end on fast acceleration Triumph 7
Jeepster Dodgy rear end Austin Healey 16
jsfbond rear end alignment Triumph 11
G Looking for tranny & rear end help Triumph 3
G TR4/4A tr4 rear end in a tr3a Triumph 10
MgKid1974 Rear End Vibration... MG 3
M RX 7 Rear end option Spridgets 33
J TR 2 rear end axle seals. Triumph 8
T BE Phantom Rear Axle End Play Spridgets 0

Similar threads

Top