1995 456GT DIY Starter Rebuild

1995 456GT.

So my starter is shot. I pulled it apart and the solenoid is cracked, corroded, and the gears are all dried out.

The new purchase options at SPUK (best prices I found) are about $475 for stock, and $600 plus shipping for the “Hi-torque” model (whatever that means). https://www.superformance.co.uk/456/electrical.html

Rebuilding starters is a common business but the more I know about it, the less I like it. What do they really do? Replace the solenoid for sure, clean and turn the armature? replace the brushes? Clean and grease the reduction gear? All for about $150.

So I went with my hunch that Bosch built millions of these things and most parts are interchangeable and still readily available.

The result, I successfully rebuilt my starter with some new parts I swapped from a Bosch factory remanufactured starter.

Project Overview.

The OEM starter is a 110 series Bosch part number 0-001-110-108.

I found a catalogue of OEM Bosch starters for reference.

http://krona74.ru/library/Auto/bosch startery.pdf

There are two 110 series Ferrari starters listed that look very similar to the 456 unit but with different clocking.
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Both have the same armature and brush holder, but different solenoids. Additionally, all the 110 series starters have the same fork lever. I figured Ferrari would make the 456 the same as those, but with a different block adapter and solenoid clocking.

I also figured the same armature was a must have but multiple brush holders and solenoids could work because the cylinders are all the same size and the solenoids all looked the same, but for clocking.

This VW starter is offered by Bosch as a remanufactured unit sold as SR34X.

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https://www.boschautoparts.com/p/remanufactured-starters-sr34x-

Fits VW

92-95 - Corrado SLC, VR6
For models with automatic transmission.
03-03 - EuroVan
1.8KW 9 Tooth Gear Fits Bosch System Gear Reduction
92-02 - EuroVan Base, Camper, CL, GL, GLS & more
For models with automatic transmission.
90-92 - Golf GTI 16-Valve
1.8KW 9 Tooth Gear Fits Bosch System Gear Reduction; Fuel Type: DIESEL; Transmission Control Type: Manual
85-92 - Golf Base, GL
For models with manual transmission.
84-92 - Jetta Base, GL, TDI
For models with manual transmission.
93-97 - Passat GLX, TDI
For models with automatic transmission

The Bosch SR34X is $143.99 plus tax and deposit + free shipping from AutohausAZ.
https://www.autohausaz.com/pn/SR34X

Two days later it arrived.

Rebuild starts in the next post.

 

If you try this, before you buy a donor starter, take your old starter apart and make sure the parts you are keeping are good. If not, this will not work unless you can find those parts elsewhere.

Here are two videos go through the strip and rebuild of a Bosch Starter. The second is on the 110 series and goes into detail on the brush box and slightly discusses the phase clocking issuer I go into below.




It takes about 15 mins each to strip and reassemble everything. 30 mins to 2hrs if you are looking for tools, inspecting as you go, flicking your phone and/or drinking beer.

Right off the bat I found limitations.

• The VW starter is counterclockwise, and the Ferrari starter is clockwise. This is not fatal but limits the parts that can be swapped.
• The magnets are on the cylinder wall so the old cylinder must be reused. I have heard you can flip the magnets, or something like that but I didn’t want to hassle that.
• The rear cylinder cover phase clocks the brushes so there are subtle differences in the two covers so the OEM cover must be reused. If the donor cover is used, the brushes will be in the wrong phase. I’ve read this can decrease performance and other bad things. See cover pics.
• The rear shaft cover must be reused to fit the OEM rear cover.
• All shaft bushings must be reused as none of the donors will fit. If they are bad, you may be able to source new ones. Mine were ok.
• The OEM reduction gear, clutch, pinion gear, and pinion shaft must be reused as one unit. The pinion gear has 11 teeth (only Ferrari) and the shaft is thicker than the donor. I tried to swap the planetary gear holder but the planetary gears on the OEM pinion shaft are pressed on (they wouldn’t come off without force that I didn’t want to apply) and too high to fit under the donor planetary gear cover.

Parts I swapped.

• Armature
• Brush Box
• Solenoid and screws. Note that every measurement I took off the solenoid was identical between OEM & donor but for a slight clocking difference that did not impact installation.
• Cylinder screws
• Fork lever and pivot
• Grommet between solenoid and reduction gear

OEM parts retained.

• Starter body
• Reduction gear, clutch, pinion shaft and gear
• All bushings (ID or OD sizes did not match)
• Cylinder, cylinder cover and shaft cover. Note these donor parts will fit nicely but cannot be used due to clockwise vs. counterclockwise rotation. The magnets are on the cylinder wall, and the cylinder cover phases the brush box slightly different for rotation direction.

All parts pulled from the OEM starter were put on the donor unit for core return credit (just get old the brush box back in the core, do not worry about brushes being in the right spot).

• Disassembly notes.
• Secure the starter in a vice held by the aluminum body with the cylinder side up. If held by the cylinder, the body may fall off, dropping everything except the cylinder to the floor.
• Remove the two extra-long screws holding the cylinder to the body, then the two shaft cover screws.
• Remove the shaft c-clip and washer.
• Remove the three solenoid screws with torx bit.
• Disconnect the solenoid wire to the brush box at the Solenoid and remove the solenoid from the body, leaving the piston. Pick-up the solenoid spring.
• Read the next part completely before proceeding. On the new donor starter, gently pry the cylinder cover off exposing the brush box. When you pull the donor brush box out, you want to keep the brushes from popping out or parts will shoot all over. And getting the brush box back on the armature later will be a real PITA. Wiggle the brush box up slightly exposing about ¼ length of the four brushes. Find a socket that is slightly larger than the spread of the brushes on the commutator. Wedge the socket into two of the bushes, pushing them back into their holders, then use a pick to pull the opposite side brushes over the socket. Then wiggle the brush box up and over the socket and out of the cylinder. Putting the brush box back on is the opposite. Just make sure all four brushes are over the commutator before you push the brush box down over the commutator, then the socket will pop out of the top. If you blow it and you have parts all over the place, just put the socket on the free-standing brush box in the same fashion. It can be done.
• Remove the cylinder from the body by pulling it upward. You may need to tap it with a rubber mallet. The armature will likely come with it but make sure you do not let it fall out. Put the donor armature in a safe space with brush box and solenoid.
• Pry and remove the rubber grommet from the body between the reduction gears and the solenoid piston.
• Now pull the gear box and solenoid cylinder out as one piece. They are connected by the fork lever. You may need to pry up the plastic fork pivot in the middle. The solenoid cylinder can be removed from the fork lever and may even fall off so watch out.

Inspection and cleaning notes.

• Read this part before you proceed. Do not pull the pinion gear or the clutch off the pinion shaft! Getting the cover over the wire c clip is a giant PITA!!!! Everything can be inspected and cleaned in place.
• Pull the cover off the OEM reduction gears and rotate the pinion shaft. The planetary gears are steel, but the outside gear is plastic. Make sure it is good. If not, you are done. Go buy a new starter. Check the pinion gears and clutch. Make sure the OEM clutch feels like the new clutch, just the opposite rotation. If the clutch is bad, you are done. Go buy a new starter.
• I cleaned everything with dawn soap, hot water, and a plastic brush. I was afraid of using chemicals on the plastic gears and magnets.

Reassembly notes.

• Inspection, cleaning, and greasing take the most time.
• I used high-temp lithium grease on all gears, fork, and the end shaft.
• I used some synthetic motor oil on the pinion shaft bushing.
• I put nothing on the pinion gear or the solenoid cylinder.
• I used Hondabond HT to seal the rear shaft cover as the gasket was shot and the donor gasket was too small.
• Everything goes back in reverse order. The cylinder and cover have cut-outs for guides and can only fit one way.
• Make sure you get the gear cover in the right spot. Take a picture before you disassemble as it is not idiot proof. There is a cut out for the rubber grommet that if not aligned will make everything too tight to rotate.
• When done, If you cannot hand rotate the pinion gear something is out of alignment or binding. Likely the gear cover.
• Test your starter before you put it on the car!!!! I just propped it up underneath and hooked the wires up and turned the key with a slo-mo iPhone video going. It worked!

Final notes.

All in, this is probably the same or less cost than a “rebuild” but with a new Bosch armature, brush box and solenoid. Any rebuild will reuse the same parts I did as others are NLA (except maybe they would replace all the bushings). The time to swap parts is probably about the same time to drop off and pick up a rebuilt unit. Maybe a little more with inspection and cleaning, phone flipping and beer drinking.

We will see if it lasts. My biggest concern is the plastic planetary gear. The donor had a steel gear insert which told me Bosch had issues with the plastic gear. If that plastic gear fails, the whole unit is shot, unless I can find a replacement.